Sinirbilim Yaz Okulu

SinirBilimin Kısa Tarihi

Adnan Kurt

v1: 27 Haziran 2011

Sinirbilim Nedir?

Neuroscience is the scientific study of the nervous system.[1] Traditionally, neuroscience has been seen as a branch of biology. However, it is currently an interdisciplinary science that collaborates with other fields such as chemistry, computer science, engineering, mathematics, medicine, philosophy, physics, and psychology. The term neurobiology is usually used interchangeably with the term neuroscience, although the former refers specifically to the biology of the nervous system, whereas the latter refers to the entire science of the nervous system.The scope of neuroscience has broadened to include different approaches used to study the molecular, cellular, developmental, structural, functional, evolutionary, computational, and medical aspects of the nervous system. The techniques used by neuroscientists have also expanded enormously, from molecular and cellular studies of individual nerve cells to imaging of sensory and motor tasks in the brain. Recent theoretical advances in neuroscience have also been aided by the study of neural networks.Given the increasing number of scientists who study the nervous system, several prominent neuroscience organizations have been formed to provide a forum to all neuroscientists and educators. For example, the International Brain Research Organization was founded in 1960,[2] the International Society for Neurochemistry in 1963,[3] the European Brain and Behaviour Society in 1968,[4] and the Society for Neuroscience in 1969.[5]

Makrosefali hastasının MRI görüntüsü

Ana Akımlar

The history of Neuroscience has been shaped by three major debates:Mind vs. brain debate (monism/dualism): are mind (cognition/behavior) and brain (physical substance) separate (dualist) or unified monist) entities?Localism vs. holism: do neurons and brain areas have specific functions (localism) or is it fairly undifferentiated, working more as an aggregate field (holism)?Nature of neural communication: Is the mind completely "created" by the brain? Can consciousness be reduced to neurons? Is there a soul that exists beyond the neurons? These questions are still hotly debated.

Drawing by Santiago Ramón y Cajal (1899) of neurons in the pigeon cerebellum

Mısırlılar

Egyptians1700 bc[Mind-Brain]First written account of the "brain," its anatomy, the meninges (covering of the brain) and CSF (Cerebrospinal fluid) on a payrus called the Edwin Smith Surgical papyrus. It may have been written by Imhotep (did anyone see the movie, "The Mummy?"). But they did not think much of this organ given that unlike the other organs, it was discarded, not preserved after death. Picture is Egyptian hieroglyph writing for "brain."

Plato

Plato427-347 bc[Mind-Brain]Created near Athens the Academy, which was the most influential school in the ancient world. He taught there until his death, and Aristotle was his most famous student. He believed the brain was the seat of mental processes.

Aristo

Aristotle384-322 bc[Mind-Brain]Believed the mind was located in the heart, which contained all emotions and thinking. The brain was instead a radiator used to cool the heart. He experimented by dissecting animals (human dissection was forbidden).

Galen

Galen130-200 ad[Neural Communication]Hailed as a great surgeon. Believed the brain receives sensory information and is responsible for motor control, using the mechanism of fluid energies. (Picture shows surgical procedures described by Galen.)

Dekart

René Descartes1596-1650[Mind-Brain][Neural Communication]Believed nerves contain fluids, or "animal spirits," which are responsible for the flow of sensory and motor information in the body. He believed in the "Balloonist Theory" which asserted that little balloons expanding would cause motion. He was adualist, believing that the mind and body are separate, communicating via the pineal gland.

Aydınlanma

Age of Enlightenment1700's[Neural Communication]From the beginning of the 18th century, known as the Age of Enlightenment, it was discovered that the nervous system is electrical in nature. The previous Ballonist Theory was disproved using the technique of water displacement. (Voltaire)

Müller

Johannes Müller1801-1858[Neural Communication]Doctrine of specific nerve energies. Different sensations are caused by different energies in nerves. Today we know this is not true, different receptors interpret the same action potentials.

Aristo

Franz Joseph Gall1758-1828[Localist/Holist Debate]Advocate of cerebral localization. One of the founders of phrenology, but used it more as a spectacle than as a scientist. With Spurzheim, divided the brain in 35 separate functions, ranging from concrete concepts like language and color to abstract ones like hope or self-esteem. (Gall was jealous of a friend who was very good with language and memory. Because this friend had big bulging eyes, he though the brain was bigger behind it, hence those brain functions must be behind the eyes!)

