A progressive and cumulative suppression of the activity of spinal neurones in the nonspinal rat

1977 ◽  
Vol 55 (1) ◽  
pp. 125-129 ◽  
Author(s):  
J. F. MacDonald ◽  
J. A. Pearson
Keyword(s):  
Electrical Stimulation ◽  
Interstimulus Interval ◽  
Noxious Stimulation ◽  
Tonic Activity ◽  
Flexor Reflex ◽  
Successive Stimulus ◽  
Spinal Neurones ◽  
Evoked Activity ◽  
Stimulation Of

Electrical stimulation of the skin of the hindpaw of the rat, at frequencies ranging from 2 to 0.2 s−1, halted the tonic or evoked activity of spinal neurones. The duration of this effect increased with each successive stimulus until it outlasted the interstimulus interval. Tonic activity did not return immediately following termination of the stimulation, and activity was often depressed for periods of up to 5 min. Neurones displaying this behaviour were found in laminae 1 and 4–7 of the cord. Some neurones failed to demonstrate this behaviour following the administration of strychnine. This phenomenon provides a possible substrate for habituation of the flexor reflex that occurs with repetitive and noxious stimulation of the skin.

Responses of rat spinal neurones to natural and electrical stimulation of colonic afferents: effect of inflammation

2000 ◽  
Vol 866 (1-2) ◽  
pp. 168-177 ◽  
Author(s):  
Teresa Olivar ◽  
Fernando Cervero ◽  
Jennifer M.A Laird
Keyword(s):  
Electrical Stimulation ◽  
Spinal Neurones ◽  
Stimulation Of

Pre- and postganglionic sympathetic activity in splanchnic nerves of rats

1981 ◽  
Vol 241 (1) ◽  
pp. R55-R61 ◽  
Author(s):  
B. G. Celler ◽  
L. P. Schramm
Keyword(s):  
Electrical Stimulation ◽  
Sympathetic Activity ◽  
Wistar Rats ◽  
Splanchnic Nerve ◽  
Ganglionic Blockade ◽  
Splanchnic Nerves ◽  
Before And After ◽  
Evoked Activity ◽  
Greater Splanchnic Nerve ◽  
Stimulation Of

Integrated sympathetic activity was recorded on anterior or posterior divisions of the greater splanchnic nerve (GSN) in anesthetized, acutely spinalized, artificially respired Wistar rats before and after ganglionic blockade by hexamethonium. Focal electrical stimulation of spinal sympathoexcitatory pathways elicited large increases in splanchnic sympathetic activity. Ganglionic blockade showed that the anterior and posterior divisions of the GSN are predominantly preganglionic and postganglionic, respectively. Histological examination of excised splanchnic nerves and sympathetic chains indicated that splanchnic postganglionic cell bodies must lie in the chain ganglia rather than within the GSN. Postganglionic responses were calculated for each rat by subtracting responses recorded after ganglionic blockade from responses recorded before ganglionic blockade. As expected, postganglionic responses exhibited longer onset latencies than preganglionic responses. However, evoked activity increased and decreased more rapidly in postganglionic fibers than in preganglionic fibers. Responses to stimulus trains were also better maintained in postganglionic than in preganglionic fibers.

The co-ordination of the protective retraction of coral polyps

1957 ◽  
Vol 240 (675) ◽  
pp. 495-529 ◽  
Keyword(s):  
Electrical Stimulation ◽  
Electrical Stimulus ◽  
Simple Theory ◽  
Conducting System ◽  
Common Theme ◽  
Single Shock ◽  
Working Model ◽  
Successive Stimulus ◽  
The Individual ◽  
Stimulation Of

The responses to electrical stimulation of a number of alcyonarian, zoanthid and madreporarian corals are described. All groups studied except gorgonids show extensive coordination over the colony. In Sarcophyton (Alcyonacea) the response is typically local at first but eventually a wave of polyp retraction can be made to spread over the colony. The astraeid corals and the alcyonarian Tubipora have over the whole colony a through-conducting system which has refractory and neuromuscular properties similar to those found in the mesenteries of actinians. In the zoanthid Palythoa successive shocks produce excitation which spreads progressively farther across the colony at each shock for as many as fifty shocks at two-second intervals. The perforate corals , Acropora, Goniopora and Porites respond to a single shock by a co-ordinated retraction of many polyps. Except in Acropora , it is characteristic of the perforate corals studied that stimulation at one point never spreads over the whole colony no matter how many stimuli are applied. The responses of the individual polyps of many corals, including Fungia , are described, and in all there is a similarity to the column, disk and tentacle responses already known in actinians, e.g. Calliactis . The concept of interneural facilitation has been analyzed by use of a working model which shows that the simple theory is inadequate as an explanation of transmission between polyps of certain species because the predicted transmission distances are either too variable or too small compared with the actual distances observed at the first electrical stimulus of the animal. The properties of the co-ordinating systems between the polyps of the various groups of corals have been considered as variations on a common theme, conduction between units which form a network. The various stages from poor co-ordination, through progressive spread at each successive stimulus, to a through-conducting condition have been interpreted as a reflexion of increasing probability of transmission from one all-or-nothing unit of the pathway to the next unit in a population of a large number of units, only a proportion of which may be active at any one time. The units may be interpreted as neurones, as is probable in parts of a single polyp, or as small regions such as polyps within which there is normally through-conduction at the first stimulus.

