Sign and goal tracker rats process differently the incentive salience of a conditioned stimulus

PLoS One. 2019 Sep 30;14(9):e0223109. doi: 10.1371/journal.pone.0223109. eCollection 2019.

Abstract

Sign and goal tracker animals show different behavioral patterns in response to conditioned stimuli, which may be driven by different neural circuits involved in processing stimuli. Here, we explored whether sign and goal-tracker profiles implicated different brain regions and responses to incentive salience of stimuli. We performed three experiments using male Wistar rats. Experiment 1 showed that lesioning the medial prefrontal cortex increased the prevalence of the goal-tracker phenotype. Experiment 2 assessed the developmental trajectory of the salience incentive attribution to a conditioned stimulus, showing that increased incentive salience of stimuli increased the prevalence of the sign-tracker phenotype in mature, but not preadolescent rats. In experiment 3, the functional impact of the medial prefrontal cortex circuits was analyzed with a latent inhibition procedure. Sign tracker rats showed a reduced latent inhibition to stimuli previously exposed when compared to goal tracker or intermediate rats. The overall results of this study highlight a key role of the medial prefrontal cortex for sign tracking behavior. The expression of sign and goal tracker phenotypes changed after lesion to the medial prefrontal cortex (experiment 1), differed across development (experiment 2), and showed differences in the attentional processes to previously exposed stimuli, as preexposure to CS was ineffective in sign tracker animals (experiment 3). These data indicate that the responses to the incentive salience of stimuli in sign tracker and goal tracker profiles are likely driven by different neural circuitry, with a different role of prefrontal cortical function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Animals
  • Attention / physiology
  • Conditioning, Classical / physiology*
  • Cues
  • Excitatory Amino Acid Agonists / toxicity
  • Goals
  • Inhibition, Psychological*
  • Male
  • N-Methylaspartate / toxicity
  • Prefrontal Cortex / drug effects
  • Prefrontal Cortex / injuries
  • Prefrontal Cortex / physiology*
  • Prefrontal Cortex / physiopathology
  • Rats
  • Rats, Wistar
  • Reinforcement, Psychology*
  • Reward
  • Stereotaxic Techniques

Substances

  • Excitatory Amino Acid Agonists
  • N-Methylaspartate

Grants and funding

This research was supported by PSI2015-65500-P grant (MINECO, FEDER, UE) and Fulbright PR2016-0100 (Ministerio de Educación, Cultura y Deporte). The authors declare no conflict of interest. one of the authors (P O’Donnell), is employed by a commercial company: "Takeda Pharmaceuticals". This company have not played a role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript and only provided financial support in the form of authors' salaries. The specific roles of this author is articulated in the ‘author contributions’ section.