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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 -
Experimental Brain Research Apr 2017The integration of inputs from vestibular and proprioceptive sensors within the central nervous system is critical to postural regulation. We recently demonstrated in...
The integration of inputs from vestibular and proprioceptive sensors within the central nervous system is critical to postural regulation. We recently demonstrated in both decerebrate and conscious cats that labyrinthine and hindlimb inputs converge onto vestibular nucleus neurons. The pontomedullary reticular formation (pmRF) also plays a key role in postural control, and additionally participates in regulating locomotion. Thus, we hypothesized that like vestibular nucleus neurons, pmRF neurons integrate inputs from the limb and labyrinth. To test this hypothesis, we recorded the responses of pmRF neurons to passive ramp-and-hold movements of the hindlimb and to whole-body tilts, in both decerebrate and conscious felines. We found that pmRF neuronal activity was modulated by hindlimb movement in the rostral-caudal plane. Most neurons in both decerebrate (83% of units) and conscious (61% of units) animals encoded both flexion and extension movements of the hindlimb. In addition, hindlimb somatosensory inputs converged with vestibular inputs onto pmRF neurons in both preparations. Pontomedullary reticular formation neurons receiving convergent vestibular and limb inputs likely participate in balance control by governing reticulospinal outflow.
Topics: Action Potentials; Animals; Brain Mapping; Cats; Consciousness; Decerebrate State; Electric Stimulation; Female; Hindlimb; Male; Motor Neurons; Movement; Reticular Formation; Rotation; Vestibule, Labyrinth
PubMed: 28188328
DOI: 10.1007/s00221-017-4875-x -
The Japanese Journal of Physiology 1990To ascertain differences in the brainstem pattern generators for straining and retching, discharges of 230 respiratory single motor units from the intercostal nerves and... (Comparative Study)
Comparative Study
To ascertain differences in the brainstem pattern generators for straining and retching, discharges of 230 respiratory single motor units from the intercostal nerves and discharges of the nerves to accessory respiratory muscles, the esophagus, and external anal and urethral sphincters were observed during straining, retching, and vomiting (fictive expulsion) in decerebrate and paralyzed dogs. Straining and retching were identified with coactivation of the phrenic nerve and the nerve to the rectus abdominis, which was elicited by distension of the rectum and stomach, respectively. Synchronous discharges with each retch and straining were always exhibited by the phrenic nerve, the nerves innervating the abdominal part of the rectus abdominis and the external anal and urethral sphincters. In contrast, different behaviours were constantly observed in four nerves. 1) The nerves to the serratus dorsalis cranialis was inhibited during straining, but activated synchronously with each retch and vomiting. 2) Vagal pharyngeal branches innervating the upper esophagus and branches of the recurrent nerve innervating the lower part of the cervical esophagus fired synchronously with straining. The esophageal nerves, on the other hand, did not fire with each retch, but did fire strongly between retches. 3) The nerve to the sacrocaudalis dorsalis lateralis discharged concomitantly with straining but did not with retches. Straining and retching behaviors exhibited by the nerves innervating other thoracic accessory inspiratory muscles (the intercartilagineus, rectus thoracis, scalenus) varied from dog to dog. The nerves innervating the thoracic parts of the rectus abdominis and obliquus externus abdominis always discharged synchronously with straining, and discharged with retches in the majority of dogs, but did not in a minority of dogs. The expiratory units from the internal intercostal nerves showed intense discharges synchronously with coactivation in straining (96%), retching (65%), and vomiting (100%). In contrast, none of the inspiratory units from the external intercostal nerves exhibited such intense discharges with straining and retching. These results suggest that the functional difference in straining and retching mainly depends on the differences in the behavior of the serratus dorsalis cranialis and esophagus. The forms of this dependence were discussed.
Topics: Anal Canal; Animals; Decerebrate State; Dogs; Esophagus; Intercostal Nerves; Respiration; Respiratory Muscles; Synaptic Transmission; Urethra; Vomiting
PubMed: 1965598
DOI: 10.2170/jjphysiol.40.789 -
BMJ Case Reports Nov 2015The control of body posture is a complex activity that needs a very close relationship between different structures, such as the vestibular system, and the muscle and... (Review)
Review
The control of body posture is a complex activity that needs a very close relationship between different structures, such as the vestibular system, and the muscle and joint receptors of the neck. Damage of even one of these structures can lead to abnormal postural reflexes. We describe a case of a woman with a left pontine ischaemia who developed a 'dystonic' extensor posture of the left limbs while turned on the right side. This clinical picture differs from previous reports on the subject, and may relate to ischaemic damage of a pontine structure involved in posture control, or of adjacent neural connections to be yet identified. To the best of our knowledge, this is the first case reported in the literature. Clinical examples of an altered interplay between vestibular and neck receptors are rare.
