Cardiac input to medullary reticular formation: neuronal responses to mechanical stimuli

1986 ◽  
Vol 251 (4) ◽  
pp. R680-R689
Author(s):  
R. W. Blair
Keyword(s):  
Reticular Formation ◽  
Sensory Modality ◽  
Receptive Fields ◽  
Arterial Occlusion ◽  
Large Mass ◽  
Mechanical Stimuli ◽  
Neuronal Responses ◽  
Medullary Reticular Formation ◽  
Discharge Rates ◽  
Reticular Neurons

Neurons in the medullary reticular formation were tested for responses to mechanical stimuli applied to the heart in cats anesthetized with chloralose and paralyzed with pancuronium. In most experiments baroreceptors were denervated. Aortic occlusion excited 15 neurons (19%) and decreased the mean discharge rates of five neurons (6%). Discrete probing of the heart elicited one to three spikes from 18 of 27 neurons tested. Thirteen of these cells had defined cardiac receptive fields; fields were large, often encompassing most of the left ventricle. Of 12 neurons tested for responses during fibrillation, 8 were excited, 2 were inhibited, and 2 were unaffected. Neurons often exhibited different sensitivities to these mechanical stimuli, as well as to ischemia produced during coronary arterial occlusion. Neurons were more likely to respond to stimuli that affected a large mass of myocardium. In addition to cardiac input, 98% of neurons in this study also received input from at least one additional sensory modality, and 39 cells were excited by somatic, auditory, and visual stimuli. Results indicate that medullary reticular neurons are responsive to mechanical events in the heart as well as to myocardial ischemia and respond to other sensory modalities.

Cardiac input to medullary reticular formation: neuronal responses to CAO

1986 ◽  
Vol 251 (4) ◽  
pp. R670-R679
Author(s):  
R. W. Blair
Keyword(s):  
Reticular Formation ◽  
Coronary Arteries ◽  
Cell Activity ◽  
Cardiac Ischemia ◽  
Neuronal Responses ◽  
Medullary Reticular Formation ◽  
Reticular Neurons ◽  
Extracellular Potentials ◽  
Medullary Neurons ◽  
Stimulation Of

Responses of 46 medullary reticular neurons to coronary arterial occlusions (CAO) of the left anterior descending (LAD) and left circumflex (CX) coronary arteries were determined in chloralose-anesthetized cats paralyzed with pancuronium. Extracellular potentials were recorded from individual neurons, in the medial reticular formation, responsive to electrical stimulation of cardiopulmonary sympathetic afferents. CAO responses were characterized by one of three patterns. Cell activity changed during myocardial ischemia (IS response). Fifteen neurons were excited during ischemia (9 +/- 2.8 to 15 +/- 3.2 spikes/s for CX occlusion and 10 +/- 3.0 to 17 +/- 4.7 spikes/s for LAD occlusion), and two were inhibited (8 +/- 3.0 to 4 +/- 3.0 spikes/s). Cell activity changed at the onset or release of occlusion and rapidly adapted (ON response). Four cells were excited at the onset of LAD occlusion (2 +/- 1.4 to 10 +/- 6.0 spikes/s), 9 cells were excited at onset of CX occlusion (5 +/- 2.5 to 16 +/- 5.6 spikes/s), and 1 cell decreased its rate at onset of CX occlusion. A combination of ON and IS responses occurred in five cells (ON-IS response). Overall, 24 neurons exhibited at least one of these responses, and 22 cells were unaffected by CAO. Thirty neurons were tested for responses to CAO of CX and LAD; neurons most often exhibited different patterns of responses to CAO of each artery. Thirty-one of 34 cells tested exhibited qualitatively, but often not quantitatively, similar responses to cardiac ischemia and to application of bradykinin to epicardium of free wall of left ventricle. Results indicate that medullary neurons often respond differentially to occlusion of different coronary arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

Horizontal Rotation Responses of Medullary Reticular Neurons in the Decerebrate Cat1

1995 ◽  
Vol 5 (3) ◽  
pp. 223-228
Author(s):  
Robert H. Schor ◽  
Bill J. Yates
Keyword(s):  
Spinal Cord ◽  
Reticular Formation ◽  
Semicircular Canal ◽  
Semicircular Canals ◽  
Response Dynamics ◽  
Medullary Reticular Formation ◽  
Decerebrate Cat ◽  
Reticular Neurons ◽  
Semicircular Canal Afferents

This study examines the response of neurons in the medullary reticular formation of the decerebrate cat to sinusoidal yaw rotations in the plane of the horizontal semicircular canals. Responsive neurons that could be antidromically activated from the spinal cord appeared to be less sensitive to the rotary stimulus than the rest of the population of responsive neurons. Most neurons had response dynamics similar to those of semicircular canal afferents.