Purkinje

Johannes Pukinje1787-1869[Neural Communication]He was first to describe a nerve cell. Contributed heavily to the field of experimental psychology. Explored sensory and visual experience after stimulation, by applying pressure and electrical current to the eyeball, etc. Discovered large nerve cells ("Pukinje Cells) with many branching extensions in the cerebral cortex.

Fluorens

Pierre Flourens1794-1867[Localist/Holist Debate]Flourens ablated the cortical tissue of dogs, rabbits and birds, showing that the eventual recovery was due to the brain's aggregate field, where the entire brain participated in behavior. He was a strong opponent of the localization theory, virtually disproving phrenologists, and advocated a holisticview of the brain, where other parts of the brain could take over the function of damaged ones.

Broca

Pierre Paul Broca1824-1880[Localist/Holist Debate]Advocated functional localization by cerebral convolution. In 1862, showing brain lesions in a stroke patient who could understand language but could not speak (could only say "tan"), he demonstrated that the left frontal lobe was responsible for articular speech. Demonstrated this in several patients. This region has since been named Broca’s area.

Wernicke

Carl Wernicke1848-1904[Localist/Holist Debate]Like Broca, Wernicke showed a similar stroke victim. But this time the patient could speak but made no sense. The damaged area was around where the temporal and parietal lobes meet in the posterior part of the left hemisphere. His findings further revived the localizationist view.

Fritsch

Gustav Fritsch1838-1907[Neural Communication] [Localist/Holist Debate]

Further supported localization of function, stimulating the brain surfaces of live dogs and frogs using electricity. This resulted in characteristic movements in the neck and hind legs.

Brodmann

Korbinian Brodmann1868-1918[Localist/Holist Debate]Categorized the brain into 52 distinct areas based on the cellular organization of the cortex in the respective regions, and therefore helped to support the localist view, which was already very strong. This was accomplished through tissue stains (i.e., histology), in order to visualize the different cell types. The difference between individual cell regions is called cytoarchitectonics, or cellular architecture.

Golgi

Camillo Golgi1843-1956[Neural Communication]Developed a silver stain that would permit the full visualization of a single neuron. He believed the brain was a continuous mass of tissue that shares a single cytoplasm. Though this theory was disproved by Cajal, they both shared the Nobel Prize in 1906.

Cajal

Santiago Ramón Y Cajal1852-1934[Neural Communication]Discovered that neurons were discrete unitary entities, and that they conducted electrical signals in only one direction. He established the Neuron Doctrine, which is the fundamental organizational and functional principle of the nervous system, stating that the neuron is the anatomical, physiological, genetic and metabolic unit of the nervous system. He won the Nobel Prize in 1906. The Neuron Doctrine proposes that the neuron is the anatomical, physiological, genetic and metabolic unit of the nervous system:Neurons are discrete and autonomous cells that can interactSynapses are gaps that separate neuronsInformation is transmitted in one direction from dendrites (input) to the axon (output)

Lashley

K. S. Lashley1890-1958[Localist/Holist Debate]Worked extensively with rats to discover where memory lies. He searched for the neural components of memory, which he called engrams. He systematically lesioned different percentages of rats' brains and then tested them in mazes they had known well. This resulted in a gradual but consistent degradation in performance. Hence the engram is not a specific connection, but rather the sum of many connections. This supported the holistic view.

Penfield

Wilder Penfield1891-1976[Localist/Holist Debate]One of the great neurosurgeons of all times, and a leading authority on epilepsy. While stimulating different sections of the cortex of epileptic patients during neurosurgery, he found that activating multiple cells would produce specific results (e.g., a patient would speak out "Grandma" -- hence the "Grandmother cell"), and on their connected regions. His localizationist views profoundly affected modern neurology and other scientific fields.

