Investigating Working Memory Capacity Processes in the Prefrontal Cortex of Marmosets

Poster Session B - Sunday, April 14, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Tsz Wai Bentley Lo¹ (tlo57@uwo.ca), Susheel Vijayraghavan¹, Lyle Muller², Julio Martinez^1,3; ¹Department of Physiology and Pharmacology, University of Western Ontario, ²Department of Mathematics, University of Western Ontario, ³Department of Psychiatry, University of Western Ontario

Working memory is a critical cognitive process for short-term information retention and manipulation. Additionally, it is a capacity-limited system, as only a certain number of items can be retained without deterioration. There has been substantial interest in using animal models to study the neurophysiology underlying working memory function and capacity in cognitive neuroscience. In this regard, the common marmoset (Callithrix jacchus) has emerged as a particularly valuable model, with its lissencephalic cortex characterized by a lack of folds (gyri), providing an ideal platform for studying cortical processing layers during cognitive tasks. Our research delves into the neural mechanisms of working memory capacity in marmosets. We conducted a behavioural and physiological examination of working memory capacity in these animals. Specifically, we trained four marmosets to engage in a delay non-match to location task. This task involves presenting the marmosets with a progressively increasing array of stimuli at different locations, challenging their working memory capacity. We then implanted two marmosets with multi-shank "volume" probes (N-form array, Plexon Inc.). Our findings reveal neurons selectively responsive to the correct target location, demonstrating persistent firing during the delay phase – a hallmark of working memory. Furthermore, through decoding analysis, we discovered that the memory load (the number of stimuli a marmoset retains) can be accurately decoded from the activity of single neurons. This study enhances our understanding of working memory capacity in a novel animal model and opens avenues for more advanced research into the neural basis of memory processing.

Topic Area: EXECUTIVE PROCESSES: Working memory