The Nobel Prizes in the field of neuroscience

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The Nobel Prizes in the field of neuroscience 2017-06-07T12:57:51+00:00

The Nobel Prizes in the field of neuroscience-from Camillo Golgi and Ramón y Cajal to John 0’Keefe and May-Britt Moser and Edvard I Moser

Gunnar Grant *

Department of Neuroscience, Karolinska Institutet, Retzius väg 8, B2:5, SE-171 77 Stockholm, Sweden

No less than 17 Nobel Prizes have been awarded the area of neuroscience and no less than 40 laureates. The first prize was given to Camillo Golgi and Ramón y CaJal in 1906 and the last one so far, to John 0’Keefe and May-Britt and Edvard I. Moser in 2014.

This presentation of the laureates will not follow the time sequence of the prizes. Instead, I have grouped them in different categories.

The RoyaI CaroIine Medico-SurgicaI Institute

The RoyaI CaroIine Medico-SurgicaI Institute at KungshoImen, cIose to the present City HaII, around 1900. This was where the decisions about the NobeI Prizes in PhysioIogy or Medicine were made from 1901 to1947, Iater on at the new KaroIinska campus

The Nobel Prize in Physiology or Medicine 1906

In 1906 CamiIIo GoIgi and Ramón y CajaI were awarded the NobeI prize "in recognition of their work on the structure of the nervous system" (From www.nobeIprize. org)

With regard to the prize in 1906 and also the prizes from 1932 and 1944 to Sherrington and Adrian and to Erlanger and Gasser I have penetrated the original documents at the Medical Nobel Committee at Karolinska Institutet. 50 years following the prize, one may get the permission to do so after application to the Committee. I have published a few articles about these prizes. 0ne of them about Golgi and Cajal is available at the Nobel website (www.nobelprize.org). Another one, about the 1932 and 1944 prizes, is available in the Journal of the History of the Neurosciences (1).

With regard to Golgi, there is no doubt that his most important contribution was his method, the reazione nera, “the black reaction”. This was a revolutionary method of staining individual nerve cell structures. He described it for the first time as a brief report entitled ” 0n the structure of the grey matter of the brain” which was published in an Italian Journal in 1873 and in a very modest way. The method makes use of prolonged immersion of pieces of nervous tissue in a weak solution of silver nitrate, following fixation in potassium or ammonia dichromate. The final result is a preparation in which the outline of the nerve cell appears in all its morphological complexity, with a well-defined outline and   all its ramifications, which can be followed and analyzed even at great distance from the cell body. The great advantage of the technique is that, for reasons that are still unknown, silver nitrate selectively impregnates only a few cells (1%-5%), which are stained black, and completely spares other cells, allowing individual cells to stand out from the background.

GoIgi's NobeI dipIoma

GoIgi's NobeI dipIoma

Two years after the publication of his method, Golgi published a paper “0n the fine structure of the olfactory bulbs”.

He also made extensive studies on cerebellum, hippocampus and the spinal cord, and made several important observations. He described the parallel fibers of the molecular layer in the cerebellum and pointed out that they could be regarded as originating from the granular layer. He also described nerve cells in the molecular layer and made a more detailed description of the Purkinje cells than previously possible, describing the ramifications of the protoplasmic processes, which was his name for the dendrites.

The studies carried out by Golgi were included in his 0pera 0mnia, published in 1903.

This impressive work also included Golgi’s important studies on the cause of malaria, which occupied his research for many years in the late 1880’s and early 1890’s.

GoIgi stained neuron from the centraI cervicaI nucIeus of a kitten [2]
An oId type sIide from the Retzius coIIection at KaroIinska Institutet, with sections from human cerebeIIum-Retzius has written, in transition: "Gift from C. GoIgi to G. Retzius 1886" (Reproduced from photo by prof. Lars 0Ison)

Although contributing with an impressive method for the study of the nervous system and making many important observations on the structure of the nervous system, Golgi made the great mistake to adhere to the so called “reticular theory”, the nerve net theory, in contradiction to “the neuron theory”, based on the nerve cell body and its extensions forming an anatomical unit. He did so even after almost all scientists studying the nervous system had accepted the neuron theory as a doctrine. His strongest opponent on this was Cajal, who already in the late 1800s had spelled out the neuron theory in his studies summarized mainly at that time in his three volume “Textura del sistema  nervioso”, published in 1897, 1899 and 1904, comprising 1800 pages and 897 original illustrations.

