| Recent research has demonstrated that greater cortical activation in the left frontal cortex is related to aphasia recovery, particularly the ability to name common objects. Based on these results, it seems plausible that external stimulation of the left frontal cortex may improve aphasia recovery. One method to increase cortical activation in a safe and painless manner is transcranial direct current stimulation (tDCS), a non-invasive method of delivering a weak polarizing electrical current to the cortex through a pair of surface sponge electrodes. The resulting effects depend on the polarity of the electrodes, in which the area under the anode electrode is more excitatory and the area under the cathode electrode is more inhibitory.;In the present study, ten persons with chronic stroke-induced aphasia underwent two separate weeks (five days per week) of anodal tDCS administration and sham (placebo-like) tDCS administration while performing a computerized anomia treatment task. During both types of tDCS, the "active" anodal electrode was placed over the designated area located on the left frontal cortex which displayed the highest degree of cortical activation during correct naming on a functional magnetic resonance imaging naming task, while the "reference" cathodal electrode was placed over the right shoulder. In order to examine the effect of tDCS administration upon picture naming, two treatment phases were compared – one which included anodal tDCS and another which included sham tDCS. Outcome measures included picture naming performance of both treated and untreated items following each treatment phase. The results revealed significantly improved picture naming of treated items following anodal tDCS compared to sham tDCS (F(1,9) = 5.72, p = 0.040), as well as improved picture naming of untreated items following anodal tDCS compared to sham tDCS, although this difference was not statistically significant (F(1,9) = 4.10, p = 0.074). Crucially, the treatment effect persisted one-week post-treatment. These findings suggest that anodal tDCS over the left frontal cortex can significantly improve picture naming in persons with aphasia and may provide an alternative or supplementary treatment approach. |
