Changes in responses of medial pontomedullary reticular neurons during repetitive cutaneous, vestibular, cortical, and tectal stimulation

1976 ◽  
Vol 39 (3) ◽  
pp. 564-581 ◽  
Author(s):  
B. W. Peterson ◽  
J. I. Franck ◽  
N. G. Daunton
Keyword(s):  
Spinal Cord ◽  
Superior Colliculus ◽  
Body Surface ◽  
Repetitive Stimulation ◽  
The Body ◽  
Response Decrement ◽  
Afferent Pathways ◽  
Stimulus Rate ◽  
Reticular Neurons ◽  
Stimulation Of

1. In cats anesthetized with chloralose, responses of medial pontomedullary reticular neurons to stimulation of the body surface, vestibular nerves, superior colliculi, pericruciate cortices, cerebral peduncles, and spinal cord were studied at different stimulus rates. Raising the rate from 1/10 s to between 1/4 s and 2/s caused a significant decrement or increment in the response of most neurons tested. Response decrement typically began near the beginning of the higher frequency stimulus sequence and increased throughout the sequence. Response increment usually began somewhat later, rose to a peak, and then declined. Recovery from response decrement or increment usually occurred within 30-60 s at a 1/10 s stimulus rate.2. Measurements of response latency and of changes occurring in the initial and longer latency portions of responses indicated that all components of a response typically decreased or increased in parallel. Background spontaneous activity did not change during response decrements, but sometimes increased during response increment.3. Where changes could be detected, response decrement usually developed more rapidly when a sequence of repetitive stimulation was repeated.4. Response decrement was most pronounced at the highest stimulation rates and lowest stimulus intensities. Response increment was usually maximal at a stimulus rate of 1/s: at lower rates less increment occurred; at higher rates responses began to exhibit decrement.5. Response changes varied with the type of stimulus applied. Response decrements predominated when the body surface, vestibular nerves, or ipsilateral superior colliculus were stimulated. Approximately equal amounts of response increment and decrement were produced by repetitive stimulation of the cerebral peduncles and contralateral superior colliculus. Stimulation of the surface of the pericruciate cortex or of the spinal cord usually produced a long-lasting response increment.6. Generalization of response decrement and increment was observed in cases where trains of stimuli at a rate of 2/s applied to one point produced changes in the response to stimulation of another point which was tested once per 10 s and where single-shock stimulation of the first point was without effect on the test response. Generalization of response decrement occurred most often when two nearby points were stimulated. Generalization of response increment appeared to spread widely between distant cutaneous points and stimuli of different kinds.7. The response decrement and increment observed in medial pontomedullary reticular neurons displayed most of the parametric features of behavioral habituation and sensitization (8, 33) and therefore appear to represent neural analogs of these latter phenomena. The properties of response decrement suggest that it may occur to a large extent within afferent pathways leading to medial reticular neurons...

Effects of cerebellar lesions and stimulation on the shivering tremor

1965 ◽  
Vol 209 (6) ◽  
pp. 1261-1266 ◽  
Author(s):  
Douglas Stuart ◽  
Kenneth Ott ◽  
Earl Eldred
Keyword(s):  
Anterior Lobe ◽  
Repetitive Stimulation ◽  
The Body ◽  
Fastigial Nucleus ◽  
Regulatory Effect ◽  
Normal Pattern ◽  
Single Shock ◽  
Cerebellar Lesions ◽  
Two Sides ◽  
Stimulation Of

Shivering responses to cold have been studied in 21 cats subjected to lesions or stimulation of the cerebellum. Reluctance gauges taped to the extremity were used to sense accelerations produced by the tremor. Shivering of normal pattern was recorded within hours after total extirpation of the cerebellum and up to 4 weeks after surgery. Cats with lesions restricted to the anterior lobe also demonstrated apparently normal rhythm shivering. Comparison of regularity, amplitude, and rate of limb tremor in cats with a hemicerebellectomy, or lesions of one dentate, interpositus, or fastigial nucleus failed to reveal significant differences between the two sides of the body. Single shock or repetitive stimulation of medial cerebellar sites through indwelling electrodes primarily caused suppression of the amplitude of an ongoing tremor, but only at thresholds well above those needed to cause clonic or tonic movements of the limb. It is concluded that the presence of the cerebellum is not requisite for initiation and maintenance of shivering and that this organ has little regulatory effect on the rhythmicity of shivering.

