ABSTRACT
Experimental Strategies for Investigating the Neurobiological Basis of Learning: The Model Systems Approach During the 1960s, a consensus developed that identification of the neurobiological basis of learning was a sufficiently complex problem that it required an experimental strategy very different than had been used previously. It was proposed that a major focus of research involve the use of "model systems," characterized as animal preparations which exhibit simple, highly stereotypic reflexes amenable to learning-dependent modification through controlled experimental conditions, for example, habituation, sensitization, and classical conditioning paradigms (Cohen, 1969; Crow & Alkon, 1980; Kandel & Spencer, 1968; Thompson et al., 1976; Thompson & Spencer, 1966; Weinberger, Diamond, & McKenna, 1984; Woody, 1974). The rationale was that experimenter-determined, phasic presentation of conditioning stimuli would facilitate identification of sensory pathways transmitting information about the environmental events controlling behavior. Likewise, the simplified nature of the behavior would facilitate identification of the motor pathways mediating the reflex and conditioned responses. Points of convergence between sensory and motor circuitry would identify synapses where neural plasticity underlying learned behavior first occurred. Such "primary sites" of plasticity then could be subjected to biochemical and molecular analyses to reveal the mechanisms responsible for information storage in the nervous system.