In 1909 -1911 the somewhat extended French version Histologie du Système Nerveux de l´Homme et des Vertébrés was published, comprising more than 1900 pages and more than 1000 original illustrations. This has been held to be the most important book ever published in neuroanatomy.

Details of dendritic ramification
The titIe page of the first voIume of GoIgi's Opera Omnia. From the Hagströmer Library, KaroIinska Institutet
Santiago Ramón y CajaI (1852-1934)
The titIe page of voIume I of Textura deI sistema nervioso 1899

With regard to the Golgi method Cajal found that it worked best on embryonic material, or on material from newborn animals or man, and he examined all parts of the brain and spinal cord with it.

The titIe page of HistoIogie du Système Nerveux, voI I
GoIgi-stained nerve ceIIs and fibres from the spinal cord. From CajaI's HistoIogie du Système Nerveux, voI I
GoIgi stained gIiaI ceIIs from the spinaI cord. From CajaI's HistoIogie du Système Nerveux, voI I
MethyIene bIue stained dorsaI coIumn fibres with intraspinaI ramifications. From CajaI's HistoIogie du Système Nerveux, voI.I

Cajal also adopted the methylene blue stain, published by Ehrlich in the late1890’s, after the Golgi method had been introduced.

Cajal also developed reduced silver nitrate impregnation methods (Bielschowsky), and used them for the visualization of neurofibrils, which could be seen in the transparent nerve cells and their extensions. He applied these methods, both for a better understanding of the interior of the nerve cell and for studies of regeneration of peripheral nerve fibres, as well as for studies of outgrowth of axons during the embryonic development, demonstrating endbulbs.

Together these discoveries can be claimed to have created the basis for classical neurophysiology.

The Nobel Prize in Physiology or Medicine 1932

In 1932 Sherrington & Adrian shared the NobeI Prize "for their discoveries regarding the functions of neurons" (From www.nobeIprize.org)

The Nobel Prize in Physiology or Medicine 1944

In 1944 ErIanger & Gasser shared NobeI prize "for their discoveries relating to the highly differentiated functions of singIe nerve fibres" (From www.nobeI-prize.org)

Sherrington was the most productive of these four laureates, publishing his first paper in 1884 and the last in 1937. His studies contributed with much of the basic concepts in neurophysiology. Much of what he published was summarized in “Selected writings of Sir Charles Sherrington”, a volume with more than 500 pages.

The titIe page of "SeIected writings of Sir CharIes Sherrington" edited by his former pupiI, Derek Denny-Brown, first in 1939 and then in reprint in 1979

In 1883, when Sherrington was 26, he became demonstrator of Anatomy at Cambridge and in 1913 at the age of 56 he became Professor of Physiology at 0xford. In Cambridge Sherrington started working on the physiology of the spinal cord. He soon made important discoveries regarding reflex functions of the spinal cord and published a large number of papers on his findings. About ten years after these studies had begun, in 1903, he was invited to give the Silliman Lectures at Yale University (1904). These lectures were published in a book with the title “The Integrative Action of the Nervous System (1906; more than 400 pages/reprinted 1947).

TitIe page and contents of "The Integrative Action of the Nervous System"
Synapse, from Sherrington, The Integrative Action of the Nervous System, 2nd ed., 1947

In these lectures Sherrington formulated the conception of the “synapse”, creating this new term, and its influence on the conduction of the nerve impulse within the nervous system. He described his studies on “reciprocal innervation” and showed that inhibition was an active phenomenon and not solely an absence of activity. This was a fundamental discovery. Depending on the location of the receptors involved in the in initiation of a reflex, he distinguished three types of receptors extero-,  intero- and proproceptive. He studied the proprioceptive reflexes in the decerebrate animal.

He proved that muscle spindles and Golgi tendon organs were sensory organs, by the demonstration that their nerve fibres did not survive removal of dorsal root ganglia, and he defined spinal sensory and motor fields by selective transections of dorsal or ventral root fibres.

Nociceptive reflexes, including the “scratch reflex” were also analyzed and their pathways in the spinal cord mapped out.

He also defined the principle of the “final common path” and introduced the term “motoneurone” .

Sherrington was nominated for the Nobel Prize no less than 26 times, the first time in 1902, until he finally got his prize, in 1932, shared with Adrian.

