:: wikimiki.org ::

Neurology

Neurology

Neurology is a branch of medicine dealing with the nervous system and its disorders. Physicians specializing in the field of neurology are called neurologists. Surgery on the nervous system is performed by physicians with specialized training - neurosurgeons, and in some cases, interventional neuroradiologists.

Field of work

Neurological disorders are disorders that affect the central nervous system (brain, brainstem and cerebellum), the peripheral nervous system (peripheral nerves - cranial nerves) included), or the autonomic nervous system (parts of which are located in both central and peripheral nervous system). Major conditions include:
- headache disorders such as migraine and tension headache (cluster headache)
- epilepsy and seizure disorders
- neurodegenerative disorders, the most common class being dementias, including Alzheimer's disease
- cerebrovascular disease, such as transient ischemic attacks, and strokes (ischemic or hemorrhagic)
- sleep disorders
- cerebral palsy
- bacterial, fungal, viral and parasitic infections of the central nervous system (encephalitis), brain envelopes (meningitis) and peripheral nerves (neuritis), such as brain abscess, herpetic meningoencephalitis, aspergilloma, cerebral hydatic cyst, tetanus, botulism
- neoplasms - tumors of the brain and its envelopes (brain tumors), spinal cord tumors, tumors of the peripheral nerves (neuroma)
- movement disorders such as Parkinson's disease, chorea, hemiballismus, tic disorder, and Gilles de la Tourette syndrome
- demyelinating diseases of the central nervous system, such as multiple sclerosis, and of the peripheral nervous system, such as Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy (CIDP)
- spinal cord disorders - tumors, infections, trauma, malformations (e.g. myelocele, meningomyelocele, tethered cord)
- disorders of peripheral nerves, muscle and neuromuscular junctions
- traumatic injuries to the brain, spinal cord and peripheral nerves
- Altered mental status, encephalopathy, stupor and coma

Clinical tasks

General caseload

Neurologists are responsible for diagnosing and treating all of the above conditions, except for surgical interventions, which fall into the responsibility of neurosurgeons, and in some cases interventional neuroradiologists. In some countries, additional legal responsibilities of a neurologist include making a finding of brain death when it is suspected that a patient is deceased, and filing the necessary paperwork for issuance of a death certificate. Neurologists frequently care for people with hereditary (genetic) disease when the major manifestations are neurologic, as is frequently the case. Neurologists may specialize in neurophysiology, the field responsible for electroencephalography (EEG), nerve conduction studies (NCS) and electromyography (EMG) as well as visual evoked potential (VEP) testing. Others may develop an interest in particular subfields, such as the movement disorders, headaches, epilepsy or neuromuscular disease.

Overlap with psychiatry

Although many mental illnesses are believed to be neurological disorders affecting the central nervous system, traditionally they are classified separately, and treated by psychiatrists. In a 2002 review article in the American Journal of Psychiatry, Professor Joseph B. Martin, Dean of Harvard Medical School and a neurologist by training, wrote that 'the separation of the two categories is arbitrary, often influenced by beliefs rather than proven scientific observations. And the fact that the brain and mind are one makes the separation artificial anyway.' (Martin JB. The integration of neurology, psychiatry and neuroscience in the 21st century. Am J Psychiatry 2002; 159:695-704) There are strong indications that neuro-chemical mechanisms play an important role in the development of, for instance, bipolar disorder and schizophrenia. As well, 'neurological' diseases often have 'psychiatric' manifestations, such as post-stroke depression, depression and dementia associated with Parkinson's disease, mood and cognitive dysfunctions in Alzheimer's disease, to name a few. Hence, there is no sharp distinction between neurology and psychiatry on a biological basis - this distinction has mainly practical reasons and strong historical roots (such as the dominance of Freud's psychoanalytic theory in psychiatric thinking in the first three quarters of the 20th century - which has since then been largely replaced by the focus on neurosciences - aided by the tremendous advances in genetics and neuroimaging recently.)

External links

- [http://www.aan.com American Academy of Neurology]
- [http://www.neuropsychological.blogspot.com/ brainblog]: news about our knowledge of the brain and behavior.
- [http://neurology.jwatch.org/ Journal Watch Neurology]: collection of the most important neurology studies for practicing clinicians, summarized and with commentary.

Medicine

Medicine is a branch of health science concerned with maintaining human health and restoring it by treating disease and injury; it is both an area of knowledge, a science of body systems and diseases and their treatment, and the applied practice of that knowledge. The practice of medical care is shared between the medical profession—physicians or doctors—and other groups of professionals, such as nurses or pharmacists (sometimes called allied health professions). Historically, only members of the medical profession proper have been considered to actually practice medicine in the strictest sense, in contrast to the allied fields of health care professionals. Clinicians can be physicians, nurses, or physician assistants -- those who provide health care or otherwise tend to their patients. The medical profession is the social and occupational structure of the group of people formally trained and authorized to apply medical knowledge. Many countries and legal jurisdictions have legal limitations on who may practice medicine or the allied medical fields. Medicine is typically seen as composed of various specialized sub-branches, such as pediatrics, gynecology, neurology, dealing with particular body systems, diseases, or areas of health. Systems of medical and healthcare practices have existed among human societies since at least the dawn of recorded history. These systems have developed in various ways in different cultures and regions. Medicine as understood in the modern period has historically been considered to be the mainstream tradition which developed in the Western world since the early modern age. Many other traditions of medicine and healthcare are still widely practiced throughout the world, most of which are still considered to be separate and distinct from Western medicine, also called biomedicine or the Hippocratic tradition. The most highly developed systems of medicine outside the Western system are the Ayurvedic tradition of India and traditional Chinese medicine. Various non-mainstream traditions of health care have also developed in the Western world distinct from mainstream medicine. The various other systems practiced among various cultures are sometimes practiced alongside or in cooperation with Western medicine, while sometimes being seen as competing traditions. Medicine is also often used amongst medical professionals as shorthand for Internal Medicine. Veterinary medicine is the practice of health care specialized for other animal species.

History of medicine

Medicine as it is practiced now is rooted in various traditions, but developed mainly in the late 18th and early 19th century in Germany (Rudolf Virchow) and France (Jean-Martin Charcot, Claude Bernard and others). The new, "scientific" medicine replaced earlier Western traditions of medicine, mostly based on the "four humours" and other pre-modern theories. The focal points of development of clinical medicine shifted to the United Kingdom and the USA by the early 1900s (Sir William Osler, Harvey Cushing). Evidence-based medicine is the recent movement to link the practice and the science of medicine more closely through the use of the scientific method and modern information science. Genomics and knowledge of human genetics is already having a large influence on medicine, as the causative genes of most monogenic genetic disorders have now identified, and the development of techniques in molecular biology and genetics are influencing medical practice and decision-making.

