Abstract:

PURPOSE: Ambiguous stimulations can induce involuntary alternation between exclusive subjective perceptions. Numerous studies have demonstrated that a number of brain regions was involved in bistable perceptual processing. Though that top-down information processing has been proposed to interpret perceptual switching, the studies so far have been limited in providing spatial or temporal information about neural activity.
METHODS: In this study we investigated neural circuits associated with bistable perception in epileptic patients who are invasively implanted electrodes to clinically localize seizure onset zones. The electrophysiological and behavioral data were simultaneously recorded from ten patients while they performed a structure-from-motion (SFM) task. Three regions of interests (hMT+, PPC and LPFC) were extracted via either individual anatomy (PPC and LPFC) or a functionally probabilistic map (hMT+).
RESULTS: During performance of the SFM task, the LPFC and PPC showed significantly increased high-gamma (HG) activity (70-150Hz) about 300ms and 200ms, respectively, before perceptual switching, while the hMT+ showed increased HG activity even after perceptual switching. The increased HG activity in the LPFC and PPC was also validated not induced by the action. During a monostabile replay task, only hMT+ area, without the PPC and LPFC, showed significantly increased HG activity about 500ms before perceptual switching.
CONCLUSIONS: The temporal difference relative to the action between top-down and bottom-up pathway may be related to the underlying neural projections, which has been proposed by recent studies. Taken together, the findings suggest that the increased lateral prefrontal cortex itself can trig the alternative bistable perception, which did not rely on hMT+ activity, thereby providing a fundamental evidence for the top-down processing model of bistable perception.

Key words: bistable perception, structure from motion, the top-down processing, high gamma, intracranial EEG