Conditioned Stimulus Control of the Expression of Sensitization of the Behavioral Activating Effects of Opiate and Stimulant Drugs
Jane Stewart Concordia University Montreal, Quebec, Canada
Sensitization is a ubiquitous biological phenomenon, seen in the long-lasting increase in response to same or weaker stimuli following presentation of a strong stimulus. Sensitization has been used to describe the enhancement of reflexive responses following their repeated elicitation (e.g., Groves & Thompson, 1970), the increased behavioral and biochemical responsiveness to drugs (e.g., Robinson & Becker, 1986) and stressors (e.g., Anisman & Sklar, 1979) following their initial presentation, the growth in the response to repeated epileptic discharge (e.g., Post, Weiss, & Pert, 1988), and the increased responsivity of the immune system following initial exposure to an antigen (e.g., Cooper, 1980). Antelman ( 1988) has argued that sensitization may be a property of cells, a simple form of memory that is manifested as a more rapid and larger response to a strong stimulus following its intermittent exposure.
Neurophysiologists have used the term sensitization, as opposed to habituation, to refer to the long-lasting increment in response occurring upon repeated presentation of a stimulus that at its initial presentation reliably elicits a response ( Groves & Thompson, 1970). Based on studies of the mammalian spinal flexion reflex ( Spencer, Thompson, & Neilson, 1966; Thompson & Spencer, 1966), Groves and Thompson argued that the processes in the central nervous system underlying such response sensitization must involve interneuronal plasticity. The fact that, following the repeated presentation of a strong stimulus, sensitization