Cessation of activity in red nucleus neurons during stimulation of the medial medulla in decerebrate rats

Mileykovskiy, Boris Y.; Kiyashchenko, Lyudmila I.; Siegel, Jerome M.

doi:10.1113/jphysiol.2002.028985

Cited by 24 publications

(11 citation statements)

References 78 publications

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“…Subsequently, the firing rates of individual sorted units were compared with the behavioral state of the animal across 6-10 pairs of high-tone and atonia periods. State-related differences in mean firing rates were tested using the Wilcoxon matched-pairs signed-rank test (Mileykovskiy et al, 2002); for all tests, alpha was set at .05. Neurons that significantly increased or decreased their firing rate during hightone periods were designated "tone-on" and "atonia-on," respectively.…”

Section: Discussionmentioning

confidence: 99%

Active medullary control of atonia in week-old rats

Karlsson

Blumberg

2005

Neuroscience

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Muscle atonia is a central feature of adult REM sleep which has recently been demonstrated to be a component of sleep in rats as young as 2 days of age (P2). The neural generation of atonia, which depends on mesopontine and medullary structures, is not fully understood in adults and has never been described in infants. In the present experiments we used electrical stimulation in decerebrated pups to identify an inhibitory area within the medial medulla of P7-10 rats. Muscle tone inhibition was consistently found on or near the midline within the ventromedial medulla, dorsal to the inferior olive, in an area that includes the nucleus gigantocellularis, nucleus paramedianis, and raphe obscurus. Chemical infusions in the same region revealed inhibitory responses to quisqualic acid but not to carbachol or corticotropin-releasing factor. Next, extracellular recordings within the medullary inhibitory area revealed neurons with atonia-on profiles; tone-on neurons were also found, typically at more lateral sites. Finally, in non-decerebrated pups, chemical lesions within the inhibitory area resulted in significant reductions in atonia durations, as well as decoupling of atonia from a second component of infant sleep, myoclonic twitching; specifically, twitches occasionally occurred during periods of high muscle tone, a condition reminiscent of "REM without atonia" as described in adults.In summary, we document the existence of an area within the ventromedial medulla of infant rats that (i) causes atonia when stimulated; (ii) contains units that exhibit atonia-related discharge profiles during sleep-wake cycling; and (iii) when lesioned, results in the partial loss of atonia and decoupling of the components of sleep. All together, these findings demonstrate that muscle atonia is actively regulated very early in ontogeny.

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Section: Discussionmentioning

confidence: 99%

Active medullary control of atonia in week-old rats

Karlsson

Blumberg

2005

Neuroscience

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“…Electrical stimulation of the medial part of the gigantocellular reticular nucleus (Mileykovskiy et al, 2002) immobilized the rat for filling a cell with Nb after a recording session. As an application of standard rectangular stimulating pulses evoked strong electrical artifacts, which impeded the control of cell labeling, we used sinusoidal currents (100–250 µA, 25 Hz, 5–15 min) for electrical stimulation of the gigantocellular reticular nucleus.…”

Section: Methodsmentioning

confidence: 99%

Duration of Inhibition of Ventral Tegmental Area Dopamine Neurons Encodes a Level of Conditioned Fear

Mileykovskiy¹,

Morales²

2011

J. Neurosci.

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It is widely accepted that midbrain dopamine (DA) neurons encode actual and expected reward values by phasic alterations in firing rate. However, how DA neurons encode negative events in the environment is still unclear because some DA neurons appear to be depressed, while others are excited by aversive stimuli. Here we show that exposure of fear-conditioned rats to the stimuli predicting electrical shock elicited in neurochemically identified ventral tegmental area (VTA) DA neurons three types of biphasic responses that contained an inhibitory pause. The duration of the inhibitory pause in these responses of VTA DA neurons was in direct proportion to the increase in respiratory rate reflecting the level of conditioned fear. Our results suggest that the duration of inhibition of VTA DA neurons encodes negative emotional values of signals predicting aversive events in the environment.

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“…Next, the firing rates of individual sorted units were compared with the behavioral state of the animal across 4–12 pairs of high tone and atonia periods. State-related differences in mean discharge rates were tested using the Wilcoxon matched-pairs signed-ranks test [74]; alpha was set at 0.05. Neurons that significantly increased their firing rates during periods of high muscle tone were designated as EMG-on, and neurons that significantly increased their firing rates during atonia periods were designates as atonia-on.…”

Section: Methodsmentioning

confidence: 99%

The Neural Substrates of Infant Sleep in Rats

et al. 2005

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Sleep is a poorly understood behavior that predominates during infancy but is studied almost exclusively in adults. One perceived impediment to investigations of sleep early in ontogeny is the absence of state-dependent neocortical activity. Nonetheless, in infant rats, sleep is reliably characterized by the presence of tonic (i.e., muscle atonia) and phasic (i.e., myoclonic twitching) components; the neural circuitry underlying these components, however, is unknown. Recently, we described a medullary inhibitory area (MIA) in week-old rats that is necessary but not sufficient for the normal expression of atonia. Here we report that the infant MIA receives projections from areas containing neurons that exhibit state-dependent activity. Specifically, neurons within these areas, including the subcoeruleus (SubLC), pontis oralis (PO), and dorsolateral pontine tegmentum (DLPT), exhibit discharge profiles that suggest causal roles in the modulation of muscle tone and the production of myoclonic twitches. Indeed, lesions in the SubLC and PO decreased the expression of muscle atonia without affecting twitching (resulting in “REM sleep without atonia”), whereas lesions of the DLPT increased the expression of atonia while decreasing the amount of twitching. Thus, the neural substrates of infant sleep are strikingly similar to those of adults, a surprising finding in light of theories that discount the contribution of supraspinal neural elements to sleep before the onset of state-dependent neocortical activity.

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Cessation of activity in red nucleus neurons during stimulation of the medial medulla in decerebrate rats

Cited by 24 publications

References 78 publications

Active medullary control of atonia in week-old rats

Active medullary control of atonia in week-old rats

Duration of Inhibition of Ventral Tegmental Area Dopamine Neurons Encodes a Level of Conditioned Fear

The Neural Substrates of Infant Sleep in Rats

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