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British Journal of Pharmacology and... Sep 1960The actions of hydroxydione sodium succinate ("Viadril") have been studied in chloralose or decerebrate cats, or cats otherwise untreated. It is virtually devoid of...
The actions of hydroxydione sodium succinate ("Viadril") have been studied in chloralose or decerebrate cats, or cats otherwise untreated. It is virtually devoid of action at the neuromuscular, ganglionic, or peripheral adrenergic synapse. After rapid intravenous injection, hydroxydione produced a transient hypotension with little bradycardia and stimulated the respiration. These effects were over in 1 to 2 min. and were reduced if injection was slow or the hydroxydione diluted. Vagotomy did not alter the depressor response, but reduced the respiratory stimulation. In the untreated or the decerebrate animal, as much as five times the anaesthetic dose of hydroxydione was required to depress the respiration or blood pressure. Chloralose potentiated these depressant actions 5 to 10 fold. Both the circulatory and the respiratory depression appeared to be mediated centrally. Decerebrate rigidity was readily lessened by hydroxydione, but the pinna reflex and conjunctival reflex were relatively resistant to its action, and the knee jerk outstandingly so.
Topics: Anesthetics; Animals; Blood Pressure; Bradycardia; Cats; Decerebrate State; Hypotension; Injections, Intravenous; Pregnanediones; Reflex; Respiration; Succinates; Vagotomy
PubMed: 13761053
DOI: 10.1111/j.1476-5381.1960.tb01273.x -
The Journal of Physiology Feb 19671. An examination of the physiological properties of cells in cat lumbar dorsal horn shows that there are three horizontal laminae which correspond approximately to...
1. An examination of the physiological properties of cells in cat lumbar dorsal horn shows that there are three horizontal laminae which correspond approximately to Rexed (1952) laminae 4, 5, and 6.2. A summary diagram (Fig. 9) suggests the relation of the laminae to each other and to afferent and descending fibres. All three laminae respond to cutaneous stimulation but only lamina 6 responds to movement. By comparing responses of cells in decerebrate and spinal preparations, it is shown that the brain stem inhibits cutaneous responses and enhances movement responses. Pyramidal tract stimulation affects cells in laminae 4, 5, and 6.3. Cells in lamina 4 have small cutaneous receptive fields and respond as though many different types of specific cutaneous afferents converge on them. Cells in lamina 5 respond as though many cells of lamina 4 converge on them. In the decerebrate animal the responses of lamina 5 cells habituate to repeated light pressure stimuli but the cells remain responsive to new stimuli in other parts of their receptive field. Impulses descending from the brain stem can switch the modality of lamina 6 cells from cutaneous to proprioceptive.
Topics: Animals; Brain Stem; Cats; Decerebrate State; Electrophysiology; Muscle Contraction; Neurons; Pentobarbital; Pyramidal Tracts; Sensory Receptor Cells; Skin Physiological Phenomena; Spinal Cord
PubMed: 6032207
DOI: 10.1113/jphysiol.1967.sp008146 -
Experimental Brain Research Mar 2013The dorsolateral reticular formation of the caudal medulla, the lateral tegmental field (LTF), participates in generating vomiting. LTF neurons exhibited complex...
The dorsolateral reticular formation of the caudal medulla, the lateral tegmental field (LTF), participates in generating vomiting. LTF neurons exhibited complex responses to vestibular stimulation in decerebrate cats, indicating that they received converging inputs from a variety of labyrinthine receptors. Such a convergence pattern of vestibular inputs is appropriate for a brain region that participates in generating motion sickness. Since responses of brainstem neurons to vestibular stimulation can differ between decerebrate and conscious animals, the current study examined the effects of whole-body rotations in vertical planes on the activity of LTF neurons in conscious felines. Wobble stimuli, fixed-amplitude tilts, the direction of which moves around the animal at a constant speed, were used to determine the response vector orientation, and also to ascertain whether neurons had spatial-temporal convergence (STC) behavior (which is due to the convergence of vestibular inputs with different spatial and temporal properties). The proportion of LTF neurons with STC behavior in conscious animals (25 %) was similar to that in decerebrate cats. Far fewer neurons in other regions of the feline brainstem had STC behavior, confirming findings that many LTF neurons receive converging inputs from a variety of labyrinthine receptors. However, responses to vertical plane vestibular stimulation were considerably different in decerebrate and conscious felines for LTF neurons lacking STC behavior. In decerebrate cats, most LTF neurons had graviceptive responses to rotations, similar to those of otolith organ afferents. However, in conscious animals, the response properties were similar to those of semicircular canal afferents. These differences show that higher centers of the brain that are removed during decerebration regulate the labyrinthine inputs relayed to the LTF, either by gating connections in the brainstem or by conveying vestibular inputs directly to the region.