Modern Zamanlar

Modern Day2000-[Neural Communication]

The communication of discrete neurons (brain cells) using electrical and chemical signals (neurotransmitters) is well established and accepted (Neuron Doctrine).[Localist/Holist Debate]

Extreme localism and holism have both been replaced by "connectionism." This view contends that lower level or primary sensory/motor functions are strongly localized but higher-level functions, like object recognition, memory, and language are the result of interconnections between brain areas. In addition, even within areas that seem to be localized for a particular function, that function is distributed among many neurons. There appears to be no "grandmother cell."[Mind/Brain]

Although most cognitive neuroscientists must believe that the mind and brain are related to each other in some way (or else their work would be meaningless!), many also believe in a soul. How can we reconcile these views? It is necessary to reconcile them?

Modern Zamanlar

Çözülmemiş Problemler

Some of the yet unsolved problems of neuroscience include:Consciousness: What is the neuronal basis of subjective experience, cognition, wakefulness, alertness, arousal and attention? How is the "hard problem of consciousness" solved? What is its function?[1]Perception: How does the brain transfer sensory information into coherent, private percepts? What are the rules by which perception is organized? What are the features/objects that constitute our perceptual experience of internal and external events? How are the senses integrated? What is the relationship between subjective experience and the physical world?Learning and memory: Where do our memories get stored and how are they retrieved again? How can learning be improved? What is the difference between explicit andimplicit memories?Neuroplasticity: How plastic is the mature brain?Development and evolution: How and why did the brain evolve? What are the molecular determinants of individual brain development?Free will, particularly the Neuroscience of free willSleep: Why do we dream? What are the underlying brain mechanisms? What is its relation to anesthesia?Cognition and decisions: How and where does the brain evaluate reward value and effort (cost) to modulate behavior? How does previous experience alter perception and behavior? What are the genetic and environmental contributions to brain function?Language: How is it implemented neurally? What is the basis of semantic meaning?Diseases: What are the neural bases (causes) of mental diseases like psychotic disorders (e.g. mania, schizophrenia), Parkinson's disease, Alzheimer's disease oraddiction? Is it possible to recover loss of sensory or motor function?[edit]

Çok Eskiden

The study of the nervous system dates back to ancient Egypt. Evidence of trepanation, the surgical practice of either drilling or scraping a hole into the skull with the purpose of curing headaches or mental disorders or relieving cranial pressure, being performed on patients dates back to Neolithic times and has been found in various cultures throughout the world. Manuscripts dating back to 1700BC indicated that the Egyptians had some knowledge about symptoms of brain damage.[6]Early views on the function of the brain regarded it to be a "cranial stuffing" of sorts. In Egypt, from the late Middle Kingdomonwards, the brain was regularly removed in preparation for mummification. It was believed at the time that the heart was the seat of intelligence. According to Herodotus, the first step of mummification is to "take a crooked piece of iron, and with it draw out the brain through the nostrils, thus getting rid of a portion, while the skull is cleared of the rest by rinsing with drugs."[7]

Sonraları

The view that the heart was the source of consciousness was not challenged until the time of Hippocrates. He believed that the brain was not only involved with sensation—since most specialized organs (e.g., eyes, ears, tongue) are located in the head near the brain—but was also the seat of intelligence. Plato also speculated that the brain was the seat of the rational part of the soul.[8] Aristotle, however, believed the heart was the center of intelligence and that the brain served to cool the blood. This view was generally accepted until the Roman physician Galen, a follower of Hippocrates and physician to Roman gladiators, observed that his patients lost their mental faculties when they had sustained damage to their brains.Abulcasis, Averroes,Avenzoar, and Maimonides, active in the Medieval Muslim world, described a number of medical problems related to the brain. Elsewhere in medieval Europe, Vesalius (1514–1564) and René Descartes (1596–1650) also made several contributions to neuroscience.

İçindekiler

Studies of the brain became more sophisticated after the invention of the microscope and the development of a staining procedure by Camillo Golgi during the late 1890s. The procedure used a silver chromate salt to reveal the intricate structures of individual neurons. His technique was used by Santiago Ramón y Cajal and led to the formation of theneuron doctrine, the hypothesis that the functional unit of the brain is the neuron. Golgi and Ramón y Cajal shared the Nobel Prize in Physiology or Medicine in 1906 for their extensive observations, descriptions, and categorizations of neurons throughout the brain. The neuron doctrine was supported by experiments following Luigi Galvani's pioneering work in the electrical excitability of muscles and neurons. In the late 19th century, Emil du Bois-Reymond, Johannes Peter Müller, and Hermann von Helmholtzdemonstrated that neurons were electrically excitable and that their activity predictably affected the electrical state of adjacent neurons.

