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Functional Connectivity of Language Regions of Stroke patients with Expressive Aphasia during Real-time fMRI Neurofeedback.

Research paper by Sujesh S Sreedharan, Arun A K M, Chandrasekaran C Kesavadas, Sylaja S P N, Rangantha R Sitaram

Indexed on: 01 Jul '20Published on: 30 Jul '19Published in: Brain connectivity



Abstract

Stroke lesions in the language centers of the brain impair the language areas and their connectivity. Rehabilitation could occur due to the recovery of language areas as well as their interconnections. This paper describes the dynamics of functional connectivity of language areas (FCL) during real-time fMRI (RT-fMRI) based neurofeedback training for post-stroke patients with expressive aphasia. The hypothesis is that FCL increases during the up-regulation of language areas during neurofeedback training and that the training improves FCL with an increasing number of sessions and restores it towards normalcy. Four Test and four Control patients with expressive aphasia were recruited for the study along with four healthy volunteers termed as the Normal group. The Test and Normal groups were administered four neurofeedback training sessions in between two test sessions, whereas the Control group underwent only the two test sessions. The training session requires the subject to exercise language activity covertly so that it up-regulates the feedback signal obtained from the Broca's area (in left inferior frontal gyrus) and amplifies the feedback when it is correlated to the Wernicke's area (in left superior temporal gyrus) using RT-fMRI. Functional connectivity was measured by Pearson's correlation coefficient. The results indicate that the functional connectivity of the Test group was weaker in the left hemisphere when compared to the normal group, and post-training the connections have strengthened (correlation coefficient increases) in the left hemisphere when compared with the control group. The connections of language areas strengthened in both hemispheres during neurofeedback based up-regulation, and multiple training sessions strengthened new pathways and restored left hemispheric connections towards normalcy.