Functional dynamics underlying near-threshold perception of facial emotions: a magnetoencephalography investigation

Abstract

Conscious perception of emotional valence of faces has been proposed to involve topdown and bottom-up information processing. Yet, the underlying neuronal mechanisms of these two processes and the implementation of their cooperation is still unclear. We hypothesized that the networks activated during the interaction of top-down and bottomup processes are the key substrates responsible for perception. We assessed the participation of neural networks involved in conscious perception of emotional stimuli near the perceptual threshold using a visual-backward-masking paradigm in 12 healthy individuals using magnetoencephalography. Providing visual stimulation near the perceptual threshold enabled us to compare correctly and incorrectly recognized facial emotions and assess differences in top-down modulation for these stimuli using coherence analysis. We found a fronto-parietal network oscillating in the lower gamma band and exerting top-down control as determined by the causality measure of phase slope index. We demonstrated that correct recognition of facial emotions involved highbeta and low-gamma activity in parietal networks, Incorrect recognition was associated with enhanced coupling in the gamma band between left frontal and right parietal regions.Our results indicate that fronto-parietal control of the perception of emotional face stimuli relies on the right-hemispheric dominance of synchronized gamma band activity.

A New Adaptive Procedure for Estimating Perceptual Thresholds: The Effects of Observer Bias and Its Correction

“…While in this article, bias was regarded as a nuisance parameter that masks subjects' sensory capacities [34], it is important to underline that in other studies, changes in bias are the parameters of interest. For instance, studying the perception of emotional stimuli in psychiatric diseases, such as depression [35], schizophrenia [36] or autism [37,38] or in healthy subjects [16,39,40], the observed higher or lower thresholds might result from a shift in the sensory bias rather than from altered sensitivity. Since the proposed method differentiates sensitivity and bias, deriving estimates for both, the method might have a wide range of applications in psychotherapy, in which would be interesting to modulate these parameters independently.…”

A new adaptive procedure for estimating perceptual thresholds: the effects of observer bias and its correction

“…While in this article, bias was regarded as a nuisance parameter that masks subjects' sensory capacities (Witte, Kober, Ninaus, Neuper, & Wood, 2013), it is important to underline that in other studies, changes in bias are the parameters of interest. For instance, studying the perception of emotional stimuli in psychiatric diseases, such as depression (Bourne & Vladeanu, 2013), schizophrenia (Gooding & Tallent, 2002 or autism (Ashwin, Wheelwright, & Baron-Cohen, 2005;Taylor, Workman, & Yeomans, 2012) or in healthy subjects (Kajal, 2018;Kajal et al, 2017;Kajal et al, 2018), the observed higher or lower thresholds might result from a shift in the sensory bias rather than from altered sensitivity. Since the proposed method differentiates sensitivity and bias, deriving estimates for both, the method might have a wide range of applications in psychotherapy, in which would be interesting to modulate these parameters independently.…”