Cellular and synaptic architecture of multisensory integration in the mouse neocortex

Area of Science:

• Neuroscience
• Sensory processing
• Cortical microcircuits

Background:

• Multisensory integration (MI) is vital for sensory processing.
• The organization of MI within cortical microcircuits remains poorly understood.

Purpose of the Study:

• To investigate the layer and cell-type specificity of MI in the rodent parietal cortex.
• To elucidate the role of inhibitory interneurons in MI.

Main Methods:

• Whole-cell recordings in mouse visuotactile areas.
• Optogenetic manipulation of parvalbumin-positive interneurons.
• Single-cell resolution calcium imaging.

Main Results:

• Spike responses showed less bimodality but greater multisensory enhancement than synaptic responses.
• MI was layer and cell-type specific, rare in inhibitory interneurons and infragranular layers.
• Scarce interneuron MI facilitates MI in neighboring pyramidal neurons.
• Gradual merging of modalities observed, with unimodal clusters in the cortical area center.

Conclusions:

• Neuronal subcircuits play distinct roles in the synaptic process of MI.
• Inhibitory interneurons are critical for enabling MI in pyramidal neurons.
• Understanding MI organization in the parietal cortex provides insights into sensory processing.