scholarly journals Long-term facilitation of phrenic nerve activity in cats: responses and short time scale correlations of medullary neurones.

1996 ◽  
Vol 490 (2) ◽  
pp. 463-480 ◽  
Author(s):  
K F Morris ◽  
A Arata ◽  
R Shannon ◽  
B G Lindsey
Keyword(s):  
Phrenic Nerve ◽  
Time Scale ◽  
Short Time Scale ◽  
Nerve Activity ◽  
Phrenic Nerve Activity ◽  
Short Time ◽  
Long Term Facilitation

Time-dependent phrenic nerve responses to carotid afferent activation: intact vs. decerebellate rats

1993 ◽  
Vol 265 (4) ◽  
pp. R811-R819 ◽  
Author(s):  
F. Hayashi ◽  
S. K. Coles ◽  
K. B. Bach ◽  
G. S. Mitchell ◽  
D. R. McCrimmon
Keyword(s):  
Phrenic Nerve ◽  
Carotid Sinus ◽  
Carotid Sinus Nerve ◽  
Short Term ◽  
Nerve Activity ◽  
A Value ◽  
Afferent Activation ◽  
Term Potentiation ◽  
Long Term Facilitation

The objectives were to determine 1) respiratory responses to carotid chemoreceptor inputs in anesthetized rats and 2) whether the cerebellar vermis plays a role in these responses. A carotid sinus nerve was stimulated (20 Hz) with five 2-min trains, each separated by approximately 3 min. During stimulation, respiratory frequency (f), peak amplitude of integrated phrenic nerve activity (integral of Phr), and their product (f x integral of Phr) immediately increased. As stimulation continued, integral of Phr progressively increased to a plateau [short-term potentiation (STP)], but f and f x integral of Phr decreased [short-term depression (STD)] to a value still above control. Upon stimulus termination, integral of Phr progressively decreased but remained above control; f and f x integral of Phr transiently decreased below baseline. After the final stimulation, integral of Phr remained above control for at least 30 min [long-term facilitation (LTF)]. Repeated 5-min episodes of isocapnic hypoxia also elicited STP, STD, and LTF. Vermalectomy lowered the CO2-apneic threshold and eliminated LTF. In conclusion, carotid chemoreceptor activation in rats elicits STP and LTF similar to that in cats; the vermis may play a role in LTF. A new response, STD, was observed.

scholarly journals Selected Contribution: Phrenic long-term facilitation requires 5-HT receptor activation during but not following episodic hypoxia

2001 ◽  
Vol 90 (5) ◽  
pp. 2001-2006 ◽  
Author(s):  
D. D. Fuller ◽  
A. G. Zabka ◽  
T. L. Baker ◽  
G. S. Mitchell
Keyword(s):  
Receptor Antagonist ◽  
Phrenic Nerve ◽  
Receptor Activation ◽  
Sprague Dawley ◽  
Nerve Activity ◽  
Sprague Dawley Rats ◽  
Episodic Hypoxia ◽  
Baseline Levels ◽  
Long Term Facilitation

Episodic hypoxia evokes a sustained augmentation of respiratory motor output known as long-term facilitation (LTF). Phrenic LTF is prevented by pretreatment with the 5-hydroxytryptamine (5-HT) receptor antagonist ketanserin. We tested the hypothesis that 5-HT receptor activation is necessary for the induction but not maintenance of phrenic LTF. Peak integrated phrenic nerve activity (∫Phr) was monitored for 1 h after three 5-min episodes of isocapnic hypoxia (arterial Po 2 = 40 ± 2 Torr; 5-min hyperoxic intervals) in four groups of anesthetized, vagotomized, paralyzed, and ventilated Sprague-Dawley rats [ 1) control ( n = 11), 2) ketanserin pretreatment (2 mg/kg iv; n = 7), and ketanserin treatment 0 and 45 min after episodic hypoxia ( n = 7 each)]. Ketanserin transiently decreased ∫Phr, but it returned to baseline levels within 10 min. One hour after episodic hypoxia, ∫Phr was significantly elevated from baseline in control and in the 0- and 45-min posthypoxia ketanserin groups. Conversely, ketanserin pretreatment abolished phrenic LTF. We conclude that 5-HT receptor activation is necessary to initiate (during hypoxia) but not maintain (following hypoxia) phrenic LTF.

