Learning, remembering and applying an arbitrary non-matching to position rule in mice

We describe maze-based behavioural methodologies to assay aspects of arbitr ary rule learning in mice. The methods allow for rapid acquisition of a non -matching to position (NMTP) rule that is relatively uninfluenced by innate behavioural strategies, and which give rise to stable baseline performance . Use of the NMTP rule under baseline conditions did not appear to be influ enced by extra-maze cues nor intra-maze cues based on olfactory information . Hence the information used to guide performance at test was probably a vi sual and/or a kinaesthetic representation of the sample. Whatever the preci se nature of the trace, its availability to guide behaviour was degraded by introducing delays between sample and test run components of the task. The characteristics of the so called 'forgetting curve' produced did not seem to be influenced by mediating strategies, whereby performance could be main tained following a delay by use of persistent olfactory cues or rehearsal o f the correct response using body position. suggesting that. to some degree the degraded performance following delays was indexing effects on short te rm memory processes. We then went on to obtain behavioural indices that may be of use in dissociating, within-subjects, between learning the basic NMT P rule and being able to apply it in a choice situation, using single and s imultaneous discrimination conditions, respectively. The data are discussed in terms of the utility of the behavioural methods to assay different psyc hological functions underlying the ability to learn, remember and apply non -matching to position rules in mice and their particular use in examining a ge-related deficits in cognitive functioning. (C) 2001 Elsevier Science BN. All rights reserved.