Experimental colitis in mice and sensitization of converging visceral and somatic afferent pathways

2006 ◽  
Vol 290 (3) ◽  
pp. G451-G457 ◽  
Author(s):  
Kenneth Lamb ◽  
Fang Zhong ◽  
G. F. Gebhart ◽  
Klaus Bielefeldt
Keyword(s):  
Experimental Colitis ◽  
The Body ◽  
Thermal Stimulation ◽  
Trinitrobenzenesulfonic Acid ◽  
Afferent Pathways ◽  
Colorectal Distension ◽  
Pain Syndromes ◽  
Response Thresholds ◽  
Frequent Micturition ◽  
Stimulation Of

Chronic pain syndromes affecting different organs often coexist. We hypothesized that sensitization of one afferent pathway may affect converging input from other areas of the body. We induced colitis in mice with 2,4,6-trinitrobenzenesulfonic acid (TNBS); control animals were treated with equal volumes of vehicle (50% ethanol) only. Visceromotor responses to graded colorectal distension, cystometrograms, and response thresholds to mechanical and thermal stimulation of both hind paws were determined on days 7 and 14. Inflammation of colon and bladder was assessed with validated histological markers and scores. TNBS caused significant colitis on day 7 that resolved by day 14; there was no evidence of bladder inflammation. There was a significant hypersensitivity to colorectal distension on day 7, which returned to normal on day 14. This was associated with bladder overactivity, as demonstrated by early onset of micturition and more frequent micturition on day 7 after TNBS administration. Colitis also significantly altered responses to mechanical and thermal stimulation of both hind paws on day 7 but not day 14. We conclude that cross talk between afferent visceral and somatic pathways may contribute to the coexistence of pain syndromes.

scholarly journals Broadly Tuned Spinal Neurons for Each Form of Fictive Scratching in Spinal Turtles

2001 ◽  
Vol 86 (2) ◽  
pp. 1017-1025 ◽  
Author(s):  
Ari Berkowitz
Keyword(s):  
Spinal Cord ◽  
Gray Matter ◽  
Body Surface ◽  
The Body ◽  
Spinal Neurons ◽  
Behavioral Choice ◽  
Spinal Cord Segment ◽  
Single Animal ◽  
Large Populations ◽  
Propriospinal Neurons

Behavioral choice can be mediated either by a small number of sharply tuned neurons or by large populations of broadly tuned neurons. This issue can be conveniently examined in the turtle spinal cord, which generates each of three forms of scratching—rostral, pocket, and caudal—in response to mechanical stimulation in each of three adjacent regions of the body surface. Previous research showed that many propriospinal neurons are broadly tuned to either the rostral scratch region or the pocket scratch region, but responses to caudal scratch stimulation could not be examined in that reduced preparation. In the current study, individual spinal neurons were recorded extracellularly from the gray matter of the turtle spinal cord hindlimb enlargement, while sites in the rostral, pocket, and caudal scratch regions were mechanically stimulated. Many neurons were broadly tuned to the caudal scratch region; other neurons were broadly tuned to either the pocket scratch or rostral scratch region. All three types were typically found within a single animal. These data are consistent with the hypothesis that the turtle spinal cord relies on large populations of broadly tuned neurons to select each of the three forms of scratching. In addition, neurons that were broadly tuned to each of the scratch regions were typically found in each spinal cord segment and within the same range of mediolateral and dorsoventral locations. Providing that these neurons are related to the selection and generation of the three forms of scratching, this would indicate that cells of this type are not segregated into distinct regions of the spinal cord gray matter.

Ventilatory response to drug-induced hypermetabolism

1975 ◽  
Vol 38 (5) ◽  
pp. 827-833 ◽  
Author(s):  
S. Levine ◽  
W. E. Huckabee
Keyword(s):  
Spinal Cord ◽  
Cervical Spinal Cord ◽  
Minute Ventilation ◽  
The Body ◽  
Low Oxygen ◽  
Drug Induced ◽  
Afferent Pathways ◽  
Co2 Gas ◽  
Ventilatory Responses ◽  
Carotid Bodies

Previous workers have demonstrated that an increase in minute ventilation accompanies tissue hypermetabolism induced by uncouplers of oxidative phosphorylation. The mechanism of this increase in minute ventilation has not been established. Accordingly, 2.5 mg/kg of 2,4-dinitrophenol (DNP) or 8–15 mg/kg of ethyl methylene blue (EMB) were infused into chloralose-anesthetized mongrel dogs; Vo2 increased 105 plus or minus 3% and VE INCREASED 107 PLUS OR MINUS 14%. Heads of vagotomized dogs were then perfused entirely with normal unchanging blood. Spinal cord remained intact. (The carotid bodies lay within the region of the perfused head.) Ventilatory responses of these head-perfused animals to breathing low oxygen and to breathing high CO2 gas mixtures were greatly attenuated. However, when DNP or EMB was infused into the body, VO2 increased 114 plus or minus 23% and VE increased 123 plus or minus 22%. When similar doses of DNP or emb were selectively administered to the head, increases in VE were limited to 21 plus or minus 6%. It is concluded that a major portion of the stimulus to ventilation, which accompanies infusion of DNP or of EMB, arises in tissues other than arterial chemoreceptors and brain. Presumably, this ventilatory stimulus is transmitted to the respiratory center via afferent pathways of the cervical spinal cord.

