The first direct recorded action potential by Hodgkin and Huxley

Sir Alan Lloyd Hodgkin

Sir Alan Lloyd Hodgkin
(1914 - 1998)

Sir Andrew Huxley

Sir Andrew Huxley
(1917 - 2012)

How does one neuron communicate with others? Now we owe it to the transmission of electric signals along nerve fibers. This signal, also known as action potential or spike, was first recorded by British neurophysiologists Sir Alan Lloyd Hodgkin and Sir Andrew Fielding Huxley more than seventy years ago. For their experimental and mathematical work on the basis of action potential, the 1963 Nobel Prize for Physiology or Medicine was awarded to them together with Sir John Carew Eccles.

Huxley became one postgraduate student from Hodgkin at Trinity College, Cambridge in 1939. At that time, it remained challenging to study objects such small as most neurons. Hodgkin and Huxley overcame this by ingeniously choosing giant axon of the Atlantic squid, which has the largest neurons ever known, thousand times thicker than their human counterparts. To record the electrical currents from the giant axon, they developed an earliest technique of electrophysiology, known as "voltage clamp", by using the electrodes to record the electrical difference from inside and outside of cell membrane. Finally, based on these two critical elements, they managed to record the action potential from an axon and published this great result in Nature.

The action potential of squid giant axon

Fig.1: The action potential of squid giant axon recorded by Hodgkin and Huxley.
(Credit: Hodgkin, Alan L., and Andrew F. Huxley)

Photomicrograph of electrode inside giant axon

Fig.2: Photomicrograph of electrode inside giant axon.
(Credit: Hodgkin, Alan L., and Andrew F. Huxley)

Their work on neurophysiology was interrupted by the World War II for several years. But they came back to research in 1952 with an elegant mathematical model which describes the ionic mechanisms underlying initiation and propagation of action potentials in the axon. This model was later on named "Hodgkin-Huxley model", containing a set of differential equations which approximated the electrical characteristics of neurons and hypothesized ion channels.

In the Nobel speech, Hodgkin said, "Research in neurophysiology is much more like paddling a small canoe on a mountain river. The river which is fed by many distant springs carries you along all right though often in a peculiar direction. You have to paddle quite hard to keep afloat. And sooner or later some of your ideas are upset and are carried downstream like an upturned canoe." Probably his unfinished sentences would be, "However, with the curiosity and passion in your mind, you will always enjoy the beautiful scenery along the river."

You may be interested in:

Hodgkin, Alan L., and Andrew F. Huxley. "Action potentials recorded from inside a nerve fibre." Nature 144, no. 3651 (1939): 710-711.

Hodgkin, Alan L., and Andrew F. Huxley. "A quantitative description of membrane current and its application to conduction and excitation in nerve." The Journal of physiology 117, no. 4 (1952): 500.