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The Journal of Physiology Oct 1964
Topics: Axons; Cats; Decerebrate State; Neural Conduction; Neurons; Neurophysiology; Research; Reticular Formation; Spinal Cord
PubMed: 14228614
DOI: 10.1113/jphysiol.1964.sp007475 -
The Journal of Physiology May 2021
Topics: Decerebrate State; Humans; Motor Neurons, Gamma; Muscle Spindles
PubMed: 33749822
DOI: 10.1113/JP281594 -
American Journal of Physiology.... Dec 2007The aim of the present study was to determine characteristics of fast oscillations in the juvenile rat phrenic nerve (Ph) and to establish their temperature and state...
The aim of the present study was to determine characteristics of fast oscillations in the juvenile rat phrenic nerve (Ph) and to establish their temperature and state dependence. Two different age-matched decerebrate, baro- and chemodenervated rat preparations, in vivo and in situ arterially perfused models, were used to examine three systemic properties: 1) generation and dynamics of fast oscillations in Ph activity (both preparations), 2) responses to anoxia (both preparations), and 3) the effects of temperature on fast oscillations (in situ only). Both juvenile preparations generated power and coherence in two major bands analogous to adult medium- and high-frequency oscillations (HFO) at frequencies that increased with temperature but were lower than in adults. At < 28 degrees C, however, Ph oscillations were confined primarily to one low-frequency band (20-45 Hz). During sustained anoxia, both preparations produced stereotypical state changes from eupnea to hyperpnea to transition bursting (a behavior present only in vivo during incomplete ischemia) to gasping. Thus the juvenile rat produces a sequential pattern of responses to anoxia that are intermediate forms between those produced by neonates and those produced by adults. Time-frequency analysis determined that fast oscillations demonstrated dynamics over the course of the inspiratory burst and a state dependence similar to that of adults in vivo in which hyperpnea (and transition) bursts are associated with increases in HFO, while gasping contains no HFO. Our results confirm that both the fast oscillations in Ph activity and the coherence between Ph pairs produced by the juvenile rat are profoundly state- and temperature-dependent.
Topics: Adaptation, Physiological; Animals; Biological Clocks; Body Temperature; Body Temperature Regulation; Decerebrate State; Diaphragm; Male; Oscillometry; Phrenic Nerve; Rats; Rats, Sprague-Dawley
PubMed: 17913868
DOI: 10.1152/ajpregu.00472.2007 -
The Journal of Physiology Aug 2020The decerebrate mouse provides a novel working model of the exercise pressor reflex (EPR). The decerebrate mouse model of the EPR is similar to the previously described...
KEY POINTS
The decerebrate mouse provides a novel working model of the exercise pressor reflex (EPR). The decerebrate mouse model of the EPR is similar to the previously described decerebrate rat model. Studying the EPR in transgenic mouse models can define exact mechanisms of the EPR in health and disease.
ABSTRACT
The exercise pressor reflex (EPR) is defined by a rise in mean arterial pressure (MAP) and heart rate (HR) in response to exercise and is necessary to match metabolic demand and prevent premature fatigue. While this reflex is readily tested in humans, mechanistic studies are largely infeasible. Here, we have developed a novel murine model of the EPR to allow for mechanistic studies in various mouse models. We observed that ventral root stimulation (VRS) in an anaesthetized mouse causes a depressor response and a reduction in HR. In contrast, the same stimulation in a decerebrate mouse causes a rise in MAP and HR which is abolished by dorsal rhizotomy or by neuromuscular blockade. Moreover, we demonstrate a reduced MAP response to VRS using TRPV1 antagonism or in Trpv1 null mice while the response to passive stretch remains intact. Additionally, we demonstrate that intra-arterial infusion of capsaicin results in a dose-related rise in MAP and HR that is significantly reduced by a selective and potent TRPV1 antagonist or is completely abolished in Trpv1 null mice. These data serve to validate the development of a decerebrate mouse model for the study of cardiovascular responses to exercise and further define the role of the TRPV1 receptor in mediating the EPR. This novel model will allow for extensive study of the EPR in unlimited transgenic and mutant mouse lines, and for an unprecedented exploration of the molecular mechanisms that control cardiovascular responses to exercise in health and disease.
Topics: Animals; Blood Pressure; Decerebrate State; Disease Models, Animal; Heart Rate; Mice; Muscle Contraction; Muscle, Skeletal; Rats; Rats, Sprague-Dawley; Reflex
PubMed: 32406099
DOI: 10.1113/JP277602 -
Journal of Neurophysiology Mar 1947
Topics: Decerebrate State; Humans
PubMed: 20291835
DOI: 10.1152/jn.1947.10.2.89 -
Nihon Hinyokika Gakkai Zasshi. the... Jun 1992
Topics: Animals; Cats; Decerebrate State; Dogs; Reflex; Urinary Bladder; Urination
PubMed: 1501387
DOI: 10.5980/jpnjurol.83.808 -
Malaria Journal Dec 2005Abnormal motor posturing is often observed in children with cerebral malaria, but the aetiology and pathogenesis is poorly understood. This study examined the risk...
