Conceptual and procedural considerations for developmental assessment of learning and memory (dys)function following...

Symptoms of memory impairment are often reported following neurotoxicant exposure. Untoward effects on the developing organism, potentially reflected as later learning disabilities and memory problems, deserve critical evaluation. Animal models providing rigorous experimental control are extremely important in this context. The psychological literature offers a variety of tasks and procedures for use across many developmental ages. Most recent progress has demonstrated evidence of associative capacity in infrahumans as early as birth, and under specific conditions even prenatally. Common to all assessments of learning and memory capabilities, however, is the requisite that these processes be inferred from overt behavior. This requirement confers the responsibility of differentiating alterations of an associative nature from those of a nonassociative nature (e.g., motivation, attention, perception, sensory adaptation, fatigue, activity, and reactivity, etc.). When across age comparisons are also of interest, additional attention must be paid to potential differences in available sensory processes, response repertoire, and ecologically relevant contextual determinants (e.g., ambient temperature, presence of familiar odors or conspecifics), particularly with preweanling and neonatal animals. Specific guidelines are offered for the criteria and implementation of controls typically necessary to provide a convincing demonstration of an associative impairment.