The overall focus of our research is to use an ablative paradigm to learn more about the differential roles played by the left and right anterior temporal regions, particularly the amygdala, in affectively modulating behavior, including the startle eyeblink. The following questions will be asked: (a) Is valence modulation of the startle response differently impacted by right versus left temporal removals involving the amygdala? Recent evidence from humans suggests that the magnitude of the startle eyeblink reflex is augmented during negative affect states and diminished during positive affect states. Although animal studies have targeted the amygdala as a key structure in fear potentiated startle, no human data currently exist concerning which neuroanatomic regions might contribute to startle, or whether hemispheric asymmetries might exist; (b) Is there differential decoupling among other emotion response systems (heart rate, skin conductance, facial EMG, verbal report) due to the integrity of right versus left anterior temporal regions? To date, prior neurobehavioral studies of emotion have relied almost exclusively on evaluation of only one or the other of these response systems of emotion (i.e., only SCR, only HR); and (c) Are finding more consistent with a global right hemisphere versus bivalent model of emotional processing? To address these questions, unilateral right and left anterior temporal lobectomy patients will be studied prior to and following surgical resections. Eyeblink startle responses will be elicited while Ss concurrently engage in affect-eliciting tasks (i.e., viewing pictures, listening to emotional sounds and sentences, or shock-induced anticipatory anxiety) that use standardized sets of emotion-eliciting stimuli. During these tasks, multiple measures of emotional responsivity will be obtained including psychophysiological (HR, bilateral SCR), somatic (bilateral EMG), bilateral eyeblinks, and verbal report. As designed, the proposed studies will enable us to determine how removal of the left versus right anterior temporal regions differentially alter emotional reactivity, and whether their alteration is valence-specific, material-specific, modality-specific, or measure-specific.