Topics: Aged, 80 and over; Decerebrate State; Female; Humans; Ischemia; Neck; Pons; Posture; Reflex, Abnormal; Seizures; Sleep Stages; Tomography, X-Ray Computed; Vestibule, Labyrinth
PubMed: 26561222
DOI: 10.1136/bcr-2015-210616 -
American Journal of Physiology.... May 2019Recent findings have shown that muscle contraction evokes an exaggerated pressor response in type 1 diabetes mellitus (T1DM) rats; however, it is not known whether the...
Recent findings have shown that muscle contraction evokes an exaggerated pressor response in type 1 diabetes mellitus (T1DM) rats; however, it is not known whether the mechanoreflex, which is commonly stimulated by stretching the Achilles tendon, contributes to this abnormal response. Furthermore, the role of mechano-gated Piezo channels, found on thin-fiber afferent endings, in evoking the mechanoreflex in T1DM is also unknown. Therefore, in male and female streptozotocin (STZ, 50 mg/kg)-induced T1DM and healthy control (CTL) rats, we examined the pressor and cardioaccelerator responses to tendon stretch during the early stage of the disease. To determine the role of Piezo channels, GsMTx-4, a selective Piezo channel inhibitor, was injected into the arterial supply of the hindlimb. At 1 wk after STZ injection in anesthetized, decerebrate rats, we stretched the Achilles tendon for 30 s and measured pressor and cardioaccelerator responses. We then compared pressor and cardioaccelerator responses to tendon stretch before and after GsMTx-4 injection (10 µg/100 ml). We found that the pressor (change in mean arterial pressure) response [41 ± 5 mmHg ( = 15) for STZ and 18 ± 3 mmHg ( = 11) for CTL ( < 0.01)] and cardioaccelerator (change in heart rate) response [18 ± 4 beats/min for STZ ( = 15) and 8 ± 2 beats/min ( = 11) for CTL ( < 0.05)] to tendon stretch were exaggerated in STZ rats. Local injection of GsMTx-4 attenuated the pressor [55 ± 7 mmHg ( = 6) before and 27 ± 9 mmHg ( = 6) after GsMTx-4 ( < 0.01)], but not the cardioaccelerator, response to tendon stretch in STZ rats and had no effect on either response in CTL rats. These data suggest that T1DM exaggerates the mechanoreflex response to tendon stretch and that Piezo channels play a role in this exaggeration.
Topics: Animals; Blood Pressure; Decerebrate State; Diabetes Mellitus, Experimental; Female; Hindlimb; Intercellular Signaling Peptides and Proteins; Male; Muscle Contraction; Muscle, Skeletal; Physical Conditioning, Animal; Rats, Sprague-Dawley; Reflex; Spider Venoms
PubMed: 30840487
DOI: 10.1152/ajpregu.00294.2018 -
The Journal of Physiology Jan 2012Recently, transgenic mice have been created with mutations affecting the components of the mammalian spinal central pattern generator (CPG) for locomotion; however, it...
Recently, transgenic mice have been created with mutations affecting the components of the mammalian spinal central pattern generator (CPG) for locomotion; however, it has currently only been possible to evoke fictive locomotion in mice, using neonatal in vitro preparations. Here, we demonstrate that it is possible to evoke fictive locomotion in the adult decerebrate mouse in vivo using l-3,4-dihydroxyphenylalanine methyl ester hydrochloride (l-DOPA) and 5-hydroxytryptophan (5HTP) following injection of the monoaminoxiadase inhibitor Nialamide. We investigate the effects of afferent stimulation and spinalization as well as demonstrate the possibility of simultaneous intracellular recording of rhythmically active motoneurones. Our results demonstrate that several features of the mouse locomotor CPG are similar to those that have been observed in rat, cat, rabbit and monkey suggesting a fairly conserved organisation and allowing for future results in transgenic mice to be extrapolated to existing knowledge of CPG components and circuitry obtained in larger species.
