Context-dependent signaling of coincident auditory and visual events in primary visual cortex

Abstract

Detecting rapid, coincident changes across sensory modalities is essential for recognition of sudden threats or events. Using two-photon calcium imaging in identified cell types in awake, head-fixed mice, we show that, among the basic features of a sound envelope, loud sound onsets are a dominant feature coded by the auditory cortex neurons projecting to primary visual cortex (V1). In V1, a small number of layer 1 interneurons gates this cross-modal information flow in a context-dependent manner. In dark conditions, auditory cortex inputs lead to suppression of the V1 population. However, when sound input coincides with a visual stimulus, visual responses are boosted in V1, most strongly after loud sound onsets. Thus, a dynamic, asymmetric circuit connecting AC and V1 contributes to the encoding of visual events that are coincident with sounds.

Head Movements Control the Activity of Primary Visual Cortex in a Luminance Dependent Manner

“…1e). Moreover, even though V1 can respond to sound 12,13 , the response to table rotations was not due to the sound of the servo motor because detaching the table from the motor, hence preserving the sound without triggering rotation, did not elicit any response (3.8%, 13 out of 341 cells, n = 3 mice, data not shown).…”

Sound induces change in orientation preference of V1 neurons: Audio-visual cross-influence

“…This non-linearity may yield a preference towards the horizontal orientations. Another important revelation from a previous study (Deneux et al, 2018) suggests that the increasing intensity of sound strengthens the neuronal response. The intensity of the stimulus we used was kept the same for the 3s, and the same 3s time was repeated for 12 min.…”

“…As summarized by Meijer and authors in their paper (Meijer et al, 2017), auditory stimuli suppress VIP interneurons which inhibit SOM cells which in turn suppresses PV (Parvalbumin; GABAergic interneurons) cells and distal dendrites (involved in non-local synapses) of supragranular pyramidal cells (Gentet, 2012;Meijer et al, 2017). This specific pathway is activated precisely in response only to non-visual inputs (Deneux et al, 2018). Indeed, pyramidal cells are entrenched by inhibitory cells (Tremblay et al, 2016).…”

“…It has been noted that short duration sounds produce weak visual responses (Brady, 2011;Deneux et al, 2018). Repeated presentation of the sound stimulus for a prolonged duration may be accountable for eliciting stronger responses in V1.…”

“…Recent studies have suggested that sound modulates light responses by impacting inhibitory neurons in the V1 cortex (Iurilli et al, 2012;Kayser & Remedios, 2012;Pluta et al, 2015;Ibrahim et al, 2016). A very recent report (Deneux et al, 2018) revealed that auditory cortex neurons project to V1 inhibitory neurons in superficial layers, especially layer 1. Indeed, area A1 sends axons to V1 where they connect to inhibitory interneurons (Iurilli et al, 2012).…”