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. 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 m