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2022 MAR 5 (NewsRx) -- By a News Reporter-Staff News Editor at Obesity, Fitness & Wellness Week -- Investigators publish new report on Central Nervous System Diseases and Conditions - [...]

Offensive aggression in golden hamsters is inhibited by 5-hydroxytryptamine [(5-HT).sub.1A] receptors and facilitated by 5-[HT.sub.3] receptor activation. As such, we sought to determine whether these receptors function similarly between animals expressing an impulsive-aggressive phenotype, as compared to normal animals. Animals were screened for aggressive and impulsive choice behaviors and categorized into Low-Aggression (L-Agg) and High-Aggression (H-Agg) groups, and then tested for behavior under effective doses of 5-[HT.sub.1A] receptor agonist 8-hydroxy-N, N-dipropyl-2-aminotetralin (DPAT; 0.1 mg/kg and 0.3 mg/kg) or 5-[HT.sub.3] receptor antagonist tropisetron (0.3 mg/kg) treatment. Low-dose DPAT treatment inhibited both behaviors in H-Agg animals, however yielding more modest effects in L-Agg animals: while high-dose DPAT effects were confounded by side effects on locomotion. Tropisetron, on the other hand, had differential effects between groups, as aggression and impulsive choice were both inhibited in H-Agg animals, while enhanced in L-Agg individuals. In addition, while the effects of the 5-[HT.sub.1A] receptor were limited, the broad effects of 5-[HT.sub.3] receptor included repetitive and impulsive elements of behavior, pointing to the importance of the receptor's role in the modulation of these particular aspects within the phenotype. Keywords: impulsivity, agorlistic, 5[HT.sub.1A] receptor, 5[HT.sub.3] receptor, reactivity DOI: 10.1037/a0020171

The present series of experiments aimed to pinpoint the source of nucleus accumbens core (AcbC) effects on delay discounting. Rats were trained with an impulsive choice procedure between an adjusting smaller sooner reward and a fixed larger later reward. The AcbC-lesioned rats produced appropriate choice behavior when the reward magnitude was equal. An increase in reward magnitude resulted in a failure to increase preference for the larger later reward in the AcbC-lesioned rats, whereas a decrease in the larger later reward duration resulted in normal alterations in choice behavior in AcbC-lesioned rats. Subsequent experiments with a peak timing (Experiments 2 and 3) and a behavioral contrast (Experiment 4) indicated that the AcbC-lesioned rats suffered from decreased incentive motivation during changes in reward magnitude (Experiments 2 and 4) and when expected rewards were omitted (Experiments 2 and 3), but displayed intact anticipatory timing of reward delays (Experiments 2 and 3). The results indicate that the nucleus accumbens core is critical for determining the incentive value of rewards, but does not participate in the timing of reward delays. Keywords: nucleus accumbens, impulsivity, delay discounting, timing, rats DOI: 10.1037/a0018464

Objective: The study assessed striatal presynaptic dopamine function in patients with different subtypes of depression. Method: Magnetic resonance imaging and positron emission tomography with [[sup.18]F]fluorodopa ([[sup.18]F]DOPA) were used to compare six depressed patients with marked affective flattening and psychomotor retardation, six depressed patients with marked impulsivity and anxiety, and 10 healthy comparison subjects. Depressed patient groups were matched for severity of depression. Results: [[sup.18]F]DOPA uptake [K.sub.i] values in the left caudate were significantly lower in patients with psychomotor retardation than in patients with high impulsivity and in comparison subjects. Conclusions: These results suggest that left caudate dopamine function differs between depressed patients with psychomotor retardation and those with impulsivity and provide direct evidence of a link between dopamine hypofunction and psychomotor retardation in depression. (Am J Psychiatry 2001; 158:314-316)

People who change visual focus rapidly are more likely to be impatient and impulsive than people who shift their gaze more slowly, according to a study published in the Jan. [...]