<P> Penfield was a groundbreaking researcher and 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 . </P> <P> 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 localization 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: it has since been established that this is due to the fractured somatotropy of the motor cortex . From these results he developed his cortical homunculus map, which is how the brain sees the body from an inside perspective . </P> <P> 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 . Reported episodes of recall occurred in less than five percent of his patients, though these results have been replicated by modern surgeons . Penfield's hypothesis on this subject was revised in 1970 . His development of the Penfield dissector, the neurosurgical technique that produced the less injurious meningo - cerebral scar, became widely accepted in the field of neurosurgery and remains in regular use . </P> <P> Penfield's scientific contributions go past the somatosensory and the motor cortices, his extensive work of the functions of the brain also included charting the functions of the parietal and temporal cortices . Of his 520 patients, 40 reported that while their temporal lobe was stimulated with an electrode they would recall dreams, smells, visual and auditory hallucinations, as well as out - of - body experiences . In his studies, Penfield found that when the temporal lobe was stimulated it produced a combination of hallucinations, dream, and memory recollection . These experiences would only last as long as the electrode stimulations were present on the cortex, and in some cases when patient experienced hallucinatory experiences that evoked certain smells, sensations of flashing light, stroking the back of their hand, and many others . Other stimulations had patients experiencing deja vu, fear, loneliness, and strangeness . Certain areas of patients' temporal lobes were stimulated with an electrode in order to experience past memories . Penfield called these perceptual illusions (physical hallucinations) interpretive responses . According to Penfield, when the temporal lobe was stimulated there were two types of perceptions experienced by patients: </P>

With electrical stimulation during brain surgery penfield reported that patients