Wilder Penfield - Neural Stimulation

Neural Stimulation

Penfield was a groundbreaking researcher and highly original surgeon. With his colleague, Herbert Jasper, he invented the Montreal procedure, in which he treated patients with severe epilepsy by destroying nerve cells in the brain where the seizures originated. Before operating, he stimulated the brain with electrical probes while the patients were conscious on the operating table (under only local anesthesia), and observed their responses. In this way he could more accurately target the areas of the brain responsible, reducing the side-effects of the surgery.

This technique also allowed him to create maps of the sensory and motor cortices of the brain (see cortical homunculus) showing their connections to the various limbs and organs of the body. These maps are still used today, practically unaltered. Along with Herbert Jasper, he published this work in 1951 (2nd ed., 1954) as the landmark Epilepsy and the Functional Anatomy of the Human Brain. This work contributed a great deal to understanding the lateralization of brain function. Penfield's maps showed considerable overlap between regions (i.e. the motor region controlling muscles in the hand sometimes also controlled muscles in the upper arm and shoulder) a feature which he put down to individual variation in brain size and localisation; we now know that this is due to the fractured somatotropy of the motor cortex.

Penfield reported that stimulation of the temporal lobes could lead to vivid recall of memories. Oversimplified in popular psychology publications, including the best-selling I'm OK, You're OK, this seeded the common misconception that the brain continuously "records" experiences in perfect detail, although these memories are not available to conscious recall. In reality, however, the reported episodes of recall occurred in less than five percent of his patients, and these results have not been replicated by modern surgeons. His development of the neurosurgical technique that produced the less injurious meningo-cerebral scar became widely accepted in the field of neurosurgery, where the "Penfield dissector" is still in daily use.