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

The role of the cholinergic system on learning abilities and memory performance has been investigated in the honeybee. The behavioural experiment was the olfactory conditioning of the proboscis extension reflex, elicited by an antennal sucrose stimulation. Intracranial scopolamine (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 interfere with acquisition of information, storage or recall processes. Neither scopolamine injections, ranging from 20 min to 5 min prior to the acquisition task, nor post-trial drug injections given in the same time-window, impaired the retention performance measured one hour after conditioning. Scopolamine injected 20 min after a learning session induced a time-dependent decrease of information retrieval, as was seen in retention testing performed from 5 min to one hour after injection. Then, the amnestic effect of intracranial scopolamine injection seems to be related to a specific and temporary inhibition of recall processes. We can conclude that, in the present task, muscarinic-like receptors are involved in information retrieval but not in acquisition or consolidation processes.