E A Witte | PubMed Health

PubMed1996

Pemoline produces ipsilateral turning behavior in unilateral 6-OHDA-lesioned rats.

1. Male Sprague-Dawley rats received either a unilateral injection of 6-hydroxy-dopamine or vehicle injection into the medial forebrain bundle. 2. Two weeks post surgery, all rats received a pemoline challenge (250 mg/kg s.c.), and rotational and stereotyped behaviors were videotaped and analyzed. 3. All rats regardless of injection expressed stereotyped behaviors and hyper-locomotion after pemoline challenge. 4. High performance liquid chromatography (HPLC) with electrochemical detection was used to evaluate changes in the levels of dopamine, serotonin and their metabolites in neostriata. 5. Rats with dopamine depleting lesions exhibited ipsilateral rotational behavior, indicating that pemoline, a central stimulant, is an indirect dopamine agonist in the rat. 6. The extent of dopamine depletion and serotonin elevation in the neostriatum in lesioned animals was related to the expression and degree of rotational behavior.

Animals↗

PubMed1996

Visual orienting and alerting in rhesus monkeys: comparison with humans.

The behavioral capacities of the rhesus monkey for several sensory and cognitive tasks appear quite similar to those of humans. To evaluate the monkey's attentional capacities, we have compared monkey and human performance on a visuospatial attentional task, the cued target detection (CTD) paradigm. Animals were trained to fixate a small spot of light while a cue and a subsequent target, are flashed in the visual periphery. In valid trials, the cue and target appeared in the same spatial location; in invalid trials, the cue and target appeared in the opposite location; in double trials, two cues were presented and the target appeared in one of their locations; in no-cue trials, the cue was omitted and the target appeared in one location. In addition, we varied cognitive control over the task initiation by making the trial onset either self-paced or computer-paced. Reaction times (RTs) to target presentation, response accuracy, and frequency of aborted trials were measured for all subjects. No significant species differences were found for the patterns of RTs for different trial types or for attentional dynamics, as indexed by the decreases in RT with increasing cue-target interval. However, humans and non-human primates reacted differently to changes in cognitive control. Humans shows significant increases in no-cue trial RTs in the auto-paced task compared to the self-paced, but no differences in overall RT between tasks; monkeys showed a significant faster overall RT for the self-paced than the computer-paced task, but no difference between no-cue RTs. The performance differences between species may be related to the training history of the animals or to known anatomical differences in cortical organization, especially in the parietal lobe.

Adult↗

PubMed1994

Arousal systems.

Recent advances in neural and behavioural pharmacology, and in intracellular recording suggest that arousal during the awake state may be regulated by multiple, interdependent neurotransmitter systems that originate in the brainstem or hypothalamus, and project to subcortical and cortical sites. We discuss efforts to determine the mechanisms by which these systems extent their effects, and the roles that they play in the control of arousal.

Animals↗