Neurophysiological Mechanisms of Language Comprehension

First, in a recording-only self-paced reading experiment, patients with epilepsy undergoing intracranial monitoring for clinical purposes will read or listen to sentences presented to them one word at time while the investigators simultaneously record neural activity through intracranial electrodes that are implanted for clinical purposes (see subject populations). At the end of the sentence, the subjects have to indicate how they comprehended the sentence by selecting which of several pictures matches the sentence they just read. Behavioral measures that the investigators record and analyze are their response times to advance to each next word in the sentence, and which picture they chose for each sentence. These behavioral measures are compared against the neural activity simultaneously recorded as they are made. Then, in a later session, the same participants will participate in a task-related stimulation experiment. This follows the exact same design as the recording-only reading experiment, the only difference is that on some trials, at controlled moments during the sentence presentation intracranial electrical stimulation is delivered through adjacent intracranial electrode contacts. The investigators will examine the effect of this stimulation on the subjects comprehension of the sentences measured by their behavior, and on the simultaneously recorded neural activity.