Objective: To examine facial emotional recognition and processing in Cervical Dystonia (CD) subjects as a test of whether Social Cognition (SoC) is impaired compared to age-matched Healthy Controls (HC), using simultaneous EEG-derived event related potentials (ERPs) and eye-tracking.

Background: CD is an Idiopathic Dystonia¹, characterized by protracted or intermittent muscle contractions causing repetitive abnormal neck movements and posture². Disruptions in the collicular-pulvinar-amygdala pathway are known to contribute to the pathophysiology of CD³ and impairment has been hypothesized to affect SoC, and the ability to recognize and process emotional facial expressions⁴. Understanding the mechanisms behind non-motor symptoms of CD may provide a framework to further elucidate the disorder’s pathophysiology.

Method: Nine adults with CD and five HC were presented with a series of emotional facial stimuli in a randomized, oddball paradigm. 80% of presented faces were neutral, with the oddballs consisting of either appetitive (happy) or aversive (disgusted) expressions. High-resolution eye tracking was used to analyse fixation on different facial regions of interest. Fixations were quantified and fixation density maps were obtained. Simultaneously, 24-channel EEGs were used to derive ERPs relating to facial emotional recognition and processing, using N170 (Fig.1) and Late Positive Potentials (LPP),(Fig.2). Unpaired t-tests were used to compare cohorts.

Results: A 1.20µV difference (p<0.28) between LPP average amplitudes was measured in CD patients compared to HC in the disgusted stimuli trials, and a .52µV difference (p<0.54) in the happy stimuli trials (Fig.2).  

No differences were reported in N170 peak amplitudes in CD compared to HC, p<0.99 for the disgust stimuli and p<0.88 for happy stimuli. No statistical difference was seen in the time spent fixating on specific facial features among cohorts.

Fixation duration density maps for each of the stimuli are shown in Fig.3.

Conclusion: Decreased LPP amplitudes recorded in CD participants may indicate impaired processing of emotional stimuli⁵, however, preserved N170 suggest intact early stage facial processing⁶.  Fixation patterns showed no group differences, implying that CD subjects in this cohort do not have to fixate on more salient facial aspects to recognize emotion.

Figure 1

Figure 2

Figure 3

References: [1] Albanese A, Bhatia KP, Cardoso F, Comella C, Defazio G, Fung VS, et al. Isolated cervical dystonia: diagnosis and classification. Movement disorders. 2023;38(8):1367-78.
[2] O’Connor S, Hevey D, Burke T, Rafee S, Pender N, O’Keeffe F. A systematic review of cognition in cervical dystonia. Neuropsychology Review. 2024;34(1):134-54.
[3] Hutchinson M, Isa T, Molloy A, Kimmich O, Williams L, Molloy F, et al. Cervical dystonia: a disorder of the midbrain network for covert attentional orienting. Front Neurol. 2014;5:54.
[4] Burke T, Monaghan R, McCormack D, Cogley C, Pinto-Grau M, O’Connor S, et al. Social cognition in cervical dystonia: A case-control study. Clinical Parkinsonism & Related Disorders. 2020;3:100072.
[5] Hajcak G, Foti D. Significance?… Significance! Empirical, methodological, and theoretical connections between the late positive potential and P300 as neural responses to stimulus significance: An integrative review. Psychophysiology. 2020;57(7):e13570.
[6] Hinojosa J, Mercado F, Carretié L. N170 sensitivity to facial expression: A meta-analysis. Neuroscience & Biobehavioral Reviews. 2015;55:498-509.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/probing-social-cognition-and-emotional-facial-expression-recognition-in-cervical-dystonia-through-integration-of-eeg-and-eye-tracking/