Polarity-dependent cerebellar transcranial direct current stimulation modulates online functions of the alerting...

To investigate the modulatory effect of anodal, cathodal and sham cerebellar transcranial direct current stimulation (ctDCS) on the efficiency of the 3 attention networks namely alerting network, orienting network, and the network of executive control.

A sham-controlled, single-blind study. Experiments were performed at the neuroscience lab of Imam Abdulrahman Bin Faisal University, Dammam, Kingdom of Saudi Arabia, between the months of January-July of 2018. Sixty-three healthy subjects were assessed for eligibility and a total of 60 subjects (30 males and 30 females) met the inclusion criteria. Subjects were randomly divided into 3 groups that received a single 20-minute session of 2 mA of anodal, cathodal or sham ctDCS while performing tasks. The tasks corresponded to the 3 attention networks-vigilance task assessed the alerting network, Posner's attention task assessed the orienting network and Flanker task assessed the network of executive control. The Edinburgh handedness inventory-short form determined the subjects' handedness.

Analysis of variance (ANOVA) showed a highly significant polarity-independent group*task effect (p=0.003) for the vigilance task. Moreover, there was a significant polarity-independent group*task effect for valid cues (p=0.006). A polarity-dependent group*task effect was observed for invalid cues (p=0.011).

Conclusion: Findings demonstrate that ctDCS modulates alerting attention and highlights a more profound effect of cerebellar modulation in attention tasks with higher cognitive load.