Abstract
Non-invasive brain stimulation (NIBS) has become a common method to study the interrelations between the brain and language functioning. This quantitative review examined the efficacy of transcranial magnetic stimulation (TMS) and direct current stimulation (tDCS) in the study of language production in healthy volunteers. Forty-two effect sizes from 28 studies which investigated the effects of NIBS on picture naming or verbal fluency in healthy participants were meta-analysed. Further sub-analyses investigated potential influences of stimulation type, site, control, and task. Random effects modelling showed a small, but reliable effect of NIBS on language production. Subsequent analyses indicated larger weighted mean effect sizes for TMS as compared to tDCS studies. No statistical differences between stimulation of frontal and temporal regions, or between picture naming and verbal fluency tasks, were observed. We conclude that NIBS is a useful method for neuroscientific studies on language production in healthy volunteers.