The embodied emotion in cerebellum: a neuroimaging study of alexithymia

Neuroimaging studies have indicated that people with alexithymia show structural and functional alterations in brain areas associated with emotional awareness, as amygdala, insula, anterior cingulate cortex, fusiform gyrus and parahippocampal gyrus, and only occasionally alterations in the cerebellar activity were reported. The main goal of the present study was to investigate the associations between gray and white matter cerebellar macro- (Voxel-Based Morphometry) and micro- (Mean Diffusivity and Fractional Anisotropy) structural measures (evaluated by means of a 3-T high-resolution structural Magnetic Resonance Imaging and a Diffusion Tensor Imaging scan protocol) and the presence of alexithymia (evaluated by means of 20-item Toronto Alexithymia Scale), in a sample of 60 healthy subjects having low, borderline or high alexithymia. As a corollary aim, the associations between volumes of amygdala, insula, anterior cingulate cortex, fusiform gyrus or parahippocampal gyrus and alexithymia scores have been investigated. Cerebellar gray matter volumes were positively associated with alexithymia scores. The subjects with high alexithymic traits had larger volumes in the bilateral Crus 1 in comparison to the remaining subjects. Volumes of right amygdala, left insula and left parahippocampal gyrus were negatively associated with the alexithymia scores. Thus, alexithymia scores were linked directly with cerebellar areas and inversely with limbic and para-limbic system, proposing a possible functional modality for the cerebellar involvement in emotional processing. The increased volumes in Crus 1 of subjects with high alexithymic traits may be related to an altered embodiment process leading to not-cognitively interpreted emotions.