LES NEURONES DE LA FORMATION RÉTICULAIRE PONTO-BULBAIRE ET LA STIMULATION TRIGÉMINALE

1962 ◽  
Vol 40 (1) ◽  
pp. 261-271
Author(s):  
Guy Lamarche ◽  
J.-M. Langlois
Keyword(s):  
Reticular Formation ◽  
Trigeminal Nerve ◽  
Neuronal Response ◽  
Receptive Fields ◽  
Central Zone ◽  
Painful Stimulus ◽  
Inhibitory Zone ◽  
Sensory Afferents ◽  
Reticular Neurons

A microphysiological study of 209 neurons of the bulbopontine reticular formation was carried out in 80 "encéphales isolés" cats. After physiological stimulations of the trigeminal nerve the following conclusions were arrived at: (1) A functional arrangement exists in the lower recticular formation. Clear differences were found between the medulla and pons. (2) The pontine reticular neurons receive mostly tactile impulses from very large receptive fields. (3) The bulbar neurons receive all modalities of the trigeminal nerve from usually limited and bilateral fields (except proprioception). Pain projects mainly in this part of the reticular core. A central zone of the medulla has all physiological types of cells and is coincidental with Magoun and Rhine's inhibitory zone. (4) There was no neuronal response typical of any sensation. (5) An increase in frequency of a response was obtained in various ways: by changing the origin of the stimulus, by-increasing the intensity of the stimulus or the area of stimulation, or by applying a painful stimulus when the cell also responded to touch. (6) It is suggested that the sensory afferents lose their specificity when they reach the reticular formation but that via this formation they serve to increase awareness and perception of sensation at higher level.

LES NEURONES DE LA FORMATION RÉTICULAIRE PONTO-BULBAIRE ET LA STIMULATION TRIGÉMINALE

1962 ◽  
Vol 40 (2) ◽  
pp. 261-271 ◽  
Author(s):  
Guy Lamarche ◽  
J.-M. Langlois
Keyword(s):  
Reticular Formation ◽  
Trigeminal Nerve ◽  
Neuronal Response ◽  
Receptive Fields ◽  
Central Zone ◽  
Painful Stimulus ◽  
Inhibitory Zone ◽  
Sensory Afferents ◽  
Reticular Neurons

A microphysiological study of 209 neurons of the bulbopontine reticular formation was carried out in 80 "encéphales isolés" cats. After physiological stimulations of the trigeminal nerve the following conclusions were arrived at: (1) A functional arrangement exists in the lower recticular formation. Clear differences were found between the medulla and pons. (2) The pontine reticular neurons receive mostly tactile impulses from very large receptive fields. (3) The bulbar neurons receive all modalities of the trigeminal nerve from usually limited and bilateral fields (except proprioception). Pain projects mainly in this part of the reticular core. A central zone of the medulla has all physiological types of cells and is coincidental with Magoun and Rhine's inhibitory zone. (4) There was no neuronal response typical of any sensation. (5) An increase in frequency of a response was obtained in various ways: by changing the origin of the stimulus, by-increasing the intensity of the stimulus or the area of stimulation, or by applying a painful stimulus when the cell also responded to touch. (6) It is suggested that the sensory afferents lose their specificity when they reach the reticular formation but that via this formation they serve to increase awareness and perception of sensation at higher level.

Thalamic VPM nucleus in the behaving monkey. I. Multimodal and discriminative properties of thermosensitive neurons

1993 ◽  
Vol 69 (3) ◽  
pp. 739-752 ◽  
Author(s):  
M. C. Bushnell ◽  
G. H. Duncan ◽  
N. Tremblay
Keyword(s):  
Neuronal Response ◽  
Receptive Fields ◽  
Thermal Stimulus ◽  
Mechanical Stimuli ◽  
Neuronal Responses ◽  
Discriminative Ability ◽  
Noxious Heat ◽  
Stimulus Response ◽  
Significant Difference ◽  
Skin Cooling