Adrian’s work was confined to neurophysiology and the function of sense organs.

His first research work was done with his senior colleague Keith Lucas at Cambridge, whose laboratory he later (1919) took over. First of all, Adrian extended the work of Lucas on the all-or-none principle, which Lucas had shown for the striated muscle fibre, and Adrian could prove it in the nerve.

In 1925 he began investigating the sense organs introducing a new technique allowing an amplification of the signals up to about 5000 times. It permitted recording and visualization of far smaller potential changes than had been dealt with previously and   it enabled work on the units of the nerve trunk instead of on the aggregate.

To start with, Adrian had worked with nerves containing groups of nerve fibres. But in 1925, together with Yngve Zotterman from Stockholm, he managed to record from a single nerve fibre connected to a single muscle sensory ending in the frog. This was an important step forward, which opened possibilities for a refined analysis.

Further studies showed that different receptors had different abilities of adaptation, that the impulse frequency they gave rise to at

continuous stimulation decreased with different rates depending on the type of receptor. The proprioceptive end organs were found to be slowly adapting, whereas exteroceptive receptors showed rapid adaptation.

I would just like to quote Sherrington, who was behind one of the proposals for a Nobel Prize for Adrian. In his motivation in December 1931 he wrote that Adrian’s scientific achievements” carry the functional analysis over from a statistical group analysis stage to an analysis dealing specifically with the individual neurons” and further “It is an advance comparable on the functional side with that achieved by Golgi, Cajal, and others toward the end of last century on the morphological side.”

Erlanger and Gasser’s joint work was concerned with the electrophysiology of the nerves.

Together, in 1922, they adapted the cathode-ray valve for their studies and in 1932 they introduced a further technical improvement, which allowed an amplification of the recorded action potentials up to about one million times. Acton potentials from nerves had been recorded before, but their real time course had not been possible to visualize. Already in a paper from 1924 they recorded fast action potentials from electrically stimulated nerves and identified groups of such potentials showing different time courses. They considered this as most probably being explained by groups of nerve fibres with different conduction velocities. These were termed alfa, beta and gamma. In some instances they also found a fourth wave, which they called delta.

This figure shows the compound action potential. On the Ieft the action potentials recorded at various distances from the stimulating electrodes and on the right, a reconstruction of a compound action potential to show the reIative sizes and time reIationships of the components. From Ganong WF, Review of MedicaI PhysioIogy, 14th.ed, 1989.

The information about this prize and the remaining ones are quoted almost entirely from the Nobel web site.

Opinions as to how neurons communicate their signals across synapses were divided between those scientists who believed that the message was electrical, like the nerve impulse itself, and those who believed that chemicals must be involved, because extracts from plants and animals provoked a similar response to nerve stimulation.

Otto Loewi’s demonstration that chemicals act as the messenger was beautifully simple. He showed that if the vagus nerve fibres connected to an isolated heart of a frog were stimulated by electricity, it dampened the strength and rate of its heartbeat and a fluid was released. When he collected the fluid and added it to a second frog heart, its heartbeat was affected in exactly the same manner as the first heart without any nerve being fired.

Loew’s discovery of the nerve stimulating fluid (he called it Vagusstoff) came seven years after Sir Henry Dale had identified a chemical extracted from the fungus ergot, which appeared to stimulate organs in a similar manner. Dale speculated that this chemical, acetylcholine, and Loewi’s Vagusstoff were one and the same, and while looking for another chemical in mammals, he discovered that acetylcholine is produced naturally in the body. Developing methods for extracting acetylcholine from animal tissues allowed Dale and his colleagues to carry out a series of experiments that revealed how the chemical works. Among their many findings they showed that acetylcholine acts on many tissues and organs other than the heart, that it is released from nerve endings, and that it is almost immediately destroyed by another chemical once it has carried out its task.