Role of peripheral tissue receptors in stimulation of ventilation by 2,4-dinitrophenol

1979 ◽  
Vol 47 (5) ◽  
pp. 1066-1073 ◽  
Author(s):  
S. Levine
Keyword(s):  
Spinal Cord ◽  
Lumbar Spinal Cord ◽  
Afferent Pathways ◽  
Lumbar Level ◽  
Complete Transection ◽  
Group I ◽  
Group Ii ◽  
Lumbar Spinal ◽  
Quantitative Contribution ◽  
Stimulation Of

Previous workers have demonstrated that hindlimb receptors can mediate some portion of the increase in VE elicited by 2,4-dinitrophenol (DNP). Liang and Hood have recently demonstrated that these hindlimb receptors communicate with the respiratory center via afferent pathways of the lumbar spinal cord. Accordingly, to determine the quantitative contribution of these hindlimb receptors to increases in VE elicited by DNP (4 mg/kg), we compared two groups of animals with respect to ventilatory, metabolic, and thermal responses elicited by this drug. Group I animals underwent complete transection of the spinal cord at the first lumbar level, whereas the spinal cord in Group II animals remained intact. Our results indicate that Group I and Group II animals did not differ with respect to increases in VE, VO2, and rectal temperature elicited by DNP. These results suggest that hindlimb receptors do not play an obligatory role in mediating increases in VE elicited by DNP. Therefore, these observations raise the possibility that multiple afferent pathways may exist for stimulation of VE by DNP.

Visceral and somatic afferent convergence onto neurons near the central canal in the sacral spinal cord of the cat

1985 ◽  
Vol 53 (4) ◽  
pp. 1059-1078 ◽  
Author(s):  
C. N. Honda
Keyword(s):  
Spinal Cord ◽  
Gray Matter ◽  
Receptive Fields ◽  
Central Canal ◽  
The Body ◽  
Wide Range ◽  
Pelvic Viscera ◽  
Somatic Receptive Fields ◽  
Sacral Spinal Cord ◽  
Stimulation Of

One hundred and sixty extracellularly and intracellularly recorded unitary discharges from the sacral or caudal spinal segments of 30 anemically decerebrated cats were studied to examine the effects of somatic and visceral afferent stimulation on neurons near the central canal (CC). The recorded unitary activity was histologically verified (by dye marks or horseradish peroxidase, HRP) as having come from the gray matter surrounding the CC that approximates Rexed's lamina X. In the absence of intentional stimulation or apparent injury by the recording electrode, 62% of the units exhibited ongoing discharges. Each unit was tested for responses to the stimulation of somatic (cutaneous and subcutaneous) and visceral (bladder and colon) structures. Seventy-six (48%) of the units responded exclusively to the stimulation of somatic receptive fields, and 10 (6%) of the units were selectively responsive to stimulation of the pelvic viscera. The activity of the remaining 74 (46%) was influenced by activity in both somatic and visceral afferent fibers. Eighteen of the 160 neurons were intracellularly marked with HRP. Based on perikaryal size and dendritic extent, it was possible to divide these cells into two partially overlapping groups. One group consisted of seven neurons with small to medium-sized perikarya, dendritic arbors largely restricted to the gray matter surrounding the CC, and small, singular somatic receptive fields. The second group comprised 11 cells with medium to large-sized soma and dendrites extending out of lamina X. These larger neurons usually possessed multiple, widely distributed somatic receptive fields. The principal finding of the present study is that in the sacral spinal cord many cells near the CC receive primary afferent inputs converging from a wide range of receptor types in somatic and visceral structures. Such neurons are capable of integrating afferent information from somatic structures on both sides of the body with information originating in pelvic viscera and midline regions such as the genitals.

