Sensory and somatosensory underpinnings of emotion processing

Abstract

Alexithymia is characterized by difficulties in recognizing one’s own emotions and others’ emotions, specially fear. Recognizing emotions is associated with remarkable changes in somatosensory and sensory (particularly visual) processing. For instance theories about emotion processing suggest a strong association between emotion processing and somatic markers. The aim of the present thesis is to assess whether the difficulties in emotion processing shown by alexitimic subjects can affect somatosensory and sensory (especially visual) processing. To this end different somatosensory modalities (e.g. temperature, pain, tactile, touch, etc) and visual stimuli (e.g. face and body expressions) were used to compare the somatosensory and sensory processing in people with high and low scores of alexithymia. These experiments provided evidence that emotional processing deficit seems to be related to the alterations in somatosensory processing (Experiments 1, and 2), in visual processing, early visual encoding (Experiments 3, 4, and 6), and in physiological reactivity, particularly visceral reactivity (Experiment 5), which prevents these individuals to correctly perceive emotions. Together, these studies suggest that the emotional difficulties in alexithymia might be grounded in the specific low-level somatosensory system. Moreover, the lack of emotional modulation at the early stage of visual processing indicates that the rapid modulation of the amygdala over the visual cortices may be reduced, thus suggesting a hyporeactivity of the amygdala in individual with high levels of alexithymia.