Poster B1, Tuesday, August 20, 2019, 3:15 – 5:00 pm, Restaurant Hall
Cross-modal plasticity in secondary auditory cortex
Emil Holmer1, Josefine Andin1, Mary Rudner1;1Linköping University
In deaf early signers (DES) secondary auditory cortex (TE3) is reorganized to support visual and cognitive processing. In the present work, we investigated plastic reorganization in TE3 for visual working memory (WM) in DES. In an fMRI experiment, 16 DES and 22 hearing non-signers (HNS) performed a sign-based n-back WM task. In the task, sequences of video-recorded lexicalized signs from the Swedish Sign Language (SSL) were presented in high or low visual resolution. Participants judged whether the present video was the same as the video n steps back in the sequence, and WM load was manipulated by varying n from one to three. Region of interest analysis was performed by obtaining mean activation separately for left and right TE3 for each participant. A two (group) by three (load) by two (resolution) by two (hemisphere) mixed ANOVA was performed. A main effect of group showed stronger relative activation across both hemispheres for DES compared to HNS. Corroborating previous studies, there was consistent deactivation compared to rest in the HNS, indicating suppression of non-relevant auditory stimuli. In contrast, for the DES, a relative activation compared to rest was observed. Further, for both groups activation varied as a function of WM load and visual resolution. For HNS, there was a consistent deactivation across all conditions. For DES, significant activation was found for 1-back at both resolutions and for 2-back in high resolution, whilst 2-back in low resolution and 3-back in both resolutions showed neither clear activation nor deactivation. There was also a significant interaction between hemisphere and group. DES showed stronger relative activation compared to HNS in both hemispheres. HNS showed more deactivation in right compared to left hemisphere, whereas no difference across hemispheres was found for DES. In conclusion, these results suggest that in DES, secondary auditory cortex support WM processing when task demands are low. Thus, the present study support the notion of cross-modal plasticity in secondary auditory cortex for DES.
Themes: Signed Language and Gesture, Control, Selection, and Executive Processes
Method: Functional Imaging