Responses of medullary reticular formation neurons to input from the male genitalia

1996 ◽  
Vol 76 (4) ◽  
pp. 2474-2482 ◽  
Author(s):  
C. H. Hubscher ◽  
R. D. Johnson
Keyword(s):  
Electrical Stimulation ◽  
Reticular Formation ◽  
Male Genitalia ◽  
Motor Behavior ◽  
The Body ◽  
Male Rats ◽  
Single Neurons ◽  
Medullary Reticular Formation ◽  
Reproductive Behaviors ◽  
Stimulation Of

1. The medullary reticular formation (MRF) is known to be involved in the modulation of certain reproductive behaviors. Ejaculation in the male, disrupted after spinal transection, may depend on a spinal-bulbo-spinal connection. To determine whether single neurons in the MRF receive sensory input from the male genitalia, the present study was undertaken using electrophysiological techniques. 2. The MRF of 14 urethan-anesthetized mature male rats was searched for single neurons responsive to bilateral electrical stimulation of the dorsal nerve of the penis (DNP). In addition, each DNP-responsive neuron was tested for responsiveness to bilateral electrical stimulation of the pelvic nerve (PN) and to mechanical stimulation (gentle touch, pressure, pinch) of the external genitalia, anus, urethra, and skin over most regions of the body. 3. A total of 165 single neurons responsive to bilateral electrical stimulation of the DNP were isolated and characterized throughout the MRF. All neurons responded to both ipsilateral and contralateral DNP stimulation. The majority of responses were excitatory, and most neurons had no background activity. Some neurons required wind-up with bilateral electrical stimulation of the DNP to respond. 4. About half of the neurons were located in the nucleus reticularis gigantocellularis (Gi); the remainder were located in surrounding (dorsal, ventral, lateral) regions of the MRF. Variations in response properties were found among neurons located in different MRF regions. 5. Eighty-eight DNP-responsive neurons were additionally responsive to bilateral electrical stimulation of the PN. None of the responses to bilateral PN were stronger than those for bilateral DNP and many (48%) were weaker. 6. Of the 165 DNP-responsive neurons, all were responsive to pressure/pinching of the penis; 16% responded to gentle stroking of the glans. Most of these neurons were additionally responsive (bilaterally) to pinching more than one (often all) of the following areas: perineum, scrotum, anus, ears, and toes (forefoot and hindfoot). 7. In conclusion, neurons located in the MRF of male rats are involved in the processing of bilaterally convergent inputs from multiple cutaneous and visceral regions of the body, including the penis and male urogenital tract. These neurons likely exert their effects by directly and/or indirectly activating ascending pathways to rostral regions of the brain important for somatovisceral sensation and motor behavior, and descending pathways to the spinal cord for modulation of segmental sexual reflexes. Contributions are likely for a wide spectrum of sensations and reproductive behaviors.

Convergence of heterotopic nociceptive information onto neurons of caudal medullary reticular formation in monkey (Macaca fascicularis)

1990 ◽  
Vol 63 (5) ◽  
pp. 1118-1127 ◽  
Author(s):  
L. Villanueva ◽  
K. D. Cliffer ◽  
L. S. Sorkin ◽  
D. Le Bars ◽  
W. D. Willis
Keyword(s):  
Electrical Stimulation ◽  
Reticular Formation ◽  
Mechanical Stimulation ◽  
Background Activity ◽  
The Body ◽  
Thermal Stimulation ◽  
Medullary Reticular Formation ◽  
Nociceptive Information ◽  
Noxious Mechanical Stimulation ◽  
Stimulation Of

