Abstract
Cross-modal interaction (CMI) could significantly influence the perceptional or decision-making process in many circumstances. However, it remains poorly understood what integrative strategies are employed by the brain to deal with different task contexts. To explore it, we examined neural activities of the medial prefrontal cortex (mPFC) of rats performing cue-guided two-alternative forced-choice tasks. In a task requiring rats to discriminate stimuli based on auditory cue, the simultaneous presentation of an uninformative visual cue substantially strengthened mPFC neurons' capability of auditory discrimination mainly through enhancing the response to the preferred cue. Doing this also increased the number of neurons revealing a cue preference. If the task was changed slightly and a visual cue, like the auditory, denoted a specific behavioral direction, mPFC neurons frequently showed a different CMI pattern with an effect of cross-modal enhancement best evoked in information-congruent multisensory trials. In a choice free task, however, the majority of neurons failed to show a cross-modal enhancement effect and cue preference. These results indicate that CMI at the neuronal level is context-dependent in a way that differs from what has been shown in previous studies.
Highlights
In real life, we often receive multiple sensory cues simultaneously
In Task 3, animals were not required to discern stimuli at all and could make a free choice. These tasks allowed us to investigate how medial prefrontal cortex (mPFC) multisensory perceptual decision strategies changed with the demands of the task
The spatiotemporal arrangement and intensities of stimuli were found to be critical for cross-modal interaction (CMI)
Summary
We often receive multiple sensory cues simultaneously (with most being visual and auditory). The brain must combine them properly and form an effective decision in response to whatever the combination represents accurately. During this process, the brain must decide what sensory inputs are related and what integrative strategy is appropriate. In the past three decades, this process of cross-modal interaction (CMI) or multisensory integration has been widely examined in many brain areas such as superior colliculus, and both primary sensory and association cortices [1,2,3,4,5,6]. Neuroimaging studies have demonstrated that CMI can directly influence perceptual decisions in both association and sensory cortices
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