Lower recognition thresholds for sad facial expressions in subthreshold depression: a longitudinal study

Subthreshold depression (StD) is more prevalent than major depressive disorder (MDD) all over the world. Previous studies have indicated that depression is associated with impaired perception of facial expressions. However, for individuals with StD, whether perceptual sensitivity toward facial expressions could be altered and whether these alterations could stabilize over time remain largely unknown. Using the QUEST psychometric procedure, here we assessed recognition thresholds of five facial expressions (angry, fear, happy, sad and neutral) for individuals with StD and non-depressed controls. These subjects were retested after approximately 2-month time intervals. At the initial assessment, individuals with StD demonstrated lower recognition thresholds (i.e., stronger sensitivity) for only sadness compared to non-depressed controls. At the follow-up assessment, we classified the StD group as two subgroups: the non-remitted and the remitted group. For the former, lower recognition thresholds for only sadness were again found; for the latter, there was no significant difference. More importantly, individuals displaying lower recognition thresholds for sadness at the initial assessment were less likely to improve in depressive symptoms at the follow-up assessment. These results indicate that the alteration of perceptual sensitivity toward the sad expression for individuals with StD is associated with the current clinical state.

Anodal tDCS and High-Frequency tRNS Targeting the Occipitotemporal Cortex Do Not Always Enhance Face Perception

There has been increasing interest in the utility of transcranial electrical stimulation as a tool to enhance cognitive abilities. In the domain of face perception, enhancements have been reported for both transcranial direct current stimulation (tDCS) and high-frequency transcranial random noise stimulation (tRNS) targeting the occipitotemporal cortex. In a series of two experiments, we attempted to replicate these findings for face identity perception, and extend on previous studies, to determine if similar enhancements are also observed for object and facial expression perception. In Experiment 1, using a single blind, between-subjects design in healthy volunteers (N = 53), we examined whether anodal tDCS over the occipitotemporal cortex enhanced performance on tasks involving perception of face identity, facial expression, and object stimuli, when compared to sham stimulation. We failed to replicate previous findings of enhanced performance on face and object perception, nor extend findings to facial expression perception. In Experiment 2, using a single blind, between-subjects design (N = 39), we examined the effect of high-frequency tRNS over the occipitotemporal cortex using the same three tasks employed in Experiment 1. We failed to replicate previous findings of enhanced face perception following high-frequency tRNS over the occipitotemporal cortex, relative to sham stimulation (although we used different stimulation parameters to that employed in a previous study). We also found no evidence of enhanced facial expression and object perception following high-frequency tRNS. The findings align with a growing body of studies that have failed to replicate previously reported enhancements following administration of tDCS and hint for different efficacy of, on first sight, related stimulation protocols. Future studies should explore the foundation of these differential effects in greater detail.

Automatic Change Detection to Facial Expressions in Adolescents: Evidence from Visual Mismatch Negativity Responses

Adolescence is a critical period for the neurodevelopment of social-emotional processing, wherein the automatic detection of changes in facial expressions is crucial for the development of interpersonal communication. Two groups of participants (an adolescent group and an adult group) were recruited to complete an emotional oddball task featuring on happy and one fearful condition. The measurement of event-related potential was carried out via electroencephalography and electrooculography recording, to detect visual mismatch negativity (vMMN) with regard to the automatic detection of changes in facial expressions between the two age groups. The current findings demonstrated that the adolescent group featured more negative vMMN amplitudes than the adult group in the fronto-central region during the 120–200 ms interval. During the time window of 370–450 ms, only the adult group showed better automatic processing on fearful faces than happy faces. The present study indicated that adolescent’s posses stronger automatic detection of changes in emotional expression relative to adults, and sheds light on the neurodevelopment of automatic processes concerning social-emotional information.