Cerebellar transcranial direct current stimulation modulates timing but not acquisition of conditioned eyeblink responses in SCA3 patients

•Compared to sham tDCS, a two-week regimen comprising daily cerebellar anodal tDCS sessions did not affect acquisition of conditioned eyeblink responses in SCA3 patients.•Cerebellar anodal tDCS induced a temporal shift of conditioned responses in the direction of the unconditioned stimulus.•Acquisition impairments were inversely associated with cognitive dysfunction but not with ataxia severity.•Timing of conditioned responses was associated with disease duration but not with cognitive dysfunction.•Our findings provide evidence that cerebellar tDCS is capable of modifying cerebellar function in SCA3 patients.