Model of thalamocortical slow-wave sleep oscillations and transitions to activated states (original) (raw)
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Dynamic Analysis of the Conditional Oscillator Underlying Slow Waves in Thalamocortical Neurons
Frontiers in neural circuits, 2016
During non-REM sleep the EEG shows characteristics waves that are generated by the dynamic interactions between cortical and thalamic oscillators. In thalamic neurons, low-threshold T-type Ca(2+) channels play a pivotal role in almost every type of neuronal oscillations, including slow (< 1 Hz) waves, sleep spindles and delta waves. The transient opening of T channels gives rise to the low threshold spikes (LTSs), and associated high frequency bursts of action potentials, that are characteristically present during sleep spindles and delta waves, whereas the persistent opening of a small fraction of T channels, (i.e., ITwindow) is responsible for the membrane potential bistability underlying sleep slow oscillations. Surprisingly thalamocortical (TC) neurons express a very high density of T channels that largely exceed the amount required to generate LTSs and therefore, to support certain, if not all, sleep oscillations. Here, to clarify the relationship between T current density a...
The thalamocortical network as a single slow wave-generating unit
Current opinion in neurobiology, 2014
During non-REM sleep the EEG is dominated by slow waves which result from synchronized UP and DOWN states in the component neurons of the thalamocortical network. This review focuses on four areas of recent progress in our understanding of these events. Thus, it has now been conclusively demonstrated that the full expression of slow waves, both of natural sleep and anesthesia, requires an essential contribution by the thalamus. Furthermore, the modulatory role of brainstem transmitters, the function of cortical inhibition and the relative contribution of single neocortical neurons to EEG slow waves have started to be carefully investigated. Together, these new data confirm the view that a full understanding of slow waves can only be achieved by considering the thalamocortical network as a single functional and dynamic unit for the generation of this key EEG rhythm.
Brain Research, 1992
The extrapolation from recent neurophysiologica! findings concerning the dependency of spindle and slow-wave oscillations of thalamocortical neurons on membrane potential to macroscopic EEG events, predicts a reciprocal relation between spindle activity and slow-wave activity (SWA) in thalamic and cortical EEG during non-rapid-eye-movement sleep (NREMS). To test this hypothesis, the EEG recorded in 8 cats, from the nucleus centralis lateralis of the thalamus and from the skull during a 12-h baseline dark period and during a 12-h recovery dark period, following a 12h sleep deprivation, were analyzed. Per 12-:, epoch, sleep-wake behaviour was determined and spectral power density was computed in the sJ~'r~,J..wave frequency range (0.5-4.0 Hz) and in the spindle frequency region (or activity: 11.0-14.5 Hz)'. ?'~ analyze the development of EEG power densities in the course of NREMS and during the transition from NREMS to REMS, the last e~-~,~ch of wakefulness and the first 15 e~ochs of NREMS, as well as the last epochs of NREMS and the first epoch of REMS were selected from the NREM-REM cycles. For each animal the values were averaged over 4-h intervals. In the cortical EEG, SWA was minimal at NREMS onset and increased progressively in the course of NREMS. SWA declined sharply prior to REMS. or Activity increased gradually towards a uniform level after NREMS onset. During the transition to REMS, or activity initially increased and then decreased rapidly. In the thalamic EEG, the time course of SWA paralleled that of the cortex. However, the development of or activity during the first part of NREMS differed: in the thalamic EEG, tr activity was maximal during the beginning of NREMS and slightly decreased thereafter. After sleep :eprivafion, SWA within NREMS was markedly enhanced in both lhc cortical and the thalamic EEG. Sigma activity was attenuated in the thalamic EEG, whereas in the cortical EEG it was temporarily elevated. The present data show that, in the thalamic EEG, an inverse relation exists between spindle and slow-wave activity during baseline NREMS. This relation is preserved after sleep deprivation, in the cortical EEG, a reciprocal relation between spindling and SWA is less evident.
Journal of …, 2005
To better understand population phenomena in thalamocortical neuronal ensembles, we have constructed a preliminary network model with 3,560 multicompartment neurons (containing soma, branching dendrites, and a portion of axon). Types of neurons included superficial pyramids (with regular spiking [RS] and fast rhythmic bursting [FRB] firing behaviors); RS spiny stellates; fast spiking (FS) interneurons, with basket-type and axoaxonic types of connectivity, and located in superficial and deep cortical layers; low threshold spiking (LTS) interneurons, which contacted principal cell dendrites; deep pyramids, which could have RS or intrinsic bursting (IB) firing behaviors, and endowed either with nontufted apical dendrites or with long tufted apical dendrites; thalamocortical relay (TCR) cells; and nucleus reticularis (nRT) cells. To the extent possible, both electrophysiology and synaptic connectivity were based on published data, although many arbitrary choices were necessary. In addit...
