Neural oscillations promoting perceptual stability and perceptual memory during bistable perception

Michael Zhu,Richard Hardstone,Biyu J He

doi:10.1038/s41598-022-06570-4

Abstract

Ambiguous images elicit bistable perception, wherein periods of momentary perceptual stability are interrupted by sudden perceptual switches. When intermittently presented, ambiguous images trigger a perceptual memory trace in the intervening blank periods. Understanding the neural bases of perceptual stability and perceptual memory during bistable perception may hold clues for explaining the apparent stability of visual experience in the natural world, where ambiguous and fleeting images are prevalent. Motivated by recent work showing the involvement of the right inferior frontal gyrus (rIFG) in bistable perception, we conducted a transcranial direct-current stimulation (tDCS) study with a double-blind, within-subject cross-over design to test a potential causal role of rIFG in these processes. Subjects viewed ambiguous images presented continuously or intermittently while under EEG recording. We did not find any significant tDCS effect on perceptual behavior. However, the fluctuations of oscillatory power in the alpha and beta bands predicted perceptual stability, with higher power corresponding to longer percept durations. In addition, higher alpha and beta power predicted enhanced perceptual memory during intermittent viewing. These results reveal a unified neurophysiological mechanism sustaining perceptual stability and perceptual memory when the visual system is faced with ambiguous input.

Highlights

Ambiguous images elicit bistable perception, wherein periods of momentary perceptual stability are interrupted by sudden perceptual switches
To test whether perturbing neural activity in the right inferior frontal gyrus (rIFG) causes changes in perceptual stability during bistable perception, we carried out an HD-transcranial direct-current stimulation (tDCS) experiment with a double-blind, within-subject cross-over design (N = 24)
The three experimental sessions differed in tDCS manipulation and included: (1) anodal high-definition tDCS (HD-tDCS) over the right inferior frontal gyrus; (2) anodal HD-tDCS over the occipital pole (Occ; Fig. 1B, Left); (3) sham stimulation over either the rIFG or Occ

Summary

Introduction

Ambiguous images elicit bistable perception, wherein periods of momentary perceptual stability are interrupted by sudden perceptual switches. Ambiguous images—wherein ambiguity of a visual image is sufficiently high as to trigger continuous perceptual alternations between possible interpretations—offer an excellent experimental paradigm to unravel how the visual system resolves perception when sensory input is a mbiguous[2,3,4] When viewing these ambiguous images, the visual input remains static while perceptual outcome changes spontaneously; this allows disentangling neural activities related to low-level sensory processing from those giving rise to the content of perceptual a wareness[3,5]. This paradigm is well suited for investigating neural mechanisms that promote perceptual switching vs perceptual stability, which manifest as spontaneous changes in perception and prolonged percept durations, respectively. Instead of presenting a static ambiguous image, a blank period is inserted in between repeated presentations of the same image; this simple manipulation results in a significant

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Discussion

Conclusion