Practice of medicine

The practice of medicine combines both science and art. Science and technology are the evidence base for many clinical problems for the general population at large. The art of medicine is the application of this medical knowledge in combination with intuition and clinical judgment to determine the proper diagnoses and treatment plan for this unique patient and to treat the patient accordingly. Central to medicine is the patient-doctor relationship established when a person with a health concern or problem seeks the help of a physician (i.e. the medical encounter). Other health professionals similarly establish a relationship with a patient and may perform interventions from their perspective, e.g. nurses, radiographers and therapists. As part of the medical encounter, the doctor needs to:
- develop a relationship with the patient
- gather data (medical history and physical examination combined with laboratory or imaging studies)
- analyze and synthesize that data (assessment and/or differential diagnosis), and then
- develop a treatment plan (further testing, therapy, watchful observation, referral and follow-up)
- treat the patient accordingly
- assess the progress of treatment and alter the plan as necessary. The medical encounter is documented in a medical record, which is a legal document in many jurisdictions. One method that is used is called the problem-oriented medical record (POMR), which includes a problem list of diagnoses and a "SOAP" method of documentation for each visit:
- S - Subjective, the medical history of the problem from the point-of-view of the patient.
- O - Objective, the physical examination and any laboratory or imaging studies.
- A - Assessment, is the medical decision-making process including the differential diagnoses and most probable diagnoses.
- P - Plan, the way resolve the problem and monitor progress

Medical systems

Medicine is practiced within the medical system of a particular culture or government. Leaving aside tribal cultures, the most significant divide in developed countries is that between universal health care and the market based health care (such as practiced in the U.S.).

Patient-doctor relationship

The doctor-patient relationship and interaction is a central process in the practice of medicine. There are many perspectives from which to understand and describe it. An idealized physician's perspective, such as is taught in medical school, sees the core aspects of the process as the physician learning from the patient his symptoms, concerns and values; in response the physician examines the patient, interprets the symptoms, and formulates a diagnosis to explain the symptoms and their cause to the patient and to propose a treatment. In more detail, the patient presents a set of complaints or concerns about his health to the doctor, who then obtains further information about the patient's symptoms, previous state of health, living conditions, and so forth, and then formulates a diagnosis and enlists the patient's agreement to a treatment plan. Importantly, during this process the doctor educates the patient about the causes, progression, outcomes, and possible treatments of his ailments, as well as often providing advice for maintaining health. This teaching relationship is the basis of calling the physician doctor, which originally meant "teacher" in Latin. The patient-doctor relationship is additionally complicated by the patient's suffering (patient derives from the Latin patiens, "suffering") and limited ability to relieve it on his own. The doctor's expertise comes from his knowledge about, or experience with, other people who have suffered similar symptoms, and his presumed ability to relieve it with medicines or other therapies about which the patient may initially have little knowledge. The doctor-patient relationship can be analyzed from the perspective of ethical concerns, in terms of how well the goals of non-maleficence, beneficence, autonomy, and justice are achieved. Many other values and ethical issues can be added to these. In different societies, periods, and cultures, different values may be assigned different priorities. For example, in the last 30 years medical care in the Western World has increasingly emphasized patient autonomy in decision making. The relationship and process can also be analyzed in terms of social power relationships (e.g., by Michel Foucault), or economic transactions. Physicians have been accorded gradually higher status and respect over the last century, and they have been entrusted with control of access to prescription medicines as a public health measure. This represents a concentration of power and carries both advantages and disadvantages to particular kinds of patients with particular kinds of conditions. A further twist has occurred in the last 25 years as costs of medical care have risen, and a third party (an insurance company or government agency) now often insists upon a share of decision-making power for a variety of reasons, reducing freedom of choice of both doctors and patients in many ways. The quality of the patient-doctor relationship is important to both parties. The better the relationship in terms of mutual respect, knowledge, trust, shared values and perspectives about disease and life, and time available, the better will be the amount and quality of information about the patient's disease transferred in both directions, enhancing accuracy of diagnosis and increasing the patient's knowledge about the disease. In some settings, e.g. the hospital ward, the patient-doctor relationship is much more complex, and many other people are involved when somebody is ill: relatives, neighbors, rescue specialists, nurses, technical personnel, social workers and others.

Clinical skills

Main articles: Medical history, Physical examination. A complete medical evaluation includes a medical history, a physical examination, appropriate laboratory or imaging studies, analysis of data and medical decision making to obtain diagnoses, and treatment plan. The components of the medical history are:
- Chief complaint (CC) - the reason for the current medical visit.
- History of present illness (HPI) - the chronological order of events of symptoms. A mnemonic PQRST is sometimes helpful in obtaining the history:
- Provocative-palliative factors - what makes a symptom worse or better.
- Quality - description of the symptom
- Region - which part of the body is affected
- Severity - what is the intensity of the symptom; using a scale of 0-10 (10 worst)
- Timing - what is the course of the symptom
- Current activity - occupation, hobbies, what the patient actually does.
- Medications - what drugs including OTCs, and home remedies, as well as herbal remedies such as St. John's Wort. Allergies are recorded.
- Past medical history (PMH/PMHx) - other medical diagnoses, past hospitalizations and operations, injuries, past infectious diseases and/or vaccinations, history of known allergies.
- Review of systems (ROS) - an outline of additional symptoms to ask which may be missed on HPI, generally following the body's main organ systems (heart, lungs, digestive tract, urinary tract, etc).
- Social history (SH) - birthplace, residences, marital history, social and economic status, habits (including diet, medications, tobacco, alcohol).
- Family history (FH) - listing of diseases in the family that may impact the patient. A family tree is sometimes used. The physical examination is the examination of the patient looking for signs of disease. The doctor uses his senses of sight, hearing, touch, and sometimes smell (taste has been made redundant by the availability of modern lab tests). Four chief methods are used: inspection, palpation, percussion, and auscultation; smelling may be useful (e.g. infection, uremia, diabetic ketoacidosis). The clinical examination involves study of:
- Vital signs include height, weight, body temperature, blood pressure, pulse, respiration rate, hemoglobin oxygen saturation
- General appearance of the patient
- Skin
- Head, eye, ear, nose, and throat (HEENT)
- Cardiovascular - heart and blood vessels
- Respiratory - lungs
- Abdomen and rectosigmoid
- Genitalia
- Spine and extremities - musculoskeletal
- Neurological and psychiatric Laboratory and imaging studies results may be obtained, if ncessary. The medical decision-making (MDM) process involves analysis and synthesis of all the above data to come up with a list of possible diagnoses (the differential diagnoses), along with an idea of what needs to be done to obtain a definitive diagnosis that would explain the patient's problem. The treatment plan may include ordering additional laboratory tests and studies, starting therapy, referral to a specialist, or watchful observation. Follow-up may be advised. This process is used by primary care providers as well as specialists. It may take only a few minutes if the problem is simple and straightforward. On the other hand, it may take weeks in a patient who has been hospitalized with multi-system problems, with involvement by several specialists. On subsequent visits, the process may be repeated in an abbreviated manner to obtain any new history, symptoms, physical findings, and lab or imaging results or specialist consultations.