Özelleşmiş Alanlar

In parallel with this research, work with brain-damaged patients by Paul Broca suggested that certain regions of the brain were responsible for certain functions. At the time, Broca's findings were seen as a confirmation of Franz Joseph Gall's theory that language was localized[clarification needed] and certain psychological functions were localized in the cerebral cortex.[9][10] The localization of function hypothesis was supported by observations of epileptic patients conducted by John Hughlings Jackson, who correctly inferred the organization of the motor cortex by watching the progression of seizures through the body. Carl Wernicke further developed the theory of the specialization of specific brain structures in language comprehension and production. Modern research still uses the Brodmann cerebral cytoarchitectonic map (referring to study of cell structure) anatomical definitions from this era in continuing to show that distinct areas of the cortex are activated in the execution of specific tasks.[11]

Modeller&Matematik

In 1952, Alan Lloyd Hodgkin and Andrew Huxley presented a mathematical model for transmission of electrical signals in neurons of the giant axon of a squid, action potentials, and how they are initiated and propagated, known as the Hodgkin-Huxley model. In 1961-2, Richard FitzHugh and J. Nagumo simplified Hodgkin-Huxley, in what is called theFitzHugh–Nagumo model. In 1962, Bernard Katz modeled neurotransmission across the space between neurons known as synapses. In 1981 Catherine Morris and Harold Lecar combined these models in the Morris-Lecar model. In 1984, J. L. Hindmarsh and R.M. Rose further modeled neurotransmission.Beginning in 1966, Eric Kandel and James Schwartz examined the biochemical analysis of changes in neurons associated with learning and memory storage.

Çağdaş Sinirbilim

The scientific study of the nervous system increased significantly during the second half of the twentieth century, principally due to revolutions in molecular biology, electrophysiology, and computational neuroscience. It has become possible to understand, in much detail, the complex processes occurring within a single neuron. However, how networks of neurons produce complex cognitions and behaviors is still poorly understood.― The task of neural science is to explain behavior in terms of the activities of the brain. How does the brain marshal its millions of individual nerve cells to produce behavior, and how are these cells influenced by the environment...? The last frontier of the biological sciences—their ultimate challenge—is to understand the biological basis of consciousness and the mental processes by which we perceive, act, learn, and remember. — Eric Kandel, Principles of Neural Science, 4th ed. ‖The nervous system is composed of a network of neurons along with other, supportive, cells (e.g., glial cells). Neurons form functional circuits, each responsible for specific functions of behavior at the organismal level. Thus, neuroscience can be studied at many different levels, ranging from the molecular and cellular levels to the systems and cognitive levels.

Moleküler Düzeyde

At the molecular level, the basic questions addressed in molecular neuroscience include the mechanisms by which neurons express and respond to molecular signals and how axons form complex connectivity patterns. At this level, tools from molecular biology and genetics are used to understand how neurons develop and how genetic changes affect biological functions. The morphology, molecular identity, and physiological characteristics of neurons and how they relate to different types of behavior are also of considerable interest.At the cellular level, the fundamental questions addressed in cellular neuroscience include the mechanisms of how neurons process signals physiologically and electrochemically. They address how signals are processed by dendrites, somas and axons, and how neurotransmitters and electrical signals are used to process signals in a neuron.[clarification needed] Another major area of neuroscience is directed at investigations of the development of the nervous system. These questions include the patterning and regionalization of the nervous system, neural stem cells, differentiation of neurons and glia, neuronal migration, axonal and dendritic development, trophic interactions, and synapse formation.

