Effects of apomorphine and haloperidol on response suppression learning of young chicks.
In four experiments, the effects of augmenting or blocking dopamine receptor activity on response suppression learning of Colburn X Colburn chicks were determined. In each experiment, 4-day-old chicks were trained to key peck for heat reward and then tested for response suppression learning by using either a response-contingent punishment or an extinction-punishment task. Before response suppression testing, different groups of chicks were injected ip with apomorphine (1.0, 2.0, or 4.0 mg/kg) either alone or after pretreatment with haloperidol (0.5 or 1.0 mg/kg). Regardless of the response suppression task used, chicks injected with apomorphine had difficulty inhibiting their responding; whereas, chicks injected with haloperidol, either alone or before apomorphine treatment, responded on fewer trials than saline-treated chicks. During extinction testing, 4-day-old chicks given only apomorphine showed the typical suppressive effect of punishment on responding rather than the paradoxical punishment-induced increase in responding found in normal 1-day-old chicks. These results indicate that activation of dopamine receptors retards response suppression learning of the 4-day-old chick, but functional changes in central dopaminergic mechanisms are not primarily responsible for the normal age-dependent improvement in response suppression learning of the young chick.
D000367:Age Factors; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D001070:Appetitive Behavior / Q000187:drug effects; D001245:Association Learning / Q000187:drug effects; D001362:Avoidance Learning / Q000187:drug effects*; D001921:Brain / Q000187:drug effects*; D002645:Chickens; D003216:Conditioning, Operant / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005108:Extinction, Psychological / Q000187:drug effects; D006220:Haloperidol / Q000494:pharmacology*; D011954:Receptors, Dopamine / Q000187:drug effects*
D011954:Receptors, Dopamine; D006220:Haloperidol; D001058:Apomorphine