title: Dopamine agonists and antagonists can produce an attenuation of response bias in a temporal discrimination task depending on discriminability of target duration.
abstract: The current study examined the effects of the D2 agonist (quinpirole) and D2 antagonist (eticlopride) on temporal discrimination performance in a conditional discrimination task (Experiment I) and a delayed conditional discrimination task (Experiment II). In both experiments rats discriminated between a scheduled stimulus duration of 3 s versus 9 s. Consistent with previous reports, overall discrimination performance decreased in a dose-dependent manner with both drugs. Changes in response bias (the tendency to choose-short or choose-long irrespective of actual stimulus duration), however, were best characterized in terms of both drugs tending to attenuate the bias effects normally observed during baseline drug-free performance. Specifically, the 'choose-short' bias observed in Experiment I and at a relatively short, 0.1 s, delay in Experiment II became less extreme with increasing doses. In addition, the 'choose-long' bias observed at a relatively long, 6 s, delay in Experiment II also became less extreme with increasing doses. Thus, whether there was an apparent shift from a short response bias to long, or vice versa, was the product of the delay interval between stimulus presentation and choice rather than whether the drug in question was a D2 agonist or antagonist. Such an attenuation of bias may have arisen because of subjects confounding the delay interval with the actual discriminative stimulus duration.
authors.affiliation: Victoria University of Wellington, New Zealand. david.harper@vuw.ac.nz
authors.forename: David N
authors.initials: DN
authors.lastname: Harper
authors.forename: Lewis A
authors.initials: LA
authors.lastname: Bizo
authors.forename: Heather
authors.initials: H
authors.lastname: Peters
mesh_terms: D000818:Animals; D002755:Choice Behavior / Q000187:drug effects* / Q000502:physiology; D003213:Conditioning, Psychological / Q000187:drug effects / Q000502:physiology; D004193:Discrimination Learning / Q000187:drug effects* / Q000502:physiology; D015259:Dopamine Agents / Q000494:pharmacology; D008297:Male; D019257:Quinpirole / Q000494:pharmacology; D051381:Rats; D011930:Reaction Time / Q000187:drug effects* / Q000502:physiology; D017448:Receptors, Dopamine D2 / Q000187:drug effects* / Q000378:metabolism; D012457:Salicylamides / Q000494:pharmacology; D018709:Statistics, Nonparametric; D013998:Time Perception / Q000187:drug effects* / Q000502:physiology
chemical_list: D015259:Dopamine Agents; D017448:Receptors, Dopamine D2; D012457:Salicylamides; D019257:Quinpirole; C045989:eticlopride