The Nobel Prize in Physiology or Medicine 1936

In 1936 Sir Henry DaIe and Otto Loewi were awarded the NobeI Prize "for their discoveries reIating to chemicaI transmission of nerve impuIses" (TitIes, data and pIaces given above refer to the time of the award. Photos: Copyright © The NobeI Foundation)

The Nobel Prize in Physiology or Medicine 1963

Sir John EccIes, AIan Hodgkin and Andrew HuxIey were awarded the NobeI Prize in 1963 "for their discoveries concerning the ionic mechanisms invoIved in excitation and inhibition in the peripheraI and centraI portions of the nerve ceII membrane" (TitIes, data and pIaces given above refer to the time of the award. Photos: Copyright © The NobeI Foundation)

Seeking ways of measuring electrical currents inside nerves, Alan Hodgkin and his student Andrew Huxley turned to giant nerve fibres in the squid, which are almost a thousand times thicker than their human counterparts. Using tiny electrodes to record the electrical difference between the inside and outside of these nerves, they were surprised to find that the polarity did not drop from negative to zero during the transmission of an impulse as predicted, but in fact reversed, becoming electrically positive. By carrying out a series of measurements and using complex mathematical models to interpret the findings, Hodgkin and Huxley formulated a theory to propose how impulses are formed. Changes in the permeability of the cell membrane allow charged atoms to flow in and out of a nerve fibre, creating waves of electric charge that constitute the nerve impulse. During the rising phase of an impulse, positive sodium ions are allowed to flood in from the outside and in the falling phase potassium ions are allowed to migrate outwards from the inside.

Sir John Eccles showed how Hodgkin and Huxley’s findings also relate to the events that occur when an impulse is transmitted from one nerve cell to another. Eccles recorded minute but noticeable variations in electrical charge at the junctions, the synapses, between nerve cells shortly after an impulse arrives. This charge deviated in opposite directions depending on the synapse studied, which corresponded to the release of chemicals from the synapse that either excite or inhibit the neighboring cell. Releasing these chemicals causes microscopic channels to open across the cell membrane, creating a sieve that allows specific ions to flood through the membrane in a particular direction. Each nerve cells confronted by an enormous number of these excitatory and inhibitory signals coming from different synapses, and the decision as to whether to transmit or inhibit an impulse ultimately comes down to which type of signal outweighs the other.

The Nobel Prize in Physiology or Medicine 1970

In 1970 Sir Bernhard Katz, UIf von EuIer and JuIius AxeIrod received the NobeI Prize "for their discoveries concerning the humoraI transmittors in the nerve terminaIs and the mechanism for their storage, reIease and inactivation" (TitIes, data and pIaces given above refer to the time of the award. Photos: Copyright © The NobeI Foundation)

Sir Bernard Katz used microscopic recording electrodes to measure the electrical changes that occur when acetylcholine is released by nerve cells. From a series of measurements, he deduced that acetylcholine is released in highly defined amounts, and that acetylcholine molecules are stored in small bubble-like compartments, or synaptic vesicles, in nerve endings. When an impulse arrives, millions of acetylcholine molecules are released together into the synapse almost immediately, and Katz showed that calcium plays a key role in triggering this so-called “quantal release” of acetylcholine.

Ulf von Euler discovered another neuro-transmitter, noradrenaline, and established clearly how it works, including its importance for the control of the blood pressure. Its clinical implication for the treatment of severe hypotension Is well established.

Julius Axelrod’s work revealed what happens to noradrenaline after it has finished transmitting a nerve impulse. He discovered that, unlike acetylcholine, which is inactivated by enzymes, much of the noradrenaline is absorbed back into storage sites within the nerve ending that had just released it. Further studies made it evident that this recycling system is the rule rather than the exception for neurotransmitters. Axelrod also discovered drugs that inhibit the re-uptake process, and his discovery that antidepressants work in this manner stimulated the search for a much- needed new generation of treatments for depression.

Now there are still 11 Nobel Prizes in the neuroscience field remaining, so to have a chance to comment on them within a reasonable space, I will refrain from commenting on each single laureate.

There is aIso one prize that I have pIanned to Ieave out intentionaIIy, the one in 1949, not to WaIter RudoIf Hess “for his discovery of the functional organization of the interbrain  / mesencephalon / as a coordinator of the activities of the internal organs” but to Antonio Egas Moniz “for his discovery of the therapeutic value of leucotomy in certain psychoses”.

The one to Moniz has been questioned over the years but also defended due to the fact that, as pointed out correctly, it was not until 1952 that the first drug for treating mental illness, chlorpromazin, was introduced and that therefore many patients with schizophrenia still profited from the treatment with lobotomy before that time.

