P 35. Investigating a causal role of the supramarginal gyrus for pitch memory using transcranial direct current stimulation

Abstract

Functional neuroimaging studies have shown an activation of the supramarginal gyrus during recognition pitch memory tasks and also showing a positive correlation of stronger activation of the left supramarginal gyrus and better task performance on the pitch memory task (Gaab et al., 2003, 2006). A previous transcranial direct current stimulation study using cathodal stimulation over the left supramarginal gyrus reported a detrimental effect on short-term pitch memory performance; indicating an important role of the left supramarginal gyrus for pitch memory (Vines et al., 2006). The current study investigated a causal involvement of the left supramarginal gyrus for the pitch memory process in non-musicians by using anodal and sham transcranial direct current stimulation to see whether this has a significant effect on the performance across different pitch memory paradigms (a recognition and a recall pitch memory task were used). A face memory task, used as a visual control task, was included to determine whether effects are specific to pitch memory. A between subject design was used. The two groups, which were matched by age, gender and pitch memory performance (evaluated in a preliminary test), either received anodal or sham stimulation over the left supramarginal gyrus and completed the three tasks in randomised order (between-subject design). The results show that the anodal group performed significantly better on both pitch memory tasks (see Figs. 1 and 2) but performance did not differ on the face memory task. These findings provide strong support for the causal involvement of the supramarginal gyrus specifically for the pitch memory process. Anodal stimulation facilitates pitch memory. Additionally, a post hoc analysis of the serial position curve of pitch items in the recall task showed that anodal transcranial direct current stimulation does not effect a particular point of the working-memory process (recency or primacy effects) but boosts pitch memory performance in general. Anodal stimulation over the supramarginal gyrus increased pitch memory performance significantly suggesting that the supramarginal gyrus could be responsible for the storage of pitch information in the memory process.