1. Recordings were made in anesthetized monkeys from neurons in the medullary reticular formation (MRF) caudal to the obex. Responses of 19 MRF neurons to mechanical, thermal, and/or electrical stimulation were examined. MRF neurons exhibited convergence of nociceptive cutaneous inputs from widespread areas of the body and face. 2. MRF neurons exhibited low levels of background activity. Background activity increased after periods of intense cutaneous mechanical or thermal stimulation. Nearly all MRF neurons tested failed to respond to heterosensory stimuli (flashes, whistle sounds), and none responded to joint movements. 3. MRF neurons were excited by and encoded the intensity of noxious mechanical stimulation. Responses to stimuli on contralateral limbs were greater than those to stimuli on ipsilateral limbs. Responses were greater to stimuli on the forelimbs than to stimuli on the hindlimbs. 4. MRF neurons responded to noxious thermal stimulation (51 degrees C) of widespread areas of the body. Mean responses from stimulation at different locations were generally parallel to those for noxious mechanical stimulation. Responses increased with intensity of noxious thermal stimulation (45-50 degrees C). 5. MRF neurons responded with one or two peaks of activation to percutaneous electrical stimulation applied to the limbs, the face, or the tail. The differences in latency of responses to stimulating two locations along the tail suggested that activity was elicited by activation of peripheral fibers with a mean conduction velocity in the A delta range. Stimulation of the contralateral hindlimb elicited greater responses, with lower thresholds and shorter latencies, than did stimulation of the ipsilateral hindlimb. 6. Electrophysiological properties of monkey MRF neurons resembled those of neurons in the medullary subnucleus reticularis dorsalis (SRD) in the rat. Neurons in the caudal medullary reticular formation could play a role in processing nociceptive information. Convergence of nociceptive cutaneous input from widespread areas of the body suggests that MRF neurons may contribute to autonomic, affective, attentional, and/or sensory-motor processes related to pain.

scholarly journals Global Cerebral Vasodilatation Elicited by Focal Electrical Stimulation within the Dorsal Medullary Reticular Formation in Anesthetized Rat

1983 ◽  
Vol 3 (3) ◽  
pp. 270-279 ◽  
Author(s):  
Costantino Iadecola ◽  
Masatsugu Nakai ◽  
Ehud Arbit ◽  
Donald J. Reis
Keyword(s):  
Electrical Stimulation ◽  
Reticular Formation ◽  
Medial Longitudinal Fasciculus ◽  
Medullary Reticular Formation ◽  
Tissue Samples ◽  
The Central Nervous System ◽  
Cerebral Vasodilatation ◽  
Cervical Sympathetic ◽  
Global Increase ◽  
Stimulation Of

We examined the effects of electrical stimulation of a restricted area of the dorsal medullary reticular formation (DMRF) on regional cerebral blood flow (CBF) in anesthetized (by chloralose), paralyzed (by curare) rats. CBF was measured in tissue samples by the Kety principle, with 14C-iodoantipyrine as indicator. Stimulation of DMRF elicited a widespread, significant increase in CBF in 12 of 13 areas. The increase in flow was greatest in cerebral cortex, up to 240% of control. However, it was also substantially increased in selected regions of telencephalon, diencephalon, mesencephalon, and lower brainstem, but not cerebellum. In contrast, electrical stimulation of the midline (interstitial nucleus of the medial longitudinal fasciculus) 1 mm medial to the DMRF did not change CBF. The increase in CBF evoked by DMRF stimulation persisted after transection of the spinal cord at C1 or cervical sympathetic trunk. We conclude that excitation of neurons originating in or passing through the DMRF can elicit a potent and virtually global increase of CBF. The effect appears to be mediated by intrinsic pathways of the central nervous system.

scholarly journals Atonia-Related Regions in the Rodent Pons and Medulla

2000 ◽  
Vol 84 (4) ◽  
pp. 1942-1948 ◽  
Author(s):  
T. Hajnik ◽  
Y. Y. Lai ◽  
J. M. Siegel
Keyword(s):  
Electrical Stimulation ◽  
Brain Stem ◽  
Reticular Formation ◽  
Muscle Tone ◽  
Neck Muscle ◽  
Medullary Reticular Formation ◽  
Anatomical Distribution ◽  
Hindlimb Muscles ◽  
The Brain ◽  
Stimulation Of

