Discharge properties of pontine reticulospinal neurons during sleep-waking cycle

Abstract

1. Reticulospinal neurons were identified by antidromic invasion from spinal cord electrodes chronically implanted at C4 in cats. 2. Most of the neuronal population studied lay within the medial portion of the giant cell field from the anterior pontine and to the anterior medullary reticular formation (FTG). A few cells were found in the tegmental reticular nucleus (TRC) which has not previously been known to project to the spinal cord. 3. Extracellular action potentials from the neuronal somata of the identified neurons were recorded continuously throughout naturally occurring sleep-waking cycles. 4. The identified reticulospinal neurons shared three properties, suggesting a generator function in desynchronized sleep (D) (with previously recorded but unidentified FTG neurons): selectivity (or concentration of discharge in D); tonic latency (or firing rate increases beginning several minutes prior to D); and phasic latency (or firing rate increases occurring prior to eye movements within D). 5. The location, discharge properties, and spinal projections of FTG neurons are, thus, all consistent with the hypothesis that they may directly mediate some of the descending excitatory and inhibitory influences on spinal reflex pathways in desynchronized sleep.

REM sleep and dreaming: towards a theory of protoconsciousness

“…Meanwhile, the parallel development of basic neurophysiology focused on sleep itself and ignored consciousness [126][127][128][129][130][131] . This line of work was informed by the idea of neuronal clocks -first suggested by Thomas Graham-Brown, a pupil of Sherrington 132 -and famously evidenced by the studies of circadian rhythms 133 , which were found to be controlled in the suprachiasmatic nucleus of the hypothalamic brainstem 134 .…”

Glycine-Mediated Postsynaptic Inhibition is Responsible for REM Sleep Atonia

“…11,12 These cells activate premotor inhibitory interneurons in the region of the nucleus gigantocellularis which, in turn, discharge selectively during REM sleep. [13][14][15][16][17][18] They innervate motoneurons and promote their postsynaptic inhibition during REM sleep. 9,[17][18][19][20][21][22] Nevertheless, in 2008, Brooks and Peever 23 claimed that a "considerable controversy" exists regarding the neural mechanisms underlying REM sleep atonia (although they did not provide any references or data to support this claim).…”

Physical motion in dreams: One measure of three theories.

“…Reticulospinal motor neurons, whose activity in waking is phase locked to somatic movement, are tonically excitable and fire phasically in REM sleep (Ito & McCarley, 1984; Steriade & McCarley, 1990, p. 337); owing to inhibition of spinal motor neurons, supraspinal motor commands are not enacted (Pompeiano, 1967). Small movements do override muscle paralysis (Pompeiano, 1967; Wyzinski, McCarley, & Hobson, 1978); some movement large enough to produce EEG artifact is characteristic (Muzet, Naitoh, Townsend, & Johnson, 1972). However, motor activation in REM sleep does not generate actual movement except in experimentally induced REM sleep without atonia (Jouvet & Delorme, 1965) and in human REM sleep behavior disorder (Schenck, Bundlie, Ettinger, & Mahowald, 1986).…”