Investigating the Role of Ventral Posterior Lateral Nuclei (VPL) in Pain Processing

Abstract

By Akansha Khadka, Biological Sciences

Advisor: Steve Davidson

Presentation ID: 67

Abstract: 20% of adults globally experience chronic pain. Pain research is crucial to reducing the burden of chronic pain by identifying novel therapies. Pain is a multidimensional experience with affective, cognitive, emotional, and behavioral factors. My work focuses on the Ventral Posterolateral nucleus (VPL), a thalamic nucleus of the brain which acts as a relay station by sending neural signals to the cortex. It is unknown as to what aspect of the multidimensional pain circuitry, sensory or affective, the VPL contributes. The goal of my project is to investigate whether activation of the VPL alters sensory and affective behavior in naive mice. I hypothesized that activating the VPL will increase pain-related sensory but not affective behavior. To test my hypothesis, I used Designer receptors exclusively activated by designer drugs (DREADDs) to activate the neurons in the VPL in mice models. The DREADDs were used with Clozapine N-oxide (CNO), a designer drug that selectively activates the DREADD receptors. The behavior tests performed were radiant heat to test for thermal threshold, and pressure-sensitive monofilament test for mechanical threshold. To test VPL contributions to affect the conditioned place preference (CPP), open field, and elevated zero maze tests were performed. The results indicated no significant differences in affective behaviors. However, in the radiant heat test, mice with VPL activation had a significantly lower withdrawal latency compared to when the VPL was not activated. Overall, this study concluded that the VPL selectively enhances thermal sensory processing.