Cerebellar tDCS as a novel treatment for aphasia? Evidence from behavioral and resting-state functional connectivity data in healthy adults

Issue title: Special Section: Language System Plasticity in Aphasia

Guest editors: Roy Hamilton

Article type: Research Article

Authors: Turkeltaub, Peter E.^{a; b; *} | Swears, Mary K.^c | D’Mello, Anila M.^{c; d} | Stoodley, Catherine J.^{c; d; *}

Affiliations: [a] Department of Neurology, Georgetown University, Washington, D.C., USA | [b] Research Division, MedStar National Rehabilitation Hospital, Washington, D.C., USA | [c] Department of Psychology, American University, Washington, D.C., USA | [d] Center for Behavioral Neuroscience, American University, Washington, D.C., USA

Correspondence: [*] Corresponding author: Catherine J. Stoodley, Department of Psychology, American University, 4400 Massachusetts Ave NW, Washington, DC 20016, USA. Tel.: +1 202 885 1785; Fax: +1 202 885 1023; E-mail: stoodley@american.edu.

Correspondence: [*] Corresponding author: Peter E. Turkeltaub, Department of Neurology, Georgetown University Medical Center, 4000 Reservoir Road,NW; Building D, Suite 165; Washington, DC 20057, USA. Tel.: +1 202 784 1764; Fax: +1 202 687 7378; E-mail: turkeltp@georgetown.edu.

Abstract: Background: Aphasia is an acquired deficit in the ability to communicate through language. Noninvasive neuromodulation offers the potential to boost neural function and recovery, yet the optimal site of neuromodulation for aphasia has yet to be established. The right posterolateral cerebellum is involved in multiple language functions, interconnects with left-hemisphere language cortices, and is crucial for optimization of function and skill acquisition, suggesting that cerebellar neuromodulation could enhance aphasia rehabilitation. Objective: To provide preliminary behavioral and functional connectivity evidence from healthy participants that cerebellar neuromodulation may be useful for rehabilitation of aphasia. Methods: In Experiment 1, 76 healthy adults performed articulation and verbal fluency tasks before and after anodal, cathodal or sham transcranial direct current stimulation (tDCS) was applied over two cerebellar locations (anterior, right posterolateral). In Experiment 2, we examined whether anodal tDCS over the right posterolateral cerebellum modulated resting-state functional connectivity in language networks in 27 healthy adults. Results: TDCS over the right posterolateral cerebellum significantly improved phonemic fluency. Cerebellar neuromodulation increased functional connectivity between the cerebellum and areas involved in the motor control of speech, and enhanced the correlations between left-hemisphere language and speech-motor regions. Conclusion: We provide proof-of-principle evidence that cerebellar neuromodulation improves verbal fluency and impacts resting-state connectivity in language circuits. These findings suggest that the cerebellum is a viable candidate for neuromodulation in people with aphasia.

Keywords: Aphasia, cerebellum, transcranial direct current stimulation (tDCS), language, neuromodulation, resting-state fMRI

DOI: 10.3233/RNN-150633

Journal: Restorative Neurology and Neuroscience, vol. 34, no. 4, pp. 491-505, 2016