Amphetamine-induced sensitization and spontaneous stereotypy in deer mice.

Stereotyped behavior is commonly observed in neurodevelopmental disorders (e.g., autism, intellectual and developmental disability) and in a wide variety of animal species maintained in restricted environments. Stereotyped behavior can also be induced by psychostimulants, an effect potentiated by repeated intermittent exposure to these drugs (behavioral sensitization). The present study evaluated whether similar neuroadaptations in cortical-basal ganglia circuitry underlie the expression and development of spontaneous stereotypy and psychostimulant-induced sensitization. Sensitization was induced in deer mice with the degree of sensitization being dependent on housing condition but not age or environmental context. Environmentally enriched animals showed the least behavioral sensitization. Despite demonstrating robust sensitization in both older and younger animals, independent of context, behavioral sensitization was not associated with any alteration in the development or expression of spontaneous stereotypy in deer mice. Moreover, the frequency of baseline spontaneous stereotypy did not predict response to amphetamine challenge in either sensitized or non-sensitized mice. Thus, the present findings do not support the notion that sensitization-related neuroadaptations in cortical-basal ganglia circuitry are similar to those neuroadaptations that underlie spontaneous or environmentally linked stereotypy.