Scanning Patterns of Faces do not Explain Impaired Emotion Recognition in Huntington Disease: Evidence for a High Level Mechanism

Abstract

In the current study, we aimed to investigate the emotion recognition impairment in Huntington’s disease (HD) patients and define whether this deficit is caused by impaired scanning patterns of the face. To achieve this goal, we recorded eye movements during a two-alternative forced-choice emotion recognition task. HD patients in pre-symptomatic (n = 16) and symptomatic (n = 9) disease stages were tested and their performance was compared to a control group (n = 22). In our emotion recognition task, participants had to indicate whether a face reflected one of six basic emotions. In addition, and in order to define whether emotion recognition was altered when the participants were forced to look at a specific component of the face, we used a second task where only limited facial information was provided (eyes/mouth in partially masked faces). Behavioral results showed no differences in the ability to recognize emotions between pre-symptomatic gene carriers and controls. However, an emotion recognition deficit was found for all six basic emotion categories in early stage HD. Analysis of eye movement patterns showed that patient and controls used similar scanning strategies. Patterns of deficits were similar regardless of whether parts of the faces were masked or not, thereby confirming that selective attention to particular face parts is not underlying the deficits. These results suggest that the emotion recognition deficits in symptomatic HD patients cannot be explained by impaired scanning patterns of faces. Furthermore, no selective deficit for recognition of disgust was found in pre-symptomatic HD patients.

Abnormal Visual Scanning of Emotionally Evocative Natural Scenes in Huntington’s Disease

“…That is, investigations into the neural correlates of facial emotion recognition in HD, using EEG (Croft et al, 2014), fMRI (Dogan et al, 2013), and MRI (Harrington et al, 2014), indicated an association between altered visual processing and emotion recognition. Nevertheless, a single study in HD that measured eye-movements during emotion processing did not find evidence for altered visual scanning (Van Asselen et al, 2012). This study, however, took a very different approach, compared to the approach in our study, by examining the visual scanning of faces, rather than scenes, and by measuring the scanning of specific regions of interest, rather than measuring global scanning patterns.…”

“…This study, however, took a very different approach, compared to the approach in our study, by examining the visual scanning of faces, rather than scenes, and by measuring the scanning of specific regions of interest, rather than measuring global scanning patterns. Specifically, the study looked at the number of fixations and fixation durations for the eye, nose, and mouth regions, and found no differences between the HD and control groups (Van Asselen et al, 2012). Van Asselen et al (2012) suggest that this lack of group differences in visual scanning indicates that impaired facial emotion recognition in HD may occur due to a high-level emotional mechanism, rather than due to altered visual scanning.…”

“…Specifically, the study looked at the number of fixations and fixation durations for the eye, nose, and mouth regions, and found no differences between the HD and control groups (Van Asselen et al, 2012). Van Asselen et al (2012) suggest that this lack of group differences in visual scanning indicates that impaired facial emotion recognition in HD may occur due to a high-level emotional mechanism, rather than due to altered visual scanning. In contrast to the visual scanning of facial features, no research in HD to date has examined parameters characterizing global visual scanning behavior for emotional scenes.…”

“…The findings in PD of unaffected scanning locations when viewing emotional faces, but abnormal global viewing activity for emotional scenes, considered together with known overlaps in neural circuitries affected and emotional processing abnormalities shared across PD and HD, highlights the possibility that parameters characterizing the global scanning of scenes may also be altered in HD. Thus, although the only study that has looked at scanning of facial features in HD did not find a deficit in visual scanning (Van Asselen et al, 2012), we wished to examine the global visual scanning of scenes to see whether we would find alterations in HD.…”

Emotional dysfunctions in neurodegenerative diseases

“…Whereas some studies point toward a specific deficit in recognizing facial disgust (Gray et al, ; Hennenlotter et al, ), others reveal a general impairment in recognizing negative emotions (Johnson et al, ; Labuschagne et al, ; Rees et al, ). However, intact emotion recognition competencies in premanifest HD have also been reported (Novak et al, ; Van Asselen et al, ), which might be due to variability in disease severity or gene dosage.…”