Settings where medical care is delivered

See also clinic, hospital, and hospice Medicine is a diverse field and the provision of medical care is therefore provided in a variety of locations. Primary care medical services are provided by physicians or other health professionals who has first contact with a patient seeking medical treatment or care. These occur in physician's office, clinics, nursing homes, schools, home visits and other places close to patients. About 90% of medical visits can be treated by the primary care provider. These include treatment of acute and chronic illnesses, preventive care and health education for all ages and both sex. Secondary care medical services are provided by medical specialists in their offices or clinics or at local community hospitals for a patient referred by a primary care provider who first diagnosed or treated the patient. Referrals are made for those patients who required the expertise or procedures performed by specialists. These include both ambulatory care and inpatient services, emergency rooms, intensive care medicine, surgery services, physical therapy, labor and delivery, endoscopy units, diagnostic laboratory and medical imaging services, hospice centers, etc. Some primary care providers may also take care of hospitalized patients and deliver babies in a secondary care setting. Tertiary care medical services are provided by specialist hospitals or regional centers equipped with diagnostic and treatment facilities not generally available at local hospitals. These include trauma centers, burn treatment centers, advanced neonatology unit services, organ transplants, high-risk pregnancy, radiation oncology, etc. Modern medical care also depends on information - still delivered in many health care settings on paper records, but increasingly nowadays by electronic means.

Branches of medicine

Working together as an interdisciplinary team, many highly trained health professionals besides medical practitioners are involved in the delivery of modern health care. Some examples include: nurses, laboratory scientists, pharmacists, physiotherapists, speech therapists, occupational therapists, dietitians and bioengineers. The scope and sciences underpinning human medicine overlap many other fields. Dentistry and psychology, while separate disciplines from medicine, are sometimes also considered medical fields. Physician assistants, nurse practitioners and midwives treat patients and prescribe medication in many legal jurisdictions. Veterinary medicine applies similar techniques to the care of animals. Medical doctors have many specializations and subspecializations which are listed below.

Basic sciences

- Anatomy is the study of the physical structure of organisms. In contrast to macroscopic or gross anatomy, cytology and histology are concerned with microscopic structures.
- Biochemistry is the study of the chemistry taking place in living organisms, especially the structure and function of their chemical components.
- Biostatistics is the application of statistics to biological fields in the broadest sense. A knowledge of biostatistics is essential in the planning, evaluation, and interpretation of medical research. It is also fundamental to epidemiology and evidence-based medicine.
- Cytology is the microscopic study of individual cells.
- Embryology is the study of the early development of organisms.
- Epidemiology is the study of the demographics of disease processes, and includes, but is not limited to, the study of epidemics.
- Genetics is the study of genes, and their role in biological inheritance.
- Histology is the study of the structures of biological tissues by light microscopy, electron microscopy and immunohistochemistry.
- Immunology is the study of the immune system, which includes the innate and adaptive immune system in human, for example.
- Microbiology is the study of microorganisms, including protozoa, bacteria, fungi, and viruses.
- Neuroscience is a comprehensive term for those disciplines of science that are related to the study of the nervous system. A main focus of neuroscience is the biology and physiology of the human brain.
- Nutrition is the study of the relationship of food and drink to health and disease, especially in determining an optimal diet. Medical nutrition therapy is done by dietitians and is prescribed for diabetes, cardiovascular diseases, weight and eating disorders, allergies, malnutrition and neoplastic diseases.
- Pathology is the study of disease - the causes, course, progression and resolution thereof.
- Pharmacology is the study of drugs and their actions.
- Physiology is the study of the normal functioning of the body and the underlying regulatory mechanisms.
- Toxicology is the study of hazardous effects of drugs and poisons.

Diagnostic specialties

- Clinical laboratory sciences are the clinical diagnostic services which apply laboratory techniques to diagnosis and management of patients. In the United States these services are supervised by a Pathologist. The personnel that work in these medical laboratory departments are technically trained staff, each of whom usually hold a medical technology degree, who actually perform the tests, assays, and procedures needed for providing the specific services.
- Transfusion medicine is concerned with the transfusion of blood and blood component, including the maintenance of a "blood bank".
- Cellular pathology is concerned with diagnosis using samples from patients taken as tissues and cells using histology and cytology.
- Clinical chemistry is concerned with diagnosis by making biochemical analysis of blood, body fluids and tissues.
- Hematology is concerned with diagnosis by looking at changes in the cellular composition of the blood and bone marrow as well as the coagulation system in the blood.
- Clinical microbiology is concerned with the in vitro diagnosis of diseases caused by bacteria, viruses, fungi, and parasites.
- Clinical immunology is concerned with disorders of the immune system and related body defenses. It also deals with diagnosis of allergy.
- Radiology is concerned with imaging of the human body, e.g. by x-rays, x-ray computed tomography, ultrasonography, and nuclear magnetic resonance tomography.
- Interventional radiology is concerned with using imaging of the human body, usually from CT, ultrasound, or fluoroscopy, to do biopsies, place certain tubes, and perform intravascular procedures.
- Nuclear Medicine uses radioactive substances for in vivo and in vitro diagnosis using either imaging of the location of radioactive substances placed into a patient, or using in vitro diagnostic tests utilizing radioactive substances.

