The deafferented reticular thalamic nucleus generates spindle rhythmicity
M. Steriade, L. Domich, G. Oakson and M. Deschenes The hypothesis that nucleus reticularis thalami (RE) is the generator of spindle rhythmicity during electroencephalogram (EEG) synchronization was tested in acutely prepared cats. Unit discharges and focal waves were extracellularly recorded in the...
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Veröffentlicht in: | Journal of neurophysiology 1987-01, Vol.57 (1), p.260-273 |
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Zusammenfassung: | M. Steriade, L. Domich, G. Oakson and M. Deschenes
The hypothesis that nucleus reticularis thalami (RE) is the generator of
spindle rhythmicity during electroencephalogram (EEG) synchronization was
tested in acutely prepared cats. Unit discharges and focal waves were
extracellularly recorded in the rostral pole of RE nucleus, which was
completely disconnected by transections from all other thalamic nuclei. In
some experiments, additional transections through corona radiata created a
triangular island in which the rostral RE pole survived with the caudate
nucleus, putamen, basal forebrain nuclei, prepyriform area, and the
adjacent cortex. Similar results were obtained in two types of experiments:
brain stem-transected preparations that exhibited spontaneous spindle
sequences, and animals under ketamine anesthesia in which transient
spindling was repeatedly precipitated during recording by very low doses of
a short-acting barbiturate. Both spindle-related rhythms (7- to 16-Hz waves
grouped in sequences that recur with a rhythm of 0.1-0.3 Hz) are seen in
focal recordings of the deafferented RE nucleus. The presence of spindling
rhythmicity in the disconnected RE nucleus contrasts with total absence of
spindles in cortical EEG leads and in thalamic recordings behind the
transection. Oscillations within the same frequency range as that of
spontaneous spindles can be evoked in the deafferented RE nucleus by
subcortical white matter stimulation. In deafferented RE cells, the burst
structure consists of an initially biphasic acceleration-deceleration
pattern, eventually leading to a long-lasting tonic tail. Quantitative
group data show that the burst parameters of disconnected RE cells are very
similar to those of RE neurons with intact connections. In the deafferented
RE nucleus, spike bursts of RE neurons recur periodically (0.1-0.3 Hz) in
close time-relation with simultaneously recorded focal spindle sequences.
The burst occurrence of deafferented RE cells is greatly reduced after
systemic administration of bicuculline. The preservation of both
spindle-related rhythms in the disconnected RE nucleus, together with our
recent experiments showing abolition of spindle oscillations in thalamic
nuclei after lesions of RE nucleus (24), demonstrate that RE nucleus is the
generator of spindle rhythms. |
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ISSN: | 0022-3077 1522-1598 |
DOI: | 10.1152/jn.1987.57.1.260 |