Related Experiment Videos
Mesopontine contribution to the expression of active 'twitch' sleep in decerebrate week-old rats
1Program in Behavioral and Cognitive Neuroscience, Department of Psychology, E11 Seashore Hall, The University of Iowa, Iowa City, IA 52242, USA.
Insights
The mesopontine region is crucial for active sleep in infant rats, as decerebrations reduced myoclonic twitching. This finding supports the role of the brainstem in infant active sleep regulation.
Area of Science:
- Neuroscience
- Developmental Biology
- Sleep Research
Background:
- Infant active sleep, characterized by myoclonic twitching, is often considered homologous to adult REM sleep.
- Recent challenges to this homology necessitate investigation into the neural substrates of infant active sleep.
Purpose of the Study:
- To determine if the mesopontine region, known to be vital for adult REM sleep, is also essential for infant active sleep.
- To investigate the neural basis of active sleep in infant rats.
Main Methods:
- Performed decerebrations at different levels of the pons and midbrain in infant rats.
- Quantified the effects of these lesions on myoclonic twitching frequency and temporal organization.
Main Results:
- Caudal pontine decerebrations significantly reduced myoclonic twitching by 76%.
- Rostral pontine decerebrations reduced twitching by 40%, while midbrain transections had no significant effect.
- Pontine decerebrations selectively impacted high-frequency twitching, suggesting a role beyond spinal circuits.
Conclusions:
- The mesopontine region plays a critical role in the expression of active sleep in infant rats.
- These findings suggest a conserved neural mechanism for active/REM sleep across development.
Abstract:
Myoclonic twitching is a ubiquitous feature of infant behavior that has been used as an index of active sleep. Although the active sleep of infants differs in some ways from the REM sleep of adults, their marked similarities have led many to view them them as homologous behavioral states. Recently, however, this view has been challenged. One avenue for resolving this issue entails examination of the neural substrates of active sleep. If the neural substrates of active sleep were found to be similar to those of REM sleep, then this would support the view that the two states are homologous. Therefore, in the present study, decerebrations were performed in the pons and midbrain to determine whether the mesopontine region is important for the expression of active sleep in infants, just as it is for the expression of REM sleep in adults. It was found that, in comparison to controls, caudal pontine decerebrations reduced myoclonic twitching by 76%, rostral pontine decerebrations reduced twitching by 40%, and midbrain transections had no significant effect on twitching. Moreover, analysis of the temporal organization of twitching indicated that pontine decerebrations predominantly affected high-frequency twitching while leaving unaffected the low-frequency twitching that is thought to be contributed by local spinal circuits at this age. These results indicate that the mesopontine region plays a central role in the expression of active sleep in infant rats.