The scientific career of Alexander Forbes spanned fifty-six years of active research and saw the development of the realm of neurophysiology to which he contributed over 100 publications.
As a proper Bostonian of his day he could scarcely avoid going to Harvard. He graduated in 1905. He also received a Master’s Degree in Biology from that institution in 1906 before undertaking a degree at Harvard Medical School. By the time he received his M.D. in 1910 he had been infected with the lure of the research laboratory while he learned the rudiments of electrophysiology with Professor G. H. Parker. In his fourth year of studies he was challenged by application of these techniques to problems in inhibition in the central nervous system reflex pathways under the guidance of Professor Walter B. Cannon.
After Forbes graduated Dr. Cannon immediately offered him the position of Instructor in Physiology, but further suggested he go to Liverpool to work with Sir Charles Sherrington for two years. In England Forbes also spent a short time with Keith Lucas and E. D. Adrian in Cambridge while they were pioneering the biophysics of peripheral nerve.
Forbes returned to Harvard Medical School “armed with a Sherrington Guillotine and a Lucas pendulum” (1) and a mind prepared to attempt the process of grafting the precise biophysical techniques of peripheral nerve studies to the relatively complex reflexes studies by the Sherrington school. With Alan Gregg he proceeded to develop electrical recordings of the myographic results of flexor reflexes. The two papers which resulted demonstrated electrical recordings of central reflex phenomena for the first time. (2) The tool of the time was the string galvanometer. Forbes had one of the first in New England.
However, the spread of World War I now began to modify everyone’s plans. Forbes who had grown up in a seafaring family was an expert in off-shore navigation. He enlisted in the Navy. To his surprise instead of going to sea he was assigned to work with a firm called Submarine Signal Corp. (later to become Raytheon) where the priority was development of submarine detection devices, the classical “pingers” used on submarine chasers.
Postwar in 1918 Forbes utilized his electrical experience to develop vacuum tube amplification for the string galvanometer. The result was a fifty fold increase in sensitivity (to 20 uV/cm at 200 Hz). This was a remarkable breakthrough! He could now display spike potentials of propagated impulses with significant detail. The resulting paper published with Thacher in 1920 pioneered amplification and recording techniques and provided reliable observations which Forbes immediately put to use studying the phenomena of reflex action. (3)
Another season in England in 1921 working with Adrian led Forbes and Adrian to write a paper which demonstrated definitively that CNS motor units followed the all-or-nothing principle. (4) Forbes followed that the next year with a magnificent review article which established him as master of the new developments in neurophysiology. (5) To understand the significance of being able to state that the CNS is made of nerve fibers that have the same properties as peripheral nerve fibers one must remember that the leading theory of inhibition at that time, the McDougall drainage theory of inhibition, postulated that “.. the CNS had channels in which nervous energy moved just like water in a pipe with many branches, so that if some branches were open there would be drainage from a reservoir of ‘free nervous energy’ with a consequent ‘inhibition’ of flow along other channels.” (6) Forbes further suggested that understanding mechanisms of transmission of nerve to muscle would shed light on the function of central synapses. On the strength of that publication he was promoted from Instructor directly to Associate Professor. He would become full Professor in 1936.
In subsequent years Forbes went on to develop the idea that reverberating circuits and delay paths explain to a considerable extent prolonged excitatory responses. He also had the correct idea on muscle tonus, postulating that prolonged contraction was due to motor neurons firing at slow frequencies. These ideas were later verified by on-going studies by Denny-Brown, Adrian and Bronk when better techniques became available. Another classic paper was published in 1940 with Renshaw and Morison on the analysis of field potentials in the CNS. (7)
Although physiology was his mainstream, Dr. Forbes was also accomplished at sailing, figure skating, skiing and riding. He piloted his own airplane and grumbled good naturedly when forced to relinquish night flying certification after his seventieth birthday. This latter avocation had led him to spend summers in the mid-thirties perfecting the techniques of taking oblique photograms from the cockpit of a small airplane while he mapped the uncharted coast of Labrador. As World War II approached, although close to 60 years of age, he again enlisted in the Navy to avail the military of his wealth of geographical knowledge of the Northern Atlantic coast. His expertise was vital to the selection of sites for airstrips in Labrador expediting the transfer of fighter planes from North America to Europe.
When Dr. Forbes became Emeritus Professor in 1948 he moved from the Harvard Medical School to the Harvard Biological Laboratories in Cambridge, Massachusetts. There he and George Wald pursued studies on the comparative physiology of color vision in laboratory space made available by Dr. John Welsh. Their work helped to establish that three separate pigments in the retina of the eye are involved in perception of color.
Alexander Forbes died in 1965 at the age of eighty-three. Dr. Forbes is remembered as a man of enormous accomplishment, and a rare zest and enthusiasm for life. As one of the founding Trustees of the Grass Foundation he endowed that organization with a love for the adventure of new ideas, a priority for assisting young investigators, and a program focus to direct its resources to the growth of neurophysiology. Because he was a life-long neighbor of MBL and collaborator and friend of many of the early MBL community, the Grass Foundation has named these two annual lectures as an on-going memorial.
1) Alexander Forbes Memorial, Harvard University Gazette, Vol. LXI, No. 5 October 16, (1965).
2) A. Forbes, and A. Gregg, American J. Physiol., 37: 118, (1915) Ibid, 30: 172, (1915).
3) A. Forbes and C. Thacher, American J. Physiol., 52: 409, (1920).
4) E. D. Adrian and A. Forbes, J. Physiol., 456: 301, (1922).
5) A. Forbes, Physiol. Rev., 2: 361, (1922).
6) J. C. Eccles, Perspectives in Biology and Medicine. 13, No. 3, Spring, (1970).
7) B. Renshaw, A. Forbes, R. B. Morison, J. Neurophysiol., 3: 73, (1946).