scholarly journals Coupled slow and delta oscillations between cuneothalamic and thalamocortical neurons in the chloralose anesthetized cat

1996 ◽  
Vol 219 (2) ◽  
pp. 107-110 ◽  
Author(s):  
Jorge Mariño ◽  
Luis Martinez ◽  
Antonio Canedo
1983 ◽  
Vol 49 (6) ◽  
pp. 1349-1363 ◽  
Author(s):  
J. E. Dayhoff ◽  
G. L. Gerstein

In this paper we apply the two methods described in the companion paper (4) to experimentally recorded spike trains from two preparations, the crayfish claw and the cat striate cortex. Neurons in the crayfish claw control system produced favored patterns in 23 of 30 spike trains under a variety of experimental conditions. Favored patterns generally consisted of 3-7 spikes and were found to be in excess by both quantized and template methods. Spike trains from area 17 of the lightly anesthetized cat showed favored patterns in 16 of 27 cases (in quantized form). Some patterns were also found to be favored in template form; these were not as abundant in the cat data as in the crayfish data. Most firing of the cat neurons occurred at times near stimulation, and the observed patterns may represent stimulus information. Favored patterns generally contained up to 7 spikes. No obvious correlations between identified neurons or experimental conditions and the generation of favored patterns were apparent from these data in either preparation. This work adds to the existing evidence that pattern codes are available for use by the nervous system. The potential biological significance of pattern codes is discussed.


1992 ◽  
Vol 37 (3) ◽  
pp. 335
Author(s):  
W.A. Murphy ◽  
R.K. Minkes ◽  
T.J. McMahon ◽  
J.S. Hood ◽  
D.B. McNamara ◽  
...  

Brain ◽  
2021 ◽  
Author(s):  
Joel Frohlich ◽  
Daniel Toker ◽  
Martin M Monti

Abstract A common observation in EEG research is that consciousness vanishes with the appearance of delta (1 – 4 Hz) waves, particularly when those waves are high amplitude. High amplitude delta oscillations are very frequently observed in states of diminished consciousness, including slow wave sleep, anaesthesia, generalised epileptic seizures, and disorders of consciousness such as coma and vegetative state. This strong correlation between loss of consciousness and high amplitude delta oscillations is thought to stem from the widespread cortical deactivation that occurs during the “down states” or troughs of these slow oscillations. Recently, however, many studies have reported the presence of prominent delta activity during conscious states, which casts doubt on the hypothesis that high amplitude delta oscillations are an indicator of unconsciousness. These studies include work in Angelman syndrome, epilepsy, behavioural responsiveness during propofol anaesthesia, postoperative delirium, and states of dissociation from the environment such as dreaming and powerful psychedelic states. The foregoing studies complement an older, yet largely unacknowledged, body of literature that has documented awake, conscious patients with high amplitude delta oscillations in clinical reports from Rett syndrome, Lennox-Gastaut syndrome, schizophrenia, mitochondrial diseases, hepatic encephalopathy, and nonconvulsive status epilepticus. At the same time, a largely parallel body of recent work has reported convincing evidence that the complexity or entropy of EEG and magnetoencephalogram or MEG signals strongly relates to an individual’s level of consciousness. Having reviewed this literature, we discuss plausible mechanisms that would resolve the seeming contradiction between high amplitude delta oscillations and consciousness. We also consider implications concerning theories of consciousness, such as integrated information theory and the entropic brain hypothesis. Finally, we conclude that false inferences of unconscious states can be best avoided by examining measures of electrophysiological complexity in addition to spectral power.


1986 ◽  
Vol 251 (3) ◽  
pp. G375-G381 ◽  
Author(s):  
W. W. Lautt ◽  
C. V. Greenway ◽  
D. J. Legare ◽  
H. Weisman

The pressure drop from the portal vein to the vena cava occurs primarily across a postsinusoidal site localized to a narrow segment (less than 0.5 cm) of hepatic veins (roughly 1.5 mm diam) in the anesthetized cat. Portal venous pressure (PVP = 8.9 +/- 0.3 mmHg) and lobar hepatic venous pressure (LVP = 8.7 +/- 0.4 mmHg) are insignificantly different, and pressure changes imposed from the presinusoidal or postsinusoidal side are equally transmitted to both pressure sites. Several types of experiments were done to validate the LVP measurement. The portal vein, hepatic sinusoids, and hepatic veins proximal to the resistance site are all under a similar pressure. Previously reported calculations of hepatic vascular resistance are in error because of incorrect assumptions of sinusoidal pressure and localization of the portal resistance site as presinusoidal. Stimulation of hepatic sympathetic nerves for 3 min caused LVP and PVP to increase equally, showing that the increased "portal" resistance is postsinusoidal across the same region of the hepatic veins that was previously localized as the site of resistance in the basal state.


