Abstract:
Sleep represents a highly conserved physiological state, seen across the animal kingdom. Various purposes of sleep have been examined, one in particular is the integral nature of sleep for learning and memory. General anaesthesia often resembles sleep, having similar behavioural outcomes and often utilizing the same neural pathways as sleep. Evidence shows that many of these anaesthetics such as isoflurane are highly detrimental to certain forms of memory and can lead to long lasting cognitive impairment. The honeybee (Apis mellifera) provides an excellent model in understanding learning and memory by utilizing a bees innate response to sucrose and their ability to create associative memories easily. The aims of this thesis was to determine the impacts of two anaesthetic agents: isoflurane and xenon on the consolidation of a long-term associative memory, a extinction memory and the reacquisition of a previously acquired response. Isoflurane (x2 = 18.4705, df = 2, p < 0.001). and xenon (x2=4.903, df=2, p = 0.086). treated bees exhibited a decrease in associative memory response rates. There was no significant difference between the groups after post-extinction treatment. Yet both anaesthetics had low response rates, potentially indicating enhancement of the extinction response. Anaesthetics non-significantly showed slower rates of reacquisition compared to sleep and sleep deprived groups, but showed no difference in a retention test 24 hours later. Despite the different modes of action xenon and isoflurane take to produce anaesthesia, their impacts on memory paradigms were similar. This thesis shows the flexibility of olfactory conditioning in the honeybee. Further refinement of to the methods used would allow an exceptional way to study the effects of general anaesthetics on memory and learning in the honeybee.