Electrical stimulation of circumscribed areas of the pontine and medullary reticular formation inhibits muscle tone in cats. In this report, we present an analysis of the anatomical distribution of atonia-inducing stimulation sites in the brain stem of the rat. Muscle atonia could be elicited by electrical stimulation of the nuclei reticularis pontis oralis and caudalis in the pons as well as the nuclei gigantocellularis, gigantocellularis alpha, gigantocellularis ventralis, and paragigantocellularis dorsalis in the medulla of decerebrate rats. This inhibitory effect on muscle tone was a function of the intensity and frequency of the electrical stimulation. Average latencies of muscle-tone suppressions elicited by electrical stimulation of the pontine reticular formation were 11.02 ± 2.54 and 20.49 ± 3.39 (SD) ms in the neck and in the hindlimb muscles, respectively. Following medullary stimulation, these latencies were 11.29 ± 2.44 ms in the neck and 18.87 ± 2.64 ms in the hindlimb muscles. Microinjection of N-methyl-d-aspartate (NMDA, 7 mM/0.1 μl) agonists into the pontine and medullary inhibitory sites produced muscle-tone facilitation, whereas quisqualate (10 mM/0.1 μl) injection induced an inhibition of muscle tone. NMDA-induced muscle tone change had a latency of 31.8 ± 35.3 s from the pons and 10.5 ± 0.7 s from the medulla and a duration of 146.7 ± 95.2 s from the pons and 55.5 ± 40.4 s from the medulla. The latency of quisqualate (QU)-induced reduction of neck muscle tone was 30.1 ± 37.9 s after pontine and 39.5 ± 21.8 s after medullary injection. The duration of muscle-tone suppression induced by QU injection into the pons and medulla was 111.5 ± 119.2 and 169.2 ± 145.3 s. Smaller rats (8 wk old) had a higher percentage of sites producing muscle-tone inhibition than larger rats (16 wk old), indicating an age-related change in the function of brain stem inhibitory systems. The anatomical distribution of atonia-related sites in the rat has both similarities and differences with the distribution found in the cat, which can be explained by the distinct anatomical organization of the brain stem in these two species.

Global increase in cerebral metabolism and blood flow produced by focal electrical stimulation of dorsal medullary reticular formation in rat

1983 ◽  
Vol 272 (1) ◽  
pp. 101-114 ◽  
Author(s):  
Costantino Iadecola ◽  
Masatsugu Nakai ◽  
Sima Mraovitch ◽  
David A. Ruggiero ◽  
Lewis W. Tucker ◽  
...  
Keyword(s):  
Blood Flow ◽  
Electrical Stimulation ◽  
Reticular Formation ◽  
Cerebral Metabolism ◽  
Medullary Reticular Formation ◽  
Global Increase ◽  
Stimulation Of

OVULATORY DISCHARGE OF GONADOTROPHINS INDUCED BY HYPOTHALAMIC STIMULATION IN CASTRATED MALE RATS BEARING A TRANSPLANTED OVARY

1966 ◽  
Vol 51 (2) ◽  
pp. 281-289 ◽  
Author(s):  
J. Moll ◽  
G. H. Zeilmaker
Keyword(s):  
Electrical Stimulation ◽  
Preoptic Area ◽  
Hypothalamic Stimulation ◽  
Male Rats ◽  
Corpora Lutea ◽  
Histological Changes ◽  
Experimental Animals ◽  
Cumulus Oophorus ◽  
Dc Current ◽  
Stimulation Of

ABSTRACT Castrated young adult inbred male rats bearing ovarian transplants were subjected to electrical stimulation of the hypothalamus. This was done in order to investigate whether discharge of ovulatory amounts of gonadotrophins could be induced in such male animals by this procedure. Bilateral stimulations with unipolar electrodes and a DC current of 1.5 mA applied during 10 seconds induced in the ovarian grafts histological changes indicating the discharge of ovulatory amounts of gonadotrophins. In animals killed one day after stimulation these changes consisted of displacement of the ova towards the centre of the follicles with loosening of the cumulus oophorus. In one animal the ova had left the follicles. In animals killed three days after stimulation numerous young corpora lutea could be observed. These results were obtained with electrode tips either close to the median eminence, or in the preoptic area. Shamstimulations were ineffective. Some of the experimental animals received progesterone pretreatment. This rendered the stimulations ineffective, if continued until the day preceding stimulation, but seemed without effect on the results of stimulation, if two or three days without progesterone preceded the stimulations.

