The Organization of Working Memory Networks is Shaped by Early Sensory Experience

Abstract

Early deafness results in crossmodal reorganization of the superior temporal cortex (STC). Here, we investigated the effect of deafness on cognitive processing. Specifically, we studied the reorganization, due to deafness and sign language (SL) knowledge, of linguistic and nonlinguistic visual working memory (WM). We conducted an fMRI experiment in groups that differed in their hearing status and SL knowledge: deaf native signers, and hearing native signers, hearing nonsigners. Participants performed a 2-back WM task and a control task. Stimuli were signs from British Sign Language (BSL) or moving nonsense objects in the form of point-light displays. We found characteristic WM activations in fronto-parietal regions in all groups. However, deaf participants also recruited bilateral posterior STC during the WM task, independently of the linguistic content of the stimuli, and showed less activation in fronto-parietal regions. Resting-state connectivity analysis showed increased connectivity between frontal regions and STC in deaf compared to hearing individuals. WM for signs did not elicit differential activations, suggesting that SL WM does not rely on modality-specific linguistic processing. These findings suggest that WM networks are reorganized due to early deafness, and that the organization of cognitive networks is shaped by the nature of the sensory inputs available during development.

Working Memory for Linguistic and Non-linguistic Manual Gestures: Evidence, Theory, and Application

“…The absence of activation differences between linguistic and non-linguistic working memory in the study by Cardin et al (2017) confirms the suggestion of Ding et al (2015) that the functional significance of the reorganized networks is related to visuospatial working memory rather than working memory for sign language as such. Nonetheless, these findings mean that the superior temporal cortex of congenitally deaf individuals reorganizes not only for perceptual processing of visual stimuli but also for their cognitive processing, such as working memory.…”

“…This extended the work of Ding et al (2015) using individuals with early deafness but with diverse language experience, by demonstrating that recruitment of superior temporal cortex in congenitally deaf individuals still takes place when language skills are well established and is thus not simply caused by poorly established language skills ( MacSweeney and Cardin, 2015 ). Further, in the study by Cardin et al (2017) , the deaf compared to hearing participants showed increased resting state connectivity between frontal regions and the superior temporal cortex, and this finding was replicated by Ding et al (2016) with deaf Chinese participants. These findings show that congenital deafness leads to reorganization of working memory networks.…”

“…There is accumulating evidence that the superior temporal cortex is engaged in working memory processing in deaf signers in a manner that is not observed in hearing individuals ( Cardin et al, 2017 , see Table 1 ; Ding et al, 2015 ). In particular, British deaf signers showed activation of the bilateral posterior superior temporal cortex during a 2-back working memory task, irrespective of whether it was based on BSL signs or moving nonsense objects ( Cardin et al, 2017 ).…”

“…There is accumulating evidence that the superior temporal cortex is engaged in working memory processing in deaf signers in a manner that is not observed in hearing individuals ( Cardin et al, 2017 , see Table 1 ; Ding et al, 2015 ). In particular, British deaf signers showed activation of the bilateral posterior superior temporal cortex during a 2-back working memory task, irrespective of whether it was based on BSL signs or moving nonsense objects ( Cardin et al, 2017 ). This extended the work of Ding et al (2015) using individuals with early deafness but with diverse language experience, by demonstrating that recruitment of superior temporal cortex in congenitally deaf individuals still takes place when language skills are well established and is thus not simply caused by poorly established language skills ( MacSweeney and Cardin, 2015 ).…”

“…Nonetheless, these findings mean that the superior temporal cortex of congenitally deaf individuals reorganizes not only for perceptual processing of visual stimuli but also for their cognitive processing, such as working memory. This perceptual and cognitive reorganization may be related to the performance advantage of deaf signers over hearing non-signers on visual working memory tasks ( Wilson et al, 1997 ; Geraci et al, 2008 ; MacSweeney and Cardin, 2015 ; Rudner et al, 2016b ; Cardin et al, 2017 ).…”