Social Cognition in Cervical Dystonia: Integrating EEG and Eye-Tracking for Insights on Emotional Face Recognition

Cervical dystonia (CD) is a rare movement disorder, characterized by involuntary muscle contractions in the head and neck, leading to abnormal movements and posture. Apart from motor impairment, a sizable proportion of CD patients demonstrate non-motor symptoms, impaired social cognition and abnormal sensory processing. Understanding these non-motor symptoms can provide a framework to further understand the pathophysiology of this rare disorder. In this study, emotional facial stimuli were presented to a cohort of three CD and five healthy control (HC) subjects, while electroencephalogram and high-resolution eye tracking were simultaneously recorded. Fixation density maps were derived from the eye tracking, and regions of interest on the face were analyzed. Two important electrophysiological markers for face and emotion recognition in event related potentials, N170 and Late Positive Potentials (LPP) were derived. Neutral, appetitive (happy) and aversive (disgust) were utilized to compare the CD group with HC using unpaired t-tests. In the disgust expression, the CD group had a 50% reduction in N170 amplitude, of -3.81 ± 1.3μV compared with the HC group of -7.35 ± 2.43μV (p<0.06). Furthermore, CD participants fixated longer on more salient aspects of expression such as the mouth (29.67% vs. 16.26%; p<0.40) and did not fixate on the more subtly expressive regions such as the nasolabial fold (1.69% vs 10.85%; p<0.39). Although CD subjects are fixating on more salient regions of facial emotion compared to HC, CD N170s and LPPs are still attenuated, potentially supporting reduced social cognition.Clinical Relevance- This work aimed to assess social cognition as a potential endophenotype for CD, by concurrently analyzing EEG and eye-tracking, which has the potential to lead to further understanding of the pathophysiology of the disorder. This study introduces a novel paradigm integrating gaze and neural measurements with emotion recognition study in CD.