Dimensions of impulsivity are associated with poor spatial working memory performance in monkeys

Area of Science:

• Neuroscience
• Behavioral Genetics
• Primate Cognition

Background:

• Impulsive behavior and novelty seeking are key temperament traits linked to attention deficit/hyperactivity disorder (ADHD) and its neurocognitive endophenotypes.
• Genetic variations, particularly in the dopamine D4 receptor gene (DRD4), contribute to these behavioral traits.

Purpose of the Study:

• To investigate the relationship between impulsivity dimensions and spatial working memory in adolescent male monkeys.
• To explore the influence of dopamine D4 receptor gene (DRD4) genotype on this relationship.

Main Methods:

• Adolescent male monkeys were assessed using ecologically valid tests for impulsive approach and aggression.
• A delayed response task was used to evaluate spatial working memory performance.
• Subjects were grouped based on impulsivity levels (low vs. high) and DRD4 genotype (common vs. rare allele).

Main Results:

• High-impulsive monkeys, regardless of DRD4 genotype, showed reduced spatial working memory performance with increasing delays compared to low-impulsive subjects.
• An inverse relationship was observed between impulsivity and working memory capacity.
• Impulsive behaviors explained overlapping and independent variance in working memory, while CSF monoamine metabolite levels did not significantly differentiate groups, though rare DRD4 allele carriers showed higher turnover.

Conclusions:

• Dimensions of impulsivity negatively impact spatial working memory performance in adolescent monkeys.
• These effects on working memory may operate through different underlying mechanisms, even if the behavioral phenotype appears similar.
• Temperament traits like impulsivity are crucial factors influencing cognitive functions relevant to disorders like ADHD.