1. The role of the thalamic ventroposterior medial (VPM) nucleus in the discriminative aspects of nociception and thermoreception was evaluated in alert, trained rhesus monkeys. Single-unit responses were recorded from VPM while the monkeys performed a battery of tasks involving noxious heat, innocuous cool, and air-puff stimuli presented to the face. The discriminative ability of the monkey was compared directly with the responses of single neurons, to determine whether the neuronal response could subserve the monkey's discriminative behavior. 2. Most thermally sensitive neurons exhibited multimodal properties. Only 18% responded exclusively to heat (HT-Heat neurons), whereas 27% responded to innocuous mechanical, as well as noxious mechanical and heat stimuli (WDR-Heat). Twenty-three percent responded to innocuous mechanical stimuli and innocuous skin cooling (Mechano-Cool), and 32% responded to mechanical, innocuous cool, and noxious heat stimuli (WDR-Heat-Cool). 3. Almost all mechanical receptive fields were confined to one division of the trigeminal nerve. This was true for all of the above categories of VPM neurons, even those showing highly convergent properties (WDR-Heat-Cool). 4. Heat-activated neurons produced graded responses to noxious skin heating in the 46 to 49 degrees C range. Stimulus-response functions of neurons that responded to both heat and cool did not differ from those of neurons that responded exclusively to skin heating. 5. When the monkeys were detecting small changes in the intensity of a noxious heat stimulus (e.g., from 47 to 47.1–47.8 degrees C), heat-activated neurons responded to the smallest temperature changes that could be detected by the monkeys. Further, there was a high correlation between the monkey's success in detecting the stimulus changes and the magnitude of the neuronal responses to those changes. 6. Although the responsiveness of VPM cool-activated neurons was not compared with the monkeys' threshold for detecting cooling changes, larger stimulus changes (2 degrees C) that the monkey reliably detected produced significant neuronal responses. Further studies are needed to determine whether VPM neurons respond to the smallest detectable changes in skin cooling. 7. Several thermally sensitive VPM neurons were tested under two attentional conditions: 1) while the monkey was required to attend to a visual stimulus, and 2) while it was required to attend to the thermal stimulus to obtain reward. None showed a significant difference in heat- or cool-evoked activity in the two attentional states.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of Chronic Dorsal Column Lesions on Pelvic Viscerosomatic Convergent Medullary Reticular Formation Neurons

2004 ◽  
Vol 92 (6) ◽  
pp. 3596-3600 ◽  
Author(s):  
Charles H. Hubscher ◽  
Richard D. Johnson
Keyword(s):  
Reticular Formation ◽  
Male Genitalia ◽  
Cranial Nerves ◽  
Dorsal Column ◽  
Control Group ◽  
Neuronal Responses ◽  
Spinal Level ◽  
Medullary Reticular Formation ◽  
Thoracic Spinal ◽  
Dorsal Column Lesion

Single medullary reticular formation (MRF) neurons receive multiple somatovisceral convergent inputs originating from many different spinal and cranial nerves, including the pelvic nerve (PN), dorsal nerve of the penis (DNP), and the abdominal branches of the vagus. In a previous study, the input to MRF from the male genitalia was shown to be eliminated with chronic 30-day dorsal hemisection at the T8 spinal level. In this study, the effect of a smaller chronic lesion [dorsal column lesion (DCx)] on MRF neuronal responses was examined. Responses to bilateral electrical stimulation of the DNP remained. MRF neuronal responses to non-noxious (touch/stroke) levels of penile stimulation, however, were eliminated; only responses to noxious pinch remained. No differences were found for the number of neurons responding to noxious distention of the colon between the DCx and control groups. Although no differences were found across these groups for the percent MRF responses to vagal stimulation, the mean response latency for the DCx group was twice the sham-DCx/intact control group. Taken together, these results indicate that the MRF receives at least some of its input from the male genitalia via pathways located within the dorsal columns at the mid-thoracic spinal level.

Vagal afferent modulation of spinal nociceptive transmission in the rat

1989 ◽  
Vol 62 (2) ◽  
pp. 401-415 ◽  
Author(s):  
K. Ren ◽  
A. Randich ◽  
G. F. Gebhart
Keyword(s):  
Blood Pressure ◽  
Receptive Fields ◽  
Mechanical Stimuli ◽  
Neuronal Responses ◽  
Noxious Heat ◽  
Thoracic Spinal Cord ◽  
Nociceptive Transmission ◽  
Anesthetized Rats ◽  
Thoracic Spinal ◽  
Vagal Afferent