Topics: Action Potentials; Animals; Brain Mapping; Cats; Consciousness; Decerebrate State; Medulla Oblongata; Neurons; Vestibule, Labyrinth
PubMed: 23274644
DOI: 10.1007/s00221-012-3376-1 -
Journal of Neurophysiology Oct 2011Distinct rhythmic behaviors involving a common set of motoneurons and muscles can be generated by separate central nervous system (CNS) networks, a single network, or...
Distinct rhythmic behaviors involving a common set of motoneurons and muscles can be generated by separate central nervous system (CNS) networks, a single network, or partly overlapping networks in invertebrates. Less is known for vertebrates. Simultaneous activation of two networks can reveal overlap or interactions between them. The turtle spinal cord contains networks that generate locomotion and three forms of scratching (rostral, pocket, and caudal), having different knee-hip synergies. Here, we report that in immobilized spinal turtles, simultaneous delivery of types of stimulation, which individually evoked forward swimming and one form of scratching, could 1) increase the rhythm frequency; 2) evoke switches, hybrids, and intermediate motor patterns; 3) recruit a swim motor pattern even when the swim stimulation was reduced to subthreshold intensity; and 4) disrupt rhythm generation entirely. The strength of swim stimulation could influence the result. Thus even pocket scratching and caudal scratching, which do not share a knee-hip synergy with forward swimming, can interact with swim stimulation to alter both rhythm and pattern generation. Model simulations were used to explore the compatibility of our experimental results with hypothetical network architectures for rhythm generation. Models could reproduce experimental observations only if they included interactions between neurons involved in swim and scratch rhythm generation, with maximal consistency between simulations and experiments attained using a model architecture in which certain neurons participated actively in both swim and scratch rhythmogenesis. Collectively, these findings suggest that the spinal cord networks that generate locomotion and scratching have important shared components or strong interactions between them.
Topics: Animals; Decerebrate State; Electric Stimulation; Extremities; Female; Interneurons; Lumbar Vertebrae; Male; Models, Neurological; Nerve Net; Periodicity; Physical Stimulation; Reflex; Spinal Cord; Swimming; Turtles
PubMed: 21734103
DOI: 10.1152/jn.00460.2011 -
Journal of Neurophysiology Jun 2014The vestibular nuclei integrate information from vestibular and proprioceptive afferents, which presumably facilitates the maintenance of stable balance and posture....
The vestibular nuclei integrate information from vestibular and proprioceptive afferents, which presumably facilitates the maintenance of stable balance and posture. However, little is currently known about the processing of sensory signals from the limbs by vestibular nucleus neurons. This study tested the hypothesis that limb movement is encoded by vestibular nucleus neurons and described the changes in activity of these neurons elicited by limb extension and flexion. In decerebrate cats, we recorded the activity of 70 vestibular nucleus neurons whose activity was modulated by limb movements. Most of these neurons (57/70, 81.4%) encoded information about the direction of hindlimb movement, while the remaining neurons (13/70, 18.6%) encoded the presence of hindlimb movement without signaling the direction of movement. The activity of many vestibular nucleus neurons that responded to limb movement was also modulated by rotating the animal's body in vertical planes, suggesting that the neurons integrated hindlimb and labyrinthine inputs. Neurons whose firing rate increased during ipsilateral ear-down roll rotations tended to be excited by hindlimb flexion, whereas neurons whose firing rate increased during contralateral ear-down tilts were excited by hindlimb extension. These observations suggest that there is a purposeful mapping of hindlimb inputs onto vestibular nucleus neurons, such that integration of hindlimb and labyrinthine inputs to the neurons is functionally relevant.
Topics: Animals; Biomechanical Phenomena; Cats; Decerebrate State; Ear; Electric Stimulation; Hindlimb; Microelectrodes; Movement; Neurons; Nose; Proprioception; Rotation; Vestibular Nuclei
PubMed: 24671527
DOI: 10.1152/jn.00855.2013 -
The Journal of Clinical Investigation Jun 2011Rather than arising from the passive accumulation of excess calories, obesity is a state in which the biologically defended level of body fat stores increases due to...