Ongoing and Stimulus-Evoked Activity of Sympathetically Correlated Neurons in the Intermediate Zone and Dorsal Horn of Acutely Spinalized Rats

2000 ◽  
Vol 83 (5) ◽  
pp. 2699-2707 ◽  
Author(s):  
David Chau ◽  
Devin G. Johns ◽  
Lawrence P. Schramm
Keyword(s):  
Dorsal Horn ◽  
Intermediate Zone ◽  
The Other ◽  
Noxious Stimulation ◽  
Renal Sympathetic Nerve Activity ◽  
Other Hand ◽  
Evoked Activity ◽  
Processing Properties ◽  
Injured Patients ◽  
Stimulation Of

We have shown previously that in the acutely spinalized anesthetized rat the activities of many dorsal horn interneurons (DHN) at the T10 level are correlated positively with both ongoing and stimulus-evoked renal sympathetic nerve activity (RSNA) and therefore may belong to networks generating RSNA after acute, cervical, spinal transection. In the present study, we recorded from both DHN and interneurons in the intermediate zone (IZN) of the T10spinal segment in acutely C1-transected, chloralose-anesthetized, artificially respired rats. The activities of a similar percentage of IZN and DHN were correlated positively with ongoing RSNA, but the peaks of spike-triggered averages of RSNA based on the activity of IZN were larger, relative to dummy averages, than spike-triggered averages of RSNA based on the activity of DHN. Sympathetically correlated DHN and IZN differed in their responses to noxious somatic stimuli. Most correlated DHN had relatively simple somatic fields; they were excited by noxious stimulation of the T10 and nearby dermatomes and inhibited by stimulation of more distal dermatomes. As we have shown previously, the excitatory and inhibitory fields of these neurons were very similar to fields that, respectively, excited and inhibited RSNA. On the other hand, the somatic fields of 50% of sympathetically correlated IZN were significantly more complex, indicating a difference between either the inputs or the processing properties of IZN and DHN. Sympathetically correlated IZN and DHN also differed in their responses to colorectal distension (CRD), a noxious visceral stimulus. CRD increased RSNA in 11/15 rats and increased the activity of most sympathetically correlated T10 IZN. On the other hand, CRD decreased the activity of a majority of sympathetically correlated T10 DHN. These observations suggest that the same stimulus may differentially affect separate, putative, sympathoexcitatory pathways, exciting one and inhibiting the other. Thus the magnitude and even the polarity of responses to a given stimulus may be determined by the modality and location of the stimulus, the degree to which multiple pathways are affected by the stimulus, and the ongoing activity of presympathetic neurons, at multiple rostrocaudal levels, before stimulation. A multipathway system may explain the variability in autonomic responses to visceral and somatic stimuli exhibited in spinally injured patients.

Anatomy and physiology of a nociceptive modulatory system

1985 ◽  
Vol 308 (1136) ◽  
pp. 361-374 ◽  
Keyword(s):  
Spinal Cord ◽  
Electrical Stimulation ◽  
Tail Flick ◽  
Noxious Stimulation ◽  
Spinal Neurons ◽  
Nociceptive Transmission ◽  
Anatomy And Physiology ◽  
Negative Feedback Circuit ◽  
Clinically Significant ◽  
Stimulation Of

