Abstract
Visual short-term memory (VSTM) refers to the retention of visual information from the immediate environment over brief intervals. In patients with mild cognitive impairment, pharmacologically increasing synaptic levels of acetylcholine (ACh) facilitates VSTM by boosting the rate of information processing (Bublak et al., 2011). We therefore hypothesized that cholinergic enhancement would improve VSTM performance in healthy subjects. Synaptic ACh levels were elevated by administration of the cholinesterase inhibitor donepezil in a placebo-controlled, double blind crossover design. Subjects were presented with a set of colored squares for either 100 or 200 ms. Consolidation of the set was disrupted by subsequent presentation of a visual mask. A second set of colored squares was then presented, and subjects were asked to report whether the second set was identical to the first or whether one of the squares changed color. In order to control task difficulty across subjects, we assessed the effects of donepezil for set sizes that were based on each subject’s VSTM capacity (k), measured prior to the pharmacological manipulation. We found that for 100 ms stimulus presentation, cholinergic enhancement improved VSTM performance, consistent with the hypothesized role of ACh on information processing in VSTM. However, no effect of donepezil on VSTM performance was observed for longer stimulus durations (200 ms). Our results suggest that cholinergic enhancement improves VSTM only when performance is limited by the amount of time subjects view the material to be remembered.
Meeting abstract presented at VSS 2013