Rather than arising from the passive accumulation of excess calories, obesity is a state in which the biologically defended level of body fat stores increases due to defects in the homeostatic process that matches food intake and energy expenditure over time. By deleting leptin receptors from distinct brain regions and neuronal subsets, researchers are beginning to identify the neuroanatomical substrates responsible for this regulation. In this issue of the JCI, Scott et al. demonstrate that loss of leptin receptors in a subset of hindbrain neurons increases food intake in mice, but, unlike what is observed when leptin receptors are deleted from hypothalamic neurons, these mice compensate by increasing energy expenditure and hence do not become obese. Although many brain areas can regulate energy intake and/or energy expenditure, it is likely that only a small subset of neurons actively matches the two over time. It is vital to clarify how this works if we are to improve our understanding of obesity pathogenesis and options available for its treatment.
Topics: Animals; Body Weight; Brain; Decerebrate State; Energy Intake; Energy Metabolism; Feeding Behavior; Homeostasis; Humans; Hyperphagia; Leptin; Mice; Mice, Knockout; Neurons; Obesity; Organ Specificity; Peptide Hormones; Rats; Receptors, Leptin
PubMed: 21606602
DOI: 10.1172/JCI58027 -
The Journal of Physiology Jun 19681. The effects produced by stimulation of the central end of transected ventral roots were observed on spontaneous and evoked vesical contractions and on the firing of...
1. The effects produced by stimulation of the central end of transected ventral roots were observed on spontaneous and evoked vesical contractions and on the firing of sacral parasympathetic neurones.2. Recurrent inhibition of sacral parasympathetic neurones was demonstrated at frequencies of stimulation above 10/sec and at intensities above threshold for the parasympathetic axons.3. Recurrent inhibition was present in chloralose cats, as well as in decerebrate animals and was unaffected by chronic spinal transection.4. Interneurones were located which are presumed to be the autonomic equivalents of the somatic Renshaw cells. They were synaptically activated by antidromic stimulation of preganglionic fibres in sacral ventral roots.5. The inhibition of vesical contractions and the firing of the interneurones was reduced when the intravesical pressure was raised.6. The recurrent inhibition was unaffected by the intravenous injection of dihydro-beta-erythroidine.7. Strychnine reduced the recurrent inhibition in some experiments but the results were inconsistent. The effects of picrotoxin were inconclusive.8. The possible role of recurrent inhibition in micturition is discussed.
Topics: Alkaloids; Animals; Axons; Cats; Cordotomy; Decerebrate State; Electrophysiology; Evoked Potentials; Interneurons; Parasympathetic Nervous System; Picrotoxin; Pressure; Sacrum; Strychnine; Urinary Bladder
PubMed: 5243140
DOI: 10.1113/jphysiol.1968.sp008524 -
Stimulation of spinal δ-opioid receptors attenuates the exercise pressor reflex in decerebrate rats.American Journal of Physiology.... Jun 2019A reflex arising from contracting hindlimb muscle is responsible in part for the increases in arterial pressure and heart rate evoked by exercise. The afferent arm of...
A reflex arising from contracting hindlimb muscle is responsible in part for the increases in arterial pressure and heart rate evoked by exercise. The afferent arm of this reflex comprises group III and IV afferents. δ-Opioid receptors are expressed predominately on the spinal endings of group III afferents, whereas μ-opioid receptors are expressed predominately on the spinal endings of group IV afferents. Using stimuli that activated group III afferents, namely static contraction, calcaneal tendon stretch, and lactic acid injection into the superficial epigastric artery, we tested the hypothesis that, in rats with either patent or ligated femoral arteries, activation of pre- and postsynaptic δ-opioid receptors in the dorsal horn attenuated pressor reflex responses to these stimuli. In rats with patent arteries or ligated femoral arteries, [d-Pen]enkephalin (DPDPE), a δ-opioid agonist injected intrathecally (10 μg in 10 μl), significantly attenuated the pressor responses to contraction, stretch, and lactic acid (all < 0.05). Naltrindole, a δ-opioid receptor antagonist, prevented the attenuation. In contrast, DPDPE did not attenuate the pressor response to capsaicin injection into the superficial epigastric artery in either group of rats (both > 0.05). Intrathecal injection of saline (10 μl), the vehicle for DPDPE, had no effect on the pressor responses in either group of rats. We conclude that activation of spinal δ-opioid receptors attenuates reflexes evoked by group III afferents in both freely perfused and ligated rats.
