| Summary: | Thesis (M. Sc.), Memorial University of Newfoundland, 1999. Behavioural Neuroscience Bibliography: p. 73-80 The purpose of this study was to investigate whether a stable point of entry (POE) is required for rats to solve a spatial learning problem in a curtain-enclosed environment containing a large visual cue panel, and to use both behavioural measures and place cell recordings to determine the basis of these solutions. Ten of sixteen male Long Evans rats learned to locate the baited corner of a square box, regardless of whether they had a fixed or randomly varying POE through the curtain, suggesting that a fixed POE is not necessary for learning on this type of dry-land appetitive task. Probe trials revealed that the rats could use either their internal sense of direction or the visual cue to locate the goal, but rarely used the cue unless explicit measures were taken to disorient them. Disorientation only led to cue use if the animals were also deprived of access to a view of the room prior to passage through the curtain, suggesting that the rats' orientation was being obtained from room geometry. The rats did not seem to be calling up new maps with an orientation anchored to the POE. Place fields maintained stable positions across trials in the box, unless cue rotation was combined with disorientation, in which case fields rotated by an amount corresponding with the rotation of the cue. These results provide converging lines of evidence that rats prefer to use their internal sense of direction in this type of problem, but are willing to rely on visual cues if they have been perceptibly disoriented.
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