Grant: Master's Award: Canada Graduate Scholarships

Working memory (WM) is the ability to briefly store a limited amount of information for subsequent use in goal-oriented behaviour. WM impairment is a cognitive symptom in many disorders, and its understanding could help develop new treatments and interventions that improve daily functioning. Visual WM (VWM) rests on the integrity of persistent neuronal activity within a frontoparietal network that includes the lateral intraparietal (LIP) area of the posterior parietal cortex (PPC). Using the rhesus macaque (Macaca mulatta) as an animal model, studying the persistent activity of different neuronal types in LIP anatomical subdivisions during a tractable VWM task promises to reveal how the PPC contributes to VWM. Specifically, any difference between neuronal types and between LIP subdivisions, which are cytoarchitecturally distinct, will inform us of the microcircuitry and mechanisms underlying persistent activity. Neuronal activity will be recorded while monkeys perform a visual sequential comparison task, in which they indicate the difference between two visual arrays temporarily separated by a retention interval. Manipulating array size helps establish a principled and quantitative link between memory demand and persistent activity during the retention interval, which is taken to instantiate VWM storage. Neuronal type (putative pyramidal neuron or interneuron) is assessed by the shape of the action potentials, and recording location is carefully determined. Determining VWM functions of LIP area will provide insights into the frontoparietal network and into the microcircuitry elements substantiating WM. This knowledge of VWM neurophysiology will have vast applications for treatments and interventions for WM deficits, and it will inform optimized educational practices.