The human mirror neuron system in a population with deficient self-awareness: an fMRI study in alexithymia

Neuroanatomical correlates of trait anhedonia in patients with schizophrenia: a voxel-based morphometric study

The aim of this study was to characterize the association between trait anhedonia and regional gray matter volume in patients with schizophrenia. Forty-six patients with schizophrenia and 56 healthy controls underwent magnetic resonance imaging (MRI) to acquire high-resolution T1-weighted images. Trait anhedonia was measured using the Chapman Revised Physical Anhedonia Scale (PAS). Voxel-based morphometry was performed to investigate brain volume correlates of trait anhedonia. Several brain regions in the patient group, including the left precuneus and right posterior cingulate (PCC), were found to show significantly less correlation with PAS scores than those of the control group. Post-hoc analysis revealed that negative correlations between the regional gray matter volume and the PAS scores in the patient group were found at a trend level in the left precuneus and the right PCC. In conclusion, these findings suggest that trait anhedonia in patients with schizophrenia could possibly be associated with a volume deficit in brain regions related to default-mode, which reflects the impairment of self-referential processing and reward anticipation.

The impact of coping style on gaze duration

The understanding of individual differences in response to threat (e.g., attentional bias) is important to better understand the development of anxiety disorders. Previous studies revealed only a small attentional bias in high-anxious (HA) subjects. One explanation for this finding may be the assumption that all HA-subjects show a constant attentional bias. Current models distinguish HA-subjects depending on their level of tolerance for uncertainty and for arousal. These models assume that only HA-subjects with intolerance for uncertainty but tolerance for arousal ("sensitizers") show an attentional bias, compared to HA-subjects with intolerance for uncertainty and intolerance for arousal ("fluctuating subjects"). Further, it is assumed that repressors (defined as intolerance for arousal but tolerance for uncertainty) would react with avoidance behavior when confronted with threatening stimuli. The present study investigated the influence of coping styles on attentional bias. After an extensive recruiting phase, 36 subjects were classified into three groups (sensitizers, fluctuating, and repressors). All subjects were exposed to presentations of happy and threatening faces, while recording gaze durations with an eye-tracker. The results showed that only sensitizer showed an attentional bias: they gazed longer at the threatening face rather than at the happy face during the first 500 ms. The results support the findings of the relationship between anxiety and attention and extend these by showing variations according to coping styles. The differentiation of subjects according to a multifaceted coping style allows a better prediction of the attentional bias and contributes to an insight into the complex interplay of personality, coping, and behavior.

Individual differences in socioaffective skills influence the neural bases of fear processing: the case of alexithymia

Being exposed to fear signals makes us feel threatened and prompts us to prepare an adaptive response. In our previous studies, we suggested that amygdala (AMG) and premotor cortex (PM) play a role in the preparation of the observers' motor response required by the situation. The present experiment aimed at assessing how interindividual differences in alexithymia--a personality trait associated with deficits in emotional reactivity and regulation--influence the neural network associated with the perception of fear. Using fMRI, we scanned 34 healthy subjects while they were passively observing fearful body expressions. Applying a dimensional approach, we performed correlation analyses between fear-related brain areas and alexithymia scores among all participants. Using a categorical approach, we conducted a between-group comparison (13 high vs. 12 low-alexithymia subjects). Our results were threefold. First, the right AMG activity in response to fearful stimuli was negatively correlated with the level of difficulty to identify emotions. Second, PM activity was linked to reduced subjective emotional reactivity. Third, the between-group comparison revealed greater activity in anterior cingulate cortex (ACC) for high than low-alexithymia scorers. Moreover, the relationship between ACC and PM was in opposite direction in individuals with high (negative link) and low (positive link) alexithymia. Therefore, compared to our previous findings, we hereby further reveal how ACC interacts with PM to sustain self-regulation of one's own emotional state in response to threatening social signals. Moreover, this neural mechanism could account for the description of the "cold-blooded" personality of individuals with alexithymia.