Emotion recognition and inhibitory control in manifest and pre-manifest Huntington’s disease: evidence from a new Stroop task

Huntington’s disease(HD)is a genetic neurodegenerative disorder that affects not only the motor but also the cognitive domain.In particular,cognitive symptoms such as impaired executive skills and deficits in recognizing other individuals’mental state may emerge many years before the motor symptoms.This study was aimed at testing two cognitive hypotheses suggested by previous research with a new Stroop task created for the purpose:1)the impairment of emotion recognition in HD is moderated by the emotions’valence,and 2)inhibitory control is impaired in HD.Forty manifest and 20 pre-manifest HD patients and their age-and gender-matched controls completed both the traditional“Stroop Color and Word Test”(SCWT)and the newly created“Stroop Emotion Recognition under Word Interference Task”(SERWIT),which consist in 120 photographs of sad,calm,or happy faces with either congruent or incongruent word interference.On the SERWIT,impaired emotion recognition in manifest HD was moderated by emotion type,with deficits being larger in recognizing sadness and calmness than in recognizing happiness,but it was not moderated by stimulus congruency.On the SCWT,six different interference scores yielded as many different patterns of group effects.Overall our results corroborate the hypothesis that impaired emotion recognition in HD is moderated by the emotions’valence,but do not provide evidence for the hypothesis that inhibitory control is impaired in HD.Further research is needed to learn more about the psychological mechanisms underlying the moderating effect of emotional valence on impaired emotion recognition in HD,and to corroborate the hypothesis that the inhibitory processes involved in Stroop tasks are not impaired in HD.Looking beyond this study,the SERWIT promises to make important contributions to disentangling the cognitive and the psychomotor aspects of neurological disorders.The research was approved by the Ethics Committee of the“Istituto Leonarda Vaccari”,Rome on January 24,2018.

Electroencephalographic coherences during emotion identification task

Coherence, a measure of spectral similarity, may estimate cortical coupling between two EEG signals as a function of frequency. The coherence between EEG signals from different brain areas depends on the structural connection and functional coupling between two regions. The theory of hemispheric specialization proposes left hemisphere activation to positive emotions and right one to negative emotions. Other proposal is that right hemisphere activation occurs with emotional stimuli. In the present study EEG coherences were calculated during the presentation of the International Affective Pictures to 36 healthy male university students. The subjects’ task was to determine the valence of the stimuli. Base line recording were done with subjects observing the blank monitor. Our results showed higher coherences during the emotional condition. No differences between negative and positive emotions were obtained. Neutral pictures evoked the highest coherence values. These data suggest that coherences between functionally coupled brain areas do not reflect emotional recognition of the valence of stimuli, but they are internal indicators of different mental processes such as memory, mental effort and arousal. Our findings do not support the theory of hemispheric specialization, neither the theory of right hemisphere;rather they suggest a complex activation pattern that involves mostly frontal areas in connection with the entire cortex.