Language-related potentials specific to human language cortex.

Event-related potentials following silently named object pictures were recorded directly from the exposed left hemisphere of the human cortex at sites whose relation to naming was subsequently established by electrical stimulation mapping. Two simultaneous potential changes are specific to sites where stimulation disrupts naming: slow potentials as premotor sites and focal desynchronization at posterior sites surrounding the Sylvian fissure. These anatomically specific changes are also specific to the task--present with silent naming and absent in a spatial task with the same visual input. Overt speech is also preceded by slow potentials with earliest onset at premotor sites.