Abstract
Alpha-range (8-12 Hz) neural rhythms, prominent over occipital cortex, can serve as a predictor of performance on visual tasks. Specifically, visual performance and attentional selection have been shown to co-vary with the ongoing alpha cycle recorded on the scalp. Despite their impact on visual performance, little is known about the intracortical origins of alpha rhythms and how alpha cycles impact visual processing. Here, we study laminar neural activity in primate visual cortex in order to determine a mechanistic link between alpha cycles and visually evoked spiking responses. Two macaque monkeys (Macaca radiata) fixated while static grating stimuli were presented inside of the receptive field under study. During this time, we recorded alpha-range local field potentials and multiunit spiking activity from all layers of V1 simultaneously. We found that throughout several hundred milliseconds of visual stimulation, spiking activity in all layers was strongly decreased at the time of alpha troughs recorded in the deep, feedback-recipient cortical layers compared to the level of columnar spiking at alpha peaks. Specifically, the magnitude of population spiking activity at the time of alpha troughs was nearly half that at alpha peaks, suggesting that alpha induces pulsed inhibition of visual responses at the earliest stages of cortical processing. Lastly in order to probe the potential role of feedback afferences, we will present a comparison of intracolumnar coupling between alpha and visual spiking responses between the two attentional states.
Meeting abstract presented at VSS 2015