The reticular nucleus revisited

What is the role of the thalamic nuclei in consciousness? In a recent article by Fuentealba and Steriade discusses the inhibutory neurotransmitter GABA and its role in the early sleep stages.

The reticular nucleus revisited: Intrinsic and network properties of a thalamic pacemaker

Pablo Fuentealba and Mircea Steriade

Progress in Neurobiology

Volume 75, Issue 2 , February 2005, Pages 125-141

Abstract

The intrinsic and network properties of thalamic reticular (RE) neurons, which release the potent inhibitory neurotransmitter γ-aminobutyric acid (GABA), endow them with oscillatory properties within the frequency range of sleep spindles (7-15 Hz), a hallmark brain rhythm that characterizes early sleep stages. The original hypothesis that RE neurons are pacemakers of spindles, based on absence of this oscillation in thalamocortical (TC) systems after disconnection from RE nucleus and presence of spindle rhythmicity in the deafferented RE nucleus, is supported by new experimental results in vivo, in vitro and in computo showing that interactions through chemical synapses as well as electrical coupling among inhibitory RE neurons lead to generation and synchronization of spindle sequences within the nucleus. Besides their pacemaking role in spindle generation, RE neurons are crucially implicated in the inhibition of TC neurons during cortically generated spike-wave (absence) seizures, which may explain the obliteration of signals from the external world and unconsciousness during these epileptic fits.

ScienceDirect

”SCR Comment: This seems to fit nicely with theories implicating the thalamus in both normal consciousness as well as different kins of loss of consciousness. Such could include:

1. Llin�s & Ribary – “Consciousness and the Brain: The Thalamocortical Dialogue in Health and Disease”
2. Revonsuo & Newman – “Binding & Consciousness” pdf”