Endogenous dopamine transmission is crucial for motor skill recovery after stroke.

Ischemic stroke frequently causes motor impairments. Despite exercise can improve motor outcomes, many stroke survivors remain life-long disabled. Understanding the mechanisms associated with motor recovery after a stroke is necessary to develop treatments. Here, we show that endogenous DA transmission is required for optimal motor skill recovery following photothrombotic stroke in rats. Blockade of dopamine D1 and D2 receptors impaired the recovery of a forelimb reaching task and decreased the rats' motivation to complete full training sessions. Our data indicate that dopamine transmission is important to drive motor rehabilitation after stroke through motivational aspects and ultimately suggest that augmented motivation and reward feedback could be an interesting strategy to increase the effectiveness or rehabilitation.

Investigating Motor Skill Learning Processes with a Robotic Manipulandum.

Skilled reaching tasks are commonly used in studies of motor skill learning and motor function under healthy and pathological conditions, but can be time-intensive and ambiguous to quantify beyond simple success rates. Here, we describe the training procedure for reach-and-pull tasks with ETH Pattus, a robotic platform for automated forelimb reaching training that records pulling and hand rotation movements in rats. Kinematic quantification of the performed pulling attempts reveals the presence of distinct temporal profiles of movement parameters such as pulling velocity, spatial variability of the pulling trajectory, deviation from midline, as well as pulling success. We show how minor adjustments in the training paradigm result in alterations in these parameters, revealing their relation to task difficulty, general motor function or skilled task execution. Combined with electrophysiological, pharmacological and optogenetic techniques, this paradigm can be used to explore the mechanisms underlying motor learning and memory formation, as well as loss and recovery of function (e.g. after stroke).

The effects of prenatal cocaine, post-weaning housing and sex on conditioned place preference in adolescent rats.

RATIONALE: Gestational exposure to cocaine now affects several million people including adolescents and young adults. Whether prenatal drug exposures alter an individual's tendency to take and/or abuse drugs is still a matter of debate. OBJECTIVES: This study sought to answer the question "Does prenatal exposure to cocaine, in a dose-response fashion, alter the rewarding effects of cocaine using a conditioned place preference (CPP) procedure during adolescence in the rat?" Further, we wanted to assess the possible sex differences and the role of being raised in an enriched versus impoverished environment. METHODS: Virgin female Sprague-Dawley rats were dosed daily with cocaine at 30 mg/kg (C30), 60 mg/kg (C60), or vehicle intragastrically prior to mating and throughout gestation. Pups were culled, fostered and, on postnatal day (PND) 23, placed into isolation cages or enriched cages with three same-sex littermates and stimulus objects. On PND43-47, CPP was determined across a range of cocaine doses. RESULTS: C30 exposure increased sensitivity to the rewarding effects of cocaine in adolescent males, and being raised in an enriched environment further enhanced this effect. Rats exposed to C60 resembled the controls in cocaine CPP. Overall, females were modestly affected by prenatal cocaine and enrichment. CONCLUSIONS: These data support the unique sensitivity of males to the effects of gestational cocaine, that moderate prenatal cocaine doses produce greater effects on developing reward circuits than high doses and that housing condition interacts with prenatal treatment and sex such that enrichment increases cocaine CPP mostly in adolescent males prenatally exposed to moderate cocaine doses.