Clinical disciplines

- Anesthesiology (AE), Anaesthesia (BE), is the clinical discipline concerned with providing anesthesia. Pain medicine is often practiced by specialised anesthesiologists.
- Dermatology is concerned with the skin and its diseases.
- Emergency medicine is concerned with the diagnosis and treatment of acute or life-threatening conditions, including trauma, surgical, medical, pediatric, and psychiatric emergencies.
- General practice, Family practice, family medicine or primary care is, in many countries, the first port-of-call for patients with non-emergency medical problems. Family doctors are usually able to treat over 90% of all complaints without referring to specialists.
- Hospital medicine is the general medical care of hospitalized patients. Doctors whose primary professional focus is hospital medicine are called hospitalists.
- Internal medicine is concerned with systemic diseases of adults, i.e. those diseases that affect the body as a whole , (restrictive ,current meaning) or with all adult non-operative somatic medicine (traditional , inclusive meaning) , thus excluding pediatrics , surgery , gynaecology & obstetrics and psychiatry. There are several subdisciplines of internal medicine:
- Cardiology is concerned with the heart and cardiovascular system and their diseases.
- Critical care medicine is concerned with the therapy of patients with serious and life-threatening disease or injury. Intensive care medicine employs invasive diagnostic techniques and (temporary) replacement of organ functions by technical means. Also known as Intensive care medicine. This field is often associated with Pulmonology.
- Endocrinology is concerned with the endocrine system, i.e. endocrine glands and hormones, usually Diabetes or Thyroid diseases.
- Gastroenterology is concerned with the alimentary tract.
- Geriatrics is concerned with medical care of the elderly.
- Hematology (or haematology) is concerned with the blood and its diseases.
- Hepatology is concerned with the liver and biliary tract, and is usually a part of Gastroenterology
- Infectious diseases is concerned with the study, diagnosis and treatment of diseases caused by biological agents.
- Nephrology is concerned with diseases of the kidneys.
- Oncology is devoted to the study, diagnosis and treatment of cancer and other malignant diseases, and is often grouped with Hematology.
- Pulmonology (or chest medicine, respiratory medicine or lung medicine) is concerned with diseases of the lungs and the respiratory system.
- Rheumatology is devoted to the diagnosis and treatment of inflammatory diseases of the joints and other organ systems, such as arthritis.
- Neurology is concerned with the diagnosis and treatment of nervous system diseases.
- Obstetrics and Gynecology (often abbreviated as Ob/Gyn) are concerned respectively with childbirth and the female reproductive and associated organs. Reproductive medicine and fertility medicine are generally practiced by gynecological specialists.
- Palliative care is a relatively modern branch of clinical medicine that deals with pain and symptom relief and emotional support in patients with terminal diseases (cancer, heart failure).
- Pediatrics (or paediatrics) is devoted to the care of infants, children, and adolescents. Like internal medicine, there are many pediatric subspecialities for specific age ranges, organ systems, disease classes and sites of care delivery. Most subspecialities of adult medicine have a pediatric equivalent such as pediatric cardiology, pediatric endocrinology, pediatric gastroenterology, pediatric hematology, and pediatric oncology, pediatric ophthalmology, and neonatology.
- Physical medicine and rehabilitation (or physiatry) is concerned with functional improvement after injury, illness, or congenital abnormality.
- Preventive medicine is the branch of medicine concerned with preventing disease.
- Community health care or public health is an aspect of health services concerned with threats to the overall health of a community based on population health analysis.
- Occupational medicines principal role is the provision of health advice to organisations and individuals to ensure that the highest standards of health and safety at work can be achieved and maintained.
- Psychiatry is a branch of medicine that studies and treats mental disorders. Related non-medical fields are psychotherapy and clinical psychology. There are several subdisciplines of Psychiatry:
- Child & adolescent psychiatry focuses on the care of children and adolescents with mental/emotional/learning problems (i.e., ADHD, Autism, family conflicts).
- Geriatric psychiatry focuses on the care of elderly people with mental illnesses (i.e., dementias, post stroke cognitive changes, depression).
- Addiction psychiatry focuses on substance abuse and its treatment.
- Forensic psychiatry focuses on the interface of psychiatry and the Law.
- Radiation therapy is concerned with the therapeutic use of ionizing radiation and high energy elementary particle beams in patient treatment.
- Surgical specialties - there are many medical disciplines that employ operative treatment. Some of these are highly specialized and are often not considered subdisciplines of surgery, although their naming might suggest so.
- General surgery is traditionally defined as the specialty of surgery of the skin, endocrine glands, and abdomen (and, sometimes, the mammary glands). In some countries, it is still deemed a pre-requisite training prior to progression to training in certain sub-specialties, but lately has evolved into its own sub-specialty.
- Cardiovascular surgery is the surgical specialty that is concerned with the heart and major blood vessels of the chest.
- Neurosurgery is concerned with the operative treatment of diseases of the nervous system.
- Maxillofacial surgery (technically a subspeciality of dentistry)
- Ophthalmology deals with the diseases of the eyes and their treatment.
- Orthopedic surgery consists on surgery of the locomotor system.
- Otolaryngology (or otorhinolaryngology or ENT/ear-nose-throat) is concerned with treatment of ear, nose and throat disorders. The term head and neck surgery defines a closely related specialty which is concerned mainly with the surgical management of cancer of the same anatomical structures.
- Pediatric surgery treats a wide variety of thoracic and abdominal (and sometimes urologic) diseases of childhood.
- Plastic surgery includes aesthetic surgery (operations that are done for other than medical purposes) as well as reconstructive surgery (operations to restore function and/or appearance after traumatic or operative mutilation).
- Surgical oncology is concerned with curative and palliative surgical approaches to cancer treatment.
- Urology focuses on the urinary tracts of males and females, and on the male reproductive system. It is often practiced together with andrology ("men's health").
- Vascular surgery is surgery of "peripheral" blood vessels, i.e. those outside of the chest (usually operated on by cardiovascular surgeons) and of the central nervous system (treated by neurosurgery).
- Urgent Care focuses on delivery of unscheduled, walk-in care outside of the hospital emergency department for injuries and illnesses that are not severe enough to require care in an emergency department.
Interdisciplinary fields
Interdisciplinary sub-specialties of medicine are:
- Aerospace medicine deals with medical problems related to flying and space travel.
- Bioethics is a field of study which concerns the relationship between biology, science, medicine and ethics, philosophy and theology.
- Clinical pharmacology is concerned with how systems of therapeutics interact with patients.
- Conservation medicine studies the relationship between human and animal health, and environmental conditions. Also known as ecological medicine, environmental medicine, or medical geology.
- Diving medicine (or hyperbaric medicine) is the prevention and treatment of diving-related problems.
- Evolutionary medicine is a perspective on medicine derived through applying evolutionary theory.
- Forensic medicine deals with medical questions in legal context, such as determination of the time and cause of death.
- Medical humanities includes the humanities (literature, philosophy, ethics, history and religion), social science (anthropology, cultural studies, psychology, sociology), and the arts (literature, theater, film, and visual arts) and their application to medical education and practice.
- Medical informatics and medical computer science are relatively recent fields that deal with the application of computers and information technology to medicine.
- Nosology is the classification of diseases for various purposes.
- Sports medicine deals with the treatment and preventive care of athletics, amateur and professional. The team includes specialty physicians and surgeons, athletic trainers, physical therapists, coaches, other personnel, and, of course, the athlete.
- Therapeutics is the field, more commonly referenced in earlier periods of history, of the various remedies that can be used to treat disease and promote health [http://2.1911encyclopedia.org/T/TH/THERAPEUTICS.htm] [http://www.britannica.com/eb/article-9106176?query=Therapeutics&ct=].
- Travel medicine or emporiatrics deals with health problems of international travelers or travelers across highly different evironments.
Medical education
See also Medical doctor (BE), Physician (AE), and Medical school. Medical training involves several years of university study followed by several more years of residential practice at a hospital. Entry to a medical degree in some countries (such as the United States) requires the completion of another degree first, while in other countries (such as the United Kingdom, Australia and New Zealand) medical training can be commenced as an undergraduate degree immediately after secondary education. The name of the medical degree gained at the end varies: some countries (e.g. the US) call it "Doctor of Medicine" (abbreviated 'M.D.'), while other countries (mostly following the British Oxbridge system) call it "Medicinæ Baccalaureus & Baccalaureus Chirurgiæ" (Latin for "Bachelor of Medicine/Bachelor of Surgery", Old English: "Chirurgie"); this is technically a double degree, frequently abbreviated 'MB BChir', 'MB ChB', 'MB BS' (or variations thereof), dependent on the medical school. In either case, graduates of a medical degree may call themselves physician. In the US and some other countries there is a parallel system of medicine which is equal in all aspects of education, legality, and practice to M.D.'s. It is called osteopathic medicine (generic term: "osteopathy") which awards the degree of "Doctor of Osteopathic Medicine" (abbreviated 'D.O.'). In many countries, a doctorate of medicine does not involve original research as does, in distinction, a Ph.D.. Once graduated from medical school most physicians (both M.D.'s and D.O.'s) begin their residency/house post training, where skills in a speciality of medicine are learned, supervised by more experienced doctors. The first year of residency is known as the "intern" year (USA) or "junior/pre-registration house officer" year (UK). The duration of residency training depends on the speciality. A medical graduate can then enter general practice and become a general practitioner (or primary care internist in the USA); training for these is generally shorter, while specialist training is typically longer. Medical education is a never ending endeavor. In addition to continually reading relevant medical journals, physicians require a number of continuing medical education (CME)credits annually to be recertified. These can be acquired by attending conferences, lectures, online, and through other sources.
Medical devices
See also the main articles: implant, artificial limbs, corrective lenses, cochlear implants, ocular prosthetics, facial prosthetics, somato prosthetics, surgical prosthetics, maxillo-facial prosthetics and dental implants Medical devices are devices used by health professionals as tools in diagnosis, treatment, or other aspects of patient care.
Legal restrictions
In most countries, it is a legal requirement for medical doctors to be licensed or registered. In general, this entails a medical degree from a university and accreditation by a medical board or an equivalent national organization, which may ask the applicant to pass exams. This restricts the considerable legal authority of the medical profession to doctors that are trained and qualified by national standards. It is also intended as an assurance to patients and as a safeguard against charlatans that practice inadequate medicine for personal gain. While the laws generally require medical doctors to be trained in "evidence based", Western, or Hippocratic Medicine, they are not intended to discourage different paradigms of health and healing, such as alternative medicine or faith healing.
Criticism
Criticism of medicine has a long history. In the Middle Ages, it was not considered a profession suitable for Christians, as disease was considered Godsent, and interfering with the process a form of blasphemy. Barber-surgeons generally had a bad reputation that was not to improve until the development of academic surgery as a speciality of medicine, rather than an accessory field. Through the course of the twentieth century, doctors focused increasingly on the technology that was enabling them to make dramatic improvements in patients' health. The ensuing development of a more mechanistic, detached practice, with the perception of an attendent loss of patient-focused care led to further criticisms. This issue started to reach collective professional consciousness in the 1970s and the profession had begun to respond by the 1980s and 1990s. Perhaps the most devastating criticism of modern medicine came from Ivan Illich, in his 1976 work Medical Nemesis. In his view, modern medicine only medicalises disease, causing loss of health and wellness, while generally failing to restore health by eliminating disease. The human being thus becomes a lifelong patient. Other less radical philosophers have voiced similar views, but none were as virulent as Illich. (Another example can be found in Technopoly: The Surrender of Culture to Technology by Neil Postman, 1992, which criticises overreliance on technological means in medicine.) Criticism of modern medicine has led to some improvements in the curricula of medical schools, which now teach students systematically on medical ethics, holistic approaches to medicine, the biopsychosocial model and similar concepts. The inability of modern medicine to properly address many common complaints continues to prompt many people to seek support from alternative medicine. Although most alternative approaches lack scientific validation, some report improvement of symptoms after obtaining alternative therapies. The bioscience medical paradigm and the alternative / complementary healthcare paradigms may differ to such an extent that what constitutes scientific evidence is contested. Many medical doctors also practice alternative medicine alongside the orthodox. Medical errors are also the focus of many complaints and negative coverage. Practitioners of human factors engineering believe that there is much that medicine may usefully gain by emulating concepts in aviation safety, where it was long ago realized that it is dangerous to place too much responsibility on one "superhuman" individual and expect him or her not to make errors. Reporting systems and checking mechanisms are becoming more common in identifying sources of error and improving practice. Radical critics of certain medical traditions may hold that whole fields or traditions of medicine are intrinsically harmful or ineffective. They would reject any use or support of practices belonging to that tradition. However, generally, there is spectrum of efficacy on which all traditions lie; some are more effective, some are less effective, but nearly all contain some harmful practices and some effective ones. Naturally, though, most individuals or groups seeking a healthcare practice to improve their own health would seek a tradition with the maximum degree of efficacy.
See also

