Expression without recognition: contributions of the human amygdala to emotional communication

The neurobiology of social cognition

Recent studies have begun to elucidate the roles played in social cognition by specific neural structures, genes, and neurotransmitter systems. Cortical regions in the temporal lobe participate in perceiving socially relevant stimuli, whereas the amygdala, right somatosensory cortices, orbitofrontal cortices, and cingulate cortices all participate in linking perception of such stimuli to motivation, emotion, and cognition. Open questions remain about the domain-specificity of social cognition, about its overlap with emotion and with communication, and about the methods best suited for its investigation.

Automatic activation of positive but not negative attitudes after traumatic brain injury

This study investigated social judgment problems of an individual (AM) with bilateral frontal and temporal lobe damage including damage to the amygdala. We hypothesized that AM could automatically process positive, but not negative evaluative information and could process both types of evaluative information using controlled processing. In Phase 1 of Experiment 1 AM and controls were shown a series of words one at a time and were required to make good/bad judgments as quickly as possible. Results showed that AM was more likely than controls to rate words as good, and was significantly slower to make good/bad judgments of negatively, but not positively, evaluated words. In Phase 2 AM was shown a prime (positive or negative) then target (positive or negative) and instructed to evaluate whether the target word was good or bad. Results showed that AM responded more quickly when prime and target were both positive, but not when prime and target were both negative, whereas controls showed both types of priming. Experiment 2 determined whether AM's impaired processing of negative evaluative information could be abolished under controlled processing. AM was explicitly instructed to generate positive and negative connotations of a series of single words and given essentially unlimited time. Under these conditions, AM and controls did not differ significantly in their ability to generate positive versus negative connotations of words. In Experiment 3 AM and controls both showed normal semantic priming effects. The results are interpreted within the component process model of memory.

The amygdala: vigilance and emotion

Here we provide a review of the animal and human literature concerning the role of the amygdala in fear conditioning, considering its potential influence over autonomic and hormonal changes, motor behavior and attentional processes. A stimulus that predicts an aversive outcome will change neural transmission in the amygdala to produce the somatic, autonomic and endocrine signs of fear, as well as increased attention to that stimulus. It is now clear that the amygdala is also involved in learning about positively valenced stimuli as well as spatial and motor learning and this review strives to integrate this additional information. A review of available studies examining the human amygdala covers both lesion and electrical stimulation studies as well as the most recent functional neuroimaging studies. Where appropriate, we attempt to integrate basic information on normal amygdala function with our current understanding of psychiatric disorders, including pathological anxiety.