Postinspiratory neuronal activities during behavioral control, sleep, and wakefulness

Abstract

Cells that discharge in early expiration and inhibit other respiratory cells purportedly cause a separate phase of the respiratory cycle that has been named "postinspiration." Our objective was to study these postinspiratory cells in the intact unanesthetized cat during sleep, wakefulness, and behavioral inhibition of inspiration, but we were unable to find cells with strong and consistent activity confined to early expiration. Instead, we found that various cell types were active in early expiration. They included inspiratory-expiratory phase-spanning cells, retrofacial augmenting expiratory cells with bursts in early expiration, retrofacial decrementing expiratory cells, tonic expiratory cells, and cells with variable activity in the early part of expiration. Just as the cell types active during early expiration were heterogeneous so too were their activities during behavioral inhibition of inspiration and during sleep. These results suggest that the state of early expiration is determined by many different cell types rather than a single class of postinspiratory cells.

Medullary raphe neurones and baroreceptor modulation of the respiratory motor pattern in the cat

“…The inclusion of two E‐Decr neurones indicates that cells so classified do not constitute a homogeneous population; E‐Decr neurones recorded along the rostral‐caudal extent of the VRG‐Bötzinger region exhibit various discharge patterns (Lindsey et al 1987; Orem & Trotter, 1992). The η 2 values for E‐Decr neurones with short time scale correlations ranged from low values reported for E‐Decr neurones in awake behaving animals (Orem & Trotter, 1992) to values approaching those of phasic E‐Decr neurones in numerical simulations of the respiratory network that, in part, motivated this work (Balis et al 1994). Cross‐correlation, spike‐triggered averaging and related approaches used in this study overcome some of the shortcomings of classification schemes based solely upon discharge patterns of single neurones and their responses, which do not address connectivity.…”

Pathogenesis of Obstructive and Central Sleep Apnea

“…Third, neurons that modulate arousal (active awake, less active, or inactive asleep), such as serotonergic or noradrenergic neurons, have a tonic excitatory influence on upper airway motoneurons such as hypoglossal motoneurons (32,33). This has been called the "wakefulness stimulus" and generally increases muscle activity (34,35). With these three inputs, pharyngeal muscle activity is linked to respiration, local conditions in the airway (negative pressure), and arousal state (wake vs. sleep) (36).…”

Cholinergic Modulation Of Respiratory Brain‐Stem Neurons And Its Function In Sleep–Wake State Determination

“…The behaviour of brain-stem respiratory neurons during REM sleep has been studied by extracellular recording of neuronal activity in the unanaesthetized and unrestrained cat. 35 The mechanism underlying the increased excitability of brain-stem respiratory neurons and altered respiratory frequency in REM sleep is not yet known. 2 and indicate that both inspiratory and expiratory neurons can increase their discharge rate in REM compared with non-REM sleep.…”

“…34 It should be noted that early expiratory neurons showed considerable variability in their responses; while some showed significant increases in firing rate, others did not, resulting in no net change in discharge rate between SW and REM sleep. 35 The mechanism underlying the increased excitability of brain-stem respiratory neurons and altered respiratory frequency in REM sleep is not yet known. There is a close breath-by-breath correlation between REM sleep-specific discharge in mid-brain reticular formation neurons and respiratory output, 36 suggesting that reticular formation activation may provide, or be correlated with, enhanced excitatory drive to respiratory CPG neurons during REM sleep.…”