Neurological Disorders: Trace Conditioning
Cognition, especially the loss of cognitive abilities in dementias such as Alzheimer's disease, later-stage Parkinson's disease, and Huntington's disease, as well as in schizophrenia, is a major focus of research. This area has been hampered particularly by the lack of rapid assays that specifically target the learning and memory losses associated with these diseases, i.e. learning and memory dependent on areas of the brain such as the hippocampus. Assays generally used, such as the eight-arm radial arm maze or delayed non-matching-to-sample procedures require significant time and training. However, animals learn aversive conditioning very easily and it has been found that this can be combined with ‘trace’ conditioning, in which there is a time interval between the signal stimulus and the aversive stimulus itself, to provide a rapidly (3-5 trials) learned response that is dependent upon the function of the hippocampus. This assay has been automated to increase objectivity and make it appropriate for high throughput behavioral analysis. Pharmacological validation of this test has been performed. Impairment of contextual and auditory-cue fear conditioning has been observed after administration of the muscarinic receptor antagonist scopolamine (Rudy et al., 1996).
