Segregation of Emotional Function in Subcortical Structures: MEG Evidence

C. Styliadis, A.A. Ioannides, P.D. Bamidis, and C. Papadelis

Abstract:Arousal and valence are the primary dimensions of human emotion. However, the degree to which these dimen- sions correlate to complex subcortical structures (i.e. amygda- la, cerebellum) that are anatomically homogeneous is still elusive. Magnetoencephalography (MEG) recordings were performed on 12 healthy individuals exposed to affective sti- muli from the International Affective Picture System (IAPS) collection using a 2 (Valence levels) x 2 (Arousal levels) design. Source power was estimated using a beamformer within 1-30 and 30-100 Hz bands. Activations referring to the subcortical sub-regions were defined through probabilistic cytoarchitectonic maps (PCMs). Within the 1-30 Hz band, right laterobasal (LB) amygdala activity mediates negative valence (elicited by unpleasant stimuli) while left centromedial (CM) activity correlates to the interaction of valence by arous- al (arousing pleasant stimuli). Within the 30-100 Hz band, cerebellar VIIIa lobule of the Vermis and left hemispheric VIIa Crus II lobule activity mediate high arousal while left hemispheric V lobule correlates to the interaction of valence by arousal (arousing pleasant stimuli). Our results support that distinct sub-regional subcortical activity responds specifically to valence and arousal dimensions as well as combinations of the two, pronouncing the sophisticated nature of emotion. Given the anatomical interconnections between amygdala and cerebellum, future studies may focus on the interplay of their specific sub-regions.