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Poster C30 in Poster Session C - Friday, August 9, 2024, 11:15 am – 1:15 pm, Johnson Ice Rink
Inter-hemispheric prefrontal mechanisms of within- and across-trial working memory
Melanie Tschiersch1, Akash Umakantha2, Ryan C. Williamson2, Matthew A. Smith2, Joao Barbosa3, Albert Compte1 (); 1IDIBAPS, Barcelona, Spain, 2Carnegie Mellon University, Pittsburgh, PA, 3École Normale Supérieure, Paris, France
Working memory (WM) refers to short-term information maintenance and its processing. Recent evidence suggests an interplay between persistent activity and activity-silent mechanisms in the prefrontal cortex (PFC) for WM maintenance and history effects (serial dependence) (Barbosa, Stein et al., 2020). However, the PFC has so far been viewed as one entity, even though neurons in the PFC display a contralateral preference (Funahashi et al., 1989). It is therefore still unclear how neural representations of WM maintenance and serial dependence relate across hemispheres. Here, we answer this question by analyzing behavior and bilateral PFC neural recordings from three monkeys performing a visuo-spatial delayed response task. We found behavioral and neural evidence for diffusing memories and serial dependence. Interestingly, the neural correlates of memory drift were weakly, but significantly, correlated across hemispheres, suggesting weak hemispheric interactions. When comparing several two-area bump-attractor models with varying degrees of tuned and untuned across-area connections, we found that tuning of across-area connections is necessary for error correlations to emerge. The model further predicted either private or shared serial dependence drift across hemispheres based on increasing connectivity strength. The data confirmed a private history-drift and we therefore conclude that faint, but specific connections underlie continuous working memory across prefrontal hemispheres.
Keywords: working memory hemisphere serial dependence prefrontal cortex