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"Neural activity in the central and basolateral nuclei of the amygdala is correlated with the skin conductance response"
ABSTRACT
The basolateral (BLA) and central (CeA) nuclei of the amygdala are thought to carry out dissociable functions. The basolateral nuclei are involved in the context-dependent evaluation of emotional stimuli while the central nucleus is critical for the initiation of somatic and autonomic responses. We hypothesized that neurons of the central nucleus will modulate their firing rate in relation to autonomic markers of emotion, such as the skin conductance response (SCR). To test this hypothesis, we recorded SCR in conjunction with neural activity from MRI-confirmed nuclei of the amygdala from one adult male monkey (Macaca mulatta). The monkey was trained to maintain gaze within the boundary of stimulus images depicting monkey facial expressions, human faces, food items, monkey perinea, and abstract images.
The minimal latency for SCR generation following stimulus presentation is 1 s. For each isolated neuron, therefore, the average firing rate was calculated for a window of 1 s preceding the onset of SCRs. The average value of the firing rate in this window was compared to multiple windows of equal length during baseline activity. Sixty percent of neurons in the central nucleus showed a significant modulation of firing rate 1 s prior to the onset of the SCR. Of the neurons with modulations prior to the SCR, approximately equal numbers of neurons increased and decreased activity. About half of the neurons of the basolateral nucleus of the amygdala showed significant modulation of firing rate prior to the onset of the SCR. Interestingly, these neurons more consistently decreased firing rate in this period. Our data can be understood when considering the anatomical connections within the nuclei of the amygdala. We hypothesize that the part of the feedforward network from the basolateral nucleus to the central nucleus that is involved in the initiation of somatic and autonomic response is inhibitory. The consistent decrease in activity of the neurons of the basolateral nucleus may release the central nucleus from inhibition and facilitate the initiation of skin conductance responses.
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