Although efferent control of sensory transmission is a well-established concept, a specific network for nociceptive modulation has only recently been discovered. This network includes interconnected components at midbrain, medullary and spinal levels. At the midbrain level, electrical stimulation of the periaqueductal grey (p.a.g.) inhibits spinal neurons that respond to noxious stimuli as well as nociceptor-induced reflexes and escape behaviour in a variety of species. Midbrain stimulation also produces analgesia in patients with clinically significant pain. The rostral ventral medulla (r.v.m.) has similar behavioural and physiological effects and mediates midbrain antinociceptive actions at the level of the spinal cord. Endorphins are present at all levels of this nociceptive modulating network. Opiate microinjections at p.a.g., r.v.m. or spinal levels produce analgesia, presumably by mimicking the actions of the endorphins. The nociceptive modulatory system is diffusely organized, highly interconnected and appears to act as a unit whether activated by opiates or electrical stimulation. There are two classes of r.v.m. neurons the activity of which is correlated with the occurrence of reflexes induced by noxious stimulation. One class (the on-cell) accelerates, the other class (the off-cell) pauses just before tail flick. Both classes project to the spinal cord and are excited by electrical stimulation of the midbrain. However, when morphine is injected either systemically or into the p.a.g., the off-cell is excited and the on-cell stops firing. The off-cell is probably the r.v.m. output cell that inhibits nociceptive transmission at the level of the spinal cord. The function of the on-cell is not clear. The nociceptive modulatory system can be activated by a variety of stressful environmental factors, which are often, but not necessarily, noxious. The idea that the system acts as a simple negative feedback circuit is not consistent with its known properties.

Delayed Punishment of Positively Reinforced Bar Presses

1967 ◽  
Vol 21 (1) ◽  
pp. 205-210 ◽  
Author(s):  
Douglas E. Miller ◽  
Larry D. Reid ◽  
Paul B. Porter
Keyword(s):  
Electrical Stimulation ◽  
Interstimulus Interval ◽  
Negative Reinforcement ◽  
Neural Interaction ◽  
Lever Pressing ◽  
Delayed Punishment ◽  
The Brain ◽  
Maximal Suppression ◽  
Stimulation Of ◽  
Reward And Punishment

Combining positive and negative reinforcement (both being electrical stimulation of the brain) for lever pressing by 4 rats produced a gradient of suppression as the 2 qualities of reinforcement were separated temporally. Maximal suppression occurred with an interstimulus interval of about 1 sec. This maximum was interpreted as marking the intersection of a waning interaction of the neurological aspects of reward and punishment and a delay-of-punishment gradient. After the 1 sec. of neural interaction, the greater the delay of punishment the less the suppression of responding.

Inhibitory effects of excess sympathetic activity on parasympathetic vasodilation in the rat masseter muscle

2007 ◽  
Vol 293 (2) ◽  
pp. R729-R736 ◽  
Author(s):  
Hisayoshi Ishii ◽  
Takeharu Niioka ◽  
Hidekazu Watanabe ◽  
Hiroshi Izumi
Keyword(s):  
Electrical Stimulation ◽  
Sympathetic Activity ◽  
Masseter Muscle ◽  
Lingual Nerve ◽  
Dependent Manner ◽  
Tonic Activity ◽  
Inhibitory Effects ◽  
Cervical Sympathetic ◽  
Dose Dependent ◽  
Stimulation Of

The present study was designed to examine the effect of sympathetic tonic activity on parasympathetic vasodilation evoked by the trigeminal-mediated reflex in the masseter muscle in urethane-anesthetized rats. Sectioning of the superior cervical sympathetic trunk (CST) ipsilaterally increased the basal level of blood flow in the masseter muscle (MBF). Electrical stimulation of the peripheral cut end of the CST for 2 min using 2-ms pulses ipsilaterally decreased in a dependent manner the intensity (0.5–10 V) and frequency (0.1–5 Hz) of the MBF. The CST stimulation for 2 min at <0.5 Hz with 5 V using 2-ms pulses seems to be comparable with the spontaneous activity in the CST fibers innervating the masseter vasculature, because this stimulation restored the basal level of the MBF to the presectioned values. Parasympathetic vasodilation evoked by electrical stimulation of the central cut end of the lingual nerve in the masseter muscle was markedly reduced by CST stimulation for 2 min with 5 V using 2-ms pulses in a frequency-dependent manner (0.5–5 Hz). Intravenous administration of phentolamine significantly reduced the vasoconstriction induced by CST stimulation in a dose-dependent manner (0.1–1 mg/kg), but pretreatment with either phentolamine or propranolol failed to affect the sympathetic inhibition of the parasympathetic vasodilation. Our results suggest that 1) excess sympathetic activity inhibits parasympathetic vasodilation in the masseter muscle, and 2) α- and β-adrenoceptors do not contribute to sympathetic inhibition of parasympathetic vasodilation, and thus some other types of receptors must be involved in this response.

