Mouse frontal cortex mediates additive multisensory decisions

• Published in: Neuron (Cambridge, Mass.) Mass.), 2023-08, Vol.111 (15), p.2432-2447.e13
• Main Authors: Coen, Philip, Sit, Timothy P.H., Wells, Miles J., Carandini, Matteo, Harris, Kenneth D.
• Format: Article
• Language: English
• Subjects: Acoustic Stimulation - methods; Animals; audiovisual; Auditory Cortex - physiology; Auditory Perception - physiology; decision-making; Frontal Lobe; Mice; mixed selectivity; neural coding; optogenetics; parietal cortex; Photic Stimulation - methods; prefrontal cortex; visual cortex; Visual Perception - physiology
• ISSN: 0896-6273; 1097-4199
• DOI: 10.1016/j.neuron.2023.05.008

The brain can combine auditory and visual information to localize objects. However, the cortical substrates underlying audiovisual integration remain uncertain. Here, we show that mouse frontal cortex combines auditory and visual evidence; that this combination is additive, mirroring behavior; and that it evolves with learning. We trained mice in an audiovisual localization task. Inactivating frontal cortex impaired responses to either sensory modality, while inactivating visual or parietal cortex affected only visual stimuli. Recordings from >14,000 neurons indicated that after task learning, activity in the anterior part of frontal area MOs (secondary motor cortex) additively encodes visual and auditory signals, consistent with the mice’s behavioral strategy. An accumulator model applied to these sensory representations reproduced the observed choices and reaction times. These results suggest that frontal cortex adapts through learning to combine evidence across sensory cortices, providing a signal that is transformed into a binary decision by a downstream accumulator. •Mice combine visual and auditory evidence additively to solve an audiovisual task•Optogenetic inactivation indicates a key role for frontal cortex in the task•After learning, neurons in frontal area MOs represent stimuli and predict choice•An accumulator model applied to their activity reproduces mouse behavior Coen, Sit, et al. train mice in an audiovisual task and show that they combine evidence across modalities additively, even when it is conflicting. This combination relies on activity in frontal area MOs. After learning, this activity represents auditory and visual stimuli additively and can be used to reproduce behavior.