Properties of projections from vestibular nuclei to medial reticular formation in the cat

1975 ◽  
Vol 38 (6) ◽  
pp. 1421-1435 ◽  
Author(s):  
B. W. Peterson ◽  
C. Abzug
Keyword(s):  
Reticular Formation ◽  
Central Region ◽  
Vestibular Nucleus ◽  
Extracellular Recording ◽  
Vestibular Nuclei ◽  
Medullary Reticular Formation ◽  
Pentobarbital Anesthesia ◽  
Antidromic Responses ◽  
Series Of Experiments ◽  
Stimulation Of

In one series of experiments, vestibular neurons that could be activated antidromically by stimulation of the contralateral medial reticular formation were studied with extracellular recording in cats under pentobarbital anesthesia. These neurons were found in all of the four main vestibular nuclei, but were less prevalent in dorsal Deiters' nucleus and in the central region of the superior vestibular nucleus than elsewhere. Regions of the pontine and medullary reticular formation from which neurons in different vestibular nuclei were activated corresponded to the pattern of vestibuloreticular projections described by neuroanatomists. 2. Latencies of antidromic responses to stimulation of the contralateral reticular formation ranged from 0.6 to over 3 ms, indicating a relatively slow transfer of activity from vestibular nuclei to reticular formation.

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.

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.

Cardiovascular reflexes following lesions in medullary reticular formation

1965 ◽  
Vol 208 (2) ◽  
pp. 283-288 ◽  
Author(s):  
John W. Manning
Keyword(s):  
Blood Pressure ◽  
Reticular Formation ◽  
Tissue Injury ◽  
Cardiac Activity ◽  
Cardiovascular Reflexes ◽  
Medullary Reticular Formation ◽  
Cardiovascular Reflex ◽  
Vascular Reflex ◽  
Inferior Olivary ◽  
Stimulation Of

In 19 anesthetized cats acute destruction of large portions of the medullary reticular formation was achieved with the aid of a radio-frequency lesion maker. Midline structures were spared by confining the lesions to the dorsolateral medulla. Tissue injury extended from a level rostral to the inferior olivary complex to the obex. These lesions in the medullary vasomotor area did not alter significantly the cardiovascular reflex adjustments to bilateral occlusion of the carotid arteries or to the stimulation of the central end of the cut sciatic nerve. In addition, an increase in contractile force, heart rate, and blood pressure evoked by stimulation of pressor areas in the posterior hypothalamus could be obtained following the lesions. The preparations were critically dependent upon supramedullary connections to maintain vascular tone and circulatory reflex adjustments, for decerebration in the lesioned animal brought about a reduction in blood pressure and a loss of vascular reflex responses. These findings suggest that supramedullary centers exert tonic as well as phasic influences on vascular and cardiac activity that is independent of the medullary vasomotor area.

Stimulation of the Medullary Reticular Formation in Cold-Injured Brain

1989 ◽  
Vol 6 (4) ◽  
pp. 279-287
Author(s):  
SEIGO NAGAO ◽  
MASAMITSU KAWAUCHI ◽  
TOMOYA OGAWA ◽  
TAKASHI OHMOTO
Keyword(s):  
Reticular Formation ◽  
Medullary Reticular Formation ◽  
Injured Brain ◽  
Stimulation Of
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