BACKGROUND
Abnormal motor posturing is often observed in children with cerebral malaria, but the aetiology and pathogenesis is poorly understood. This study examined the risk factors and outcome of posturing in Kenyan children with cerebral malaria.
METHODS
Records of children admitted to Kilifi district hospital with cerebral malaria from January, 1999 through December, 2001 were reviewed for posturing occurring on or after admission. The clinical characteristics, features of raised intracranial pressure, number of seizures and biochemical changes in patients that developed posturing was compared to patients who did not.
RESULTS
Of the 417 children with complete records, 163 (39.1%) had posturing: 85 on admission and 78 after admission to hospital. Decorticate posturing occurred in 80, decerebrate in 61 and opisthotonic posturing in 22 patients. Posturing was associated with age > or = 3 years (48.1 vs 35.8%, p = 0.01) and features of raised intracranial pressure on funduscopy (adjusted OR 2.1 95%CI 1.2-3.7, p = 0.009) but not other markers of severity of disease. Unlike decorticate posturing, decerebrate (adjusted OR 1.9 95%CI 1.0-3.5) and opisthotonic posturing (adjusted OR 2.9 95%CI 1.0-8.1) were, in addition, independently associated with recurrence of seizures after admission. Opisthotonus was also associated with severe metabolic acidosis (OR 4.2 95%CI 3.2-5.6, p < 0.001). Thirty one patients with posturing died. Of these, 19 (61.3%) had features suggestive of transtentorial herniation. Mortality and neurological deficits on discharge were greatest in those developing posturing after admission.
CONCLUSION
Abnormal motor posturing is a common feature of cerebral malaria in children. It is associated with features of raised intracranial pressure and recurrence of seizures, although intracranial hypertension may be the primary cause.
Topics: Brain Stem; Child, Preschool; Coma; Decerebrate State; Female; Humans; Infant; Intracranial Hypertension; Kenya; Logistic Models; Malaria, Cerebral; Male; Retrospective Studies; Risk Factors; Seizures; Time Factors
PubMed: 16336645
DOI: 10.1186/1475-2875-4-57 -
The Journal of Physiology Sep 19961. In order to study fusimotor control in reduced preparations, soleus muscle spindle afferents were recorded in premammillary decerebrate cats (n = 15) during crossed...
1. In order to study fusimotor control in reduced preparations, soleus muscle spindle afferents were recorded in premammillary decerebrate cats (n = 15) during crossed extensor reflexes and, after spinalization, during locomotion produced by either clonidine or L-beta-3,4-dihydroxyphenylalanine (L-DOPA). The soleus muscle was oscillated sinusoidally (0.25 mm, 4 Hz) and the afferent mean firing rate and modulation were calculated. An increase in firing rate was assumed to arise from activity in dynamic gamma-motoneurones (dynamic gamma-drive) when associated with an increase in modulation to stretching, and in static gamma-motoneurones (static gamma-drive) when modulation decreased. 2. At rest in all preparations the firing rate and modulation in primary muscle spindle afferents were generally much higher than after de-efferentation (ventral root section), suggesting a predominant dynamic gamma-drive. Clonidine decreased and even eliminated this presumed resting gamma-drive in many afferents, both in the decerebrate (7 of 8) and the spinal (6 of 18) state. This effect on gamma-drive may account, at least in part, for its suppressive effect on spasticity in humans. 3. When locomotion commenced in clonidine-treated spinal cats, primary afferents generally fired with much higher mean rates (+121%) and lower sensitivities (-32%), suggesting a large increase in static gamma-drive (possibly accompanied by a small decrease in dynamic gamma-drive). These high rates were usually maintained tonically throughout the step cycle. However, a third of the afferents were silenced during locomotor contractions, and de-efferentation had no significant effect on their firing rates. Thus, for some spindles alpha-activity can occur without significant gamma-drive. 4. During locomotion in L-DOPA-treated spinal cats the inferred static gamma-drive only occurred phasically, coactivated with the EMG, though it could precede the EMG by 100-500 ms. In the flexion phase both the afferent rate and modulation were lower than before locomotion, suggesting a lack of effective gamma-drive. 5. Crossed extensor reflexes in decerebrate cats also produced a substantial increase in primary afferent firing rate (+187%) and decrease in sensitivity (-37%), again suggesting increased static gamma-drive (n = 18). This gamma-drive was largely independent of EMG activity and often occurred without alpha-activity. The mean firing rate of secondary muscle spindle afferents increased significantly during locomotion (with L-DOPA) and crossed extensor reflexes, again indicating increased static gamma-drive. Clonidine reduced or eliminated the gamma-drive in seven of eight afferents during crossed extensor reflexes. 6. In conclusion, although there are some common features, such as a predominant static gamma-drive in all walking preparations, the pattern of static and dynamic gamma-drive is not closely linked to alpha-activity under the conditions studied. As well as gamma-drive without alpha-activity, we have shown for the first time that alpha-motoneurones can be activated without significant gamma-drive to many spindles during behavioural tasks.