Identification of interneurons with contralateral, caudal axons in the lamprey spinal cord: synaptic interactions and morphology

1982 ◽  
Vol 47 (5) ◽  
pp. 961-975 ◽  
Author(s):  
J. T. Buchanan
Keyword(s):  
Spinal Cord ◽  
Motor Coordination ◽  
Contralateral Side ◽  
Müller Cell ◽  
The Body ◽  
Intracellular Stimulation ◽  
Muller Cell ◽  
Axon Branch ◽  
Dorsal Cells ◽  
Stimulation Of

1. As part of a continuing investigation of the organization of the spinal cord of the lamprey, propriospinal interneurons with axons projecting contralaterally and caudally (CC interneurons) were surveyed with intracellular recordings. 2. CC interneurons were identified by recording their axon spikes extracellularly in the spinal cord during intracellular stimulation of the cell body. The axon projections of Cc interneurons were confirmed after intracellular injection and development of horseradish peroxidase. 3. Intracellular stimulation of CC interneurons produced synaptic potentials in myotomal motoneurons, lateral interneurons and other CC interneurons that lay caudally on the opposite side of the spinal cord. Most CC interneurons were inhibitory, but some were excitatory. 4. CC interneurons were divided into three classes on the basis of reticulospinal Muller cell inputs. CC1 interneurons were excited by the ipsilateral Muller cell B1 and the contralateral Mauthner cell. CC1 interneurons were inhibitory. They were excited polysynaptically by ipsilateral sensory dorsal cells and were inhibited by contralateral dorsal cells. They were distinguished morphologically by having no rostral axon branch and no contralateral dendrites. CC1 interneurons were phasically active during fictive swimming with their peak depolarizations preceding those of myotomal motoneurons by about 0.15 cycle. 5. CC2 interneurons were also inhibitory, but they were distinguished from CC1 interneurons by their excitation from the ipsilateral Muller cells B2-4 nd by their thin rostral and thicker caudal axonal branches on the contralateral side of the spinal cord. 6. CC3 interneurons were excitatory, and they were inhibited by the ipsilateral Muller cell I1. CC3 interneurons could have contralateral dendrites and bifurcating axons, and they had lower average axonal conduction velocities than CC1 and CC2 interneurons. 7. Inhibitory CC interneurons may be important for motor coordination in the lamprey. Movements of the lamprey body during reflexes and swimming consist of contraction and relaxation of myotomal muscles on opposite sides of the body. By being coactive with ipsilateral myotomal motoneurons, inhibitory CC interneurons could contribute to the inhibition of contralateral motoneurons during these movements.

scholarly journals Flexibility of Motor Pattern Generation Across Stimulation Conditions by the Neonatal Rat Spinal Cord

2010 ◽  
Vol 103 (3) ◽  
pp. 1580-1590 ◽  
Author(s):  
David A. Klein ◽  
Angelica Patino ◽  
Matthew C. Tresch
Keyword(s):  
Spinal Cord ◽  
Electrical Stimulation ◽  
Muscle Activation ◽  
Motor Pattern ◽  
Pattern Generation ◽  
Neonatal Rat ◽  
Rat Spinal Cord ◽  
Afferent Pathways ◽  
Motor Pattern Generation ◽  
Stimulation Of

Previous studies have demonstrated that “locomotor-like” rhythmic patterns can be evoked in the isolated neonatal rat spinal cord by several means, including pharmacological neuromodulation and electrical stimulation of various pathways. Recent studies have used stimulation of afferent pathways to evoke rhythmic patterns, relying on synaptic activation of interneuronal systems rather than global imposition of neuromodulatory state by pharmacological agents. We use the in vitro neonatal rat spinal cord with attached hindlimb to examine the muscle activation patterns evoked by stimulation of these different pathways and evaluate whether stimulation of these pathways all evoke the same patterns. We find that the patterns evoked by bath application of serotonin (5-HT) and N-methyl-d-aspartic acid (NMDA) consisted of alternation between hip flexors and extensors and similar alternation was observed in the patterns evoked by electrical stimulation of the cauda equina (CE) or contralateral fifth lumbar (L5) dorsal nerve root. In contrast, the knee extensor/hip flexor rectus femoris (RF) and knee flexor/hip extensor semitendinosus (ST) were activated differentially across stimulation conditions. In 5-HT/NMDA patterns, RF was active in late flexion and ST in late extension. In CE patterns, these two muscles switched places with RF typically active in late extension and ST active in flexion. In L5 patterns, ST was activated in extension and RF was silent or weakly active during flexion. There were also systematic differences in the consistency of rhythms evoked by each stimulation method: patterns evoked by electrical stimulation of CE or L5 were less consistently modulated with the rhythm when compared with 5-HT/NMDA-evoked patterns. All differences were preserved following deafferentation, demonstrating that they reflect intrinsic properties of spinal systems. These results highlight the intrinsic flexibility of motor pattern generation by spinal motor circuitry which is present from birth and provides important information to many studies examining spinal pattern generating networks.

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