Colloquium on the Brain and Cognition with Hey-Kyoung Lee, PhD, Johns Hopkins University

This seminar is being held virtually. Please click here to attend. 

Cross-modal plasticity in adults

Cross-modal plasticity refers to the adaptation of the brain after losing a sensory modality, which enables the organism to navigate the world with the remaining senses. One such example seen in blind subjects is the activation of the visual cortex by Braille or speech. Such cross-modal recruitment is thought to be beneficial as it allows the spared sensory information to be processed by a larger cortical area. In addition, there is enhancement and refinement of the remaining senses via compensatory plasticity of the spared sensory cortices. We found that a short duration of vision loss triggers large-scale circuit plasticity across the primary sensory cortices even in adults. Such cross-modal plasticity is robust and manifests differently in the deprived visual cortex (V1) and the spared auditory cortex (A1). Plasticity in V1 mainly involves potentiation of intracortical excitatory synapses, while in A1 it manifests as potentiation of the feedforward pathways at the expense of intracortical inputs. Mechanistically, plasticity observed in both V1 and A1 conforms to Hebbian plasticity coupled to the “sliding threshold” metaplasticity. I will discuss the functional consequences of the circuit level cortical plasticity, and present data that cross-modal plasticity is observed even earlier in the sensory processing at the level of thalamic gating.