AI and HCI: Two Fields Divided by a Common Focus

AI Magazine ◽  
2009 ◽  
Vol 30 (4) ◽  
pp. 48 ◽  
Author(s):  
Jonathan Grudin
Keyword(s):  
Time Scale ◽  
Short Time Scale ◽  
Intelligent Behavior ◽  
History Of ◽  
Short Time ◽  
Competition For Resources

Although AI and HCI explore computing and intelligent behavior and the fields have seen some cross-over, until recently there was not very much. This article outlines a history of the fields that identifies some of the forces that kept the fields at arm’s length. AI was generally marked by a very ambitious, long-term vision requiring expensive systems, although the term was rarely envisioned as being as long as it proved to be, whereas HCI focused more on innovation and improvement of widely-used hardware within a short time-scale. These differences led to different priorities, methods, and assessment approaches.  A consequence was competition for resources, with HCI flourishing in AI winters and moving more slowly when AI was in favor. The situation today is much more promising, in part because of platform convergence: AI can be exploited on widely-used systems.

scholarly journals Antipersistent dynamics in short time scale variability of self-potential signals

2000 ◽  
Vol 43 (2) ◽  
Author(s):  
V. Cuomo ◽  
M. Lanfredi ◽  
V. Lapenna ◽  
M. Macchiato ◽  
M. Ragosta ◽  
...  
Keyword(s):  
Time Scale ◽  
Order Structure ◽  
Short Time Scale ◽  
Spatial And Temporal Variability ◽  
Scale Invariant ◽  
Geophysical Monitoring ◽  
Scale Properties ◽  
Short Time ◽  
Self Potential

Time scale properties of self-potential signals are investigated through the analysis of the second order structure function (variogram), a powerful tool to investigate the spatial and temporal variability of observational data. In this work we analyse two sequences of self-potential values measured by means of a geophysical monitoring array located in a seismically active area of Southern Italy. The range of scales investigated goes from a few minutes to several days. It is shown that signal fluctuations are characterised by two time scale ranges in which self-potential variability appears to follow slightly different dynamical behaviours. Results point to the presence of fractal, non stationary features expressing a long term correlation with scaling coefficients which are the clue of stabilising mechanisms. In the scale ranges in which the series show scale invariant behaviour, self-potentials evolve like fractional Brownian motions with anticorrelated increments typical of processes regulated by negative feedback mechanisms (antipersistence). On scales below about 6 h the strength of such an antipersistence appears to be slightly greater than that observed on larger time scales where the fluctuations are less efficiently stabilised.

scholarly journals Phrenic long-term depression evoked by intermittent hypercapnia is modulated by serotonergic and adrenergic receptors in raphe nuclei

2018 ◽  
Vol 120 (1) ◽  
pp. 321-329 ◽  
Author(s):  
Ivona Stipica Safic ◽  
Renata Pecotic ◽  
Ivana Pavlinac Dodig ◽  
Zoran Dogas ◽  
Zoran Valic ◽  
...  
Keyword(s):  
Phrenic Nerve ◽  
Adrenergic Receptors ◽  
Receptor Agonist ◽  
Control Group ◽  
Long Term Depression ◽  
Nerve Activity ◽  
Phrenic Nerve Activity ◽  
Anesthetized Rats ◽  
Baseline Values

Intermittent hypercapnia evokes prolonged depression of phrenic nerve activity (phrenic long-term depression, pLTD). This study was undertaken to investigate the role of 5-HT and α2-adrenergic receptors in the initiation of pLTD. Adult male urethane-anesthetized, vagotomized, paralyzed, and mechanically ventilated Sprague-Dawley rats were exposed to a protocol of acute intermittent hypercapnia (AIHc; 5 episodes of 15% CO2in air, each episode lasting 3 min). The experimental group received microinjection of the selective 5-HT1Areceptor agonist 8-hydroxy-2-(dipropylamino)tetralin hydrobromide (8-OH-DPAT), the broad-spectrum 5-HT antagonist methysergide, or the α2-adrenergic antagonist yohimbine, whereas the control group received microinjection of 0.9% saline into the caudal raphe region. Peak phrenic nerve activity (pPNA) and burst frequency ( f) were analyzed during baseline (T0), during 5 hypercapnic episodes (THc1–THc5), and at 15, 30, and 60 min after the end of the last hypercapnic episode. In the control group, pPNA decreased 60 min after the end of the last hypercapnic episode compared with baseline values, i.e., pLTD developed ( P = 0.023). In the 8-OH-DPAT group, pPNA significantly decreased at T15, T30, and T60 compared with baseline values, i.e., pLTD developed ( P = 0.01). In the methysergide and yohimbine groups, AIHc did not evoke significant changes of the pPNA at T15, T30, and T60 compared with baseline values. In conclusion, activation of 5-HT1Areceptors accentuated induction of pLTD, whereas blockade of α2-adrenergic receptors prevented development of pLTD following AIHc in anesthetized rats. These results suggest that chemical modulation of 5-HT and α2-adrenergic receptors in raphe nuclei affects hypercapnia-induced pLTD, offering important insights in understanding the mechanisms involved in development of respiratory plasticity.NEW & NOTEWORTHY Hypercapnia is a concomitant feature of many breathing disorders, including obstructive sleep apnea. In this study, acute intermittent hypercapnia evoked development of phrenic long-term depression (pLTD) 60 min after the last hypercapnic episode that was preserved if the selective 5-HT1Areceptor agonist 8-hydroxy-2-(dipropylamino)tetralin hydrobromide was microinjected in the caudal raphe region before the hypercapnic stimulus. This study highlights that both 5-HT and adrenergic receptor activation is needed for induction of pLTD in urethane-anesthetized rats following intermittent hypercapnia exposure.

