Summary
Presumed serotonin-containing neurons in the nucleus centralis superior (NCS) in freely moving cats showed a slow, rhythmic discharge rate during quiet waking (X = 2.41 ± 0.12 spikes/s), and displayed a strong positive correlation with level of behavioral arousal. Unit activity during phasic and tonic arousal, as elicited by acoustic stimuli, was increased by 76% and 31%, respectively, and unit activity decreased to active waking levels as the arousal response habituated. During active waking, unit activity was significantly increased by 18% as compared to quiet waking, but there was no correlation between unit activity and phasic body movements. NCS unit activity showed a significant decrease of 15% during drowsiness (first appearance of EEG synchronization) as compared to quiet waking, and then progressive decreases during the early (−27%), middle (−41%) and late (−67%) phases of slow wave sleep. During all phases of slow wave sleep, the occurrence of sleep spindles was frequently associated with a transitory decrease in unit activity. The discharge rate would typically decrease during the few seconds immediately preceding the spindle, remain at this low level during the occurrence of the spindle, and then increase immediately after the spindle. NCS unit activity showed decreases of 73% during Pre-REM (the 60 s immediately before REM onset) and 84% during REM, as compared to quiet waking. Unit activity reappeared on the average 2.7 s before the end of REM with significant increases in activity of 60% and 28% during the first second and first 10 s of unit activity, respectively, as compared to quiet waking. NCS neurons showed no significant changes in activity across the 24-h light-dark cycle, when behavioral state was held constant. Seventy-eight % of NCS units were excited by phasic auditory stimulation, with a mean latency of 41 ± 3 ms and a mean duration of 34 ± 4 ms. The response to repetitive auditory stimulation showed no evidence of habituation and was even present during sleep. A similar response was evoked by phasic visual stimulation in 68% of the cells tested. A small subset of cells (12%) were inhibited by phasic auditory and visual stimuli. NCS neurons were inhibited by low doses of 5-methoxy-N,N-dimethyltryptamine (50 μg/kg, i.m.) or LSD (50 μg/kg, i.p.). These data demonstrate that serotonin-containing NCS neurons exhibit properties very similar to those in the nucleus raphe dorsalis, but are different in many respects from medullary serotonergic neurons.
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References
Aghajanian GK, Haigler HJ (1974) L-Tryptophan as a selective histochemical marker for serotonergic neurons in single-cell recording studies. Brain Res 81: 364–372
Bell C, Buendia N, Sierra G, Sequndo JP (1963) Mesencephalic responses to natural and repeated sensory stimuli. Experientia 19: 308–312
Bobillier P, Petitjean F, Salvert D, Ligier M, Seguin S (1975) Differential projections of the nucleus raphe dorsalis and nucleus raphe centralis as revealed by autoradiography. Brain Res 85: 205–210
Dahlström A, Fuxe K (1964) Evidence for the existence of monoamine-containing neurons in the central nervous system. I. Demonstration of monoamines in the cell bodies of brainstem neurons. Acta Physiol Scand 62, Suppl 232: 1–55
Favale E, Loeb C, Rossi GF, Sacco G (1961) EEG synchronization and behavioral signs of sleep following low frequency stimulation of the brainstem reticular formation. Arch Ital Biol 99: 1–22
Fuxe K (1965) Evidence for the existence of monoamine neurons in the central nervous system.IV. Distribution of monoamine nerve terminals in the central nervous system. Acta Physiol Scand Suppl 247: 39–85
Haigler HJ, Aghajanian GK (1974) Lysergic acid diethylamide: a comparison of effects on serotonergic neurons and neurons receiving a serotonergic input. J Pharmacol Exp Ther 188: 688–699
Heym J, Steinfels GF, Jacobs BL (1982) Activity of serotonin-containing neurons in the nucleus raphe pallidus of freely moving cats. Brain Res 251: 259–276
Jacobs BL, McGinty DJ, Harper RM (1973) Brain unit activity during sleep-wakefulness: a review. In: Philips MI (ed) Brain unit activity during behavior. Thomas, Springfield, Ill, pp 165–178
Jacobs BL, Mosko SS, Trulson ME (1977) The investigation of the role of serotonin in mammalian behavior. In: Drucker-Colin RR, McGaugh JL (eds) Neurobiology of sleep and memory. Academic Press, New York, pp 99–133
