Edgar Adrian, 1st Baron Adrian

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British neurophysiologist (1889–1977)

Adrian, a lawyer's son, was born in London and studied at Cambridge University and St. Bartholomew's Hospital, London, where he obtained his MD in 1915. He returned to Cambridge in 1919, was appointed professor of physiology in 1937, and became the master of Trinity College, Cambridge, in 1951, an office he retained until his retirement in 1965. He was raised to the British peerage in 1955.

Adrian's greatest contribution to neurophysiology was his work on the nerve impulse. When he began it was known that nerves transmit nerve impulses as signals, but knowledge of the frequency and control of such impulses was minimal. The first insight into this process came from Adrian's colleague Keith Lucas, who demonstrated in 1905 that the impulse obeyed the ‘all-or-none’ law. This asserted that below a certain threshold of stimulation a nerve does not respond. However, once the threshold is reached the nerve continues to respond by a fixed amount however much the stimulation increases. Thus, increased stimulation, although it stimulates more fibers, does not affect the magnitude of the signal itself.

It was not until 1925 that Adrian advanced beyond this position. By painstaking surgical techniques he succeeded in separating individual nerve fibers and amplifying and recording the small action potentials in these fibers. By studying the effect of stretching the sternocutaneous muscle of the frog, Adrian demonstrated how the nerve, even though it transmits an impulse of fixed strength, can still convey a complex message. He found that as the extension increased so did the frequency of the nerve impulse, rising from 10 to 50 impulses per second. Thus, he concluded that the message is conveyed by changes in the frequency of the discharge. For this work Adrian shared the 1932 Nobel Prize for physiology or medicine with Charles Sherrington.

The English neurophysiologist Edgar Douglas Adrian, 1st Baron Adrian of Cambridge (born 1889), shared the Nobel Prize for Physiology or Medicine with Sir Charles Sherrington for their discoveries regarding the functions of neurons.

Edgar Douglas Adrian, born in London on Nov. 30, 1889, was the second son of A. D. Adrian, legal adviser to the Local Government Board. He entered Trinity College, Cambridge, in 1908 and graduated with honors in the natural sciences in 1911. He then embarked on research in physiology, and in 1913 he was elected a fellow of Trinity. Thereafter he took his clinical courses at St. Bartholomew's Hospital, London, and he graduated in medicine at Cambridge in 1915. During the remainder of World War I he studied service men suffering from nerve injuries and nervous diseases, and after the war he lectured on the nervous system at Cambridge. There he was Foulerton research professor of the Royal Society from 1929 until 1937, when he became professor of physiology in Cambridge University.

Early Researches on Single Nerve Fibers

Much experimental work during the 19th and early 20th centuries had shown that, when an isolated motor nerve was stimulated electrically, the resulting nerve impulse not only caused contraction of the muscle associated with that nerve but was accompanied by a change of electric potential (the action current) at the active point of the nerve. This current passed along the nerve at great speed. It was sufficiently strong to be measured by a very delicate capillary electrometer, and the oscillations produced in the mercury level could be recorded by photography on a moving strip of paper. At any point on the nerve the activity lasted for only a few thousandths of a second, and that point became temporarily refractory to further stimulation as soon as the impulse had passed it. In 1909 Keith Lucas proved the important "all-or-none" principle in muscle, that is, in a motor nerve. This principle implied that, in a nerve fibril, a stimulus just strong enough to cause a contraction in the muscle fibers which it supplied produced a maximum contraction in these fibers. In a motor nerve an increase in the stimulus acted by bringing more nerve fibers into action.

By the early 1920s practically all the work in this field had been done on motor nerves because the instruments then available were not sufficiently sensitive to detect the extremely minute impulses produced by the stimulation of sensory nerves. Adrian had been a pupil of Keith Lucas, and before the war, while he was Lucas's assistant, they had discussed the possibility of amplifying the minute currents in sensory nerves and of sensitive methods for recording them. Lucas died in an airplane accident in 1916, and when Adrian returned to Cambridge after the war he began experiments on the lines previously discussed with Lucas. By 1927, using a three-or four-valve amplifier, he had attained a 5000 amplification. By varying the tension in a frog's muscle Adrian showed that the "all-or-none" principle applies also to sensory nerves. But he soon found that his results were influenced by the fact that even the smallest sensory nerves receive impulses from many end organs. It was therefore necessary to study the reactions in single nerve fibers.

