Does the ascending cholinergic projection inhibit or excite neurons in the rat thalamic reticular nucleus?

1986 ◽  
Vol 56 (5) ◽  
pp. 1310-1320 ◽  
Author(s):  
Y. Kayama ◽  
I. Sumitomo ◽  
T. Ogawa
Keyword(s):  
Cholinergic Neurons ◽  
Sensory Stimulation ◽  
Thalamic Reticular Nucleus ◽  
Resting Potential ◽  
Reticular Nucleus ◽  
Laterodorsal Tegmental Nucleus ◽  
Unit Recording ◽  
Tonic Firing ◽  
Tegmental Nucleus ◽  
Low Threshold

In rats anesthetized with urethan, neuronal activity was recorded in those portions of the thalamic reticular nucleus (TR) excitable by visual, somatosensory, or auditory input. Observations were made on changes in rate and pattern of discharge of these neurons during repetitive stimulation of the laterodorsal tegmental nucleus (LDT), which is composed of cholinergic neurons projecting to the thalamus. In general, TR neurons showed spontaneous activity consisting of sporadic bursts of several spikes and responded to sensory stimulation with bursts of spikes which repeated several times. Weak LDT stimulation depressed or eliminated the occurrence of both spontaneous and evoked burst discharges. When LDT stimulation was sufficiently strong, however, the majority of TR neurons resumed their tonic discharges. In some animals the cortical EEG was recorded simultaneously with unit recording in TR. Suppression of burst discharges in TR was obtained even with LDT stimulation weaker than the threshold for desynchronizing the EEG. The induction of tonic discharge, on the other hand, required stimulation strong enough to produce desynchronization. The effects of LDT stimulation, such as the suppression of bursts and the induction of tonic discharge, were mimicked by acetylcholine and were antagonized by scopolamine, both drugs being applied ionophoretically. Cooling of the visual cortex abolished LDT-induced tonic discharges of visual TR neurons. A recent report and our preliminary observation show that, when the resting potential is relatively hyperpolarized, TR neurons generated a burst of spikes superposed on a low-threshold broad spike, which is inactivated and replaced with tonic firing by depolarization. Supported by these facts, the present results suggest that cholinergic input depolarizes TR neurons directly and that further depolarization occurs indirectly via activated cortex when the LDT stimulation is sufficiently strong to desynchronize EEG.

Cholinergic influence of the laterodorsal tegmental nucleus on neuronal activity in the rat lateral geniculate nucleus

1986 ◽  
Vol 56 (5) ◽  
pp. 1297-1309 ◽  
Author(s):  
Y. Kayama ◽  
M. Takagi ◽  
T. Ogawa
Keyword(s):  
Brain Stem ◽  
Lateral Geniculate Nucleus ◽  
Cholinergic Neurons ◽  
Photic Stimulation ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Laterodorsal Tegmental Nucleus ◽  
Tegmental Nucleus ◽  
Lateral Geniculate ◽  
Stimulation Of ◽  
Relay Neurons

The effect of stimulation of the laterodorsal tegmental nucleus (LDT) on the activity of single neurons in the dorsal lateral geniculate nucleus was studied in rats anesthetized with urethan. The LDT is the largest aggregation of cholinergic neurons in the brain stem that project to the thalamus, and in the rat is sufficiently compact to permit its localized stimulation. Position of stimulating electrodes was confirmed on histological sections processed with NADPH-diaphorase histochemistry, which in the rat brain stem selectively stains cholinergic neurons. Repetitive stimulation of the LDT at 200 Hz increased the firing rate of substantially all geniculate relay neurons and weakly depressed the activity of intrinsic interneurons. These effects usually occurred within several hundred milliseconds after the onset of stimulation and began to fade within a few seconds, despite continuing stimulation. The excitatory effects on relay neurons were blocked by scopolamine applied ionophoretically or intravenously, but not by noradrenergic antagonists, suggesting the cholinergic nature of LDT-induced excitation. During LDT stimulation the number of spikes evoked by photic stimulation of the receptive field of relay neurons usually increased, but it remained unchanged in a few cases. The increase was due to simple enhancement of photic responses or due to conversion of phasic type responses to tonic ones. As to the balance of background activity and photic responses, the effects of LDT stimulation varied from neuron to neuron. Even in a given neuron, the effects varied depending on its excitability level or the nature of the photic stimulation. These results show that the cholinergic projection from the LDT may be involved in the ascending reticular activating system, although the functional significance of the activating system in visual information processing in the geniculate nucleus remains to be clarified.

