Transcranial Magnetic Stimulation (TMS)Original ArticleTMS Over the Right Precuneus Reduces the Bilateral Field Advantage in Visual Short Term Memory Capacity

- We examined the role of the precuneus in visual short term memory (VSTM) capacity.
- We tested if a bilateral field advantage in VSTM capacity can be reduced using TMS.
- The bilateral field advantage diminished with TMS over the right precuneus.
- Bilateral presentation may induce competition for representation.
- TMS over the right precuneus may augmented this process (i.e. extinction).

BackgroundSeveral studies have demonstrated a bilateral field advantage (BFA) in early visual attentional processing, that is, enhanced visual processing when stimuli are spread across both visual hemifields. The results are reminiscent of a hemispheric resource model of parallel visual attentional processing, suggesting more attentional resources on an early level of visual processing for bilateral displays [e.g. Sereno AB, Kosslyn SM. Discrimination within and between hemifields: a new constraint on theories of attention. Neuropsychologia 1991;29(7):659-75.]. Several studies have shown that the BFA extends beyond early stages of visual attentional processing, demonstrating that visual short term memory (VSTM) capacity is higher when stimuli are distributed bilaterally rather than unilaterally.Objective/hypothesisHere we examine whether hemisphere-specific resources are also evident on later stages of visual attentional processing.MethodsBased on the Theory of Visual Attention (TVA) [Bundesen C. A theory of visual attention. Psychol Rev 1990;97(4):523-47.] we used a whole report paradigm that allows investigating visual attention capacity variability in unilateral and bilateral displays during navigated repetitive transcranial magnetic stimulation (rTMS) of the precuneus region.ResultsA robust BFA in VSTM storage capacity was apparent after rTMS over the left precuneus and in the control condition without rTMS. In contrast, the BFA diminished with rTMS over the right precuneus.ConclusionThis finding indicates that the right precuneus plays a causal role in VSTM capacity, particularly in bilateral visual displays.