Audiovisual stimuli enhance narrowband gamma activity along the mouse thalamocortical visual circuit

Abstract

To what extent thalamic activity can contribute to multisensory integration at cortical level is unclear. To explore this aspect, we used the mouse narrowband gamma oscillations (NBG), which arise from the lateral geniculate nucleus (LGN) and from upstream retinal inputs, as a tool to investigate potential thalamic audiovisual information transfer to the primary visual cortex (V1). We found that simultaneous bimodal audiovisual stimulation increased the power of V1 NBG. Pharmacological and optogenetic manipulations demonstrated that V1 NBG audiovisual responses occurred independently of primary auditory cortex activation. LGN recordings revealed that the majority of its neurons exhibited audiovisual properties. These properties comprised an increase of both the visual-evoked response and gamma-rhythmicity, indicating that the modulation of V1 NBG by audiovisual stimuli likely has a thalamic origin. Our results reveal a previously unreported subcortical source of audiovisual information transfer in V1 and suggest a new role for the LGN as a multisensory integration and relay center.