Showing papers by "Andrew P. Holmes published in 1998"

Neural Correlates of Levels of Emotional Awareness: Evidence of an Interaction between Emotion and Attention in the Anterior Cingulate Cortex

Abstract: Recent functional imaging studies have begun to identify the neural correlates of emotion in healthy volunteers. However, studies to date have not differentially addressed the brain areas associated with the perception, experience, or expression of emotion during emotional arousal. To explore the neural correlates of emotional experience, we used positron emission tomography (PET) and 15O-water to measure cerebral blood flow (CBF) in 12 healthy women during film- and recallinduced emotion and correlated CBF changes attributable to emotion with subjects' scores on the Levels of Emotional Awareness Scale (LEAS), a measure of individual differences in the capacity to experience emotion in a differentiated and complex way. A conjunction analysis revealed that the correla tions between LEAS and CBF during film- and recall-induced emotion overlapped significantly ( z = 3.74, p < 0.001) in Brodmann's area 24 of the anterior cingulate cortex (ACC). This finding suggests that individual differences in the ability to accurately detect emotional signals interoceptively or exteroceptively may at least in part be a function of the degree to which the ACC participates in the experiential processing and response to emotion cues. To the extent that this finding is consistent with the functions of the ACC involving attention and response selection, it suggests that this neural correlate of conscious emotional experience is not exclusive to emotion.

Pallidotomy in Parkinson's disease increases supplementary motor area and prefrontal activation during performance of volitional movements. An (H2O)-O-15 PET study (vol 120, pg 1301, 1997)

Abstract: Supplementary motor area and right dorsal prefrontal cortex activation in Parkinson's disease is selectively impaired during volitional limb movements. Since posteroventral pallidotomy improves motor performance in Parkinson's disease patients 'off' medication (i.e. off medication for 9-12 h), we hypothesized that it would also concomitantly increase supplementary motor area and dorsal prefrontal cortex activation. Six Parkinson's disease patients with a median total motor Unified Parkinson's Disease Rating Scale (UPDRS) of 52.5 (range 34-66) 'off' medication underwent unilateral right posteroventral pallidotomy. The patients had H2(15)O PET when 'off' medication before and 3-4 months after surgery. Each PET study comprised four to six measurements of regional cerebral blood flow either at rest or while performing regularly paced joystick movements in freely selected directions (forward, backward, left or right) using the left hand. Pre- and postoperative scans were performed in an identical manner and the associated levels of activation were compared using statistical parametric mapping. After pallidotomy, the median total motor UPDRS score 'off' medication decreased by 34.7% (P = 0.03) and mean response times of joystick movements following the pacing tones improved by 13.8% (P = 0.08). Relative increases in activation of the supplementary motor area and right dorsal prefrontal cortex were observed during joystick movements (P < 0.001). Decreased activation was seen in the region of the right pallidum (P = 0.001). We conclude that pallidotomy reduces pallidal inhibition of thalamocortical circuits and reverses, at least partially, the impairment of supplementary motor area and dorsal prefrontal cortex activation associated with Parkinson's disease.