A Snapshot seminar hosted by the School of Physiology, Pharmacology and Neuroscience
Abstract: Everyday decision-making requires us to collect, evaluate and integrate multiple pieces of evidence. For example, when we get dressed, we consider daily activities, weather forecast and personal preferences. Here, we successfully trained two rhesus macaques to perform a decision-making task, that aimed to mimic the components of an everyday decision, but that was sufficiently simplified to be studied in an animal model: the Sequential Probability Ratio Task (SPRT). We measured each monkey's baseline behaviour and identified that they performed the task with different strategies respectively. In addition, we recorded neural activity from the Lateral Intraparietal area (LIP) and Dorsolateral Prefrontal Cortex (DLPFC): obtained through a series of electrophysiological recordings using laminar probes. Activity in LIP has been related to the accumulation and integration of evidence into a decision variable (DV), however whether its role is causal has been of debate. Given its noted role in working memory and reward processing, we recorded from DLPFC with the aim of addressing any similarities and or differences in its activity, compared to LIP. To date, this is the only study that has recorded, simultaneously, activity from LIP and DLPFC in response to the SPRT. Both areas behaved largely similarly, but again with inconsistencies across monkeys. We further manipulated the availability of dopamine (DA) D1 receptors (D1Rs), through the systemic administration of selective D1R agonists (stimulation) and antagonists (inhibition). DA exerted different modulatory effects over the behaviour of each monkey. But one consistency lends insight into the debate surrounding the causal role of reward, providing supporting evidence for the Incentive Salience (IC) hypothesis. DA-ergic effects on neural activity were few and only observed in DLPFC. Deficits of decision-making are notable in neuropsychiatric disorders whose aetiology is characterised by a dysfunction of the neuromodulator dopamine (DA) (e.g., Parkinson’s Disease). Thus, our results are translational to patient populations.