ИСТИНА

1 Behavioural and Translational Neuroscience Department, VU medical center, Amsterdam 2 Vrije Universiteit Research Master Neurosciences program, Amsterdam Would you rather have €5 now or €50 in one week? Would you wait one year for the larger payoff? As the delay increases, we switch our preference for more immediate, smaller rewards. This process of reward devaluation is called delay discounting. We assess the degree of delay aversive impulsivity in rodents using the delayed reward task (DRT). Rodents must choose between a small, immediate reward or a delayed, larger reward, with delays increasing across trials within a session. The brain region implicated in updating online reward values is the Orbitofrontal Cortex (OFC). The OFC is ideally positioned to integrate sensory information and project to subcortical associative learning nodes to iteratively fine-tune decision-making according to outcomes (Schoenbaum et. al 2006). Lesioning studies in the medial OFC during the DRT yield inconsistent results, indicating that the OFC is implicated in both decreased (Mobini et al. 2002) and increased (Winstanley 2004; Mar et al. 2011) willingness to wait. The aim of this current project is to clarify the online role of glutamatergic output cells in the OFC subregions during impulsive decision-making, by temporarily inactivating them during choice execution or reward consumption phases of the DRT. 25 rats are trained in the DRT; 4 weeks prior to testing experimental groups underwent bilateral viral infusion and fiber implantation to either the medial (n=9) or lateral (n=9) OFC with pAAV-CaMKIIa-Arch3.0-eYFP construct. A control group received bilateral injection with a non-light sensitive construct pAAV-CaMKIIa-eYFP, to either the medial (n=4) or lateral (n=3) OFC and fiber implantation. We hypothesize that optical inactivation (532nm) of the medial OFC glutamatergic neurons will compromise updating of reward representations and lead to altered delay discounting. Preliminary data in the lab (n = 10) indicates that optogenetic inactivation to the lateral OFC during reward consumption does not alter the discounting behavior.