A study of the anatomy and physiology of sleep in the rock hyrax, Procavia capensis
The rock hyrax, Procavia capensis, is a social diurnal mammal that typically lives in colonies on rocky outcrops and is found throughout most parts of Southern Africa. The aim of this thesis was to describe the sleep phenomenology of the rock hyrax. By means of immunohistochemistry the location and distribution of the cholinergic, catecholaminergic, serotonergic, orexinergic, histaminergic, and the GABAergic systems were described. For the most part these systems and their terminal network distributions followed the general mammalian organisational plan; however, several features, potentially unique to the rock hyrax, were found. These include the presence of cholinergic neurons in the AD and AV nuclei of the dorsal thalamus, parvo- and magnocellular divisions of the cholinergic LDT and PPT nuclei. A dense orexinergic terminal network distribution was noted in the regions coincident with the AD nucleus, a feature only observed in other diurnal mammals. Parvalbumin neurons did not show any association to the sleep related nuclei, whereas calbindin and calretinin neurons were found in all sleep related areas, though with differing densities and some homogeneities. The physiological measurable parameters of sleep were recorded continuously for 72 h under both solitary and social conditions and compared to determine whether differences existed. The results revealed that no major differences existed between the social and solitary conditions, but sleep intensity and REM duration (particularly REM0) was more pronounced in the social condition. REM was ambiguous in these animals, and led to its subdivision into REM1 and REM0. It is possible that REM1 could be a form of low voltage slow wave sleep, but further investigation is required. If REM1 is a form of NonREM sleep it would imply that the rock hyrax has the lowest amount of REM sleep of any terrestrial mammal studied to date.
Ph.D., Faculty of Science, University of the Witwatersrand, 2011
Human physiology, Human anatomy, Anatomy, Rock hyrax, Physiology