Transcranial Cerebellar Direct Current Stimulation Enhances Verb Generation but Not Verb Naming in Poststroke Aphasia

Abstract

Although the role of the cerebellum in motor function is well recognized, its involvement in the lexical domain remains to be further elucidated. Indeed, it has not yet been clarified whether the cerebellum is a language structure per se or whether it contributes to language processing when other cognitive components (e.g., cognitive effort, working memory) are required by the language task. Neuromodulation studies on healthy participants have suggested that cerebellar transcranial direct current stimulation (tDCS) is a valuable tool to modulate cognitive functions. However, so far, only a single case study has investigated whether cerebellar stimulation enhances language recovery in aphasic individuals. In a randomized, crossover, double-blind design, we explored the effect of cerebellar tDCS coupled with language treatment for verb improvement in 12 aphasic individuals. Each participant received cerebellar tDCS (20 min, 2 mA) in four experimental conditions: (1) right cathodal and (2) sham stimulation during a verb generation task and (3) right cathodal and (4) sham stimulation during a verb naming task. Each experimental condition was run in five consecutive daily sessions over 4 weeks. At the end of treatment, a significant improvement was found after cathodal stimulation only in the verb generation task. No significant differences were present for verb naming among the two conditions. We hypothesize that cerebellar tDCS is a viable tool for recovery from aphasia but only when the language task, such as verb generation, also demands the activation of nonlinguistic strategies.

Consensus Paper: Cerebellum and Emotion

“…In addition, an increase in cerebello-cerebral connectivity was demonstrated. Marangolo et al [39] replicated these results in a study group of 12 patients with chronic aphasia after left-hemispheric stroke for verb generation. However, they did not find an effect on verb naming and argued that cerebellar stimulation might only be meaningful if the language task also involved nonlinguistic processes [39].…”

“…Marangolo et al [39] replicated these results in a study group of 12 patients with chronic aphasia after left-hemispheric stroke for verb generation. However, they did not find an effect on verb naming and argued that cerebellar stimulation might only be meaningful if the language task also involved nonlinguistic processes [39]. Obviously, these findings now require a replication in a large population of patients, but this could indicate that there are opportunities for multi-focal stimulation to target specific networks [37].…”

Impact of Combined Transcranial Direct Current Stimulation and Speech-language Therapy on Spontaneous Speech in Aphasia: A Randomized Controlled Double-blind Study

“…The two main naming tasks found in the literature are naming of nouns and naming of verbs. The share is larger for nouns naming because of its use when authors use standardized language evaluation batteries (Baker et al, 2010;Branscheidt et al, 2018;Campana et al, 2015;Cherney et al, 2013;Fiori et al, 2011;Flöel et al, 2011;Fridriksson et al, 2018;Galletta et al, 2015;Kang et al, 2011;Lee et al, 2011;Marangolo et al, 2013aMarangolo et al, , 2013bMarangolo et al, , 2014Marangolo et al, , 2016Marangolo et al, , 2017Marangolo et al, , 2018Meinzer et al, 2016;Monti et al, 2008;Pestalozzi et al, 2018;Polanowska et al, 2013;Sandars et al, 2017;Santos et al, 2013Santos et al, , 2017Shah-Basak et al, 2015;Spielmann et al, 2018;Vestito et al, 2014;Vines et al, 2011;Volpato et al, 2013;You et al, 2011). Furthermore, generalization has been measured in several studies: some of them assessed the transfer of competence on an untrained task (Lee et al, 2011;Marangolo et al, 2011Marangolo et al, , 2013aMarangolo et al, , 2013bMarangolo et al, , 2014Marangolo et al, , 2016Marangolo et al, , 2017Manenti et al, 2015;…”

Transcranial direct current stimulation (tDCS) for improving aphasia after stroke: a systematic review with network meta-analysis of randomized controlled trials

“…A total of 21 patients received active tDCS to improve performance in naming verbs (number of studies = 3, number of study arms = 6) [40,43,47]. The intervention types studied were anodal tDCS (one study arm with 4 participants) [40], cathodal tDCS (one study arm with 3 participants) [47], or dual tDCS (one study arm with 4 participants) [43]. A total of 10 participants received sham tDCS as a comparator intervention (number of study arms = 3) [40,43,47].…”