Multisensory task demands temporally extend the causal requirement for visual cortex in perception

Abstract

Primary sensory areas constitute crucial nodes during perceptual decision making. However, it remains unclear to what extent they mainly constitute a feedforward processing step, or rather are continuously involved in a recurrent network together with higher-order areas. We found that the temporal window in which primary visual cortex is required for the detection of identical visual stimuli was extended when task demands were increased via an additional sensory modality that had to be monitored. Late-onset optogenetic inactivation preserved bottom-up, early-onset responses which faithfully encoded stimulus features, and was effective in impairing detection only if it preceded a late, report-related phase of the cortical response. Increasing task demands were marked by longer reaction times and the effect of late optogenetic inactivation scaled with reaction time. Thus, independently of visual stimulus complexity, multisensory task demands determine the temporal requirement for ongoing sensory-related activity in V1, which overlaps with report-related activity.

Triple dissociation of visual, auditory and motor processing in primary visual cortex

“…Our finding that auditory changes not only modulated, but evoked spiking in V1 of naive and visually trained mice as well as in mice trained to discriminate auditory and visual signals, suggests a broader role for auditory signals in V1 than only sharpening visual tuning. As shown elsewhere, auditory signals in V1 do not become causally important for audition during MST training, as V1 optogenetic inhibition impacts visual but not auditory change detection performance (Oude Lohuis et al, 2022). Even if auditory inputs to visual cortex are not directly relevant for detecting single visual features, they are hypothesized to fit in a broader view of sensory cortical function (Meijer et al, 2019; Pennartz, 2015, 2009; Petro et al, 2017), where crossmodal interactions serve to orchestrate perception across a larger cortical network, guide crossmodal attention, and inform visual processing in distributed networks about ongoing auditory events.…”

A novel task to investigate vibrotactile detection in mice

“…This transgenic line is often used in studies in which area-specific optogenetic inactivation is used, and has been successfully used as an experimental model to study sensory processing and decision making—see e.g. [ 8 , 37 , 40 ]. Comparable results are therefore expected with different mouse lines.…”

“…Thus, after associating stimulus presentation to reward delivery (Stage 1), in Stage 2 mice had to learn to perform licking actions to obtain a reward, and to time licking actions to sensory stimuli. Each trial consisted of a stimulus period with a vibration lasting for 2 s. Intertrial periods had a random duration between 5 to 20 s based on an exponential distribution wit ( Fig 2A , Stage 2) [ 37 ]. The exponential distribution had a mean of 1 s, with a minimum (offset) value of 5 s and a cut-off at 20 s. Note that the probability of having an ITI longer than 20 s is smaller than 0.001%.…”

“…The exponential distribution had a mean of 1 s, with a minimum (offset) value of 5 s and a cut-off at 20 s. Note that the probability of having an ITI longer than 20 s is smaller than 0.001%. Thus, the hazard rate can be assumed as flat for ITI values larger than 5 s. Each trial was categorized as a ‘Hit’ when a lick was performed during the stimulus period and after a grace period of 100 ms from stimulus onset, to account for physiological reaction time [ 37 ]. A reward was delivered immediately following the detection of the first lick.…”

“…Consequently, our understanding of the microcircuit-level physiology of somatosensation in—for instance—limbs and paws mostly comes from studies involving passive stimulation of mechanoreceptors [ 35 , 36 ]. The limited availability of tasks suitable to study skin somatosensory perception is problematic, since engagement in a task has been shown to strongly influence how sensory information is processed within the thalamocortical system [ 11 , 15 , 37 , 38 ]. Thus, passive stimulation of receptors is insufficient to fully understand how somatosensory processing operates.…”