December 3, 2020

Lateral phase differences in a population model of the visual cortex are sufficient for the development of rhythmic spatial sampling

When attending to many spatially distributed visual stimuli, attention is reweighted rhythmically at 4-8 Hz. The probability of detection depends on the phase at which a stimulus is deployed relative to this intrinsic rhythm. The reweighting oscillations can be observed both electrophysiologically and behaviorally, and appear to be regulated by the pulvinar. Based on these findings, we considered the computational consequences of allowing feedback to shape the distribution of inhibitory oscillations from the thalamus, as measured by a local field potential (LFP) phases in the 8 Hz low alpha-band, across laterally-connected regions of the visual cortex. We constructed a population activity model with lateral and feedforward connections. In agreement with prior models, we found that the sign of the lateral phase difference in the inhibitory low-frequency oscillations regulated the direction of communication between the laterally-connected regions. Furthermore, the phase difference induced periodicity in the dynamics of a downstream winner-takes-all attractor network such that periodic switching between states was observed. We finally simulated a simple spatial attention task. We found rhythmic 8 Hz sampling between two regions when a lateral phase difference was present-an effect that disappeared when the lateral phase difference was zero. These findings are in agreement with spatial attention literature and suggest that lateral phase differences are essential for manifesting communicational asymmetries in laterally-connected visual cortices. Our model predicts that population-specific phase differences are critical for sampling the spatial extent of stimuli.Competing Interest StatementThe authors have declared no competing interest.

 bioRxiv Subject Collection: Neuroscience

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