Taste Responses of Neurons in the Hamster Solitary Nucleus Are Modulated by the Central Nucleus of the Amygdala

2002 ◽  
Vol 88 (6) ◽  
pp. 2979-2992 ◽  
Author(s):  
Cheng-Shu Li ◽  
Young K. Cho ◽  
David V. Smith
Keyword(s):  
Electrical Stimulation ◽  
Signal To Noise Ratio ◽  
Central Nucleus ◽  
Homocysteic Acid ◽  
Excitatory Response ◽  
Afferent Information ◽  
Parabrachial Nuclei ◽  
Evoked Activity ◽  
Stimulation Of

Previous studies have shown a modulatory influence of forebrain gustatory areas, such as the gustatory cortex and lateral hypothalamus, on the activity of taste-responsive cells in the nucleus of the solitary tract (NST). The central nucleus of the amygdala (CeA), which receives gustatory afferent information, also exerts descending control over taste neurons in the parabrachial nuclei (PbN) of the pons. The present studies were designed to investigate the role of descending amgydaloid projections to the NST in the modulation of gustatory activity. Extracellular action potentials were recorded from 109 taste-responsive cells in the NST of urethan-anesthetized hamsters and analyzed for a change in excitability following electrical and chemical stimulation of the CeA. Electrical stimulation of the CeA orthodromically modulated 36 of 109 (33.0%) taste-responsive NST cells. An excitatory response was observed in 33 (30.28%) cells. An initial decrease in excitability to electrical stimulation of the CeA, suggestive of postsynaptic inhibition, was observed in three (2.75%) NST taste cells. NST cells modulated by the CeA were significantly less responsive to taste stimuli than cells that were not. Many of these cells were under the modulatory influence of the contralateral CeA (28/36 = 77.8%) as well as the ipsilateral (22/36 = 61.1%); 14 (38.9%) were excited bilaterally. Latencies for excitation were longer after ipsilateral than after contralateral CeA stimulation. Microinjection of dl-homocysteic acid (DLH) into the CeA mimicked the effect of electrical stimulation on each of the nine cells tested: DLH excited eight and inhibited one of these electrically activated NST cells. Application of subthreshold electrical stimulation to the CeA during taste trials increased the taste responses of every CeA-responsive NST cell ( n = 7) tested with this protocol. These effects would enhance taste discriminability by increasing the signal-to-noise ratio of taste-evoked activity.

Temporal Summation Governs Part of the Minimum Alveolar Concentration of Isoflurane Anesthesia

2003 ◽  
Vol 98 (6) ◽  
pp. 1372-1377 ◽  
Author(s):  
Robert C. Dutton ◽  
Yi Zhang ◽  
Caroline R. Stabernack ◽  
Michael J. Laster ◽  
James M. Sonner ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Interstimulus Interval ◽  
Temporal Summation ◽  
Minimum Alveolar Concentration ◽  
Cumulative Effect ◽  
Noxious Stimulation ◽  
Isoflurane Anesthesia ◽  
Aspartate Receptor ◽  
Interstimulus Intervals ◽  
Response To Change

Background General anesthesia may delay the onset of movement in response to noxious stimulation. The authors hypothesized that the production of immobility could involve depression of time-related processes involved in the generation of movement. Methods The delays (latencies) between onset of tail clamp (n = 16) or 50-Hz continuous electrical stimulation (n = 8) and movement were measured in rats equilibrated at 0.1-0.2% increasing steps of isoflurane. In other rats (n = 8), the isoflurane concentrations just permitting and preventing movement (crossover concentrations) in response to trains of 0.5-ms 50-V square-wave pulses of interstimulus intervals of 10, 3, 1, 0.3, or 0.1 s during the step increases were measured. These measures were again made during administration of intravenous MK801, an N-methyl-D-aspartate receptor antagonist that can block temporal summation (n = 6). Temporal summation refers to the cumulative effect of repeated stimuli. Crossover concentrations to 10- and 0.1-s interstimulus interval pulses ranging in voltage from 0.25-50 V were also measured (n = 4). Results The increase in concentrations from 0.6 to nearly 1.0 minimum alveolar concentration progressively increased latency from less than 1 s to 58 s. Shortening the interstimulus interval (50 V) pulses from 10 to 0.1 s progressively increased crossover concentrations from 0.6 to 1.0 minimum alveolar concentration. In contrast, during MK801 administration shortening interstimulus intervals did not change crossover concentrations, producing a flat response to change in the interstimulus interval. Increasing the voltage of interstimulus interval pulses increased the crossover concentrations but did not change the response to change in interstimulus intervals for pulses greater than 1 V. Conclusions Increasing the duration or frequency (interstimulus interval) of stimulation increases the concentration of isoflurane required to suppress movement by a 0.4 minimum alveolar concentration MK801 blocks this effect, a finding consistent with temporal summation (which requires intact N-methyl-D-aspartate receptor activity) at concentrations of up to 1 minimum alveolar concentration isoflurane.

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