Sanika Paranjape¹ (sanikap@gmail.com), Sarah Shomstein¹, Dwight Kravitz^1,2; ¹The George Washington University, ²US National Science Foundation (SBE/BCS)

Behavioral evidence has shown that there is bidirectional interference between visual working memory (VWM) and perception for low-level features (e.g., color, orientation) and high-level features (e.g., motion direction, face identity) (Teng & Kravitz, 2019; Paranjape et al, 2024). The sensorimotor recruitment hypothesis proposes that the same areas involved in encoding a stimulus are involved in maintenance, leading to interference between VWM and perception. Here, using a within-subjects design, we provide causal evidence for the involvement of MT+ cortex in mediating this interference for motion direction. In a dual-task paradigm, transcranial magnetic stimulation (TMS) was applied during the delay period between the encoding of a motion stimulus and a subsequent perceptual discrimination. Two discrimination conditions were used: 1) middle, in which the two discrimination motion directions are on either side of the maintained motion direction (in a continuous space); and 2) side, in which both discrimination motion directions are off to one side of the maintained motion direction. We replicated a behavioral effect supporting sensory recruitment, finding that the maintained information interfered with discrimination, resulting in higher discrimination thresholds for the middle condition than the side condition. The discrimination motion directions also introduced systematic biases in the continuous report of the maintained motion, with higher accuracy for the middle than the side condition. Critically, when TMS was applied to MT+ cortex, consistent with the prediction that maintenance occurs within MT+ cortex, we found a significant decrease in the interference compared to sham TMS applied at vertex. These results provide direct causal evidence that VWM maintenance occurs in the same cortices that are involved in perceptual processing of high-level stimuli, such as motion direction.

Acknowledgements: NSF BCS-2022572 to SSS and DJK; W911NF-23-2-0097 to DJK and SRM