Rana, K. D. | Search bioRxiv

bioRxiv2022

Cortical dynamics following real-time MEG neurofeedback training of the speed of shifting spatial attention: a pilot study

Neurofeedback is a technique that directs self-regulated modulation of neural activity. This is achieved by delivering real-time feedback derived from brain signals. In our previous work, we introduced a novel method, state-based neurofeedback (sb-NFB) that targets patterns of MEG signals related to shifts in spatial attention. In this pilot study, we used sb-NFB to train participants to decrease the time required to covertly shift spatial attention from one visual hemifield to the other. We characterized the changes to cortical connectivity during each training session. In addition, we run a separate, Posner-like validation task before the training sessions and after the training was complete. We found a significant main effect of training on the reaction time linked to switching spatial attention in both the training task and the validation task. This indicates the achieved improvement in shifting spatial attention generalized to another situation requiring this capability.

neuroscience↗

bioRxiv2018

The emotional valence and features of subliminal priming images impact conscious perception of facial expressions

We investigated, in young healthy subjects, how the affective content of subliminally presented priming images and their specific visual attributes impacted conscious perception of facial expressions. The priming images were broadly categorised as aggressive, pleasant, or neutral and further subcategorised by the presence of a face and by the centricity (egocentric or allocentric vantage-point) of the image content. Subjects responded to the emotion portrayed in a pixelated target-face by indicating via key-press if the expression was angry or neutral. Priming images containing a face compared to those not containing a face significantly impaired performance on neutral or angry target-face evaluation. Recognition of angry target-face expressions was selectively impaired by pleasant prime images which contained a face. For egocentric primes, recognition of neutral target-face expressions was significantly better than of angry expressions. Our results suggest that, first, the affective primacy hypothesis which predicts that affective information can be accessed automatically, preceding conscious cognition, holds true in subliminal priming only when the priming image contains a face. Second, egocentric primes interfere with the perception of angry target-face expressions suggesting that this vantage-point, directly relevant to the viewer, perhaps engages processes involved in action preparation which may weaken the priority of affect processing.

neuroscience↗