- Academic conference
- Big killers
- Complementary and alternative medicine
- Health profession
- Healthcare system
- Iatrogenesis (ill health caused by medical treatment)
- List of diseases
- List of medical abbreviations
- List of medical schools
- Important publications in medicine
- Medical equipment
- Rare diseases
External links

- [http://home.planet.nl/~hend2438/MOTW/index.htm Medicine on the Web]
- [http://www.nlm.nih.gov NLM] (National Library of Medicine, contains resources for patients and healthcare professionals)
- [http://www.vh.org Virtual Hospital] (digital health sciences library by the University of Iowa)
- [http://cancerweb.ncl.ac.uk/omd/index.html Online Medical Information]- medical news, links and resources.
- [http://www.medmark.org Online Medical Directory]
- [http://www.wikimd.org/index.php?title=Free_Medical_Resources Collection of links to free medical resources] fiu-vro:Arstitiidüs als:Medizin zh-min-nan:I-ha̍k ko:의학 ja:医学 simple:Medicine th:แพทยศาสตร์

Neuroradiology

Neuroradiology is the branch of radiology dealing with the nervous system. Radiology residents usually train in neuroradiology as one of the subspecialties in their rotation. Fellowships in neuroradiology are offered for those wishing to specialize their training. Like some other areas in radiology, neuroradiology has both diagnostic and invasive branches. The diagnostic branch utilizes tools such as CT, MRI, diagnostic angiography, and myelography to determine the problem. The diagnostic brach is often a two-year fellowship. The training for the interventional branch includes some parts of the diagnostic branch, plus techniques for treating aneurysms, arteriovenous malformations (AVMs), acute stroke, and other vascular diseases of the central nervous system. Made possible by the data relayed to the radiologist by imaging machines, these procedures are usually minimally invasive. Training for invasive neuroradiology is often a three year fellowship.

External links

[http://www.ajnr.org/ American Journal of Neuroradiology]

[http://www.asnr.org/ American Society of Neuroradiology]

Brain

In the anatomy of animals, the brain, or encephalon (Greek for "in the head"), is the higher, supervisory center of the nervous system. The term 'brain' is typically used in connection with vertebrate nervous systems, and less often with regard to the nervous system of invertebrates. In the latter, neural control is performed by collections of ganglia. The brain is an extremely complex organ: the human brain is a collection of 100 billion neurons, each linked with up to 25,000 others. This huge number of interconnecting neurons, often referred to as a neural ensemble, is what makes the brain intelligent—enabling humans to analyze sensory signals, control the body, and think. In most animals, the brain is located in the head, close to the primary sensory apparatus and the mouth. Hippocrates considered the brain to be the seat of thought, while Aristotle believed it to be a cooling system for the blood. Today the study of the mind and brain consists of Neuroscience, the field of biology that studies the brain at its various levels of organization (from single neurons to functional systems such as visual system, auditory system, motor system and others); and psychology, the study of the cognition that arises from the neural function of the brain. Attempts have also been made to directly "read" the brain, which has been accomplished in a rudimentary manner through a brain-computer interface. In recent years, several institutions and bodies have undertaken research on recreating the neural structure of the brain with aim to produce human-like cognition and intelligence in computers. The brain controls and coordinates most movement, behavior and homeostatic body functions (such as heartbeat, blood pressure, fluid balance and body temperature). The brain is responsible for cognition, emotion, memory, motor learning and other kinds of learning. However, many behaviors, such as simple reflexes and basic locomotion, can be executed under spinal cord control alone.

