Relevance of deprivation studies in understanding rapid eye movement sleep

Abstract

Rapid eye movement sleep (REMS) is a unique phenomenon essential for maintaining normal physiological processes and is expressed at least in species higher in the evolution. The basic scaffold of the neuronal network responsible for REMS regulation is present in the brainstem, which may be directly or indirectly influenced by most other physiological processes. It is regulated by the neurons in the brainstem. Various manipulations including chemical, elec-trophysiological, lesion, stimulation, behavioral, ontogenic and deprivation studies have been designed to understand REMS genesis, maintenance, physiology and functional significance. Although each of these methods has its significance and limitations, deprivation studies have contributed significantly to the overall understanding of REMS. In this review, we discuss the advantages and limitations of various methods used for REMS deprivation (REMSD) to understand neural regulation and physiological significance of REMS. Among the deprivation strategies, the flowerpot method is by far the method of choice because it is simple and convenient, exploits physiological parameter (muscle atonia) for REMSD and allows conducting adequate controls to overcome experimental limitations as well as to rule out nonspecific effects. Notwithstanding, a major criticism that the flowerpot method faces is that of perceived stress experienced by the experimental animals. Nevertheless, we conclude that like most methods, particularly for in vivo behavioral studies, in spite of a few limitations, given the advantages described above, the flowerpot method is the best method of choice for REMSD studies.

Keywords:

• flowerpot method
• locus coeruleus
• methods of REMS deprivation
• noradrenaline
• stress response

Acknowledgments

RM received DST-woman scientist postdoc fellowship. SK received CSIR fellowship while conducting her PhD. BNM received funding through research grants from UGC, DBT and JC Bose fellowship and institutional umbrella support grant under the following: DBT-BUILDER; DST-PURSE and -FIST; UGC-UPEII, -DRS and Resource Networking.

Disclosure

The authors report no conflicts of interest in this work.