Topics: 5-Hydroxytryptophan; Animals; Cats; Decerebrate State; Electric Stimulation; Female; Haplorhini; Levodopa; Locomotion; Mice; Mice, Inbred C57BL; Mice, Transgenic; Models, Animal; Monoamine Oxidase Inhibitors; Motor Neurons; Neuronal Plasticity; Nialamide; Peripheral Nerves; Rabbits; Rats; Reaction Time; Spinal Cord
PubMed: 22106172
DOI: 10.1113/jphysiol.2011.214643 -
British Medical Journal Nov 1973Five cases are described in which fear of the possibly hazardous effects of giving amphotericin to patients with kidney disease resulted in death from progressive...
Five cases are described in which fear of the possibly hazardous effects of giving amphotericin to patients with kidney disease resulted in death from progressive infection by an amphotericin-sensitive fungus (Cryptococcus neoformans in three cases, Blastomyces dermatitidis in one case, and Histoplasma capsulatum in one case).
Topics: Adrenal Insufficiency; Adult; Amphotericin B; Attitude of Health Personnel; Blastomycosis; Cryptococcosis; Decerebrate State; Drug Prescriptions; Female; Histoplasmosis; Hodgkin Disease; Humans; Kidney Diseases; Lung Diseases, Fungal; Male; Medication Errors; Meningitis; Meningoencephalitis; Mycoses; Phobic Disorders; Sarcoidosis; Spinal Diseases
PubMed: 4758449
DOI: 10.1136/bmj.4.5890.460 -
The Journal of Physiology Dec 19871. In both anaesthetized and decerebrate cats the cerebellar cortex (lobules VI, VII, VIII, IX and X) and the fastigial nucleus (f.n.) have been stimulated electrically,...
1. In both anaesthetized and decerebrate cats the cerebellar cortex (lobules VI, VII, VIII, IX and X) and the fastigial nucleus (f.n.) have been stimulated electrically, and chemically, while recording changes in phrenic nerve discharge, heart rate, arterial blood pressure and renal and femoral blood flow. 2. Stimulation of lobules VI, VII, VIII and Xb failed to elicit any cardiovascular or respiratory changes. Activation of lobule IX (the uvula), and in some preparations sub-lobule Xa, evoked cardiovascular and respiratory responses consistently. In the anaesthetized cat, electrical stimulation of the uvula evoked apnoea, a small bradycardia and a depressor response associated with vasodilatation in the hindlimb vascular bed. In contrast, stimulation in an equivalent region in a decerebrate preparation elicited an apneustic discharge, a pronounced tachycardia and a rise in arterial pressure with vasoconstriction in both renal and femoral vascular beds. In both the anaesthetized and decerebrate animals the pattern of response elicited by chemical activation was identical to that seen with electrical stimulation. 3. Electrical, or chemical, stimulation after administration of anaesthetic to the decerebrate cat then evoked an identical pattern of response to that seen in the 'intact' anaesthetized animal. This evidence suggests that the reversal in the pattern of the response in an effect of the anaesthetic agent and not the decerebration itself. 4. The only area of the f.n. to produce cardiovascular effects was the rostral region. Electrical stimulation of the rostral f.n. in both anaesthetized and decerebrate preparations inhibited central inspiratory activity and evoked tachycardia, along with a pressor response associated with vasoconstriction in both renal and femoral vascular beds. In contrast, chemical excitation of those sites in the rostral f.n. shown previously to produce pronounced cardiovascular and respiratory changes failed to elicit any changes in the recorded variables. 5. The present evidence suggests that there are two areas in the cat cerebellum which can exert pronounced cardiovascular and respiratory effects. The patterns of response elicited by electrical stimulation of the posterior cortex and rostral f.n. are mediated by two separate cerebellar-brainstem pathways as judged by the two different effects of anaesthesia on the evoked responses. We suggest that the f.n. may not play a role in the control of the cardiovascular system since chemical excitation of cell bodies of the rostral f.n. failed to elicit the so-called 'fastigial pressor response'.
Topics: Anesthesia, General; Animals; Blood Pressure; Cats; Cerebellar Cortex; Cerebellar Nuclei; Decerebrate State; Heart Rate; Hemodynamics; Phrenic Nerve; Regional Blood Flow; Respiration
PubMed: 3446792
DOI: 10.1113/jphysiol.1987.sp016813 -
Experimental Neurology Jul 2017Impaired breathing is a devastating result of high cervical spinal cord injuries (SCI) due to partial or full denervation of phrenic motoneurons, which innervate the...
