A time-structured analysis of hypothalamically induced increases in self-grooming and activity in the rat

Stressors and different manipulations of the paraventricular nucleus of the hypothalamus (PVH) increase self-grooming in the rat. To assess the effect of these PVH manipulations on the timing of grooming in relation to other ongoing behavior, the authors describe these behavioral responses by a time-structured model. The authors show the following: (a) Behavior in each treatment group can be described by a semi-Markov model. Effects of treatments can be described as changes in the parameters of this model, which reflect the tendencies to start and stop grooming and other activities. (b) The PVH manipulations increase self-grooming by increasing the tendencies to start grooming or by extending the period during which grooming occurs. (c) Grooming responses are accompanied by an increase in activity. (d) Different PVH manipulations change the temporal structure of behavior differentially, suggesting that distinct mechanisms within the PVH are involved in the precise timing of grooming in relation to other activities.