UC Berkeley

Perception proceeds by cinematic frames that are separated by an endogenousshutter,which is intrinsic to the backgroundspontaneousactivity of cerebral cortex. Cinematic displays of spatiotemporal electrocorticograms (ECoG) show turbulence, from which stable spatial patterns emerge that are correlated with perception of conditioned stimuli (CS). Extracting invariant properties of the perceptual patterns requires high-resolution measurements by high-density electrode arrays, high-order FIR filters, and the Hilbert transform giving analytic signals (instantaneous amplitudes and frequencies). Each pattern is preceded by anull spike, which is postulated to reveal asingularityin cortical dynamics that operates the shutter. A piecewise linear model is used to solve the nonlinear differential equations of mesoscopic cortical dynamics. Solutions point to the existence of a limit cycle attractor. The behavioral and physiological circumstances are described by which the trajectory of cortical dynamics may converge to the attractor and precipitate a phase transition, which destroys an existing pattern and initiates a new one.