Crossmodal plasticity in hearing loss

Crossmodal plasticity is a textbook example of the ability of the brain to reorga-nize based on use. We review evidence from the auditory system showing that such reorganization has significant limits, is dependent on pre-existing circuitry and top-down interactions, and that extensive reorganization is often absent. We argue that the evidence does not support the hypothesis that crossmodal reorganization is responsible for closing critical periods in deafness, and crossmodal plasticity instead represents a neuronal process that is dynamically adaptable. We evaluate the evidence for crossmodal changes in both developmen-tal and adult-onset deafness, which start as early as mild-moderate hearing loss and show reversibility when hearing is restored. Finally, crossmodal plasticity does not appear to affect the neuronal preconditions for successful hearing resto-ration. Given its dynamic and versatile nature, we describe how this plasticity can be exploited for improving clinical outcomes after neurosensory restoration.

Automated summary

Crossmodal plasticity is the brain's ability to reorganize based on use. However, evidence shows that this reorganization has limits and is dependent on pre-existing circuitry and top-down interactions. We argue against the hypothesis that crossmodal reorganization closes critical periods in deafness, and instead propose that it is a dynamically adaptable neuronal process. The evidence for crossmodal changes in both developmental and adult-onset deafness is evaluated, showing reversibility when hearing is restored.