Causal role of the visual cortex in working memory and perceptual bias

Working memory is a critical component of cognition as it allows for the flexible coupling of
sensory input to motor output. However, imprecise maintenance of sensory information in working memory
and the influence of intervening sensory inputs may lead to history-dependent biases in behaviour, such as
recency or contraction bias. Recent studies have proposed that approximate (Lange et al., 2021) or imbalanced
(Deneve & Jardri, 2016) hierarchical Bayesian inference may account for such biases, and have suggested a
mapping of latent sensory representations onto the hierarchical organization of neocortex. In line with this,
sensory cortical areas have been found to causally contribute to working memory maintenance (Voitov &
Mrsic-Flogel, 2022). Here, we investigate the precise role of the primary visual cortex during visual working
memory – whether selectively arbitrating perceptual biases or maintaining the latent sensory representations
in working memory. We designed a visual working memory task for head-fixed mice which enabled us to
both vary the strength of visual working memory representations and the sensory history-dependent perceptual
bias on a trial-to-trial basis. We observed distinct psychometric profiles associated with the disruption of
working memory by the presentation of repeated distractor stimuli and the perceptual biases induced by the
sensory features of these distractor stimuli. To examine the role of early sensory processing in working
memory maintenance and perceptual bias, we optogenetically inactivated the primary visual cortex (V1)
during the inter-stimulus delay periods. Inactivating V1 did not influence working memory maintenance or
perceptual bias in isolation, but instead led to behavioural deficits which were consistent with a disruptive
effect on both. Our results therefore indicate that the maintenance of visual working memory and the
perceptual biases induced by sensory history are not dissociable early on in the neocortical hierarchy.