Neuronal network analysis based on arrival times of active-sleep specific inhibitory postsynaptic potentials in spinal cord motoneurons of the cat

The neuronal network responsible for motoneuron inhibition and loss of muscle tone during active (REM) sleep can be activated by the injection of the cholinergic agonist carbachol into a circumscribed region of the brainstem reticular formation. In the present report, we studied the arrival times of...

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Bibliographic Details
Published in:Brain research 2001-07, Vol.908 (1), p.75-85
Main Authors: Engelhardt, John K, Chase, Michael H
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Carbachol - pharmacology
Cat
Cats
Cholinergic Agonists - pharmacology
Fundamental and applied biological sciences. Psychology
Inhibitory postsynaptic potential (IPSP)
Interneurons - cytology
Interneurons - physiology
Models, Neurological
Motoneuron
Motor Neurons - cytology
Motor Neurons - drug effects
Motor Neurons - physiology
Nerve Net - cytology
Nerve Net - drug effects
Nerve Net - physiology
Neural Conduction - physiology
Neural Inhibition - drug effects
Neural Inhibition - physiology
Reaction Time - drug effects
Renewal process
Sleep
Sleep, REM - physiology
Sleep. Vigilance
Spinal Cord - cytology
Spinal Cord - drug effects
Spinal Cord - physiology
Synaptic Transmission - physiology
Vertebrates: nervous system and sense organs
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Summary:The neuronal network responsible for motoneuron inhibition and loss of muscle tone during active (REM) sleep can be activated by the injection of the cholinergic agonist carbachol into a circumscribed region of the brainstem reticular formation. In the present report, we studied the arrival times of inhibitory postsynaptic potentials (IPSPs) observed in intracellular recordings from cat spinal cord motoneurons. These recordings were obtained during episodes of motor inhibition induced by carbachol or during motor inhibition associated with naturally occurring active sleep. When the observed IPSP arrival times were analyzed as a superposition of renewal processes occurring in a pool of pre-motor inhibitory interneurons, it was possible to estimate the following parameters: (1) the number of independent sources of the IPSPs; (2) the rate at which each source was bombarded with excitatory postsynaptic potentials (EPSPs); and (3) the number of EPSPs required to bring each source to threshold. From the data based upon the preceding parameters and the unusually large amplitudes of the active sleep-specific IPSPs, we suggest that each source is a cluster of synchronously discharging pre-motor inhibitory interneurons. The analysis of IPSP arrival times as a superposition of renewal processes, therefore, provides quantitative information regarding neuronal activity that is as far as two synapses upstream from the site of the recording electrode. Consequently, we suggest that a study of the temporal evolution of these parameters could provide a basis for dynamic analyses of this neuronal network and, in the future, for other neuronal networks as well.
ISSN:0006-8993
1872-6240
DOI:10.1016/S0006-8993(01)02609-9