The effect of Cabergoline, a dopamine D2 agonist, on spatial attention bias: A double blind randomised control trial

Every day individuals are bombarded with extraneous visual stimuli and consequently rely on selective spatial attention to effectively process task relevant information. However, individuals often show asymmetries in their spatial attention, a phenomenon known as spatial attention bias. Neuroanatomical, neurochemical, lesion, and genetic studies have converged to implicate dopamine, a catecholamine transporter, in modulating spatial attention bias. The current study utilised a double blind randomised control trial cross-over design to investigate the effect of Cabergoline, a dopamine D2 agonist, on spatial attention bias. Participants consisted of 24 healthy males and underwent the Greyscales task, a well-validated perceptual measure of attentional bias, and a novel visual search task, to investigate how an increase in dopamine affected spatial attentional performance. It was hypothesised that Cabergoline would increase dopamine availability in the right hemisphere and drive attention leftwards. This was not supported by the Greyscales task however was partially supported by the novel visual search task as when participant’s responded under conditions of increased perceptual load, results suggested Cabergoline may have shifted attention leftwards which subsequently resulted in reduced attentional abilities available to deal with stimuli presented in the right hemifield. Furthermore, Cabergoline may have increased selective attention in the right hemifield when there were no competing distractors present from the left hemifield. Understanding how different neurotransmitters influence spatial attention and spatial bias is important as it may aid in the development of pharmacological treatments for clinical populations where spatial deficits are prominent

Dopamine D₂ receptor modulation of human response inhibition and error awareness

Response inhibition, comprising action cancellation and action restraint, and error awareness are executive functions of considerable clinical relevance to neuropsychiatric disorders. Nevertheless, our understanding of their underlying catecholamine mechanisms, particularly regarding dopamine, is limited. Here, we used the dopamine D2 agonist cabergoline to study its ability to improve inhibitory control and modulate awareness of performance errors. A randomized, double-blind, placebo-controlled, crossover design with a single dose of cabergoline (1.25 mg) and placebo (dextrose) was employed in 25 healthy participants. They each performed the stop-signal task, a well-validated measure of action cancellation, and the Error Awareness Task, a go/no-go measure of action restraint and error awareness, under each drug condition. Cabergoline was able to selectively reduce stop-signal RT, compared with placebo, indicative of enhanced action cancellation (