John Carew Eccles

Sir John Carew Eccles (January 27, 1903–May 2, 1997) was an Australian neurophysiologist who won the 1963 Nobel Prize in Physiology or Medicine for his work on the synapse. He shared the prize together with Andrew Fielding Huxley and Alan Lloyd Hodgkin.

Research

In the early 1950s, Eccles and his colleagues performed the key experiments that would win Eccles the Nobel Prize. To study synapses in the peripheral nervous system, Eccles and colleagues used the stretch reflex as a model. This reflex is easily studied because it consists of only two neurons: a sensory neuron (the muscle spindle fiber) and the motor neuron. The sensory neuron synapses onto the motor neuron in the spinal cord. When Eccles passed a current into the sensory neuron in the quadriceps, the motor neuron innervating the quadricep produced a small excitatory postsynaptic potential (EPSP). When he passed the same current through the hamstring, the opposing muscle to the quadricep, he saw an inhibitory postsynaptic potential (IPSP) in the quadricep motor neuron. Although a single EPSP was not enough to fire an action potential in the motor neuron, the sum of several EPSPs from multiple sensory neurons synapsing onto the motor neuron could cause the motor neuron to fire, thus contracting the quadricep. On the other hand, IPSPs could subtract from this sum of EPSPs, preventing the motor neuron from firing.

Related Topics:
1950s - Reflex - Neuron - Muscle spindle - Motor neuron - Spinal cord - Quadriceps - Excitatory postsynaptic potential - Hamstring - Inhibitory postsynaptic potential - Action potential

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Apart from these seminal experiments, Eccles was key to a number of important developments in neuroscience. Until around 1949, Eccles believed that synaptic transmission was primarily electrical rather than chemical. Although he was wrong in this hypothesis, his arguments led himself and others to perform some of the experiments which proved chemical synaptic transmission. Bernard Katz and Eccles worked together on some of the experiments which elucidated the role of acetylcholine as a neurotransmitter.

Related Topics:
Neuroscience - 1949 - Synaptic transmission - Bernard Katz - Acetylcholine - Neurotransmitter

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