Repetition Suppression for Speech Processing in the Associative Occipital and Parietal Cortex of Congenitally Blind Adults

Abstract

In the congenitally blind (CB), sensory deprivation results in cross-modal plasticity, with visual cortical activity observed for various auditory tasks. This reorganization has been associated with enhanced auditory abilities and the recruitment of visual brain areas during sound and language processing. The questions we addressed are whether visual cortical activity might also be observed in CB during passive listening to auditory speech and whether cross-modal plasticity is associated with adaptive differences in neuronal populations compared to sighted individuals (SI). We focused on the neural substrate of vowel processing in CB and SI adults using a repetition suppression (RS) paradigm. RS has been associated with enhanced or accelerated neural processing efficiency and synchronous activity between interacting brain regions. We evaluated whether cortical areas in CB were sensitive to RS during repeated vowel processing and whether there were differences across the two groups. In accordance with previous studies, both groups displayed a RS effect in the posterior temporal cortex. In the blind, however, additional occipital, temporal and parietal cortical regions were associated with predictive processing of repeated vowel sounds. The findings suggest a more expanded role for cross-modal compensatory effects in blind persons during sound and speech processing and a functional transfer of specific adaptive properties across neural regions as a consequence of sensory deprivation at birth.

Analysis of continuous neuronal activity evoked by natural speech with computational corpus linguistics methods

“…However, creating a large number of stimuli to increase SNR is associated with a serious drawback. It is well known that repeated presentation of a stimulus causes a diminished neural activation, a phenomenon for which the term repetition suppression has been coined [27][28][29][30][31]. In fMRI, repetition suppression is observed as a reduced blood oxygen-level-dependent (BOLD) response elicited by a repeated stimulus, also called fMRI adaptation [32]; for a recent review see also [33].…”

Neuronal populations in the occipital cortex of the blind synchronize to the temporal dynamics of speech

“…However, studies in infants born with extensive damage to cortical regions that are typically involved in language processing may develop normal language abilities, thereby demonstrating that the language network is subject to reorganization ( Bates, 2005 ). Perhaps the most intriguing demonstrations to show that the neurobiology of language is susceptible to change due to experience come from studies showing functional selectivity to language in primary and secondary ‘visual’ areas in congenitally blind individuals ( Röder et al, 2002 ; Burton, 2003 ; Amedi et al, 2004 ; Bedny et al, 2011 ; Arnaud et al, 2013 ). Such reorganization of the language network is particularly fascinating because it arises in the absence of injury to the core language network ( Bates, 2005 ; Atilgan et al, 2017 ).…”

“…Speech comprehension requires that the brain extracts meaning from the acoustic features of sounds ( de Heer et al, 2017 ). Although several neuroimaging studies have yielded valuable insights about the processing of speech in EB adults ( Arnaud et al, 2013 ; Bedny et al, 2011 ; Büchel, 2003 ; Lane et al, 2015 ; Röder et al, 2002 ) and infants ( Bedny et al, 2015 ), these methods do not adequately capture the fast and continuous nature of speech processing. Because speech unfolds over time, understanding spoken language relies on the ability to track the incoming acoustic signal in near real-time ( Peelle and Davis, 2012 ).…”

Neuronal populations in the occipital cortex of the blind synchronize to the temporal dynamics of speech

“…However, studies in infants born with extensive damage tothe typical brain’s language areas may develop normal language abilities, demonstrating that the language network is subject to reorganization (Bates, 2005). Perhaps the most intriguing demonstration that the neurobiology of language is susceptible to change due to experience comes from studies in congenitally blind individuals showing functional selectivity to language in primary and secondary ‘visual’ areas (Roder et al, 2002; Burton, 2003; Amedi et al, 2004; Bedny et al, 2011; Arnaud et al, 2013). Such reorganization of the language network is particularly fascinating since it arisesin a system with no injuries ofthe core language network (Bates, 2005; Atilgan et al, 2017).…”

“…Speech comprehension requires that the brain extract meaning from the acoustic features of sounds(de Heer et al, 2017). Although several neuroimaging studies have yielded valuable insights about the processing of speech in early blind adults (Arnaud et al, 2013; Bedny et al, 2011; Burton, 2003; Lane et al, 2015; Röder et al, 2002)and infants (Bedny et al, 2015), these methods do not adequately capture the fast and continuous nature of speech processing. Because speech unfolds over time, understanding spoken language rely on the ability to track the incoming acoustic signal in near real-time (Peelle and Davis, 2012).…”