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The Relationship between Impulsive Behavior and Dopamine, Glutamate system

岑芯褕、黃靖涵

Abstract

The timing impulsivity of FI (Fixed interval) and DRL (Differential reinforcement of low rate) behavior has been shown by testifying individual differences. Despite behavioral characteristics being delineated, the neurochemical substrates of FI and DRL behaviors on dopamine (DA) and glutamate (Glu) receptors and reuptake transporters has remained unclear. The results indicate the involvement of timing process in the FI and DRL operant behaviors as revealed by an endophenotypic approach to impulsive action. The endophenotype of impulsive action of time-based operant behavior could be associated to different levels of DAT and GluN2A expression in the mPFC, NAc, Hippo, and dSRT.

Research Purpose

For the purpose of realizing the neurochemical mechanism behind the impulsive behavior, this study was designed 1) to examine the relationship between FI and DRL responses, and 2) to assay the underlying neurochemical substrates of DA and Glu.

Methodology

After the behavior tasks were completed, western blotting was used to measure the protein expression of DA1 receptor (D1R), DA2 receptor (D2R), and DA reuptake transporter (DAT), and Glu N-Methyl-D-aspartic acid (NMDA) receptor subunits including GluN1 (GN1), GluN2A (GN2A), and GluN2B (GN2B), in the medial prefrontal cortex (mPFC), nucleus accumbens (NAc), dorsal striatum (dSRT), hippocampus (Hippo), and amygdala (Amyg).

Conclusions and Future Work

Conclusions:

  1. There was a significant positive correlation between the efficiency and the PRP of FI-30s.
  2. The expression of DAT in the mPFC in LI group is significantly higher than that in HI group.
  3. The endophenotype of impulsive action of time-based operant behavior could be associated with different levels of DAT and GluN2A expression in the mPFC, NAc, Hippo, and dSRT.

Future work:
This study mainly explores the impulsive traits about timing and behavioral inhibition, and measures the influence of its operating brain that DA on Glu involve. In the future, its complete operating mechanism will be further explored and examined, and the clinical mental illness caused by related impulsivity will be further analyzed, so as to yield effective treatments and prevention of the related illness.