Cerebral excitation profiles in language processing: The photic probe paradigm

A photic probe paradigm was developed in order to assess the cerebral excitation patterns corresponding to acoustic and linguistic operations independently of specific signal parameters. Average Evoked Potentials (AEPs) to a photic stimulus were recorded at the anterior temporal and posterior regions of both hemispheres of subjects engaged in acoustic, phonetic, and semantic processing of verbal material. Patterns of attenuation and enhancement of the probe AEP amplitudes were observed over the left and right hemispheres, respectively, with the magnitude of change varying reliably as a function of processing task. The implications of these findings for models of cerebral specialization for language are discussed.