The importance of the brain

The brain in animals

Three groups of animals, with some exceptions, have notably complex brains: the arthropods (insects and crustaceans), the cephalopods (octopuses, squid, and similar mollusks), and the craniates (vertebrates and their cousins). The brain of arthropods and cephalopods arises from twin parallel nerve cords that extend through the body of the animal. In arthropod, the brain consists of a central brain with three divisions and large optical lobes behind each eye for visual processing. eye The brain of craniates develops from the anterior section of a single dorsal nerve cord, which later becomes the spinal cord. In craniates, the brain is protected by the bones of the skull. In vertebrates, increasing complexity in the cerebral cortex correlates with height on the phylogenetic and evolutionary tree. Primitive vertebrates, like fish, reptiles, and amphibians have cortices with fewer than six layers of neurons, a structure known as allocortex (also named heterotypic cortex) (Martin, 1996). More complex vertebrates such as mammals have developed a six-layered neocortex (other terms: homotypic cortex, neocortex, neopallium), in addition to having some parts of the brain that are allocortex (Martin, 1996). In mammals, increasing convolutions of the brain, called gyri, are characteristic of animals with more advanced brains. These convolutions evolved to provide a larger surface area for a greater number of neurons, while keeping the volume of the brain compact enough to fit inside the skull.

The human brain

The structure of the human brain is different from that of other animals in several significant ways. These differences have allowed for many abilities over and above those of other animals, such as advanced cognitive skills. Human encephalization is especially pronounced in the neocortex, the most complex part of the cerebral cortex. The proportion of the human brain that is devoted to the neocortex—and the most advanced part within it, the prefrontal cortex—is larger than in all other animals. Humans enjoy unique neural capacities, but much of the human neuroarchitecture is shared with ancient species. Basic systems that alert the nervous system to stimulus, that sense events in the environment, and that monitor the condition of the body are similar to those of the most basic vertebrates. The neural circuitry underlying human consciousness includes both the advanced neocortex and protypical structures of the brain stem. The human brain also has a a million billion synaptic connections, making it one of the most densely connected network systems in the known universe; however, more complex structures may exist.

Pathology of the brain

The loss of function in the brain fulfills some definitions of death. Injuries to the brain tend to affect large areas of the organ, sometimes causing major deficits in intelligence, memory and control of the body. Head trauma, caused, for example, by vehicle and industrial accidents, is a leading cause of death in youth and middle age. In these cases, more damage is typically caused by resultant swelling (edema) than by the impact itself. Stroke, caused by the blockage of blood vessels in the brain, is another major cause of death from brain damage. Other problems in the brain can be more accurately classified as diseases rather than injuries. Neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, motor neurone disease, and Huntington's disease, are caused by the gradual death of individual neurons, leading to decrements in movement control, memory, and cognition. Currently, only the symptoms of these diseases can be treated, but stem cell research may offer a cure. Mental illness, such as clinical depression, schizophrenia, bipolar disorder, and post-traumatic stress disorder, are brain diseases that impact on the personality and typically on other aspects of mental and somatic function. These disorders may be treated by psychiatric therapy, by pharmaceutical intervention, or by a combination of treatments; therapeutic effectiveness varies significantly among individuals. pharmaceutical Some infectious diseases affecting the brain are caused by viral and bacterial infection(s). Infection of the meninges, the membrane that covers the brain, can lead to meningitis. Bovine spongiform encephalopathy (also known as mad cow disease), is deadly in cattle and is linked to prions. Kuru is a similar prion-borne degenerative brain disease affecting humans. Both are linked to the ingestion of neural tissue, and may be an evolutionary defense against cannibalism. Viral or bacterial causes have been substantiated in multiple sclerosis, Parkinson's disease, Lyme disease, encephalopathy and encephalomyelitis. Some brain disorders are congenital. Tay-Sachs disease, Fragile X syndrome, Down syndrome, and Tourette syndrome are all linked to genetic and chromosomal errors. Malfunctions in the embryonic development of the brain can be caused by genetic factors, by drug use, and disease during a mother's pregnancy.

Other matters

Some philosophers consider that "brain" is synonymous with "mind", while others (such as strong AI theorists) believe that the mind is analogous to software and the brain to hardware. This issue—related to the mind-body problem—and many other issues, are the subjects of the area of the philosophy of mind. Questions asked in this field typically relate to the nature of consciousness and whether non-human animals are conscious beings. Computer scientists have produced computer systems called neural networks, loosely based on the structure of neuron connections in the brain. Artificial intelligence seeks to replicate brain function—although not necessarily brain mechanisms—but as yet is an immature science. Creating algorithms to mimic a biological brain is extremely difficult because the brain is not a static arrangement of circuits, but a network of vastly interconnected neurons that are constantly changing their connectivity and sensitivity. More recent work in both neuroscience and artificial intelligence models the brain using the mathematical tools of chaos theory and dynamical systems. Brain activity can be detected by electrodes, raising the possibility of "brain-computer interface". The reverse path has been demonstrated: brain implants have been used to generate artificial hearing and (crude and experimental) artificial vision for deaf and blind people; brain pacemakers are now commonly used to regulate brain activity in conditions such as Parkinson's disease. Both of these avenues of research are confronted with potentially serious ethical implications. For example, by placing electrodes in the brain and using a remote control, researchers have been able to remotely control the movements of a rat, combining commands of what to do with the stimulation of the brain pleasure centers. This raises the possibility of creating an electronically controlled biological "ratbot" that could be used in dangerous circumstances.

The biology of the brain

Despite the variance of the species in which the brain is found there are many common features in its cellular make-up, its structure and its function. On a cellular level, the brain is composed of two classes of cell, neurons and glia, both of which contain several different cell types which perform different functions. Interconnected neurons form neural networks (or neural ensembles). These networks are similar to man-made electrical circuits in that they contain circuit elements (neurons) connected by biological wires (nerve fibers). Of course, these do not form simple one-to-one electrical circuits (as is the case in many man-made circuits), neurons typically connect to at least a thousand other neurons. These highly specialized circuits make up systems which are the basis of perception, action and higher cognitive function. The brain contains anatomical and functional divides. In mammals, the most obvious partitioning of the brain is into the cerebrum (Latin for "brain", a large, anterior part that consists of two convoluted hemispheres and deep nuclei), cerebellum (Latin for "small brain", a smaller, structure behind the cerebrum with two rippled hemispheres and deep cerebellar nuclei), and brain stem (an elongated structure connecting the brain to the spinal cord). These parts are further divided into hemispheres, lobes, gyri, cortices, cytoarchitectonic and functional areas, nuclei, layers, fiber tracks and so forth. In summary, the chemical and electrical impulses continually passing through the cells of the brain produce all control, action and cognitive function in the body.

Histology

lobe Neurons, the cells that generate action potentials and convey them to other cells, constitute the chief class of brain cells. In each particular brain area, input (or afferent) neurons, output (or efferent) neurons and interneurons are typically found. Input neurons are recipients of projections from other brain areas. Output neurons project to the other areas. Interneurons are the neurons which do not leave the area. In addition to neurons, the brain contains glial cells in the proportion roughly 10 glial cells to every neuron; these are traditionally seen to perform supportive roles to neurons and fill out the space between them (hence its name, Greek for 'glue'). Most types of glia in the brain (and the rest of the central nervous system) are present in the entire nervous system, exceptions include oligodendrocytes which insulate neural axons (a role performed by Schwann cells in the peripheral nervous system). Oligosaccharides are the defining factor between white matter and grey matter in the brain—white matter is composed of myelinated (insulated) axons, whereas grey matter contains mostly cell soma, dendrites and unmyelinated portions of axons and glia and a smaller proportion of myelinated axons. In mammals, the brain also contains a certain amount of connective tissue called the meninges which is a system of membranes that separate the skull from the brain. The three-layered covering is made of, from the outside in, dura mater, arachnoid and pia mater (the latter two are connected and thus often considered as a single layer, the pia-arachnoid). Below the arachnoid is the subarachnoid space which contains cerebrospinal fluid which protects the nervous system. Blood vessels enter the central nervous system through the perivascular space above the pia mater. A blood-brain barrier protects the brain from unwanted substances that might enter it through the blood. The brain is suspended in cerebrospinal fluid, which circulates between layers of the meninges and through cavities in the brain called ventricles. It is important both chemically (metabolism) and mechanically (shock-prevention).

