Perception and priming of affective faces in temporal lobectomy patients

Eighteen patients who had undergone standard anterior temporal lobectomy including removal of the amygdala and hippocampus (9 left, LTL; 9 right, RTL) were administered an Affective Task composed of faces depicting negative emotions, and a Neutral Task consisting of faces with different lighting and orientation conditions. Both tasks required judgment of poser identity and indication of decision by pressing a reaction time button. Subjects were shown a set of photos in an Exposure Phase, followed by a Test Phase in which the photos previously seen (primed) were mixed with new photos (unprimed). The LTL subjects performed better than the RTL subjects for both the RT and accuracy data in both the Neutral and Affective Tasks. The performance of the LTL subjects improved when the task had an affective component (Affective vs. Neutral Task), whereas the RTL subjects did not show this benefit. In terms of specific emotions, for the LTL group, pain was responded to most slowly and shock was the emotion responded to most quickly, and significantly more quickly than in the RTL group. Fear was the emotion responded to most slowly by the RTL group and significantly more slowly when compared to the LTL group. The only priming effect was a reverse priming for pain, such that stimuli seen before were respondedto less accurately than new stimuli; this was not related to lesion side.