Sistem Düzeyinde

At the systems level, the questions addressed in systems neuroscience include how neural circuits are formed and used anatomically and physiologically to produce functions such as reflexes, sensory integration, motor coordination, circadian rhythms, emotional responses, learning, and memory. In other words, they address how these neural circuits function and the mechanisms through which behaviors are generated. For example, systems level analysis addresses questions concerning specific sensory and motor modalities: how does vision work? How do songbirds learn new songs and bats localize with ultrasound? How does the somatosensory system process tactile information? The related fields of neuroethology and neuropsychology address the question of how neural substrates underlie specific animal and human behaviors. Neuroendocrinology and psychoneuroimmunology examine interactions between the nervous system and the endocrine and immune systems, respectively.

Bilişsel Düzeyde

At the cognitive level, cognitive neuroscience addresses the questions of how psychological functions are produced by neural circuitry. The emergence of powerful new measurement techniques such as neuroimaging (e.g., fMRI, PET, SPECT), electrophysiology, and human genetic analysis combined with sophisticated experimental techniques from cognitive psychology allows neuroscientists and psychologists to address abstract questions such as how human cognition and emotion are mapped to specific neural substrates.Neuroscience is also allied with the social and behavioral sciences as well as nascent interdisciplinary fields such as neuroeconomics, decision theory, and social neuroscience to address complex questions about interactions of the brain with its environment.

Nobel Ödülleri

Year of Award Name(s) Field of Study

1906Golgi, Camillo Structure of the Nervous System

Ramon y Cajal, Santiago Structure of the Nervous System

1911 Gullstrand, Allvar Optics of the Eye

1914 Barany, Robert Physiology and pathology of the vestibular apparatus

1927 Wagner-Jauregg, Julius Discovery of Malaria inoculation to treat dementia paralytica

1932

Adrian, Edgar Douglas Function of neurons in sending messages

Sherrington, Sir Charles Scott Function of neurons in the brain and spinal cord

1936Dale, Sir Henry Hallett Chemical transmission of nerve impulses

Loewi, Otto Chemical transmission of nerve impulses

1944Erlanger, Joseph Differentiated functions of single nerve fibers

Gasser, Herbert Spencer Differentiated functions of single nerve fibers

1949

Egas Moniz, Antonio Caetano Abreu Freire

Leucotomy for certain psychoses

Hess, Walter Rudolph The "interbrain" (hypothalamus) used to control activity of internal organs

1957 Bovet, Daniel Work on synthetic substances that inhibit action of body substances.

Nobel Ödülleri

1961 Von Bekesy, Georg Function of the cochlea

1963

Eccles, Sir John Carew Ionic mechanisms of nerve cell membrane

Hodgkin, Sir Alan Lloyd Ionic mechanisms of nerve cell membrane

Huxley, Sir Andrew Fielding Ionic mechanisms of nerve cell membrane

1967

Granit, Ragnar Arthur Mechanisms of Vision - Wavelength discrimination of the eye

Hartline, Halden Keffer Mechanisms of Vision

Wald, George Mechanisms of Vision - chemical processes

1970

Axelrod, Julius Humoral transmitters in sympathetic nerves

Katz, Sir Bernard Release of neurotransmitters from nerve terminals

von Euler, Ulf Svante Humoral transmitters in sympathetic nerves

1973

Lorenz, Konrad Zacharias Ethology

Tinbergen, Nikolaas Ethology

von Frisch, Karl Ethology

1976Blumberg, Baruch S. Mechanisms for origin and dissemination of infection disease

Gajdusek, Daniel Carleton Mechanisms for origin and dissemination of infection disease

1977Guillemin, Roger Production of peptides in the brain

Schally, Andrew Victor Production of peptides in the brain

1979Cormack, Allan MacLeod Invention of computer-assisted tomography

Hounsfield, Sir Godfrey Newbold Invention of computer-assisted tomography

1981

Hubel, David Hunter Information processing in the visual system

Sperry, Roger Wolcott Functions of the right and left hemispheres of the brain

Wiesel, Torsten N. Information processing in the visual system

Nobel Ödülleri

1982Vane, John Robert Discovery of prostaglandins

Bergstrom, Sune K. Discovery of prostaglandins

1986Cohen, Stanley Control of nerve cell growth

Levi-Montalcini, Rita Control of nerve cell growth

1991Neher, Erwin Function of single ion channels in cells

Sakmann, Bert Function of single ion channels in cells

1994Gilman, Alfred G. Discovery of G-protein coupled receptors and their role in signal transduction

