Recent functional imaging studies showed that memory retrieval is associated with activation in the prefrontal cortex during the encoding process. However, a cause-effect link between prefrontal activity and encoding has not been demonstrated. The purpose of this protocol is to test the hypothesis that inhibitory repetitive transcranial magnetic stimulation (rTMS) over left prefrontal cortex interferes with encoding of verbal items (words) into episodic memory, thereby identifying this region as a substrate mediating verbal encoding. Identification of the role of the prefrontal cortex in verbal memory encoding is the first step to try to develop strategies to enhance such encoding processes in patients with memory impairments, an issue of relevance in neurorehabilitation. We plan to apply rTMS over left prefrontal cortex and over two control sites, during encoding of verbal and nonverbal items into episodic memory. Normal, healthy volunteers will be studied. The outcome measure will be performance on a subsequent memory test for words presented during left prefrontal rTMS, as compared to performance for words presented during rTMS over the control sites or without rTMS. This measure will indicate if left prefrontal stimulation can disrupt memory encoding of words relative to other stimulation sites or to no stimulation. A secondary outcome measure will be performance on a subsequent memory test for words presented during left prefrontal rTMS, as compared to performance for pictures presented during left prefrontal rTMS. This measure will indicate if disruption of left prefrontal function with TMS affects verbal and more than non-verbal memory encoding.
INCLUSION CRITERIA: INCLUSION CRITERIA: Healthy right handed volunteers, aged 18-35 years, will be included in this protocol. EXCLUSION CRITERIA: Exclusion criteria for this study will be any current medical or surgical condition or psychiatric or neurological illness. Furthermore, any individual who is on medication with potential influence on nervous system function, who has a history of surgery with metallic implants or known history of metallic particles in the eye, cardiac pacemaker, neural stimulators, cochlear implants, pregnancy, or history of drug abuse, will be excluded from the study.