Topics: Animals; Decerebrate State; Enkephalin, D-Penicillamine (2,5)-; Femoral Artery; Heart Rate; Male; Muscle Contraction; Muscle, Skeletal; Physical Conditioning, Animal; Physical Exertion; Rats, Sprague-Dawley; Receptors, Opioid, delta; Receptors, Opioid, mu; Reflex
PubMed: 30943058
DOI: 10.1152/ajpregu.00013.2019 -
Journal of Neurophysiology May 1999Recruitment order among motoneurons from different motor nuclei. The principles by which motoneurons (MNs) innervating different multiple muscles are organized into...
Recruitment order among motoneurons from different motor nuclei. The principles by which motoneurons (MNs) innervating different multiple muscles are organized into activity are not known. Here we test the hypothesis that coactivated MNs belonging to different muscles in the decerebrate cat are recruited in accordance with the size principle, i.e., that MNs with slow conduction velocity (CV) are recruited before MNs with higher CV. We studied MN recruitment in two muscle pairs, the lateral gastrocnemius (LG) and medial gastrocnemius (MG) muscles, and the MG and posterior biceps femoris (PBF) muscles because these pairs are coactivated reliably in stretch and cutaneous reflexes, respectively. For 29/34 MG-LG pairs of MNs, the MN with lower CV was recruited first either in all trials (548/548 trials for 22 pairs) or in most trials (225/246 trials for 7 pairs), whether the MG or the LG MN in a pair was recruited first. Intertrial variability in the force thresholds of MG and LG MNs recruited by stretch was relatively low (coefficient of variation = 18% on average). Finally, punctate stimulation of the skin over the heel recruited 4/4 pairs of MG-LG MNs in order by CV. By all of these measures, recruitment order is as consistent among MNs from these two ankle muscles as it is for MNs supplying the MG muscle alone. For MG-PBF pairings, the MN with lower CV was recruited first in the majority of trials for 13/24 pairs and in reverse order for 9/24 pairs. The recruitment sequence of coactive MNs supplying the MG and PBF muscles was, therefore, random with respect to axonal conduction velocity and not organized as predicted by the size principle. Taken together, these findings demonstrate for the first time, that the size principle can extend beyond the boundaries of a single muscle but does not coordinate all coactive muscles in a limb.
Topics: Animals; Cats; Decerebrate State; Differential Threshold; Female; Male; Motor Neurons; Muscle, Skeletal; Neural Conduction; Physical Stimulation; Recruitment, Neurophysiological; Skin; Tarsus, Animal; Thigh; Time Factors
PubMed: 10322083
DOI: 10.1152/jn.1999.81.5.2485 -
The Journal of Neuroscience : the... Jun 2004Spinal cord modularity impacts on our understanding of reflexes, development, descending systems in normal motor control, and recovery from injury. We used independent... (Comparative Study)
Comparative Study
Spinal cord modularity impacts on our understanding of reflexes, development, descending systems in normal motor control, and recovery from injury. We used independent component analysis and best-basis or matching pursuit wavepacket analysis to extract the composition and temporal structure of bursts in hindlimb muscles of frogs. These techniques make minimal a priori assumptions about drive and motor pattern structure. We compared premotor drive and burst structures in spinal frogs with less reduced frogs with a fuller repertoire of locomotory, kicking, and scratching behaviors. Six multimuscle drives explain most of the variance of motor patterns (approximately 80%). Each extracted drive was activated with pulses at a single time scale or common duration (approximately 275 msec) burst structure. The data show that complex behaviors in brainstem frogs arise as a result of focusing drives to smaller core groups of muscles. Brainstem drives were subsets of the muscle groups from spinal frogs. The 275 msec burst duration was preserved across all behaviors and was most precise in brainstem frogs. These data support a modular decomposition of frog behaviors into a small collection of unit burst generators and associated muscle drives in spinal cord. Our data also show that the modular organization of drives seen in isolated spinal cord is fine-tuned by descending controls to enable a fuller movement repertoire. The unit burst generators and their associated muscle synergies extracted here link the biomechanical "primitives," described earlier in the frog, rat, and cat, and to the elements of pattern generation examined in fictive preparations.
Topics: Animals; Axotomy; Behavior, Animal; Brain Stem; Decerebrate State; Electrodes, Implanted; Electromyography; Hindlimb; Motor Activity; Muscle, Skeletal; Rana catesbeiana; Reflex; Signal Processing, Computer-Assisted; Spinal Cord; Statistics as Topic; Synaptic Transmission
PubMed: 15175397
DOI: 10.1523/JNEUROSCI.5626-03.2004