1975 ◽  
Vol 39 (4) ◽  
pp. 562-566 ◽  
Author(s):  
W. J. Whalen ◽  
P. Nair

In the carotid body (CB) of the anesthetized cat tissue Po2 (Pto2) measured with a micro O2 electrode averaged about 65 mmHg at normal arterial pressure (mean = 96 mmHg). Pto2 correlated significantly with the hematocrit of the arterial blood but not with % saturation. When arterial pressure was reduced (mean = 58 mmHg) by bleeding Pto2 fell significantly. Phentolamine injection (1 mg/kg iv) at the reduced pressure caused Pto2 to rise significantly. At normal arterial pressure blowing moistened O2 over the CB did not affect Pto2 if the electrode tip was about 90 mum into the CB. At a reduced pressure (and blood flow) the sensitive depth increased to about 301 mum, and to about 600 mum when flow was stopped. We concluded that a) the increased chemoceptor discharge usually seen with hemorrhage is due to reduced Pto2; b) the reduction in Pto2 is probably due to reduced blood flow which is, in turn, caused partly, at least, by sympathetic nervous system activity; c) O2 content, rather than Po2, may determine chemoreceptor discharge rate; and d) there are no barriers in the CB which are impermeable to O2.


2019 ◽  
Vol 31 (8) ◽  
pp. 1205-1215 ◽  
Author(s):  
Victor J. Boucher ◽  
Annie C. Gilbert ◽  
Boutheina Jemel

Studies that use measures of cerebro-acoustic coherence have shown that theta oscillations (3–10 Hz) entrain to syllable-size modulations in the energy envelope of speech. This entrainment creates sensory windows in processing acoustic cues. Recent reports submit that delta oscillations (<3 Hz) can be entrained by nonsensory content units like phrases and serve to process meaning—though such views face fundamental problems. Other studies suggest that delta underlies a sensory chunking linked to the processing of sequential attributes of speech sounds. This chunking associated with the “focus of attention” is commonly manifested by the temporal grouping of items in sequence recall. Similar grouping in speech may entrain delta. We investigate this view by examining how low-frequency oscillations entrain to three types of stimuli (tones, nonsense syllables, and utterances) having similar timing, pitch, and energy contours. Entrainment was indexed by “intertrial phase coherence” in the EEGs of 18 listeners. The results show that theta oscillations at central sites entrain to syllable-size elements in speech and tones. However, delta oscillations at frontotemporal sites specifically entrain to temporal groups in both meaningful utterances and meaningless syllables, which indicates that delta may support but does not directly bear on a processing of content. The findings overall suggest that, although theta entrainment relates to a processing of acoustic attributes, delta entrainment links to a sensory chunking that relates to a processing of properties of articulated sounds. The results also show that measures of intertrial phase coherence can be better suited than cerebro-acoustic coherence in revealing delta entrainment.


1997 ◽  
Vol 78 (1) ◽  
pp. 129-136 ◽  
Author(s):  
Ming-Chu Xi ◽  
Rong-Huan Liu ◽  
Jack Yamuy ◽  
Francisco R. Morales ◽  
Michael H. Chase

Xi, Ming-Chu, Rong-Huan Liu, Jack Yamuy, Francisco R. Morales, and Michael H. Chase. Electrophysiological properties of lumbar motoneurons in the α-chloralose-anesthetized cat during carbachol-induced motor inhibition. J. Neurophysiol. 78: 129–136, 1997. The present study was undertaken 1) to examine the neuronal mechanisms responsible for the inhibition of spinal cord motoneurons that occurs in α-chloralose-anesthetized cats following the microinjection of carbachol into the nucleus pontis oralis (NPO), and 2) to determine whether the inhibitory mechanisms are the same as those that are responsible for the postsynaptic inhibition of motoneurons that is present during naturally occurring active sleep. Accordingly, the basic electrophysiological properties of lumbar motoneurons were examined, with the use of intracellular recording techniques, in cats anesthetized with α-chloralose and compared with those present during naturally occurring active sleep. The intrapontine administration of carbachol resulted in a sustained reduction in the amplitude of the spinal cord Ia monosynaptic reflex. Discrete large-amplitude inhibitory postsynaptic potentials (IPSPs), which are only present during the state of active sleep in the chronic cat, were also observed in high-gain recordings from lumbar motoneurons after the injection of carbachol. During carbachol-induced motor inhibition, lumbar motoneurons exhibited a statistically significant decrease in input resistance, membrane time constant and a reduction in the amplitude of the action potential's afterhyperpolarization. In addition, there was a statistically significant increase in rheobase and in the delay between the initial-segment (IS) and somadendritic (SD) portions of the action potential (IS-SD delay). There was a significant increase in the mean motoneuron resting membrane potential (i.e., hyperpolarization). The preceding changes in the electrophysiological properties of motoneurons, as well as the development of discrete IPSPs, indicate that lumbar motoneurons are postsynaptically inhibited after the intrapontine administration of carbachol in cats that are anesthetized with α-chloralose. These changes in the electrophysiological properties of lumbar motoneurons were found to be comparable with those that take place during the atonia of active (rapid-eye-movement) sleep in chronic cats. The present results support the conclusion that the neural system that is responsible for motor inhibition during naturally occurring active sleep can also be activated in α-chloralose-anesthetized cats following the injection of carbachol into the NPO.


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