The reactions in a single nerve fiber were first demonstrated in 1926 by Adrian, working at Cambridge with a Swedish collaborator. In a frog muscle they were able to dissect out a strip containing a single muscle spindle attached to a single nerve fiber. When this muscle spindle was stimulated by stretching the muscle strip, they obtained a regular series of responses at intervals of 0.03 second. Adrian also found that in all the sense organs that give a prolonged discharge under a constant stimulus - such as muscle spindles and tactile endings - the record shows a rhythmic series of impulses, their frequency depending on the rate of development of the stimulus and on its intensity. In the case of a muscle spindle the frequency therefore depends on the extent and rapidity of the stretch. The stimulus acts as a trigger to release a nerve impulse. The total activity of a fiber can be increased by increasing the frequency of the impulses produced, but not by increasing the strength of the stimulus. The message in a nerve fiber can therefore be varied only by changing the frequency and duration of the discharge.

These experiments also showed that nerves possess the power of adaptation. A steady current passed through a frog muscle produced only one impulse, owing to the very rapid adaptation of the nerve. But steady tension on a muscle spindle, in which adaptation is very slow, produces a succession of impulses in the nerve fiber.

Adrian then turned to the sequence of events in sensory end organs in general. By 1928 he had shown that, in the case of pressure on the skin, the frequency of the impulses varied with the rate of increase of pressure and declined when the pressure remained constant. But when an object touches the skin, there is at that moment a sudden and rapid outburst of impulses, after which the impulses cease. In the case of pain he was unable to obtain clear-cut results or to confirm that pain is due to impulses in specific pain fibers. It seemed possible that pain might be due to very slow impulses.

Activity of Nerve Cells

In 1931 Adrian began to study impulses arising automatically in the brain, for example, in the cells of the respiratory center. In the isolated brain of a goldfish he found the impulses had a regular frequency of 20 to 60 a minute, corresponding in frequency with the gill movements of an intact fish. In an attempt to reduce the number of nerve cells concerned in the reactions, he next investigated the persistent activity that occurs in excised portions of the central ganglia of the water beetle Dytiscus, in which the activity shows the characteristic rhythm of the respiration in that insect. He concluded that the activity of nerve cells is probably due to a slow depolarization of the cell body or its dendrites. The active state in a group of nerve cells implies a surface change like that in the nerve fiber, but, contrary to the momentary change in the nerve fiber, it can persist for long periods and vary in intensity.

It was for the researches described up to this point that Adrian shared the Nobel Prize in 1932.

Rhythm of the Higher Centers

In 1929 Hans Berger discovered that, if electrodes were applied to the head of a conscious subject, a rhythmic disturbance having a frequency of about 10 per second could be recorded. These waves - Berger's alpha rhythm - were often present when the eyes were closed but disappeared when they were opened. The tracing recording the waves was called an electroencephalogram (EEG). About 1934, and later, Adrian studied these waves thoroughly and greatly extended their usefulness in conditions such as epilepsy. He showed that the rhythm occurs essentially in an inattentive subject. If the subject's eyes, when open, gaze at a uniform screen or are covered by glasses that blur the vision, the rhythm decreases only slightly. Adrian found that the waves were produced in a large area of the occipital and parietal regions of the cortex. He also found that, if the subject looked at a screen illuminated by a light flickering at, say, 18 flickers a second, the brain rhythm kept pace with the rate of flicker. In 1934 he also showed that the cerebellum has a spontaneous rhythm of very high frequency waves (150 to 250 per second).

Special Senses and Cortical Representation

A cat, when dropped in any position from a height, always lands on its feet owing to positional impulses received by the vestibular nucleus in the hindbrain. During the war Adrian found that this nucleus reacted to two different kinds of responses, and he studied variations in them induced by changes in the position of the body. In 1943 he studied the impulses received by the cerebellum of a monkey when various parts of its body were moved passively, and he was able to define the different areas in the cerebellum associated respectively with the forelimb, the hindlimb, and the face region.

In 1943 Adrian also studied the relative sizes of the sensory receiving areas of the cerebral cortex connected with different parts of the body in various animals. He found that the size of an area depended on the importance of the information received by it. In humans, the fingers, important in exploring the environment, received generous representation. In the cat the emphasis is on the forelimb, and in the pig the whole of the receiving area appears to be devoted to the snout. In 1946 Adrian found that in the pony and sheep the area devoted to the nostrils is as large as that for the whole of the rest of the body.