Jouvet M (1960) Telencephalic and rhombencephalic sleep in the cat. In: Wolstenholme GEW, O'Connor M (eds) The nature of sleep. Little Brown, Boston, pp 188–208
Kleitman N (1963) Sleep and wakefulness. University Press, Chicago, Ill, pp 103–113
Magnes J, Moruzzi G, Pompeiano O (1961) Synchronization of the EEG produced by low frequency electrical stimulation of the region of the solitary tract. Arch Ital Biol 99: 33–67
McGinty DJ, Harper RM (1976) Dorsal raphe neurons: depression of activity during sleep in cats. Brain Res 101: 569–576
Morrison AR, Bowker RM (1975) The biological significance of PGO spikes in the sleeping cat. Acta Neurobiol Exp 35: 821–840
Poitras D, Parent A (1978) Atlas of the distribution of mono-amine-containing nerve cell bodies in the brain stem of the cat. J Comp Neurol 179: 699–718
Pompeiano O (1965) Ascending and descending influences of somatic afferent volleys in unrestrained cats: supraspinal inhibitory control of spinal reflexes during naturally and reflexly induced sleep. In: Jouvet M (ed) Aspects anatomo-functionnels de al physiologie du sommeil. Centre Nat Rech Sci, Paris, pp 309–395
Pujol JF, Buguet A, Froment JL, Jones B, Jouvet M (1971) The central metabolism of serotonin in the cat during insomnia: a neurophysiological and biochemical study after administration of p-chlorophenylalanine or destruction of the raphe system. Brain Res 29: 195–212
Reis DJ, Corvelli A, Connors J (1969) Circadian and ultradian rhythms of serotonin regionally in cat brain. J Pharmacol Exp Ther 167: 328–333
Scheibel ME, Scheibel AB (1965) The response of reticular units to repetitive stimuli. Arch Ital Biol 103: 279–299
Sheu YS, Nelson JP, Bloom FE (1974) Discharge patterns of cat raphe neurons during sleep and waking. Brain Res 73: 263–276
Simon RP, Gershon MD, Brooks DC (1973) The role of raphe nuclei in the regulation of ponto-geniculo-occipital wave activity. Brain Res 58: 313–330
Steinbusch HWM (1981) Distribution of serotonin-immunoreactivity in the central nervous system of the rat-cell bodies and terminals. Neuroscience 6: 557–618
Steriade M, Deschenes M, Wyzinski P, Hale JY (1974) Input-output organization of the motor cortex and its alterations during sleep and waking. In: Petre-Quadens O, Schlag J (eds) Basic sleep mechanisms. Academic Press, New York, pp 143–200
Sterman MB, Knousi T, Lehamann, Clemente CD (1965) Crcadian sleep and waking patterns in the laboratory cat. Electroencephalogr Clin Neurophysiol 19: 509–517
Trulson ME, Jacobs BL (1979a) Raphe unit activity in freely moving cats: Correlation with level of behavioral arousal. Brain Res 163: 135–150
Trulson ME, Jacobs BL (1979b) Effects of 5-methoxy-N,N-dimethyltryptamine on behavior and raphe unit activity in freely moving cats. Eur J Pharmacol 54: 43–50
Trulson ME, Jacobs BL (1979c) Dissociations between the effects of LSD on behavior and raphe unit activity in freely moving cats. Science 205: 515–518
Trulson ME, Jacobs BL (1983) Raphe unit activity in freely moving cats: Lack of diurnal variation. Neurosci Lett 36: 285–290
Trulson ME, Jacobs BL, Morrison AR (1981) Raphe unit activity across the sleep-waking cycle in normal cats and in pontine lesioned cats displaying REM sleep without atonia. Brain Res 226: 75–91
Trulson ME, Howell GA, Brandstetter JW, Frederickson MH, Frederickson CJ (1982) In vitro recording of raphe unit activity: Evidence for endogenous rhythms in presumed serotonergic neurons. Life Sci 31: 785–790
Trulson ME, Trulson VM (1982a) Activity of nucleus raphe pallidus neurons across the sleep waking cycle in freely moving cats. Brain Res 237: 232–237
Trulson ME, Trulson VM (1982b) Differential effects of phasic auditory and visual stimuli on the activity of nucleus raphe dorsalis and nucleus raphe pallidus neurons in freely moving cats. Neurosci Lett 32: 137–142
Williams HL, Morlock HC, Morlock JV (1966) Instrumental behavior during sleep. Psychophysiology 2: 208–216
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Trulson, M.E., Crisp, T. & Trulson, V.M. Activity of serotonin-containing nucleus centralis superior (raphe medianus) neurons in freely moving cats. Exp Brain Res 54, 33–44 (1984). https://doi.org/10.1007/BF00235816
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DOI: https://doi.org/10.1007/BF00235816