How Auditory Experience Differentially Influences the Function of Left and Right Superior Temporal Cortices

Abstract

To investigate how hearing status, sign language experience, and task demands influence functional responses in the human superior temporal cortices (STC) we collected fMRI data from deaf and hearing participants (male and female), who either acquired sign language early or late in life. Our stimuli in all tasks were pictures of objects. We varied the linguistic and visuospatial processing demands in three different tasks that involved decisions about (1) the sublexical (phonological) structure of the British Sign Language (BSL) signs for the objects, (2) the semantic category of the objects, and (3) the physical features of the objects.Neuroimaging data revealed that in participants who were deaf from birth, STC showed increased activation during visual processing tasks. Importantly, this differed across hemispheres. Right STC was consistently activated regardless of the task whereas left STC was sensitive to task demands. Significant activation was detected in the left STC only for the BSL phonological task. This task, we argue, placed greater demands on visuospatial processing than the other two tasks. In hearing signers, enhanced activation was absent in both left and right STC during all three tasks. Lateralization analyses demonstrated that the effect of deafness was more task-dependent in the left than the right STC whereas it was more task-independent in the right than the left STC. These findings indicate how the absence of auditory input from birth leads to dissociable and altered functions of left and right STC in deaf participants.SIGNIFICANCE STATEMENT Those born deaf can offer unique insights into neuroplasticity, in particular in regions of superior temporal cortex (STC) that primarily respond to auditory input in hearing people. Here we demonstrate that in those deaf from birth the left and the right STC have altered and dissociable functions. The right STC was activated regardless of demands on visual processing. In contrast, the left STC was sensitive to the demands of visuospatial processing. Furthermore, hearing signers, with the same sign language experience as the deaf participants, did not activate the STCs. Our data advance current understanding of neural plasticity by determining the differential effects that hearing status and task demands can have on left and right STC function.

Emmorey_Reading_Chapter_2020

“…A regression analysis revealed that greater dB loss was associated with greater activation in left STG auditory cortex, but no behavioral measures or demographic variables were linked to neural activation in right STG. This pattern is consistent with a recent fMRI study with congenitally deaf signers by Twomey et al (2017). These authors found that activation in left STG was sensitive to linguistic task demands, but activation in right STG was task-independent; no activation in STG (left or right) was observed for hearing signers performing the same tasks.…”

Auditory and speech function after cochlear implantation in prelingually deaf children with white matter lesions

“…Meanwhile, architectural and functional integrity of the temporal lobe is the first pass effect in speech rehabilitation . Any lesions involved in hearing loss, afferent stimulus interruption, or myelin hypoplasia, could eventually lead to a decreased volume or the inactivation of the auditory centre . There is little universal agreement on the plasticity of the auditory centre after hearing restoration.…”

“…20 Any lesions involved in hearing loss, afferent stimulus interruption, or myelin hypoplasia, could eventually lead to a decreased volume or the inactivation of the auditory centre. 21 There is little universal agreement on the plasticity of the auditory centre after hearing restoration. Our EEG source imaging results demonstrated that in prelingually deaf children, the auditory area, like the supra-temporal lobe, was able to be activated pCI.…”

Sensory experience modulates the reorganisation of temporal auditory regions for executive processing

“…Previous behavioural studies in deaf children have shown that language deprivation, and not deafness per se , negatively impacts EF (Kalback, 2004; Figueras et al, 2008; Remine et al, 2008; Marshall et al, 2015; Botting et al, 2017). It is also known that late language acquisition can impact the reorganisation of auditory areas and the neural substrates of language processing (Neville and Bavelier, 1998; MacSweeney et al, 2008a,b; Mayberry et al, 2011; Cardin et al, 2013; Ferjan Ramirez et al, 2014, 2016; Cardin et al, 2016; Twomey et al, 2017), but it is not known what effect it has on neural executive processing. Revealing the effect of language experience on executive processing in the brain will provide unique insights into the nature and mechanisms of this relationship.…”