Brain lesions and emotional processing

This thesis focus on how emotions are processed in the brain, starting from a discussion of the most influential tools used in emotional research. Specifically, vocal and verbal characteristics, facial characteristics, and body expressions are analyzed in depth as methodological tools to measure emotions, along with neuroimaging techniques such as EEG, MEG, fMRI, and multivoxel patterns analysis. The focus then shift towards those brain regions that, thanks to lesion studies, are proved to be the most influential in the processing of emotions: the amygdala, the hippocampus, and the prefrontal cortex. The amygdala function is described in relation to lesion studies and to its role in depression, in the processing of negative emotion, and in emotional memory. Some insights on hemispheric specialization and gender differences are also highlighted. Studies conducted on patients with damage to the hippocampus or with retrograde or anterograde amnesia, provide strong support for the idea that the hippocampus function is related to the formation and consolidation of declarative memories and its interaction with emotional experiences is taken into consideration. Lastly, the role of different regions of the prefrontal cortex, specifically the orbitofrontal cortex, the anterior cingulate cortex, the medial prefrontal cortex, and the lateral prefrontal cortex, are investigated in relation to emotions and different aspects of cognition, such as executive functions, attention, and learning. The last chapter focuses on how damage to certain brain regions can result in dysfunctional ways of dealing with emotions, including impairments in emotional regulation and recognition, and empathy. Emotion regulation is essential for mental health and social functioning, and damage to the frontal lobe and orbitofrontal cortex can result in higher level of aggression and violence, in difficulties regulating arousal during emotional events or in making normal economic decisions in social situations. Emotional awareness, or the recognition of one's own feelings, can be impaired after traumatic brain injuries. In particular, the damage to the anterior insula or anterior cingulate cortex is correlated with higher levels of alexithymia and poor emotion recognition abilities. On the other hand, the amygdala plays a particular role in emotion recognition of others, specifically in the visual recognition of facial expressions, with particular emphasis on the recognition of fear. Empathy, or the ability to share others' emotions, can be disrupted in neurological and neuropsychiatric diseases, and lesions in the prefrontal cortex, orbitofrontal gyrus, temporal lobe, anterior insula, anterior cingulate cortex, and amygdala can result in deficits in affective empathy.