Behavioural phenotyping of mouse mutants

Assessment of age-associated cognitive deficits in rats: a tricky business

Every living organism is affected by changes as a consequence of aging. Perhaps the most appropriate concept to describe age-related changes is that of 'functional age'. Laboratory rodents are especially suited as models of cognitive aging in humans, because they have a relatively short life-span and because many tests have been developed to investigate their cognitive performance. Examples from studies using the Morris water escape task were chosen to describe and discuss factors which must be considered before drawing conclusions about age-related cognitive deficits. In particular, the roles of rearing and housing conditions, of sensorimotor impairments, and of motivational differences between young and old rats are discussed. Conclusions are drawn about how aging studies should be conceived and performed.

The fallacy of behavioral phenotyping without standardisation

Behavioral phenotyping of mutant mice is a new and challenging task for the behavioral neuroscientist. Therefore, standardisation of the experimental conditions is required to permit comparisons between the results of experiments within and between laboratories. Once mutation-induced behavioral changes have been identified, phenotyping of mouse mutants should be performed along a systematic trajectory, which allows for an in-depth characterisation of the mutant under investigation.