Modern neuropsychology owes an unusual debt to epilepsy surgery. Attempts to treat focal seizures safely created opportunities to study memory, language, intelligence and behaviour before and after precisely localised brain operations.
Why surgeons needed cognitive testing
Removing epileptogenic tissue could improve seizures but also risk memory, language or other cognitive functions.
Clinicians therefore needed methods to measure cognition before surgery and detect changes afterwards.
Penfield, Hebb and early frontal-lobe observations
At the Montreal Neurological Institute, Wilder Penfield worked with psychologist Donald Hebb to study behavioural and intellectual effects of frontal-lobe surgery.
These observations helped challenge simplistic assumptions that large frontal resections always produced global intellectual decline.
Brenda Milner enters epilepsy surgery
Hebb recommended Brenda Milner to Penfield. Milner began systematic neuropsychological study of epilepsy surgery patients and became one of the most influential figures in cognitive neuroscience.
Her work linked medial temporal structures with specific forms of memory.
H.M. changes memory science
Patient H.M., who underwent bilateral medial temporal surgery for severe epilepsy outside the Montreal programme, developed profound anterograde amnesia.
Milner’s study of H.M. demonstrated that memory is not a single faculty. Skills and habits could be learned even when new episodic memories could not be formed normally.
Lateralisation and the temporal lobes
Studies of unilateral temporal-lobe surgery helped show that verbal and non-verbal memory could be affected differently depending on the hemisphere and the individual’s functional organisation.
This became important in presurgical risk assessment.
Neuropsychology becomes part of epilepsy-team care
Modern presurgical neuropsychology evaluates baseline cognition, helps interpret lateralising patterns, estimates postoperative risk and supports rehabilitation and counselling.
It is no longer merely a research add-on to surgery.
Epilepsy patients changed neuroscience
Many principles now taught in cognitive neuroscience—multiple memory systems, hemispheric specialisation and the cognitive effects of focal lesions—were shaped by people undergoing epilepsy investigation and treatment.
That contribution deserves to be recognised as part of epilepsy history.
Related reading
Sources and further reading
Evidence checked: September 2026.