Effect of stimulation of the medullary reticular formation on cerebral vasomotor tonus and intracranial pressure

1987 ◽  
Vol 66 (4) ◽  
pp. 548-554 ◽  
Author(s):  
Seigo Nagao ◽  
Tsukasa Nishiura ◽  
Hideyuki Kuyama ◽  
Masakazu Suga ◽  
Takenobu Murota
Keyword(s):  
Intracranial Pressure ◽  
Reticular Formation ◽  
Cerebral Blood Volume ◽  
Systemic Arterial Pressure ◽  
Brain Swelling ◽  
Dorsomedial Nucleus ◽  
Medullary Reticular Formation ◽  
Content Type ◽  
Fine Print ◽  
Stimulation Of

✓ The authors report the results of a study to evaluate the effect of stimulation of the medullary reticular formation on cerebral vasomotor tonus and intracranial pressure (ICP) after the hypothalamic dorsomedial nucleus and midbrain reticular formation were destroyed. Systemic arterial pressure (BP), ICP, and local cerebral blood volume (CBV) were continuously recorded in 32 cats. To assess the changes in the cerebral vasomotor tonus, the vasomotor index defined by the increase in ICP per unit change in BP was calculated. In 29 of the 32 animals, BP, ICP, and CBV increased simultaneously immediately after stimulation. The increase in ICP was not secondary to the increase in BP, because the vasomotor index during stimulation was significantly higher than the vasomotor index after administration of angiotensin II. The vasomotor index was high during stimulation of the area around the nucleus reticularis parvocellularis. In animals with the spinal cord transected at the C-2 vertebral level, ICP increased without a change in BP. These findings indicate that the areas stimulated in the medullary reticular formation play an important role in decreasing cerebral vasomotor tonus. This effect was not influenced by bilateral superior cervical ganglionectomy, indicating that there is an intrinsic neural pathway that regulates cerebral vasomotor tonus directly. In three animals, marked biphasic or progressive increases in ICP up to 100 mm Hg were evoked by stimulation. The reduction of cerebral vasomotor tonus and concomitant vasopressor response induced by stimulation of the medullary reticular formation may be one of the causes of acute brain swelling.

scholarly journals Calcium-induced calcium release activates spontaneous miniature outward currents in newt medullary reticular formation neurons

2018 ◽  
Vol 120 (6) ◽  
pp. 3140-3154 ◽  
Author(s):  
Daniel B. Yaeger ◽  
Emma J. Coddington
Keyword(s):  
Action Potential ◽  
Reticular Formation ◽  
Calcium Release ◽  
Motor Behavior ◽  
Brain Slices ◽  
Medullary Reticular Formation ◽  
Outward Currents ◽  
Decay Times ◽  
Action Potential Threshold ◽  
Potential Threshold

