The effect of frontoparietal paired associative stimulation on decision-making and working memory.
Cortex; a journal devoted to the study of the nervous system and behavior
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Nord, C., Popa, T., Smith, E., Hannah, R., Doñamayor, N., Weidacker, K., Bays, P., et al. (2019). The effect of frontoparietal paired associative stimulation on decision-making and working memory.. Cortex; a journal devoted to the study of the nervous system and behavior, 117 266-276. https://doi.org/10.1016/j.cortex.2019.03.015
Previous single-site neurostimulation experiments have unsuccessfully attempted to shift decision-making away from habitual control, a fast, inflexible cognitive strategy, towards goal-directed control, a flexible, though computationally expensive strategy. We employed a dual-target neurostimulation approach in 30 healthy participants, using cortico-cortical paired associative stimulation (ccPAS) to target two key nodes: lateral prefrontal cortex (LPFC) and intraparietal sulcus (IPS), to test whether decision-making can be artificially shifted from habitual toward goal-directed control. Participants received three active stimulations, delivered at least six days apart (each involving 100 paired pulses over the IPS and LPFC, varying the interstimulus interval): two interventional, time-relevant ccPAS (10ms interval) and one control, non-time-relevant ccPAS (100ms interval). Following stimulation, participants completed a sequential learning task, measuring goal-directed/habitual control, and a working memory task. IPSLPFC ccPAS (stimulating IPS, then LPFC with a 10ms interval) shifted decision-making from habitual toward goal-directed control, compared to control ccPAS, but this effect was only visible in a post-hoc contrast. There was no effect of LPFCIPS ccPAS, nor an effect of any PAS condition on working memory. Previous studies have shown ccPAS effects outside the motor domain targeting prefrontal regions on response inhibition, attentional bias, and alpha asymmetry. The present study measures the behavioural effects of parietal-prefrontal PAS, focusing on a highly complex decision-making task and working memory. If confirmed in larger studies, this would be the first instance of neurostimulation successfully shifting decision-making from habitual to goal-directed control, putatively via inducing long-term potentiation between the IPS and LPFC. However, we found no effect in the other direction (LPFCIPS ccPAS), and no effect on working memory overall. PAS is a relatively new neuromodulatory technique in the cognitive arsenal, and this study could help guide future approaches in healthy and disordered decision-making.
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External DOI: https://doi.org/10.1016/j.cortex.2019.03.015
This record's URL: https://www.repository.cam.ac.uk/handle/1810/291227
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