Self-grooming in animals is an innate behaviour that is involved in hygiene maintenance and other physiologically important processes, including thermoregulation, social communication and de-arousal. It is one of the most frequently observed behaviours in awake rodents and has a patterned, sequential organization with characteristic cephalocaudal progression. Self-grooming is remarkably similar across species in several taxa. Humans engage in self-grooming, and this behaviour shows some similarity to that seen in other animals. However, human self-grooming behaviour can become pathological, for example, during stressful conditions or in certain neuropsychiatric disorders.
The assessment of rodent self-grooming is potentially useful for translational neuroscience research, as aberrant rodent self-grooming can be related to human disorders in which abnormal self-grooming is a symptom. However, it is important to note that animal selfgrooming cannot be considered an exact model of any particular human pathology. Rather, the broader value of rodent self-grooming is as a model of complex repetitive, self-directed and sequentially patterned behaviours. Therefore, rather than viewing rodent self-grooming behaviour as a direct correlate of a particular symptom, it may be best considered as an indirect index of several behavioural phenomena that may be relevant to human brain disorders, including chains of motor action and complex patterning of motor activities. From this broad viewpoint, the analysis of rodent self-grooming may help in understanding the neural mechanisms of hierarchical motor control that underlie complex sequential behaviours in general, and may also provide valuable mechanistic insights into their dysregulation.
Neurophysiology, genetics and pharmacology have been used to study this interesting complex behaviour in rodents. In this Review, we discuss findings from this work and highlight the potential implications of assessing rodent self-grooming behaviour for understanding human brain disorders. We propose that rodent self-grooming is an important behavioural phenotype that can be used to understand the neural basis of complex action patterns in other species, including humans, in both normal and abnormal conditions. This Review does not discuss heterogrooming (a form of grooming behaviour that is directed towards another animal, which occurs in other contexts, such as maternal, sexual and aggressive or social behaviours), or peripheral and brainstem or spinal coordination mechanisms that are the ultimate targets of the forebrain control networks involved in grooming.