Neurons in the medullary reticular formation are involved in the control of postural and locomotor behaviors in all vertebrates. Reticulospinal neurons in this brain region provide one of the major descending projections to the spinal cord. Although neurons in the newt medullary reticular formation have been extensively studied using in vivo extracellular recordings, little is known of their intrinsic biophysical properties or of the underlying circuitry of this region. Using whole cell patch-clamp recordings in brain slices containing the rostromedial reticular formation from adult male newts, we observed spontaneous miniature outward currents (SMOCs) in ~2/3 of neurons. Although SMOCs superficially resembled inhibitory postsynaptic currents (IPSCs), they had slower risetimes and decay times than spontaneous IPSCs. SMOCs required intracellular Ca2+ release from ryanodine receptors and were also dependent on the influx of extracellular Ca2+. SMOCs were unaffected by apamin but were partially blocked by iberiotoxin and charybdotoxin, indicating that SMOCs were mediated by big-conductance Ca2+-activated K+ channels. Application of the sarco/endoplasmic Ca2+ ATPase inhibitor cyclopiazonic acid blocked the generation of SMOCs and also increased neural excitability. Neurons with SMOCs had significantly broader action potentials, slower membrane time constants, and higher input resistance than neurons without SMOCs. Thus, SMOCs may serve as a mechanism to regulate action potential threshold in a majority of neurons within the newt medullary reticular formation. NEW & NOTEWORTHY The medullary reticular formation exerts a powerful influence on sensorimotor integration and subsequent motor behavior, yet little is known about the neurons involved. In this study, we identify a transient potassium current that regulates action potential threshold in a majority of medullary reticular neurons.

scholarly journals Properties and Interconnections of Trigeminal Interneurons of the Lateral Pontine Reticular Formation in the Rat

2001 ◽  
Vol 86 (5) ◽  
pp. 2583-2596 ◽  
Author(s):  
M.-J. Bourque ◽  
A. Kolta
Keyword(s):  
Electrical Stimulation ◽  
Reticular Formation ◽  
Motor Pattern ◽  
High Frequency Stimulation ◽  
Motor Nucleus ◽  
Trigeminal Motor Nucleus ◽  
Postsynaptic Potentials ◽  
Frequency Stimulation ◽  
Stimulation Of

Numerous evidence suggests that interneurons located in the lateral tegmentum at the level of the trigeminal motor nucleus contribute importantly to the circuitry involved in mastication. However, the question of whether these neurons participate actively to genesis of the rhythmic motor pattern or simply relay it to trigeminal motoneurons remains open. To answer this question, intracellular recordings were performed in an in vitro slice preparation comprising interneurons of the peritrigeminal area (PeriV) surrounding the trigeminal motor nucleus (NVmt) and the parvocellular reticular formation ventral and caudal to it (PCRt). Intracellular and extracellular injections of anterograde tracers were also used to examine the local connections established by these neurons. In 97% of recordings, electrical stimulation of adjacent areas evoked a postsynaptic potential (PSP). These PSPs were primarily excitatory, but inhibitory and biphasic responses were also induced. Most occurred at latencies longer than those required for monosynaptic transmission and were considered to involve oligosynaptic pathways. Both the anatomical and physiological findings show that all divisions of PeriV and PCRt are extensively interconnected. Most responses followed high-frequency stimulation (50 Hz) and showed little variability in latency indicating that the network reliably distributes inputs across all areas. In all neurons but one, excitatory postsynaptic potentials (EPSPs) or inhibitory postsynaptic potentials (IPSPs) were also elicited by stimulation of NVmt, suggesting the existence of excitatory and inhibitory interneurons within the motor nucleus. In a number of cases, these PSPs were reproduced by local injection of glutamate in lieu of the electrical stimulation. All EPSPs induced by stimulation of PeriV, PCRt, or NVmt were sensitive to ionotropic glutamate receptor antagonists 6-cyano-7-dinitroquinoxaline and d,l-2-amino-5-phosphonovaleric acid, while IPSPs were blocked by bicuculline and strychnine, antagonists of GABAA and glycine receptors. Examination of PeriV and PCRt intrinsic properties indicate that they form a fairly uniform network. Three types of neurons were identified on the basis of their firing adaptation properties. These types were not associated with particular regions. Only 5% of all neurons showed bursting behavior. Our results do not support the hypothesis that neurons of PeriV and PCRt participate actively to rhythm generation, but suggest instead that they are driven by rhythmical synaptic inputs. The organization of the network allows for rapid distribution of this rhythmic input across premotoneuron groups.

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