Topics: Action Potentials; Afferent Pathways; Animals; Cats; Clonidine; Decerebrate State; Electrophysiology; Levodopa; Motor Activity; Motor Neurons, Gamma; Muscle Contraction; Muscle, Skeletal; Posture; Sympatholytics
PubMed: 8887786
DOI: 10.1113/jphysiol.1996.sp021636 -
American Journal of Physiology. Heart... Jun 2019Autonomic dysreflexia (AD) often occurs in individuals living with spinal cord injury (SCI) and is characterized by uncontrolled hypertension in response to otherwise... (Comparative Study)
Comparative Study
Autonomic dysreflexia (AD) often occurs in individuals living with spinal cord injury (SCI) and is characterized by uncontrolled hypertension in response to otherwise innocuous stimuli originating below the level of the spinal lesion. Visceral stimulation is a predominant cause of AD in humans and effectively replicates the phenotype in rodent models of SCI. Direct assessment of sympathetic responses to viscerosensory stimulation in spinalized animals is challenging and requires invasive surgical procedures necessitating the use of anesthesia. However, administration of anesthesia markedly affects viscerosensory reactivity, and the effects are exacerbated following spinal cord injury (SCI). Therefore, the major goal of the present study was to develop a decerebrate rodent preparation to facilitate quantification of sympathetic responses to visceral stimulation in the spinalized rat. Such a preparation enables the confounding effect of anesthesia to be eliminated. Sprague-Dawley rats were subjected to SCI at the fourth thoracic segment. Four weeks later, renal sympathetic nerve activity (RSNA) responses to visceral stimuli were quantified in urethane/chloralose-anesthetized and decerebrate preparations. Visceral stimulation was elicited via colorectal distension (CRD) for 1 min. In the decerebrate preparation, CRD produced dose-dependent increases in mean arterial pressure (MAP) and RSNA and dose-dependent decreases in heart rate (HR). These responses were significantly greater in magnitude among decerebrate animals when compared with urethane/chloralose-anesthetized controls and were markedly attenuated by the administration of urethane/chloralose anesthesia after decerebration. We conclude that the decerebrate preparation enables high-fidelity quantification of neuronal reactivity to visceral stimulation in spinalized rats. In animal models commonly used to study spinal cord injury, quantification of sympathetic responses is particularly challenging due to the increased susceptibility of spinal reflex circuits to the anesthetic agents generally required for experimentation. This constitutes a major limitation to understanding the mechanisms mediating regionally specific neuronal responses to visceral activation in chronically spinalized animals. In the present study, we describe a spinalized, decerebrate rodent preparation that facilitates quantification of sympathetic reactivity in response to visceral stimuli following spinal cord injury. This preparation enables reliable and reproducible quantification of viscero-sympathetic reflex responses resembling those elicited in conscious animals and may provide added utility for preclinical evaluation of neuropharmacological agents for the management of autonomic dysreflexia.
Topics: Anesthetics, Intravenous; Animals; Autonomic Dysreflexia; Chloralose; Decerebrate State; Disease Models, Animal; Hemodynamics; Kidney; Male; Rats, Sprague-Dawley; Reflex; Spinal Cord; Sympathetic Nervous System; Urethane
PubMed: 30875256
DOI: 10.1152/ajpheart.00724.2018 -
Journal of Neural Transmission (Vienna,... Jul 2016The lateral part of the mesopontine tegmentum contains functionally important structures involved in the control of posture and gait. Specifically, the mesencephalic... (Review)
Review
The lateral part of the mesopontine tegmentum contains functionally important structures involved in the control of posture and gait. Specifically, the mesencephalic locomotor region, which may consist of the cuneiform nucleus and pedunculopontine tegmental nucleus (PPN), occupies the interest with respect to the pathophysiology of posture-gait disorders. The purpose of this article is to review the mechanisms involved in the control of postural muscle tone and locomotion by the mesopontine tegmentum and the pontomedullary reticulospinal system. To make interpretation and discussion more robust, the above issue is considered largely based on our findings in the experiments using decerebrate cat preparations in addition to the results in animal experimentations and clinical investigations in other laboratories. Our investigations revealed the presence of functional topographical organizations with respect to the regulation of postural muscle tone and locomotion in both the mesopontine tegmentum and the pontomedullary reticulospinal system. These organizations were modified by neurotransmitter systems, particularly the cholinergic PPN projection to the pontine reticular formation. Because efferents from the forebrain structures as well as the cerebellum converge to the mesencephalic and pontomedullary reticular formation, changes in these organizations may be involved in the appropriate regulation of posture-gait synergy depending on the behavioral context. On the other hand, abnormal signals from the higher motor centers may produce dysfunction of the mesencephalic-reticulospinal system. Here we highlight the significance of elucidating the mechanisms of the mesencephalic-reticulospinal control of posture and locomotion so that thorough understanding of the pathophysiological mechanisms of posture-gait disorders can be made.
Topics: Animals; Cats; Decerebrate State; Humans; Locomotion; Midbrain Reticular Formation; Muscle Tonus; Neural Pathways; Pedunculopontine Tegmental Nucleus
PubMed: 26497023
DOI: 10.1007/s00702-015-1475-4