Dissociating linguistic and sensory neural plasticity in human superior temporal cortex
2012 (English)Conference paper, Abstract (Refereed)
The study of brain function in deaf individuals provides a unique opportunity not only to understand language independently of speech and hearing, but also to dissociate plastic changes related to adaptive sensory mechanisms from those associated with cognitive processes.In congenitally deaf individuals, sign language and simple visual stimuli reliably elicit activation in the superior temporal cortex (STC), a region usually associated with the processing of auditory input, including speech. However, it is not clear if this plasticity is driven by perceptual or cognitive mechanisms, and disentangling these effects is fundamental for establishing the relationship between the function of cortical regions, and the type of plastic changes that this functional specialisation allows.Here, we show that plastic effects in the STC have a sensory origin, whereas differential activations due to sign language experience are specific to the processing of linguistic stimuli. We dissociated between these two components by characterising the fMRI BOLD response to sign language stimuli in individuals deaf from infancy who were either early and proficient users of a sign language or had no knowledge of a sign language. There was no difference in the level of activation across groups in the right STC, indicating that plasticity in this region is mainly due to sensory deprivation. In contrast, further activations were observed in the group of signers in the left ventral STC, underpinning the role of this region in processing language. None of these activations were observed in a control group of hearing non-signers.These results show that linguistic and sensory factors cause plasticity in anatomically and functionally distinguishable substrates. Furthermore, they demonstrate that functionally distinct cortical areas preserve their perceptual and cognitive roles, but adapt their processing to deal with input from a different modality.1. Nishimura, H. et al. Sign language ‘heard’ in the auditory cortex. Nature 397, 116 (1999).2. Finney, E. M., Fine, I. & Dobkins, K.R. Visual stimuli activate auditory cortex in the deaf. Nature Neurosci 4, 1171-1173 (2001).
Place, publisher, year, edition, pages
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-88004OAI: oai:DiVA.org:liu-88004DiVA: diva2:601054
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