Article

Excitatory anodal transcranial direct current stimulation (A-tDCS) over the left
dorsal prefrontal cortex (DPFC) has been shown to improve language production.
The present study examined neurophysiological underpinnings of this effect. In a
single-blinded within-subject design, we traced effects of A-tDCS compared to
sham stimulation over the left DPFC using electrophysiological and behavioural
correlates during overt picture naming. Online effects were examined during
A-tDCS by employing the semantic interference (SI-)Effect - a marker that denotes
the functional integrity of the language system. The behavioural SI-Effect was
found to be reduced, whereas the electrophysiological SI-Effect was enhanced over
left compared to right temporal scalp-electrode sites. This modulation is
suggested to reflect a superior tuning of neural responses within
language-related generators. After -(offline) effects of A-tDCS were detected in
the delta frequency band, a marker of neural inhibition. After A-tDCS there was a
reduction in delta activity during picture naming and the resting state,
interpreted to indicate neural disinhibition. Together, these findings
demonstrate electrophysiological modulations induced by A-tDCS of the left DPFC.
They suggest that A-tDCS is capable of enhancing neural processes during and
after application. The present functional and oscillatory neural markers could
detect positive effects of prefrontal A-tDCS, which could be of use in the
neuro-rehabilitation of frontal language functions.
CI - Copyright (c) 2011 Elsevier Ltd. All rights reserved.

Langue : ANGLAIS