Massive cortical reorganization in sighted Braille readers.

Katarzyna Siuda-Krzywicka,Katarzyna Jednoróg,Ewa Sumera,Łukasz Bola,Marcin Szwed,Małgorzata Paplińska,Magdalena W Śliwińska,Artur Marchewka,Amir Amedi

doi:10.7554/elife.10762

Abstract

The brain is capable of large-scale reorganization in blindness or after massive injury. Such reorganization crosses the division into separate sensory cortices (visual, somatosensory...). As its result, the visual cortex of the blind becomes active during tactile Braille reading. Although the possibility of such reorganization in the normal, adult brain has been raised, definitive evidence has been lacking. Here, we demonstrate such extensive reorganization in normal, sighted adults who learned Braille while their brain activity was investigated with fMRI and transcranial magnetic stimulation (TMS). Subjects showed enhanced activity for tactile reading in the visual cortex, including the visual word form area (VWFA) that was modulated by their Braille reading speed and strengthened resting-state connectivity between visual and somatosensory cortices. Moreover, TMS disruption of VWFA activity decreased their tactile reading accuracy. Our results indicate that large-scale reorganization is a viable mechanism recruited when learning complex skills.

Highlights

The current view of neural plasticity in the adult brain sees it as ubiquitous but generally constrained by functional boundaries (Hoffman and Logothetis, 2009)
Our results demonstrate that the occipitotemporal visual cortex (VWFA, MNI y»-60) can represent stimuli in a modality other than vision
The fact that transcranial magnetic stimulation (TMS) to the visual word form area (VWFA) can disrupt tactile reading demonstrates the importance of this representation for sensory processing

Summary

Introduction

The current view of neural plasticity in the adult brain sees it as ubiquitous but generally constrained by functional boundaries (Hoffman and Logothetis, 2009). Experience-driven plasticity is thought to operate within the limits of sensory divisions, where the visual cortex processes visual stimuli and responds to visual training, the tactile cortex processes tactile stimuli and responds to tactile training, and so on. A departure from this rule is usually reported only during large-scale reorganization induced by sensory loss or injury (Hirsch et al, 2015; Lomber et al, 2011; Merabet and Pascual-Leone, 2010; Pavani and Roder, 2012). The ventral visual cortex, in particular, is activated in blind subjects who read Braille

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Conclusion