Rodbell, Martin Discovery of G-protein coupled receptors and their role in signal transduction

1997 Prusiner, Stanley B. Discovery of prions; a new biological principle of infection

2000

Carlsson, Arvid Signal transduction in the nervous system/dopamine

Greengard, Paul Signal transduction in the nervous system

Kandel, Eric R. Signal transduction in the nervous system/learning

2003Lauterbur, Paul C. Discoveries concerning magnetic resonance imaging

Mansfield, Sir Peter Discoveries concerning magnetic resonance imaging

2003 MacKinnon, Roderick Structural and mechanistic studies of ion channels

2004

Buck, Linda B. Discovery of odorant receptors and the organization of the olfactory system

Axel, Richard Discovery of odorant receptors and the organization of the olfactory system

Nobel Ödüllüler Hakkında

*When Santiago Ramon y Cajal was 11-years-old, he destroyed a neighbor's gate with a homemade cannon and spent three days in jail. 3

In 1898, Camillo Golgi reported that he discovered a ribbon-like apparatus inside neurons of the cerebellum. This structure now bears his name as the "Golgi apparatus."*As a soldier in the Polish army during World War II, Robert Barany was taken prisoner in 1915 and sent to Central Asia.1

*Julius Wagner-Jauregg received a diploma of Doctor of Law.2

*Antonio Caetano de Abreu Freire Egas Moniz was shot in the leg by a patient. He spent the rest of his life in a wheel chair.*Edgar D. Adrian was a descendent of Scottish philosopher David Hume.1

*The word synapse was first used in a book called A Textbook of Physiology, part three: The Central Nervous System, by Michael Foster and assisted by Charles S. Sherrington, in 1897. It was probably Charles S. Sherrington who coined the term synapse. The word "synapse" comes from Greek: "syn" meaning "together" and "haptein" meaning "to clasp."The oldest daughter of Henry Dale married Alexander Todd. Todd was awarded the Nobel Prize in Chemistry in 1957.1

*The idea for an experiment to demonstrate chemical neurotransmission came to Otto Loewi in a dream.*Joseph Erlanger's parents immigrated from Germany to the US during the gold rush.1

Spencer Gasser was a student of Joseph Erlanger.1

*Daniel Bovet spent time in South America to learn how curare was used.1

*Georg von Bekesy worked in the research laboratory of the Hungarian Post Office.2

John Eccles was knighted in 1958.1

Alan Hodgkin married the daughter of Peyton Rous. Peyton Rous won the Nobel Prize in Medicine in 1966.1

Andrew F. Huxley was knighted in 1974.1

Ragnar Granit studied with Charles Sherrington.1

Haldan Hartline used horseshoe crabs in his early experiments about the visual system.*Julius Axelrod helped develop the pain reliever called acetaminophen (Tylenol).1

*Bernard Katz served as a radar operator in the Royal Australian Air Force during World War II.1

As a student, Alfred Gilman was a member of the Yale University Concert Band.4

Martin Rodbell contracted malaria in the Philippines while serving in the Navy during World War II.4

*Nikolaas Tinbergen was sent to a concentration camp during World War II.1

*Andrew V. Schally has over 2200 publications; more than 1200 were published after he received the Nobel Prize.2

*Allan McLeod Cormack never received an MD or PhD.*Godfrey N. Hounsfield served as a radar expert for the Royal Air Force during World War II.1

*Although David H. Hubel had never taken a biology class in high school or college, he was accepted into medical school at McGill University.2

*Torsten N. Wiesel was president of his high school's athletic association.2

*As a child, Bert Sakmann designed and built model motors, sailing ships and remote controlled airplanes.4

*Eric R. Kandel played soccer and was co-captain of the track team at Erasmus Hall High School.2

As an undergraduate at the University of Washington, Linda Buck wanted to become a psychotherapist.2

*Richard Axel delivered false teeth to dentists at the age of eleven, laid carpets at twelve and served sandwiches in a delicatessen at thirteen.2

*In 1938, Otto Loewi was jailed by the Nazis in Austria. Only when he transferred his Nobel Prize money to a Nazi-controlled bank was he allowed to leave Austria.5

Ayrıntılı Gelişim

History of Neuroscience.htm