Striatal patch compartment lesions reduce habitual behaviors

Abstract

The striatum is associated with habit formation and reward association. The striatum is composed of the patch and matrix compartments, and previous studies have shown that enhanced activation of the patch compartment relative to the matrix compartment is related to inflexible behaviors, such as stereotypy. Habitual behaviors are also inflexible in nature, but whether enhanced activation of the patch compartment contributes to habitual behavior is not known. Our experiment analyzed the role of the patch compartment in habit formation, by using a targeted neurotoxin to ablate the neurons of the patch compartment prior to sucrose self‐administration. Rats were bilaterally infused in the striatum with the neurotoxin dermorphin‐saporin (DERM‐SAP) to ablate the neurons of the patch compartment or unconjugated saporin (SAP, as a control) and allowed to recover for eight days. The rats were then trained to self‐administer sucrose using a random interval paradigm proven to generate habitual sucrose consumption. We then associated sucrose consumption with a negative stimulus (LiCl). Subjects were reintroduced to the self‐administration chamber and rats that continued to lever press, despite learning to associate sucrose with a negative stimulus, were considered to exhibit habitual behavior. Our data shows that DERM‐SAP pre‐treatment reduced sucrose self‐administration upon reintroduction to the self‐administration chamber in animals that received LiCl treatment, indicating that habit formation was attenuated in these animals. This data demonstrates that the patch compartment is necessary for the development of habitual behavior.Support or Funding InformationNIH DA0235303 (KAH)Mercer University Seed Grant (KAH)