Changes in primary visual and auditory cortex of blind and sighted adults following 10 weeks of click-based echolocation training

Recent work suggests that the adult human brain is very adaptable when it comes to sensory processing. In this context it has also been suggested that structural ‘blueprints’ may fundamentally constrain neuroplastic change, e.g. in response to sensory deprivation. Here, we trained 12 blind participants (BPs) and 14 sighted participants (SPs) in echolocation over a 10-week period, and used MRI in a pre-post design to measure functional and structural brain changes. We found that BPs and SPs together showed a training-induced increase in activation in left and right V1 in response to echoes, a finding difficult to reconcile with the view that sensory cortex is strictly organised by modality. Further, BPs and SPs showed a training induced increase in activation in right A1 in response to sounds per se (i.e. not echo-specific), and this was accompanied by an increase in grey matter density in right A1 in BPs and in adjacent acoustic areas in SPs. The similarity in functional results between SPs and BPs is consistent with the idea that reorganization may be governed by similar principles in the two groups, yet our structural analyses also showed differences between the groups suggesting that a more nuanced view may be required.