Species-dependent role of crossmodal connectivity among the primary sensory cortices

When a major sense is lost, crossmodal plasticity substitutes functional processing from the remaining, intact senses. Recent studies of deafness-induced crossmodal plasticity in different subregions of auditory cortex indicate that the phenomenon is largely based on the “unmasking” of existing inputs. However, there is not yet a consensus on the sources or effects of crossmodal inputs to primary sensory cortical areas. In the present review, a rigorous re-examination of the experimental literature indicates that connections between different primary sensory cortices consistently occur in rodents, while primary-to-primary projections are absent/inconsistent in non-rodents such as cats and monkeys. These observations suggest that crossmodal plasticity that involves primary sensory areas are likely to exhibit species-specific distinctions. [Display omitted] •Crossmodal plasticity occurs following major sensory loss.•Functional properties of crossmodal plasticity differ; dependent on input pattern.•Primary-to-primary cortical inputs are consistent among rodent species.•Primary-to-primary cortical inputs are absent/inconsistent in non-rodents.•Crossmodal plasticity in primary sensory areas is likely to be species-specific.