Cortical Mapping and States era
During the Cortical Mapping and States era (1945–1964), brain electrophysiology advanced through systematic electrical stimulation and EEG recording that localized sensory and motor functions and linked evoked responses to behavior. Wilder Penfield pioneered cortical mapping by electrically stimulating exposed cortex during epilepsy surgery, producing classic sensory and motor homunculi and establishing pre-surgical localization as a clinical norm. Herbert H. Jasper refined intracranial and scalp EEG techniques, helped standardize recording and evoked-potential protocols, and contributed to the understanding of epileptiform activity and cortical rhythms related to sleep and attention. Moruzzi and Magoun formulated the brainstem reticular activating system as a framework for arousal and EEG state regulation, tying brainstem mechanisms to cortical activation, wakefulness, and attention.