scholarly journals Open-loop organization of thalamic reticular nucleus and dorsal thalamus: a computational model

2015 ◽  
Vol 114 (4) ◽  
pp. 2353-2367 ◽  
Author(s):  
Adam M. Willis ◽  
Bernard J. Slater ◽  
Ekaterina D. Gribkova ◽  
Daniel A. Llano
Keyword(s):  
Closed Loop ◽  
Open Loop ◽  
Tunable Filter ◽  
Cortical Activation ◽  
Thalamic Reticular Nucleus ◽  
Reticular Nucleus ◽  
Loop Model ◽  
Dependent Manner ◽  
Dorsal Thalamus ◽  
Low Threshold

The thalamic reticular nucleus (TRN) is a shell of GABAergic neurons that surrounds the dorsal thalamus. Previous work has shown that TRN neurons send GABAergic projections to thalamocortical (TC) cells to form reciprocal, closed-loop circuits. This has led to the hypothesis that the TRN is responsible for oscillatory phenomena, such as sleep spindles and absence seizures. However, there is emerging evidence that open-loop circuits are also found between TRN and TC cells. The implications of open-loop configurations are not yet known, particularly when they include time-dependent nonlinearities in TC cells such as low-threshold bursting. We hypothesized that low-threshold bursting in an open-loop circuit could be a mechanism by which the TRN could paradoxically enhance TC activation, and that enhancement would depend on the relative timing of TRN vs. TC cell stimulation. To test this, we modeled small circuits containing TC neurons, TRN neurons, and layer 4 thalamorecipient cells in both open- and closed-loop configurations. We found that open-loop TRN stimulation, rather than universally depressing TC activation, increased cortical output across a broad parameter space, modified the filter properties of TC neurons, and altered the mutual information between input and output in a frequency-dependent and T-type calcium channel-dependent manner. Therefore, an open-loop model of TRN-TC interactions, rather than suppressing transmission through the thalamus, creates a tunable filter whose properties may be modified by outside influences onto the TRN. These simulations make experimentally testable predictions about the potential role for the TRN for flexible enhancement of cortical activation.

Activity of cholinergic neurons in the laterodorsal tegmental nucleus during emission of 22kHz vocalization in rats

2011 ◽  
Vol 225 (1) ◽  
pp. 276-283 ◽  
Author(s):  
Stefan M. Brudzynski ◽  
Amaka Iku ◽  
Alison Harness (neé Savoy)
Keyword(s):  
Cholinergic Neurons ◽  
Laterodorsal Tegmental Nucleus ◽  
Tegmental Nucleus

scholarly journals Interleukin-1 Inhibits Putative Cholinergic Neurons in Vitro and REM Sleep when Microinjected into the Rat Laterodorsal Tegmental Nucleus

SLEEP ◽  
2010 ◽  
Vol 33 (7) ◽  
pp. 919-929 ◽  
Author(s):  
Dario Brambilla ◽  
Isabella Barajon ◽  
Susanna Bianchi ◽  
Mark R. Opp ◽  
Luca Imeri
Keyword(s):  
Rem Sleep ◽  
Interleukin 1 ◽  
Cholinergic Neurons ◽  
Laterodorsal Tegmental Nucleus ◽  
Tegmental Nucleus

Cholinergic neurons with monoamine oxidase type B (MAOB)-activity in the laterodorsal tegmental nucleus of the mouse

1999 ◽  
Vol 271 (1) ◽  
pp. 53-56 ◽  
Author(s):  
Keiko Ikemoto ◽  
Kunio Kitahama ◽  
Toshihiro Maeda ◽  
Michel Jouvet ◽  
Ikuko Nagatsu
Keyword(s):  
Monoamine Oxidase ◽  
Cholinergic Neurons ◽  
Type B ◽  
Laterodorsal Tegmental Nucleus ◽  
Tegmental Nucleus ◽  
Monoamine Oxidase Type B
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