Adrian's last writings on neurophysiology (1950-1956) dealt with the olfactory sense. The primary olfactory fibers are so short and thin that it was not possible to record from them, but he obtained records from the olfactory bulb. Deep anesthesia suppressed the spontaneous discharges from the olfactory bulb, and records were then made of the discharges produced by the animal inhaling various odoriferous substances. In the cat he distinguished three different types of discharge, associated respectively with ethereal, oily, and fishy odors. He also obtained important evidence of a process of adaptation in the olfactory nerves.

Later Life

In 1951 Adrian retired from his chair and became Master of Trinity College, Cambridge, an office which he held until 1965. He was vice-chancellor of the University of Cambridge from 1957 to 1959 and chancellor from 1968. He was also the first chancellor of the University of Leicester. In 1942 he was appointed to the Order of Merit, and in 1955 he was created 1st Baron Adrian of Cambridge.

Adrian was the recipient of many honors in addition to his Nobel Prize. In 1923 he was elected a Fellow of the Royal Society. He was its Croonian Lecturer in 1931 and its Ferrier Lecturer in 1938; he received its Royal Medal in 1934 and its Copley Medal - its highest award - in 1946. He served as its Foreign Secretary from 1946 to 1950, and he was president of the society from 1950 to 1955. In 1924 he was elected a Fellow of the Royal College of Physicians of London, and he received several honors in that college. He was president of the Royal Society of Medicine in 1960-1962, and he was awarded that society's Gold Medal in 1950. From 1962 to 1965 he was a trustee of the Rockefeller Institute. He was an honorary fellow of many foreign learned societies, and he received honorary degrees from 33 universities throughout the world.

Throughout his career Adrian wrote numerous scientific articles and published three books, each of which marks a stage in his researches: The Basis of Sensation (1928), The Mechanism of Nervous Action (1932), and The Physical Background of Perception (1947).

On August 4, 1977, Adrian died in London, England. Although he retired from Cambridge in 1965, he continued to live at the college almost until his death. Throughout his life, Adrian was active, enjoying sports such as mountain climbing, fencing, sailing, and bicycle riding. Adrian also took a keen interest in the arts, and particularly enjoyed painting, even meriting an exhibition of 80 of his works at Cambridge.

Further Reading

A short biography of Lord Adrian will be found in Nobel Lectures, Physiology or Medicine, 1922-1941 (1965). This work also contains his Nobel Lecture, which summarizes his earlier work, mainly on single nerve fibers and the end organs. There is a brief discussion of Adrian's work in general in C. Singer and E. A. Underwood, A Short History of Medicine (1962); and a few extracts from his writings are given in E. Clarke and C. D. O'Malley, The Human Brain and Spinal Cord (1968). Reference may also be made to J. F. Fulton, Physiology of the Nervous System (1949). Later biographical material appears in Notable Twentieth-Century Scientists, Volume I (Detroit: Gale, 1995) and Nobel Laureates in Medicine or Physiology (1990), edited by Daniel Fox, Marcia Meldrum, and Ira Rezak.

Adrian, Edgar Douglas, 1st Baron Adrian (1889-1977). Scientist. Born in London, Adrian went to Westminster School and Trinity College, Cambridge. Specializing in physiology, he became a fellow of his college in 1913 and then spent the First World War treating cases of shell-shock. Adrian returned to Cambridge in 1919 and published extensively on the nervous system. He shared the Nobel prize in 1932, held the chair of physiology from 1937 to 1951, and was master of Trinity from 1951 to 1965.

1st Baron Adrian (1889–1977). Adrian was born in London and educated at Westminster School, where he became a King's Scholar at the end of his first term. Like his mentor at Cambridge, Keith Lucas (1879–1916), he at first studied classics but went over to science in his last year. He went up to Cambridge as a scholar of Trinity College, where he read medicine, and became a Fellow in 1913. On the outbreak of war in 1914, he completed his medical studies at St Bartholomew's Hospital, London. After qualifying, he obtained a resident appointment at the National Hospital for Nervous Diseases, Queen Square, London, following which he became medical officer at the Connaught Military Hospital at Aldershot. After the war he returned to the Cambridge Physiological Laboratory to continue the work he had started in association with Keith Lucas, who had died as the result of a flying accident in 1916. Keith Lucas's interest had centred on 'all-or-nothing' activity in skeletal muscle and in motor nerves, and there is no doubt that Adrian conceived it to be a pious duty to carry on and complete his work.

In November 1925 he succeeded in recording with Lucas's capillary electrometer the impulse traffic in a single afferent nerve fibre. He wrote of the experiment in this way:

• At all events the great simplicity of the discharge from the sensory end organ came as an exciting and welcome surprise. Bitter experience does not encourage physiologists to suppose that their material will give predictable reactions except under the most rigorously controlled conditions, but the stretch receptors in the frog's muscle did not merely give a discharge which could be reproduced many times without variation, there was the added pleasure of finding that the discharge from each unit was a simple series of impulses varying only in frequency in accordance with the strength of the stimulus. It cannot be often that a general principle like this is as plainly revealed in the course of a single experiment.