The interplay between the intrinsic properties of thalamocortical (TC) neurons and synaptic potentials was investigated in vivo, in decorticated and intact-cortex cats, as well as in computational models to elucidate the possible mechanisms underlying the disruption of the spindle oscillation, a network phenomenon. We found that the low-threshold spikes (LTSs) in TC neurons were graded in their amplitude and latency to peak when elicited by current pulses or synaptic potentials from physiological levels of hyperpolarization. IPSPs could either delay or shunt the LTSs. Although the onset of spindles was rhythmic and did not include rebound LTSs, the end of spindles was highly aperiodic suggesting that desynchronization could contribute to the spindle termination. The desynchronization could have several sources, the main of which are (a) intrinsically generated rebound LTSs in TC neurons that occur with different delays and keep thalamic reticular (RE) neurons relatively depolarized, and/or (b) out-of-phase firing of cortical neurons due to intracortical processes that would result in depolarization of both TC and RE neurons. The present study suggests that an active cortical network participates in disrupting the spindle activities. We propose that the progression of spindles contains at least three different phases, with different origins: (a) the onset is generated by RE neurons that impose their activity onto TC neurons, without participation of cortical neurons; (b) the middle part is produced by the interplay between RE and TC neurons, with potentiation from the cortical network; and (c) the waning of spindles is due to the out-of-phase firing of TC and particularly cortical neurons that participate in the spindle termination.
Low-frequency oscillatory activities intrinsic to rat and cat thalamocortical cells
The Journal of physiology, 1991
1. Low-frequency membrane potential oscillations recorded intracellularly from thalamocortical (TC) cells of the rat and cat dorsal lateral geniculate nucleus (dLGN) and of the rat ventrobasal nucleus (VB) maintained in vitro were investigated. On the basis of their electrophysiological and pharmacological properties, four types of activity were distinguished and named: the pacemaker oscillations, the spindle-like oscillations, the 'very slow' oscillations and the 'N-methyl-D-aspartate' (NMDA) oscillations. 2. The pacemaker oscillations (95 out of 173 cells) consisted of rhythmic, large-amplitude (10-30 mV) depolarizations which occurred at a frequency of 1.8 +/- 0.3 Hz (range, 0.5-2.9 Hz) and could often give rise to single or a burst of action potentials. Pacemaker oscillations were observed when the membrane potential was moved negative to -55 and positive to -80 mV, but in a given cell the upper and lower limits of this voltage range were separated by only 13.1 +...
Control of slow oscillations in the thalamocortical neuron: a computer model
1996
We investigated computer models of a single thalamocortical neuron to assess the interaction of intrinsic voltage-sensitive channels and cortical synaptic input in producing the range of oscillation frequencies observed in these cells in oivo. A morphologically detailed model with HodgkinHuxley-like
Brain Research, 1984
In behaving cats trained to press a bar for small aliquots of milk reward, single neuronal firing patterns were monitored from the nucleus reticularis (NR) thalami during bar bressing (BP), subsequent quiet wakefulness with EEG spindles (S-QW), grooming behavior (GR) and slow-wave sleep (SWS). The temporal patterns in the neuronal spike trains were analyzed using a non-parametric method based on relative relations between sequential spike intervals. The deviations of pattern occurrences from the random model were quantified. During BP, specific patterns occurred much more often while others occurred much less often than predicted by the random model. Patterns that were dominant during BP, were selectively suppressed or virtually eliminated during S-QW, GR and SWS, despite the increased firing rate; and, vice versa, patterns that were suppressed below chance level during BP, became dominant during S-QW, GR and SWS. The magnitudes of these inversions of the statistical distribution of patterns were not random but graded and positively correlated, thus indicating that they were homeostatically controlled. Since the inversions were already evident shortly after the satiated animal ceased bar pressing, they may be related to the 'need' for sleep. On the basis of the known mechanisms of pattern generation and changes in receptors for putative transmitters, it was postulated that the inversions of pattern distribution are related to the recuperative function of SWS, i.e. resensitization of receptors that had been desensitized during the animal's stereotypic BP performance. The NR and other neuronal ensembles seem to constitute an oscillatory system with two modes of reciprocal connectivities: one is supporting wakefulness and emission of specific firing patterns, and the other is incompatible with wakefulness and instead is associated with inversion of statistical distribution of firing patterns and recuperative function of SWS.