Short.Term Reactivity Change: Xenon Effects

2021 ◽  
pp. 67-79
Author(s):  
Wei Shen ◽  
Benjamin Rouben
Keyword(s):  
Fission Product ◽  
Time Scale ◽  
Fission Products ◽  
Fuel Burnup ◽  
Short Time Scale ◽  
Neutron Absorption ◽  
Short Time ◽  
Reactivity Change

Most fission products absorb neutrons to some extent and they accumulate slowly as the fuel burnup increases, hence decrease the long-term reactivity. The neutron-absorbing fission-product xenon-135 has particular operational importance. Its concentrations can change quickly in a power maneuvre, producing major changes in neutron absorption on a relatively short-time scale (minutes).

Linguistic diversification as a long-term effect of asymmetric priming

2018 ◽  
Vol 8 (2) ◽  
pp. 253-296
Author(s):  
Andreas Baumann ◽  
Lotte Sommerer
Keyword(s):  
Mathematical Model ◽  
Population Dynamics ◽  
Time Scale ◽  
Language Change ◽  
Term Effect ◽  
Short Time Scale ◽  
Cognitive Mechanism ◽  
Long Term Effect ◽  
Short Time

Abstract This paper tries to narrow the gap between diachronic linguistics and research on population dynamics by presenting a mathematical model corroborating the notion that the cognitive mechanism of asymmetric priming can account for observable tendencies in language change. The asymmetric-priming hypothesis asserts that items with more substance are more likely to prime items with less substance than the reverse. Although these effects operate on a very short time scale (e.g. within an utterance) it has been argued that their long-term effect might be reductionist, unidirectional processes in language change. In this paper, we study a mathematical model of the interaction of linguistic items that differ in their formal substance, showing that, in addition to reductionist effects, asymmetric priming also results in diversification and stable coexistence of two formally related variants. The model will be applied to phenomena in the sublexical as well as the lexical domain.

scholarly journals Mammalian target of rapamycin is required for phrenic long-term facilitation following severe but not moderate acute intermittent hypoxia

2015 ◽  
Vol 114 (3) ◽  
pp. 1784-1791 ◽  
Author(s):  
Brendan J. Dougherty ◽  
Daryl P. Fields ◽  
Gordon S. Mitchell
Keyword(s):  
Protein Synthesis ◽  
Phrenic Nerve ◽  
Intermittent Hypoxia ◽  
Mammalian Target Of Rapamycin ◽  
Nerve Activity ◽  
Long Term Facilitation ◽  
New Protein ◽  
Mtor Activity ◽  
Dependent Mechanism

Phrenic long-term facilitation (pLTF) is a persistent increase in phrenic nerve activity after acute intermittent hypoxia (AIH). Distinct cell-signaling cascades give rise to pLTF depending on the severity of hypoxemia within hypoxic episodes. Moderate AIH (mAIH; three 5-min episodes, PaO2 ∼35–55 mmHG) elicits pLTF by a serotonin (5-HT)-dependent mechanism that requires new synthesis of brain-derived neurotrophic factor (BDNF), activation of its high-affinity receptor (TrkB), and ERK MAPK signaling. In contrast, severe AIH (sAIH; three 5-min episodes, PaO2 ∼25–30 mmHG) elicits pLTF by an adenosine-dependent mechanism that requires new TrkB synthesis and Akt signaling. Although both mechanisms require spinal protein synthesis, the newly synthesized proteins are distinct, as are the neurochemicals inducing plasticity (serotonin vs. adenosine). In many forms of neuroplasticity, new protein synthesis requires translational regulation via mammalian target of rapamycin (mTOR) signaling. Since Akt regulates mTOR activity, we hypothesized that mTOR activity is necessary for sAIH- but not mAIH-induced pLTF. Phrenic nerve activity in anesthetized, paralyzed, and ventilated rats was recorded before, during, and 60 min after mAIH or sAIH. Rats were pretreated with intrathecal injections of 20% DMSO (vehicle controls) or rapamycin (0.1 mM, 12 μl), a selective mTOR complex 1 inhibitor. Consistent with our hypothesis, rapamycin blocked sAIH- but not mAIH-induced pLTF. Thus spinal mTOR activity is required for adenosine-dependent (sAIH) but not serotonin-dependent (mAIH) pLTF, suggesting that distinct mechanisms regulate new protein synthesis in these forms of spinal neuroplasticity.

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