Anatomy

Although the histology of the brain is common to all those who have one, the structural anatomy is not. Apart from the general nature of the brain to order into lobes and suchforth, the lobes into which it has evolved are not common across the vertebrate/invertebrate divide. There are further dissimilarities within invertebrates, though vertebrates tend to share certain commonalities.

Invertebrates

In insects, the brain can be divided into four parts, the optical lobes, the protocerebrum, the deutocerebrum, and the tritocerebrum. The optical lobes are positioned behind each eye and process visual stimuli (Butler, 2000). The protocerebrum contains the mushroom bodies, which respond to smell, and the central body complex. The deutocerebrum includes the antennal lobes, which are similar to the mammalian olfactory bulb, and the mechanosensory neuropils which receive information from touch receptors on the head and antennae. The antennal lobes of flies and moths are quite complex. In cephalopods, the brain is divided into two regions: the supraesophageal mass and the subesophageal mass. These parts are divided by the animal's esophagus. The supra- and subesophageal masses are connected to each other on either side of the esophagus by the basal lobes and the dorsal magnocellular lobes. The large optic lobes are sometimes not considered to be part of the brain proper since the optic lobes anatomically separate from the brain and are joined to the brain by the optic stalks. However, the optic lobes perform much of the visual processing and can be functionally considered to be a part of the brain.

Vertebrates

In vertebrates, a gross division into three major parts is used: hindbrain (medulla oblongata and metencephalon), midbrain (mesencephalon) and forebrain (diencephalon and telencephalon). Varied taxonomies have been used by assorted schools at various times in history for the study of diverse species. An anterior part of the telencephalon called the cerebrum makes up the largest section of the mammalian brain and in humans, its surface has many deep fissures (sulci) and convolutions (gyri), giving a wrinkled appearance to the brain. In most vertebrates the metencephalon is the highest integration center in the brain, whereas in mammals this role has been adopted by the cerebrum. Behind (or in humans, below) the cerebrum is the cerebellum, a convoluted structure whose neural circuitry is often compared with crystal structure. Cerebellum participates in the control of movement. The cerebellum attaches to the hindbrain in a structure called the pons. The cerebrum and the cerebellum consist each of two halves (hemispheres). The corpus callosum connects the two hemispheres of the cerebrum. An outgrowth of the telencephalon called the olfactory bulb is a major structure in many animals, but in humans and other primates, it is relatively small. Vertebrate nervous systems are distinguished by encephalization and bilateral symmetry. Encephalization refers to the tendency for more complex organisms to gain a larger-size brains through evolutionary time. Larger vertebrates develop a complex of layered, networked and convoluted grey matter and white matter. Grey matter refers to tissue mostly comprised of neurons and can be found on the surface of cerebral cortex, as well as in clusters called nuclei deep within the brain. White matter refers to axons and their surrounding myelin insulation, which gives this tissue its white color. White matter is found in bundles of fibers known as tracts which connect the different parts of the brain. In modern species most closely related to the first vertebrates, brains are covered with gray matter that has a three-layer structure. Their brains also contain deep brain nucleus and fiber tracks forming the white matter. Most regions of the human cerebral cortex have six layers of neurons, a structure known as neocortex.

Brain Regions in Vertebrates

According to the hierarchy based on embryonic and evolutionary development, chordate brains are composed of the following regions:
- RHOMBENCEPHALON (Greek for "rhomboid brain")
- Myelencephalon (Greek for "brain marrow", also called medulla oblongata which means "long marrow" in Latin)
- Metencephalon (Greek for "after the brain"; also called hindbrain)
- pons
- cerebellum
- MESENCEPHALON (Greek for "middle brain", also called midbrain)
- tectum
- midbrain tegmentum
- substantia nigra
- crus cerebri (also called cerebral peduncles and pedunculus cerebri)
- PROSENCEPHALON
- Diencephalon (Greek for "brain in between")
- thalamus
- hypothalamus (Greek for "under the thalamus")
- pituitary gland
- epithalamus
- pineal gland
- Telencephalon (Greek for "end brain", i.e. the most rostral part of the brain; also called forebrain)
- TELENCEPHALON NUCLEI
- putamen
- caudate nucleus
- putamen
- globus pallidus
- amygdala
- CEREBRAL CORTEX
- Archipallium (Greek for "first cloak", i.e. cortex that developed first; also called archeocortex)
- hippocampus
- Paleopallium (Greek for "ancient cloak"; also called "paleocortex")
- priform(olfactory) cortex
- parahippocampal gyrus
- Neopallium (Greek for "new cloak"; also called "paleocortex"; also called neocortex and isocortex)
- frontal lobe
- temporal lobe
- parietal lobe
- occipital lobe
- insula
- cingulate cortex In addition, the brain is often subdivided into the following major parts:
- BRAINSTEM
- Medulla
- Pons
- Midbrain
- CEREBELLUM
- Cerebellar cortex
- Cerebellar nuclei
- BASAL GANGLIA (some midbrain nuclei, such as substantia nigra are usually considered as basal ganglia)
- Striatum (caudate nucleus and putamen)
- Globus pallidus
- HIPPOCAMPUS
- AMYGDALA
- THALAMUS
- HYPOTHALAMUS
- CEREBRAL CORTEX Yet alternative classifications arrange brain areas into functional systems:
- Limbic system
- Sensory systems
- Visual system
- Olfactory system
- Gustatory system
- Auditory system
- Somatosensory system
- Motor system
- Associative areas