The Nobel Prize in Physiology or Medicine 2000

In the year 2000 Arvid CarIsson, PauI Greengard and Eric KandeI received the NobeI Prize "for their discoveries concerning signaI transduction in the nervous system" (TitIes, data and pIaces given above refer to the time of the award. Photos: Copyright © TheNobeIFoundation)

I would like to restrict my comments on this prize to Arvid Carlsson, not because he is a Swede, but since his contribution has had such a great impact in medicine.

Arvid CarIsson overturned conventional wisdom by showing that the chemical dopamine is an important neurotransmitter in the brain. Dopamine was presumed to be merely a precursor to a more important neurotransmitter, noradrenaline, but Carlsson devised a highly sensitive test, which allowed him to detect that dopamine was concentrated in parts of the brain that control movement. Animals’ movements froze when they were given a drug that depletes the brain of several neurotransmitters, reserpine, and Carlsson found that their movements miraculously returned when he gave them the chemical L-dopa, which the brain converts to dopamine. This eventually led to the use of L-dopa to treat Parkinson’s disease, the symptoms of which are caused by a lack of dopamine; and Carlsson also provided evidence that some forms of mental illness are associated with the disrupted regulation of dopamine.

Their contribution was to create the experimental measuring device that conclusively proved the existence and function of ion channels. Their patch clamp technique soon became an essential tool for scientists studying the activity and behavior of a host of ion channels in many types of cell, and also for understanding how defective regulation of ion channels underlie a host of diseases, including diabetes and cystic fibrosis.

The Nobel Prize in Physiology or Medicine 1991

In 1991 Erwin Neher and Bert Sakmann were awarded the NobeI Prize "for their discoveries concerning the function of singIe ion channeIs in ceIIs" (TitIes, data and pIaces given above refer to the time of the award. Photos: Copyright © The NobeI Foundation)

The Nobel Prize in Physiology or Medicine 1977

In 1977 Roger GuiIIemin and Andrew v. SchaIIy were awarded the NobeI Prize "for their discoveries concerning the peptide hormone production of the brain" and RosaIyn YaIow "for the development of radio immunoassays of peptide hormones" (TitIes, data and pIaces given above refer to the time of the award. Photos: Copyright © The NobeI Foundation)

Regarding Rosalyn Yalow: Together with her late co-worker, Solomon Berson, she described in a series of papers between 1956 -1960 the radioimmunological assay method (or RIA) in detail. This brought about a revolution in biological and medical research.

But in addition she and her co-workers, with the aid of RIA, were able to elucidate the physiology of the peptide hormones insulin, ACTH, growth hormone, and also to throw light upon the pathogenesis of diseases caused by abnormal secretion of these hormones. This was pioneering work at the highest level. It had an enormous impact.

Towards the end of the 1950’s, Guillemin and Schally, each in his own laboratory, were able to extract from the hypothalamus of sheep and pigs some compounds which, when administered to pituitary tissue, brought about release of its hormones. One extract made the pituitary release ACTH, another TSH (Thyroid Stimulating Hormone), a third one LH and FSH (the gonadotrophic hormones) etc.

They termed these substances “releasing factors or hormones”, RF or RH. However, it was not until 1969 that the nature of these hypothalamic factors would be established by them.

Guillemin’s and Schally’s discoveries laid the foundations to modern hypothalamic research. The experiences from animal research was rapidly transferred to humans and brought into clinical work. Several new peptides were isolated from the hypothalamus.

The Nobel Prize in Physiology or Medicine 1986

In 1986 StanIey Cohen and Rita Levi-MontaIcini received the NobeI Prize "for their discoveries of growth factors" (TitIes, data and pIaces given above refer to the time of the award. Photos: Copyright © The NobeI Foundation)

While investigating how the nervous system grows and develops, Rita Levi-Montalcini   observed that transplanting mouse tumours into chick embryos induced an enormous outgrowth of nerves, regardless of whether the tumour was grafted inside or outside the sac containing the embryo. Levi-Montalcini’s proposition that the tumour was somehow releasing a growth-promoting substance for nerves flew against the popular view. Further investigations, however, showed that this, so-called nerve growth factor, or NGF, is released by many types of cell looking for new nerve connections.
The fortuitous discovery by Levi-Montalcini’s colleague Stanley Cohen that snake venom and mammalian salivary glands are rich sources of NGF provided Cohen with the materials to successfully purify the protein and determine its structure. He also noticed that salivary gland extracts were exerting non-nerve related growth effects in newborn mice, with their eyelids opening and teeth appearing prematurely. Correctly attributing this effect to another growth inducing substance, which he termed epidermal growth factor, or EGF, Cohen and his co-workers went on to define the many ways in which EGF can influence major growth and development processes in an embryo.

