Neural correlates of object identity and reward outcome in the corticohippocampal hierarchy: double dissociation between perirhinal and secondary visual cortex

Neural circuits support behavioral adaptations by integrating sensory and motor information with reward and error-driven learning signals, but it remains poorly understood how these signals are distributed across different levels of the corticohippocampal hierarchy. We trained rats on a multisensory object-recognition task and compared visual and tactile responses of simultaneously recorded neuronal ensembles in somatosensory cortex, secondary visual cortex, perirhinal cortex and hippocampus. The sensory regions primarily represented unisensory information, while hippocampus was modulated by both vision and touch. Surprisingly, secondary visual cortex but not perirhinal neurons coded object-specific information, whereas perirhinal but not visual cortical neurons signaled trial outcome. A majority of outcome-related perirhinal cells responded to a negative outcome (reward omission), whereas a minority of other cells coded positive outcome (reward delivery). Our results support a distributed neural coding of multisensory variables in the cortico-hippocampal hierarchy, with a double dissociation between higher visual cortex and perirhinal cortex in coding of object identity versus feedback on trial outcome.