Multisensory processing after a brain damage: clues on post-injury crossmodal plasticity from neuropsychology.

Current neuropsychological evidence demonstrates that damage to sensory-specific and heteromodal areas of the brain not only disrupts the ability of combining sensory information from multiple sources, but can also cause altered multisensory experiences. On the other hand, there is also evidence of behavioural benefits induced by spared multisensory mechanisms. Thus, crossmodal plasticity can be viewed in both an adaptive and maladaptive context. The emerging view is that different crossmodal plastic changes can result following damage to sensory-specific and heteromodal areas, with post-injury crossmodal plasticity representing an attempt of a multisensory system to reconnect the various senses and by-pass injured areas. Changes can be considered adaptive when there is compensation for the lesion-induced sensory impairment. Conversely, it may prove maladaptive when atypical or even illusory multisensory experiences are generated as a result of re-arranged multisensory networks. This theoretical framework posits new intriguing questions for neuropsychological research and places greater emphasis on the study of multisensory phenomena within the context of damage to large-scale brain networks, rather than just focal damage alone.