Purchase this article with an account.
Hrag Pailian, George A. Alvarez; Neuro-augmentation Reveals Dissociable Neural Substrates Underlying Storage and Manipulation in Visual Working Memory. Journal of Vision 2020;20(11):148. doi: https://doi.org/10.1167/jov.20.11.148.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Visual working memory (VWM) is the ability to remember how things looked (storage), and to imagine alternative views of a scene (manipulation). Do storage and manipulation rely upon shared or separate resources? Are these abilities fundamentally limited or can they be enhanced? Here, we leverage trans-cranial direct current stimulation (tDCS) to causally modulate neural activity in regions associated with VWM, and examine effects on storage and/or manipulation. In Exp1, we applied 20-minutes of sham or anodal tDCS (counterbalanced across sessions) to the right posterior parietal cortex (r-PPC), followed by a behavioral VWM task. In this task, participants were presented with four colored circles that were subsequently occluded. For half of all trials, occluders did not move, and participants reported the color of a cued item (probing storage). For the remaining trials, two occluders swapped positions, requiring participants to manipulate the color-location bindings of the moving items. Participants were cued to report the color of either a stationary occluder (probing storage) or one that moved (probing manipulation). Neuroenhancement effects were observed for storage (by up to 23%) – but not manipulation – trials, and only for individuals with low-storage baselines. In Exp2, we determined whether this selective storage enhancement reflects a behavioral ceiling vs. a fixed storage limit, by presenting low- and high-storage performers with no-movement trials consisting of 4 or 6 colored circles. Low-storage performers demonstrated neuroenhancement effects for both set sizes, whereas high-storage individuals improved only on 6-item trials. Lastly, in Exp3, we applied anodal tDCS to the right dorsolateral prefrontal cortex (r-dlPFC) using protocol identical to that in Exp1, and observed the opposite effect: enhancement of manipulation ability (by up to 26%) – with no effect on storage. The results suggest that limits in VWM are malleable, and that storage and manipulate abilities rely upon separate resources.
This PDF is available to Subscribers Only