1. The effects of vagal afferent stimulation (VAS) on spinal nociceptive transmission and the spinal pathway(s) mediating VAS-produced effects were examined in pentobarbital sodium- and urethane-anesthetized, paralyzed rats. The 60 units studied responded to mechanical stimuli and noxious heating (50 degrees C) of cutaneous receptive fields confined to the glabrous skin of the toes and footpads. Recording sites were located in laminae I-VI of the L3-L5 spinal segments. 2. VAS facilitated and inhibited neuronal responses to heat. In pentobarbital-anesthetized rats, responses of most (24/44) units were facilitated by low and inhibited by higher intensities of VAS. Responses of some units (15/44) were only inhibited and others (4/44) only facilitated by VAS. Inhibition produced by VAS was intensity-, pulse width-, frequency-, and stimulation duration-dependent. In urethane-anesthetized rats, responses of 6/16 units were initially facilitated, then inhibited as the intensity of VAS was increased; responses of nine units were inhibited by VAS. Quantitative comparisons of recruitment indices, mean thresholds for inhibition and mean intensities to inhibit unit responses to heat to 50% of control revealed no significant differences between the two anesthetic conditions. 3. The effects of VAS on neuronal responses to heat were dissociable from its effect on blood pressure. Regardless of the effect of VAS on unit responses to noxious heat, VAS consistently produced intensity-dependent depressor responses. The latencies to onset of inhibition and facilitation by VAS were determined by a cumulative sum technique and bin-by-bin analysis of peristimulus time histograms. The apparent latencies were 91 +/- 11 (SE) ms for inhibition and 278 +/- 59 ms for facilitation, both of which occurred before changes in blood pressure. Finally, microinjections of lidocaine into the ventrolateral funiculus (VLF) or transections of the dorsolateral funiculus (DLF) of the thoracic spinal cord attenuated VAS-produced effects on neuronal responses, but did not affect VAS-induced depressor responses. 4. The responses of 11 dorsal horn units to graded noxious heating of the skin were studied; the stimulus-response functions (SRF) were linear and monotonic throughout the temperature range examined (42-52 degrees C). VAS at intensities which inhibited unit responses to heat significantly decreased the slope of the SRF. VAS at intensities which facilitated unit responses to heat produced a leftward, parallel shift of the SRF.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Primary Afferent Neurons Innervating Guinea Pig Dura

1997 ◽  
Vol 77 (1) ◽  
pp. 299-308 ◽  
Author(s):  
Geoffrey M. Bove ◽  
Michael A. Moskowitz
Keyword(s):  
Guinea Pig ◽  
Superior Sagittal Sinus ◽  
Receptive Fields ◽  
Mechanical Stimuli ◽  
Afferent Neurons ◽  
Primary Afferent Neurons ◽  
Primary Afferent ◽  
Response Properties ◽  
Thermal Thresholds ◽  
Sagittal Sinus

Bove, Geoffrey M. and Michael A. Moskowitz. Primary Afferent Neurons Innervating Guinea Pig Dura. J. Neurophysiol. 77: 299–308, 1997. We made recordings from filaments of guinea pig nasociliary nerve to study response properties of afferent axons innervating the anterior superior sagittal sinus and surrounding dura mater. We analyzed 38 units in 14 experiments. Units were initially located with the use of mechanical stimuli, and were then characterized by their conduction velocity and sensitivities to mechanical, thermal, and chemical stimuli. Single-unit recordings revealed innervation of dura and superior sagittal sinus by slowly conducting axons, mostly in the unmyelinated range. The receptive fields were 1–30 mm2, and typically had one to three punctate spots of highest sensitivity. All units tested responded to topical application of chemical agents. Ninety-seven percent of units responded to 10−5 M capsaicin, 79% responded to a mixture of inflammatory mediators, and 37% responded to an acidic buffer (pH 5). These data underline the importance of chemical sensitivity in intracranial sensation. Heat and cold stimuli evoked responses in 56 and 41% of units tested, respectively. Although the response patterns during heating were typical of polymodal nociceptors innervating other tissues, the thresholds were lower than for other tissues (32.3–42°C). Cooling led to a phasic discharge, with thresholds between 25 and 32°C. Although units had different combinations of responses to mechanical, chemical, and thermal stimuli, when grouped by their sensitivities the groups did not differ regarding mechanical thresholds or presence of ongoing activity. This suggests that meningeal primary afferents are relatively homogeneous. Sensitivities of these units are in general consistent with nociceptors, although the thermal thresholds differ. These data provide the first detailed report of response properties of intracranial primary afferent units, likely to be involved in transmission of nociception and possibly mediation of intracranial pain.

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