This experiment finally proved that Lucas and Adrian's conception of the 'all-or-nothing' character of the propagated nervous impulse, based on indirect evidence, was true. The transmission in the nerve fibre occurs according to what today would be called impulse frequency modulation.

Adrian was always hunting big game: 'the unsatisfactory gap between two such events as the sticking of a pin into my finger and the appearance of pain in my consciousness', as he wrote in Basis of Sensation (1928). In this book he gives a summary of the experiments on the muscle spindle, on the cutaneous senses (touch, pressure, and pain), and on the optic nerve, which he performed within the course of only two years.

It is amazing to read today how at that early date he had arrived at the following fundamental view on the relation between the sensation and the impulse frequency in sensory nerve fibres:

• The simplicity of the relation is at once very natural and very surprising. It means that our mind receives all the information which can be got out of the messages from those receptors which are in touch with it, but it means also that the mental correlate is a very close copy of the physical events in the sensory nerves. The only kind of distortion which takes place in the transference from body to mind (or in the parallelism of the bodily and mental events) is that the sensations rise and fall smoothly, whereas the nervous message consists of a series of discrete impulses with pauses in between. Somewhere on the way between the two there must be a smoothing process which converts the disconnected impulses into a change of much slower period.

Adrian's study of the adaptation in various sensory receptors led him further to the suggestion, seen in Fig. 1, that the excitatory state in the receptor consists of a slow potential, the peak height of which varies with the strength of the stimulus. This receptor potential modulates the impulse frequency transmitted in the nerve fibre via relay stations (synapses) to the cerebral cortex, inducing there the 'evoked potential' which integrates the series of impulses into a 'quasi-steady effect', as Adrian suggested in 1928. 'The diagram [Fig. 1] does not bridge the gap between stimulus and sensation,' he concludes in Basis of Sensation, 'but at least it shows that the gap is a little narrower than it was before.' This was typical of his modesty. Recent parallel recordings in humans of the neural and perceptual responses to sensory stimuli have proved that there is a close linear relation between the two events, thus definitely confirming Adrian's pioneer conception of 1928.

From these early recordings followed a quick development. Adrian's simple amplifier and Keith Lucas's capillary electrometer and camera were gradually exchanged for new inventions — Matthews's iron-tongue oscillograph, cathode ray oscillographs, etc. — which enabled Adrian and the hundreds of his followers all over the world to study the inflow and outflow of nerve impulses and to record the bio-electrical events within the whole nervous system. In nearly all these fields Adrian was the leader who opened the field or who made the proper analysis and interpretation of bio-electrical phenomena: for instance, the cochlear microphonics first described by Wever and Bray, and the electroencephalogram discovered by Hans Berger in Germany.


Fig.1. Relation between stimulus, sensory message, and sensation.
Adrian used to work alone and had not more than a dozen co-workers through all his active period in the famous basement room of the Cambridge Physiology Laboratory, which covered nearly 60 years. He was Foulerton Research Professor of the Royal Society from 1929 to 1937, when he succeeded Joseph Barcroft as professor of physiology at Cambridge. In 1951 he was appointed master of Trinity College, and from 1950 to 1955 he was president of the Royal Society. He shared the Nobel Prize in physiology or medicine with Sir Charles Scott Sherrington in 1932, received the Order of Merit in 1942, and delivered the Waynflete Lectures at Magdalen College, Oxford, in 1946. These lectures were published by the Clarendon Press in the following year under the title The Physical Background of Perception.

Although Adrian never thought of himself as a psychologist, he was a founder member of the British Psychological Society and greatly encouraged the growth of experimental psychology in the University of Cambridge; in particular, he held the young Cambridge psychologist Kenneth Craik in high regard and commented on his achievement in the Waynflete Lectures. Adrian was by no means unsympathetic to psychoanalysis in spite of his firm belief that psychology should develop on the model of the biological sciences.

In 1955 he was created Baron Adrian, and in 1967 was elected chancellor of Cambridge University. He died in his eighty-eighth year, in August 1977. At his funeral, the master of Selwyn College, Professor Owen Chadwick, said: 'I am not sure what wisdom is, but whatever it is, Adrian had it'.

(Published 1987)

— Y. Zotterman/O. L. Zangwill

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