EFFECTS OF INTRACRANIAL INJECTIONS OF SCOPOLAMINE ON OLFACTORY CONDITIONING RETRIEVAL IN THE HONEYBEE

The role of the cholinergic system on learning abilities and memory pe rformance has been investigated in the honeybee. The behavioural exper iment was the olfactory conditioning of the proboscis extension reflex , elicited by an antennal sucrose stimulation. Intracranial scopolamin e (0.5 mg/kg) or saline injections (0.25 mu 1) were given at different times before or after a one trial learning session in order to interf ere with acquisition of information, storage or recall processes. Neit her scopolamine injections, ranging from 20 min to 5 min prior to the acquisition task, nor post-trial drug injections given in the same tim e-window, impaired the retention performance measured one hour after c onditioning. Scopolamine injected 20 min after a learning session indu ced a time-dependent decrease of information retrieval, as was seen in retention testing performed from 5 min to one hour after injection. T hen, the amnestic effect of intracranial scopolamine injection seems t o be related to a specific and temporary inhibition of recall processe s. We can conclude that, in the present task, muscarinic-like receptor s are involved in information retrieval but not in acquisition or cons olidation processes.