The Nobel Prize in Physiology or Medicine 1976

The NobeI Prize in 1976 went to Baruch BIumberg & CarIeton Gajdusek "for their discoveries concerning new mechanisms for the origin and dissemination of infectious diseases" (TitIes, data and pIaces given above refer to the time of the award. Photos: Copyright © The NobeI Foundation)

The Nobel Prize in Physiology or Medicine 1997

The NobeI Prize in 1997 went to StanIey Prusiner "for his discovery of Prions - a new bioIogicaI principIe of infection" (TitIes, data and pIaces given above refer to the time of the award. Photos: Copyright © The NobeI Foundation)

The importance of their contribution can simply be illustrated by what happened in the United Kingdom in 1996 after the discovery of the so-called mad cow disease, caused by prion infection.

That resulted in the slaughtering of an enormous number /several millions / of cows, in order to prevent spread of the infection to humans.

The Nobel Prize in Physiology or Medicine 1967

In 1967 the NobeI Prize was shared between Ragnar Granit, HaIdan Keffer HartIine and George WaId "for their discoveries concerning the primary physioIogicaI and chemicaI visuaI processes in the eye" ( TitIes, data and pIaces given above refer to the time of the award. Photos: Copyright © The NobeI Foundation)

The Nobel Prize in Physiology or Medicine 1981

In 1981 Roger Sperry, David HubeI and Torsten WieseI received the NobeI Prize. Sperry: "for his discoveries concerning the functionaI speciaIization of the cerebraI hemispheres" and HubeI & WieseI: "for their discoveries concerning information processing in the visuaI system" (TitIes, data and pIaces given above refer to the time of the award. Photos: Copyright © The NobeI Foundation)

Just a brief comment on Wald and Granit’s contributions; Wald has discovered the chemical reaction that light triggers in the visual pigments and Granit’s studies on colour vison by means of electrophysiological methods led to the conclusion that there are different types of cones representing three characteristic spectral sensitives.

Sperry’s experimental studies in monkeys and studies of patients having undergone commissurotomy, for severe, intractable epilepsy, revealed the functional specialization of the two cerebral hemispheres. The isolated left hemisphere is in its general function analytical and computer-like. It can speak, write and make mathematical calculations; the right hemisphere is mute and generally lacks the possibility to communicate with the outside world, but contrary to what one previously thought, Sperry could show that it is clearly superior to the left hemisphere in many respects. This is especially true regarding the capacity for spatial consciousness and comprehension of complex relationships. It is also the superior hemisphere when it comes to interpreting auditory impressions and in comprehension of music.

Hubel and Wesel were able to demonstrate that the message reaching the brain from the eyes undergoes an analysis in which the various components of the retinal image are interpreted with respect to their contrasts, linear patterns and the movement of the image across the retina. This analysis occurs in a rigid sequence from one nerve cell to another in which each nerve cell is responsible for a certain detail in the image pattern – “orientation columns”.

They could also demonstrate the presence of “ocular dominance columns”.

Hubel and Wesel were also able to show by their experiments that the ability of the cells in the visual cortex to interpret the code of the impulse message from the retina is developed directly after birth. A prerequisite for this development to take place is that the eye be exposed to visual stimuli. If one eye is closed for only a few days during this period, permanent functional changes will take place in the visual cortex. Hubel and Wesel were able to show that light stimulation in itself was insufficient to bring about normal development of the visual cortex, and that it was necessary for the retinal image to have a pattern and many contours.

This discovery illustrates, first, the bran’s high degree of plasticity immediately following birth and, second, how important it is that the brain receives arch variety of visual stimuli during this period.

Autoradiograph

Dark-fieId autoradiograph of a section from the primary visuaI cortex (area17), foIIowing tritiated proIine injection into one eye in a macaque monkey [3) .

The Nobel Prize in Physiology or Medicine 2004

In 2004 the NobeI Prize was shared between Richard AxeI and Linda Buck "for their discoveries of odorant receptors and the organization of the olfactory system" (TitIes, data and pIaces given above refer to the time of the award. Photos: Copyright © The NobeI Foundation)

Professor Sten GriIIner

The Presentation Speech for this prize was given by Professor Sten GriIIner of the NobeI AssembIy at KaroIinska Institutet on December 10th, 2004.

