Effect of spatial working memory depletion on cerebral cortical dynamics of cognitive-motor performance
Shaw, Emma Patricia
Gentili, Rodolphe J
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Prior work has validated the use of resource depletion to directly probe the role of specific cognitive functions on human performance. Specifically, intensive recruitment of cognitive resources to successfully perform a task has been shown to result in performance decrements and decreased neural activation on subsequent tasks. Much of this work, however, was not conducted within the context of cognitive-motor performance and/or did not examine the underlying brain dynamics. Therefore, this study examined the effects of depleted spatial working memory (SWM) resources, critical for spatial information processing, on performance and brain dynamics (attentional reserve and cognitive-motor effort). Performance and electroencephalography were collected as thirty-five individuals, randomly assigned to an experimental or control group, with minimal prior videogame experience completed a cognitive-motor task at an easy and a hard level of difficulty before and after undergoing SWM resource depletion (experimental) or non-depletion (control). The SWM depletion protocol required intensive mental rotation, while the non-depletion protocol did not. Attentional reserve was assessed via the novelty-P3 component of the event-related potential and cognitive-motor effort was assessed via spectral power within the theta, low- and high-alpha frequency bandwidths. The results revealed both groups exhibited similar performance improvement on the cognitive-motor task post- compared to pre-SWM depletion/non-depletion. This was accompanied with a more efficient engagement of attentional resources (decreased novelty-P3) and a refinement of cortical activity (low-/high-alpha synchrony), which may reflect a practice effect. Furthermore, the control group exhibited theta synchrony under the hard compared to the easy level of challenge across all cortical regions regardless of when the cognitive-motor task was performed. This adaptive response, however, was absent within the frontal and temporal cortical regions (important for working memory, attentional control and visuospatial processes) for the experimental group post-SWM depletion. Additionally, the experimental group, post-relative to pre-SWM depletion, exhibited temporal theta desynchrony and synchrony during the hard and easy level of challenge, respectively. These findings collectively suggest intensive cognitive task performance has a combined neurocognitive benefit (i.e., practice effect) and cost (i.e., lack of adaptive response due to depleted resources) during subsequent cognitive-motor performance requiring similar cognitive processes as that of the depleting task.