Spontaneous Perceptual Reversals reflect in Internal Rhythms, Not Metabolic Shifts or Evoked Responses

Abstract

The perceptual interpretation of a static image, such as the Necker cube, can change spontaneously, resulting in endogenously driven changes in perception. We studied how different peripheral markers of the body’s physiological state, as well as time-resolved markers of EEG-derived brain activity, modulate around such spontaneous changes in perception. Specifically, we quantified the time course of heart rate, respiration rate, respiration phase, pupil size, EEG evoked responses, and EEG time-frequency activity around spontaneous perceptual reversals, and tested how these signals differ between the two interpretations of the Necker cube. Our results show that signals relating to the body’s and brain’s momentary state differ between the two perceptual interpretations, including pupil size, respiration phase, and rhythmic EEG activity. In contrast, signals relating to metabolic state or external stimuli, including respiration rate, heart rate and EEG evoked responses, did not differ between perceptual interpretations, but were consistently modulated around these. This corroborates the notion that spontaneous changes in perception are related to specific and coordinated windows in the cardiorespiratory cycle and neural markers of arousal or top-down processing. These windows are differentially expressed across interacting physiological systems, highlighting the intricate link between perception, brain activity and bodily physiology.