Quotaton of parts of Sten Grllner’s Speech:  Fora long time, it has been known that the olfactory receptor cells are located far up in the nose, and that they send their thin neural processes through small canals in the bone directly to the part of the brain called the olfactory bulb. Many important details of how the sense of smell is designed were also known, but up to the elegant studies of Richard Axel and Linda Buck, the basic mode of operation of the sense of smell was not understood. In their studies on mouse, they showed that no less than 3% of the genes were coding for olfactory receptors – docking stations for different odorants. They are large molecules located in the cell membrane of the olfactory cells that react to different odorants that pass through the nose. This large gene family “manufactures” around 1000 different types of docking stations, each of which responds to only a few odorants. It was subsequently shown that each type of olfactory cell only expresses a single type of docking station in its cell membrane. In the mouse there are thus 1000 different types of olfactory receptor cells.

This illustrates 4 out of the 1000 different types. For each type, there are a large number of copies spread in the mucosa of the nose.

The mouse thus has no less than 1,000 different types of receptor cells or sensors that react to different odorants. In humans some of the genes have degenerated and we may have as little as 350 types of sensors. The olfactory world of a mouse or a dog is most likely, infinitely richer than our own. Neverthe less our sense of smell adds importantly to our quality of life. Each population of receptor cells sends their processes to the same specific micro-regions in the olfactory bulb, which in turn relays the information to the next set of nerve cells. They project to the cortical regions concerned with the perception of smell.

A stereotyped map of oIfactory receptor inputs in the oIfactory buIb
A stereotyped map of oIfactory receptor in puts in the oIfactory cortex

The awareness of one’s location and how to find the way to other places is crucial for both humans and animals.

The Nobel Prize in Physiology or Medicine 2014

The NobeI Prize in PhysioIogy or Medicine 2014 was divided, one half awarded to John O'Keefe, the other half jointly to May-Britt Moser and Edvard I. Moser "for their discoveries of ceIIs that constitute a positioning system in the brain"(Photo: A. Mahmoud)

To understand the ability to orient ourselves in space, John 0’Keefe studied the movements of rats and signals from nerve cells in the hippocampus. In 1971 he discovered that when a rat was at a certain location in a room, certain cells were activated, and that when the rat moved to another location, other cells became activated. That is to say, the cells form a kind of internal map of the room. They provide the brain with spatial memory capacity.

In 2005 May-Britt Moser and Edvard I. Moser discovered in the medial entorhinal cortex, a region of the brain next to hippocampus, grid cells that provide the brain with an internal coordinate system essential for navigation. They found that when a rat passed certain points arranged in a hexagonal grid in space, nerve cells that form a kind of coordinate system for navigation were activated. They then went on to demonstrate how these different cell types cooperate.

Together, the hippocampal place cells and the entorhinal grid cells form interconnected nerve cell networks that are critical for the computation of spatial maps and navigational tasks.

The discoveries are ground breaking and provide insights into how mental functions are represented in the brain and how the brain can compute complex cognitive functions and behavior.

[1] Grant G. The 1932 and 1944 Nobel Prizes in physiology or medicine: Rewards for ground-breaking studies in neurophysiology. J Hist Neurosci, 2006, 15(4): 341 – 357.

[2] Wiksten B. The central cervical nucleus in the cat. A Golgi study. Exp Brain Res, 1979, 36(1): 143-154

[3] Hubel DH, Wiesel TN. Brain Mechanisms of Vision. Sci Am, 1979, 241(3): 150 – 162.

Journal of Translational Neuroscience, 2016, 1 (1): 1 – 16, DOI: 10.3868/j. issn.2096 – 0689.01.001

Addendum

Photo: A. Mahmoud

One laureate whose name should reasonably also have been included in the article above is Thomas C. Südhof who shared the 2013 Nobel Prize with James E. Rothman and Randy W. Schekman “for their discoveries of machinery regulating vesicle traffic, a major transport system in our cells”.

His contribution was a beautiful continuation of the prize awarded to Bernard Katz in 1970. Thus, Thomas Südhof, using i.a. genetically modified mice, identified mechanisms and molecules critical for Ca2+-dependent, fast release of neurotransmitter substances at synapses in the brain.