Effects of methylphenidate on working memory in pigeons

Abstract

To assess the effects of methylphenidate on working memory, pigeons were trained in a delayed matching-to-sample task. Delay interval duration (0.2, 1, 3, 6, or 12 sec) was varied within sessions in order to separate delay-dependent from delay-independent effects of the drug on performance. A reduction in the sample response requirement from five responses to one response effectively reduced attention to the stimulus and impaired overall accuracy. Methylphenidate was administered in doses of 0.0 (saline control), 0.25, 2.5, and 10 mg/kg. Relative to performance with saline, accuracy was significantly reduced with 10 mg/kg methylphenidate to the same extent in both fixed ratio (FR) 1 and FR 5 conditions. The smaller doses had no effect, and there was no evidence that accuracy improved with drug administration. Intercepts and slopes of exponential functions fitted to measures of discriminability plotted as a function of delay showed that methylphenidate affected delay-independent aspects of performance (initial discriminability), but not delay-dependent aspects (rate of forgetting).

Forgetting from Short-Term Memory in Delayed Matching to Sample: A Reinforcement Context Model

“…The latter interpretation seems consistent with instances in which sample-stimulus conditions are held constant, but accuracy is lowered through drug administration and consequential distraction from competing alternatives. For example, administration of the drug scopolamine increases the overall difficulty of discrimination, as reflected in a reduction in the intercept of the forgetting function, consistent with much prior research on the effects of drugs on delayed matching performance in pigeons and rats (Parkes & White, 2000;White & Ruske, 2002;Wright & White, 2003). Ruske, Fisher, and compared the effects of scopolamine with a vehicle control on delayed matching performance in pigeons.…”

Dopamine and norepinephrine receptors participate in methylphenidate enhancement of in vivo hippocampal synaptic plasticity

“…As a second test of a moderate dose of MPH, we ran mice through a hippocampal dependent, delayed non-match to sample T-maze task designed to test spatial working memory, a type of memory that MPH is specifically known to enhance (Repantis et al, 2010; Wright and White, 2003). A boost in T-maze performance should mean we have a moderate therapeutic dose, as indicated in the literature by behavioral experiments in mice (Heredia et al, 2013; Huang and Huang, 2012; Lloyd et al, 2013).…”

The effects of l-amphetamine sulfate on cognition in MS patients: results of a randomized controlled trial

“…Its major mechanism of action is stimulation of dopamine release and dopamine-reuptake inhibition. Although amphetamines enhance memory in both animal models [4][5][6][7] and humans [6,8], their clinical use is limited by such side effects as hyperactivity, agitation, psychosis, and addiction [9,10]. These adverse effects are thought to be due to increase in dopamine in the subcortical areas, such as the nucleus accumens [11].…”