I used the great tit (<i>Parus major</i>) and zebra finch (<i>Taeniopygia guttata</i>) as model species to determine whether steroid hormones have effects on avian spatial learning and memory. To address this I took a four-pronged approach: First, as spatial ability is to some extent reliant on appropriate cue use, I examined cue preference in the great tit. In a one-trial associative memory task birds were trained to a compound stimulus where both colour and location cues could be used to locate a reward. By dissociating the cues on probe trials I was able to determine which cues were controlling the birds’ food-finding behaviour. The overall distribution of choices was significantly different from random but did not differ between the sexes. Both sexes exhibited a preference for the location cue over the colour cue. Second, I exploited the existence of a well-characterised memory task that tests spatial and non-spatial memory. This was an operant conditioning delayed-non-matching-to-sample spatial memory task, presented on computer-controlled touch screen. I tested for sex differnces in performance in birds maintained under a breeding season (i.e. long-day) photoperiod. No sex differences in ability to perform either the spatial or visual memory task were found. Third, I used a non-invasive technique (oral administration) to manipulate hormone levels (testosterone (T), 5α-dihydrotesterone and oestradiol, the latter two being T metabolites) and determined their effect on learning and memory. Although T improved spatial learning and memory abilities in females in Experiment 1, no treatment effects were found in males or in Experiment 2. However, T increased response latencies (time taken to peck a touch screen image) in both sexes, suggesting a beneficial role of T on memory retention. My fourth approach was to use zebra finches selectively bred for differing peak (stress-induced) CORT levels to determine whether CORT affected avian spatial memory in a similar way to that seen in mammals.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:652489 |
| Date | January 2003 |
| Creators | Hodgson, Zoe G. |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/14082 |
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