INDIVIDUAL DIFFERENCES IN ENVIRONMENTAL SENSITIVITY: HOW SEROTONIN SHAPES STIMULUS PERCEPTION AND ATTENTIONAL PRIORITIZATION

The ability to perceive and process environmental stimuli in order to respond to them is one of the most fundamental traits observed across species, and essential for survival. One key molecule influencing environmental sensitivity across the animal kingdom is serotonin, and has been implicated in highly sensitive (human) personalities. To investigate genotypic differences in stimulus perception, we employ the well-characterized constitutive serotonin transporter (SERT) knockout (KO) rat model, which exhibits increased extracellular serotonin levels. We assessed the maximal (visual) discriminative ability of rats to distinguish between simultaneously presented stimuli during a novel touchscreen-based task, in the absence of any food and/or water deprivation. Preliminary data suggests that SERT-KO rats require more trials to acquire the learning criterion (80% accuracy) than their unaffected SERT wildtype (WT) counterparts. This observation extends across all difficulty levels of the test. Furthermore, we observed that SERT KO-rats were quicker to respond to presented stimuli than SERT-WT, implying a possible dual-role of serotonin in both response-accuracy as well as latency. Future investigations will focus on the feasibility of the task within a self-pacing paradigm, where subjects are given increased agency to engage in the task, allowing a more refined characterization of the innate behavior of subjects, the effect of serotonergic (pharmacological) interventions to assess transient serotonergic dysregulation, performance in light of a distractor to assess attentional prioritization, and finally, in-vivo (electro)physiological measurements to investigate the neural underpinnings of stimulus perception.