Impaired breathing is a devastating result of high cervical spinal cord injuries (SCI) due to partial or full denervation of phrenic motoneurons, which innervate the diaphragm - a primary muscle of respiration. Consequently, people with cervical level injuries often become dependent on assisted ventilation and are susceptible to secondary complications. However, there is mounting evidence for limited spontaneous recovery of respiratory function following injury, demonstrating the neuroplastic potential of respiratory networks. Although many studies have shown such plasticity at the level of the spinal cord, much less is known about the changes occurring at supraspinal levels post-SCI. The goal of this study was to determine functional reorganization of respiratory neurons in the medulla acutely (>4h) following high cervical SCI. Experiments were conducted in decerebrate, unanesthetized, vagus intact and artificially ventilated rats. In this preparation, spontaneous recovery of ipsilateral phrenic nerve activity was observed within 4 to 6h following an incomplete, C2 hemisection (C2Hx). Electrophysiological mapping of the ventrolateral medulla showed a reorganization of inspiratory and expiratory sites ipsilateral to injury. These changes included i) decreased respiratory activity within the caudal ventral respiratory group (cVRG; location of bulbospinal expiratory neurons); ii) increased proportion of expiratory phase activity within the rostral ventral respiratory group (rVRG; location of inspiratory bulbo-spinal neurons); iii) increased respiratory activity within ventral reticular nuclei, including lateral reticular (LRN) and paragigantocellular (LPGi) nuclei. We conclude that disruption of descending and ascending connections between the medulla and spinal cord leads to immediate functional reorganization within the supraspinal respiratory network, including neurons within the ventral respiratory column and adjacent reticular nuclei.
Topics: Action Potentials; Animals; Brain Mapping; Cervical Cord; Decerebrate State; Diaphragm; Disease Models, Animal; Functional Laterality; Male; Neuronal Plasticity; Neurons; Phrenic Nerve; Rats; Rats, Sprague-Dawley; Respiratory Center; Spinal Cord Injuries; Sympathectomy, Chemical; Time Factors
PubMed: 28433644
DOI: 10.1016/j.expneurol.2017.04.003 -
The Journal of Physiology Aug 19901. In this study we have examined the roles of the lateral parabrachial nucleus (lateral PBN) and nucleus tractus solitarius (NTS) as sites mediating the circulatory...
1. In this study we have examined the roles of the lateral parabrachial nucleus (lateral PBN) and nucleus tractus solitarius (NTS) as sites mediating the circulatory responses evoked from lobule IX b of the posterior cerebellar vermis in the decerebrate and anaesthetized decerebrate rabbit. Microinjection of either kainic acid or bicuculline into the lateral PBN and NTS was undertaken to assess the importance of neurones and GABAergic mechanisms, respectively, in expressing the cardiovascular responses evoked from lobule IX b. 2. In both the decerebrate and anaesthetized decerebrate rabbit activation of neurones within the lateral PBN with a microinjection of glutamate elicited tachycardia and a pressor response together with an increase in renal sympathetic nerve discharge and vasoconstriction in the hindlimb. A microinjection of GABA into the lateral PBN evoked an opposite pattern of response. Chemical lesioning of neurones within the rostral region of the lateral PBN or pharmacological blockade of GABAA receptor, abolished or significantly attenuated the cardiovascular response (bradycardia/depressor effect) evoked from lobule IX b in the anaesthetized decerebrate rabbit. 3. In the decerebrate animal the tachycardia/pressor response elicited from lobule IX b was suppressed when either kainic acid or bicuculline was microinjected into the caudal division of the lateral PBN. 4. A bradycardia, depressor response, an abolition of on-going renal nerve activity and vasodilatation in the femoral bed were evoked by activating neurones within a restricted region of the NTS with glutamate in the decerebrate and anaesthetized decerebrate rabbit. A microinjection of GABA into the NTS produced a qualitatively opposite pattern of response. The bradycardia/depressor response evoked from lobule IX b in the anaesthetized decerebrate rabbit was not altered significantly following a microinjection of either kainic acid or bicuculline into the ipsilateral NTS. However, in the decerebrate preparation following a microinjection of bicuculline into the ipsilateral NTS the tachycardia/pressor response evoked from IX b was either abolished or in many cases reversed to the pattern of response seen in the anaesthetized decerebrate rabbit. 5. The present experiments provide evidence for two functionally distinct pathways from the cardiovascular region of lobule IX b to the lateral PBN.(ABSTRACT TRUNCATED AT 400 WORDS)
Topics: Animals; Blood Pressure; Brain Stem; Cardiovascular Physiological Phenomena; Cerebellar Cortex; Decerebrate State; Heart Rate; Medulla Oblongata; Neurons; Rabbits
PubMed: 2213606
DOI: 10.1113/jphysiol.1990.sp018186