Function

Associative areas Vertebrate brains receive signals through nerves arriving from the sensors of the organism, interpret those signals and formulate reactions based on built-in programs and learned experiences. A similarly extensive nerve network delivers signals from a brain to control muscles throughout a body. Anatomically, the majority of afferent and efferent nerves (with the exception of cranial nerves) are connected to the spinal cord, which then transfers the signals to the brain. Sensory input is processed by the brain to recognize danger, find food, identify potential mates and perform more sophisticated functions. Visual, touch, and auditory sensory pathways of vertebrates are routed to specific nuclei of the thalamus and then to regions of the cerebral cortex that are specific to each sensory system: the visual system, the auditory system and the somatosensory system. Olfactory pathways are routed to the olfactory bulb, then to various parts of the olfactory system. Taste is routed through the brainstem and then to other portions of the gustatory system. To control movement, the brain has several parallel systems of muscle control. The motor system controls voluntary muscle movement, aided by motor areas of the cerebral cortex, the cerebellum and the basal ganglia — the system that eventually projects to the spinal cord. Nuclei in the brainstem control many involuntary muscle functions such as heartrate and breathing. In addition, many automatic acts (simple reflexes, locomotion) can be controlled by the spinal cord alone. Brains also produce hormones that can influence organs and glands elsewhere in a body - conversely, brains also react to hormones produced elsewhere in the body. In mammals, most of these hormones are released into the circulatory system by a structure called the pituitary gland. It is hypothesized that developed brains derive consciousness from interaction among numerous systems within the brain. Cognitive processing in mammals occurs in the cerebral cortex but relies on mid-brain and limbic functions as well, especially those of the thalamus and hippocampus. Among "younger" (in an evolutionary sense) vertebrates, advanced processing involves progressively rostral (forward) regions of the brain. Hormones, incoming sensory information, and cognitive processing performed by the brain determine the brain state. Stimulus from any source can trigger a general arousal process that focuses cortical operations to processing of the new information. Cognitive priorities are constantly shifted by a variety of factors, such as hunger, fatigue, beliefs, unfamiliar information or threats. The simplest dichotomy related to processing of threats is the fight-or-flight response mediated by the amygdala, among other structures.

The study of the brain

Fields of study

Several areas of science specifically study the brain. Neuroscience seeks to understand the nervous system, including the brain, from a biological perspective. Psychology seeks to understand behavior and the brain. The terms neurology and psychiatry usually refer to medical applications of neuroscience and psychology, respectively. Cognitive science seeks to unify neuroscience and psychology with other fields that concern themselves with the brain, such as computer science (in Artificial intelligence and similar fields) and philosophy.

Methods of observation

Each method for observing activity in the brain has its advantages and drawbacks. Electrophysiology, in which wire electrodes are implanted in the brain, allows scientists to record the electrical activity of individual neurons or fields of neurons, but since it requires invasive surgery, this is a technique usually reserved for lab animals. By placing electrodes on the scalp, electroencephalography (EEG) measures brain waves, which are the mass changes in electrical current from the cerebral cortex, but can only detect changes over large areas of the brain and very little sub-cortical activity. Functional magnetic resonance imaging (fMRI) measures changes in blood flow in the brain, but the activity of neurons is not directly measured, nor can it be distinguished whether this activity is inhibitory or excitatory. Similarly, a PET (Positron Emission Tomography) Scan, is able to monitor glucose intake in different areas within the brain which is correlated the level of activity in that region. Behavioral tests can measure symptoms of disease and mental performance, but only provide indirect measurements of brain function and may not be practical in all animals. Finally, post-mortem analysis of the brain allows for the study of anatomy and protein expression patterns, but is only possible after the human or animal is dead.

History

Ancient Greeks had differing views on the function of the brain. Hippocrates believed the brain to be the seat of intelligence, but Aristotle held that the brain was a cooling mechanism for the blood, while the heart was the seat of intelligence. He reasoned that humans are more rational than the beasts because they have a proportionally larger brain to cool their hot-bloodedness (Bear, 2001). During the Roman Empire, the anatomist Galen dissected the brains of sheep. He concluded that since the cerebellum was hard on touch, it must control the muscles, while since the cerebrum was soft, it must be where the senses were processed. Galen further theorized that the brain functioned by movement of fluids through the ventricles (Bear, 2001). In the Age of Reason, René Descartes espoused a fluid mechanical view of the brain similar to Galen's theories. However, Descartes thought that although this explanation was adequate to explain the brain functions of animals, the higher mental functions of humans were accomplished by the soul. This theoretical separation of the mind and brain became known as the mind-body problem (Bear, 2001). In the mid-1600s, however, great progress in describing the anatomy of the brain was achieved with the works of English anatomist Thomas Willis and Flemish anatomist Vesalius. They dispelled many of the notions of Galen and Descartes and discovered many facts about the macro structure of the brain of animals and humans. In the 1700s, Luigi Galvani showed that electrically stimulating the sciatic nerve of a dissected frog caused movement of the attached muscle. His experiments led scientists away from the fluid mechanical theory of the brain and toward an electrical theory. In the 19th century, Galvani's work led to the development of research in bioelectricity and to the discovery of the membrane potential and action potential by researchers such as Emil du Bois-Reymond. The scientists of the 1800s debated whether areas of the brain corresponded to specific functions or if the brain functioned as a whole (the "aggregate field theory"). Jean Pierre Flourens championed the aggregate field theory in opposition to the pseudoscience of phrenology, founded by Franz Joseph Gall. However, the work of Paul Pierre Broca, Karl Wernicke, and Korbinian Brodmann eventually helped to show that areas of the brain had specific functions, though some functions were repeated, an idea known as parallel distributed processing (Kandel, 2001). As the 20th century approached, the anatomical works of Santiago Ramon y Cajal and Camillo Golgi laid the foundation for the study of individual neurons in the brain. Charles Scott Sherrington and Edgar Douglas Adrian furthered the study of neurons with the new techniques of electrodes and the electroencephalogram (EEG). Neurotransmitters were discovered and investigated by a number of scientists, including Otto Loewi, Henry Hallett Dale, Arvid Carlsson and many others. Modern Neuroscience experiences rapid development. The scientists use a variety of approaches to study the brain at different levels — from the molecules to systems. Extensive knowledge has been accumulated about the electrophysiological properties of different types of neurons and their responsiveness to neurotransmitters. Recordings from the brain of awake, behaving animals pioneered by Edward Evarts help to decode neuronal firing during different behaviors and cognitive processes. Miguel Nicolelis introduce multielectrode recording techniques which led to creation of brain-computer interfaces. Rapidly developing brain imaging allows scientists to study the brain in living humans and animals in ways that their predecessors could not.

The brain as a food

Like most other internal organs, the brain can serve as nourishment. For example, in the Southern United States canned pork brain in gravy can be purchased for consumption as food. This form of brain is often fried with scrambled egg to produce the famous "Eggs n' Brains". The brain of animals also features in the cuisine of France such as in the dish tête de veau, or head of calf. Although it might consist only of the outer meat of the skull and jaw, the full meal includes the brain, tongue and glands (the latter form being the favorite food of president Jacques Chirac). Similar delicacies from around the world include Mexican tacos de sesos (tacos made with cattle brain) and squirrel brain in the US South. The Anyang tribe of Cameroon practiced a tradition in which a new chief would consume the brain of a hunted gorilla while another senior member of the tribe would eat the heart. Consuming the brain and other nerve tissue of animals is not without its risks. The first problem is that the brain is made up of 60% fat due to the myelin (which by itself is 70% fat) insulating the axons of neurons and glia. As an example, a 5 oz. (0.14 kg) can of "Pork Brains in Milk Gravy", a single serving, contains 3500 milligrams of cholesterol, 1170% of our recommended daily intake. More importantly, humans can contract fatal transmissible spongiform encephalopathies such as Creutzfeldt-Jakob disease and other (prion diseases), as well as Bovine Spongiform Encephalopathy (colloquially known as "mad cow" disease) through the consumption of the infected nerve tissue of cattle and other animals - However, "there is no evidence that people can get mad cow disease from eating muscle meat". Another prion disease called kuru has been traced to a mourning ritual among the Fore<