Neural responses to broadband visual flicker in marmoset primary visual cortex

Abstract

Temporal information is ubiquitous in natural vision and must be represented accurately in the brain to allow us to interact with a constantly changing world. Recent studies have employed a random stimulation paradigm to map the temporal response function (TRF) to luminance changes in the human EEG. This approach has revealed that the visual system, when presented with broadband visual input, actively selects distinct temporal frequencies, and retains their phase-information for prolonged periods of time. This non-linear response likely originates in primary visual cortex (V1), yet, so far it has not been investigated on a neural level. Here, we characterize the steady-state response to random broadband visual flicker in marmoset V1. In two experiments, we recorded from i) marmosets passively stimulated under general anesthesia, and ii) awake marmosets, under free viewing conditions. Our results show that LFP coupling to the stimulus was broadband and unselective under anesthesia, whereas in awake animals, it was restricted to two distinct frequency components, in the alpha and beta range. Within these frequency bands, coupling adhered to the receptive field (RF) boundaries of the local populations. The responses outside the RF did not provide evidence for a propagation of stimulus information across the cortex, contrary to results in human EEG studies. This result may be explained by short fixation durations, warranting further investigation. In summary, our findings show that during awake behavior V1 neural responses to broadband information are selective for distinct frequency bands, and that this selectivity is likely controlled actively by top-down mechanisms.