Temporal Lobectomy Evidence for the Role of the Amygdala in Early Emotional Face and Body Processing

Abstract

The amygdala is believed to make invaluable contributions to visual emotion processing. Yet how this subcortical body contributes to emotion perception across time is contended. Here, we measured differences in the perceptual processing of emotional stimuli after unilateral temporal lobe and amygdala resection (TLR) in humans, using EEG. Through mass univariate analysis of brain activity, we compared responses to fearful and neutral faces (left TLR N = 8, right TLR N = 8, control N = 8), and fearful and neutral bodies (left TLR N = 9, right TLR N = 9, control N = 9). We found that TLR impaired the early-stage perceptual processing of emotional stimuli seen in the control group. Indeed, in controls a heightened responses to fearful faces was found in the 140-170 ms time window, over temporoparietal electrodes. This effect was also present in the left TLR group but disappeared in the right TLR group. For emotional bodies, brain activity was differentially sensitive to fearful stimuli at 90-120 ms in the control group, but this effect was eliminated in both TLR groups. Collectively, these results reveal the amygdala contributes to the early stages of perceptual processing that discriminate emotional stimuli from neutral stimuli. Further, they emphasize the unique role of the right medial temporal structures such as the amygdala in emotional face perception.

Keywords: EEG; amygdala; bodily emotion; emotion; facial emotion; temporal lobe resection.

Figure 1.

Results for the MUA facial emotion comparison. Left, Condensed raster plots for epochs and channels following the MUA cluster permutation analysis. Note all 64 electrodes were included in the analysis but only channels that were significantly different in any of the three groups have been shown in this representation. Orange areas indicate epochs and channels where a significant emotion based difference was found. Right, ERPs represent the pooling of clusters of electrodes that were found to be significantly different in any of the three groups for the facial expression comparison. These have been separated into temporoparietal (TP7, P5, P7, P9, PO7) and occipital (Oz, Iz) groupings. Shaded areas indicate where at least one of the pooled electrodes were found to be significantly different between the emotion condition for that group.

Figure 2.

Results for the MUA bodily emotion comparison. Left, Condensed raster plots for epochs and channels following the MUA cluster permutation analysis. Note all 64 electrodes were included in the analysis but only channels that were significantly different in any of the three groups have been shown in this representation. Orange areas indicate epochs and channels where a significant emotion-based difference was found. Right, ERPs represent the pooling of clusters of electrodes that were found to be significantly different in any of the three groups for the bodily expression comparison. These have been separated into anterior-central (CP1, C5, FC1, FC3, F8) and parieto-occipital (PO8, PO7, O1, O2, Oz, Iz) groupings. Shaded areas indicate where at least one of the pooled electrodes were found to be significantly different between the emotion condition for that group.