title: Differential effects of bihemispheric and unihemispheric transcranial direct current stimulation in young and elderly adults in verbal learning.
abstract: For the past few years, the potential of transcranial direct current stimulation (tDCS) for the treatment of several pathologies has been investigated. In the language domain, several studies, in healthy and brain-damaged populations, have already shown that tDCS is effective in enhancing naming, repetition and semantic word generation. In those studies, different tDCS electrode configurations have been tested, however, a direct comparison between different montages in verbal learning has never been conducted. In this study, we aimed to explore the impact of bihemispheric and unihemispheric tDCS on verbal learning task performance in two groups (young vs. elderly). Fifteen healthy volunteers participated per group. Each participant received three stimulation conditions: unihemispheric anodal tDCS over the left temporal area, bihemispheric tDCS over the left (anodal) and right (cathodal) temporal areas and a sham condition. During active stimulation, tDCS (20min, 2mA) was applied while each participant learned twenty pseudowords (arbitrarily assigned to corresponding pictures). No significant differences were found between the three conditions for the young group with regard to accuracy and vocal reaction times. In contrast, in the elderly group, real stimulation improved performance compared to sham but bihemispheric tDCS was more efficient than unilateral stimulation. These results suggest that bihemispheric stimulation is more effective in improving language learning but this effect is age-dependent. The hypothesis is advanced that cortical changes in the course of aging might differentially impact on tDCS efficacy on behavioral performance. These data may also have implications for treatment of stroke patients with language impairment.
authors.affiliation: IRCCS Fondazione Santa Lucia, Roma, Italy; Università degli Studi di Roma Tor Vergata, Roma, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Fiori
authors.affiliation: Department Psychology and Neurosciences, Leibniz Research Center for Working Environment and Human Factors, Dortmund, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Nitsche
authors.affiliation: IRCCS Fondazione Santa Lucia, Roma, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Iasevoli
authors.affiliation: Dipartimento di Studi Umanistici, Università Federico II, Napoli, Italy.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Cucuzza
authors.affiliation: IRCCS Fondazione Santa Lucia, Roma, Italy; Università degli Studi di Roma Tor Vergata, Roma, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Caltagirone
authors.affiliation: IRCCS Fondazione Santa Lucia, Roma, Italy; Dipartimento di Studi Umanistici, Università Federico II, Napoli, Italy. Electronic address: paola.marangolo@gmail.com.
authors.forename: Paola
authors.initials: P
authors.lastname: Marangolo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology* / Q000523:psychology; D001921:Brain / Q000502:physiology*; D004311:Double-Blind Method; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007858:Learning / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D010364:Pattern Recognition, Visual / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D013060:Speech / Q000502:physiology*; D065908:Transcranial Direct Current Stimulation / Q000379:methods; D055815:Young Adult
keywords: Age effects; Bihemispheric tDCS; Brain stimulation; Unihemispheric tDCS; Verbal learning