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.

Time structure of self-grooming in the rat: self-facilitation and effects of hypothalamic stimulation and neuropeptides.

Specific brain manipulations, such as stimulation of the paraventricular nucleus of the hypothalamus (PVH) or injections of neuropeptides, increase self-grooming in the rat. Such manipulations also affect the different movements that constitute grooming. Using models to assess the time structure of these movements, the authors demonstrate that the rules that control the time structure within grooming are different from the ones that control its initiation.

PVH lesions do not inhibit stressor-induced grooming in the rat.

Electrical and chemical stimulation of specific parts of the paraventricular hypothalamus (PVH) and the adjacent hypothalamus induce self-grooming responses in the rat. The function of this hypothalamic grooming area (HGA) is not understood. The localization of the HGA in the hypothalamus suggests that grooming, a behavioural response to stressors, is somehow linked to the neuroendocrine response to stressors.

Effect of environmental stressors on time course, variability and form of self-grooming in the rat: handling, social contact, defeat, novelty, restraint and fur moistening.

Grooming is often related to dearousal following stressors. Interestingly, electrical and chemical stimulation of the paraventricular nucleus of the hypothalamus (PVH), at levels that are known to activate the hypothalamus-pituitary adrenal axis (HPA), also elicits grooming. At the level of the PVH, the neuroendocrine stress response is apparently still linked to the behavioural response to stressors.

Grooming induced by intrahypothalamic injection of ACTH in the rat: comparison with grooming induced by intrahypothalamic electrical stimulation and i.c.v. injection of ACTH.

Intracerebroventricular (i.c.v.