scholarly journals Multimodal Sensory Responses of Nucleus Reticularis Gigantocellularis and the Responses' Relation to Cortical and Motor Activation

2010 ◽  
Vol 103 (5) ◽  
pp. 2326-2338 ◽  
Author(s):  
Eugene M. Martin ◽  
Constantine Pavlides ◽  
Donald Pfaff
Keyword(s):  
Reticular Formation ◽  
Neck Muscle ◽  
Medullary Reticular Formation ◽  
Nucleus Reticularis ◽  
Nucleus Reticularis Gigantocellularis ◽  
Arousal Mechanism ◽  
Sensory Responses ◽  
Excitatory Responses ◽  
Fast Oscillations ◽  
Large Neurons

The connectivity of large neurons of the nucleus reticularis gigantocellularis (NRGc) in the medullary reticular formation potentially allows both for the integration of stimuli, in several modalities, that would demand immediate action, and for coordinated activation of cortical and motoric activity. We have simultaneously recorded cortical local field potentials, neck muscle electromyograph (EMG), and the neural activity of medullary NRGc neurons in unrestrained, unanesthetized rats to determine whether the activity of the NRGc is consistent with the modulation of general arousal. We observed excitatory responses of individual NRGc neurons to all modalities tested: tactile, visual, auditory, vestibular, and olfactory. Excitation was directly linked to increases in neck muscle EMG amplitude and corresponded with increases in the power of fast oscillations (30 to 80 Hz) of cortical activity and decreases in the power of slow oscillations (2 to 8 Hz). Because these reticular formation neurons can respond to broad ranges of stimuli with increased firing rates associated with the initiation of behavioral responses, we infer that they are part of an elementary “first responder” CNS arousal mechanism.

Functional organization within the medullary reticular formation of the intact unanesthetized cat. III. Microstimulation during locomotion

1991 ◽  
Vol 66 (3) ◽  
pp. 919-938 ◽  
Author(s):  
T. Drew
Keyword(s):  
Reticular Formation ◽  
Muscle Activity ◽  
Functional Organization ◽  
Vastus Lateralis ◽  
Medial Longitudinal Fasciculus ◽  
Step Cycle ◽  
Medullary Reticular Formation ◽  
Extensor Muscles ◽  
Flexor Muscles ◽  
Excitatory Responses

1. This article presents the results from stimulation in 21 loci within the medullary reticular formation (MRF; between 0.5 and 2.5 mm from the midline) and in 5 loci in the medial longitudinal fasciculus (MLF) of four intact, unanesthetized cats during locomotion. Stimulus trains (11 pulses, 0.2-ms duration, 330 Hz, stimulus strength 35 microA) were applied at those loci in each track at which the most widespread effects in each of the four limbs were obtained with the cat at rest. Electromyograms were recorded from flexor and extensor muscles of each limb. 2. As previously reported, stimulation with the cat at rest generally evoked brief, short-latency, twitch responses in both flexor and extensor muscles of more than one limb. In contrast, stimulation during locomotion evoked a more complex pattern of activity in which responses were normally evoked in one or other of the muscle pairs and incorporated into the locomotor pattern. 3. In the majority of sites, the stimulation evoked excitatory responses in the flexor muscles of each of the four limbs during that period of the step cycle in which each respective muscle was naturally active; stimulation in the stance phase of locomotion, although less effective, was also capable of producing responses in these muscles. All three ipsilateral extensor muscles studied [long and lateral heads of triceps and vastus lateralis (Tri, TriL, and VL, respectively)] were normally inhibited during their phase of muscle activity, although excitatory responses were occasionally seen. Responses in the contralateral (co) Tri were invariably excitatory and were largest during the period of muscle activity, whereas responses during the period of activity of the coVL were mixed, with both excitatory and inhibitory responses being seen from any one locus. 4. Excitatory responses were normally largest when stimulation was applied during the time that the muscle was active during the locomotor cycle. Responses evoked at times when the muscle was inactive were sometimes larger than those evoked with the animal at rest; such responses were most commonly seen in the hindlimb flexors and in the coVL. 5. In both flexors and extensors of each of the four limbs, the latency of the responses was greatest when the cat was at rest and least for stimuli given during the period of activity of the respective muscle. Average latencies during the period of muscle activity ranged from a minimum of 9.0 +/- 2.6 (SD) ms for inhibitory responses in the ipsilateral Tri and TriL to a maximum of 17.1 +/- 3.0 ms for the responses evoked in the ipsilateral semitendinosus.(ABSTRACT TRUNCATED AT 400 WORDS)

Functional organization within the medullary reticular formation of intact unanesthetized cat. II. Electromyographic activity evoked by microstimulation

1990 ◽  
Vol 64 (3) ◽  
pp. 782-795 ◽  
Author(s):  
T. Drew ◽  
S. Rossignol
Keyword(s):  
Brain Stem ◽  
Reticular Formation ◽  
Functional Organization ◽  
Large Degree ◽  
Neck Muscles ◽  
Electromyographic Activity ◽  
Medullary Reticular Formation ◽  
Preceding Article ◽  
Excitatory Responses ◽  
Antagonistic Muscles

1. The present study has examined the detailed organization of the medullary reticular formation (MRF) as revealed by microstimulation (33-ms trains of 0.2-ms duration pulses at 330 Hz and 35 microA or less) in the intact, chronically implanted, unanesthetized cat. Stimulus-locked electromyographic (EMG) responses were recorded from flexors and extensors of each of the four limbs, as well as bilaterally from muscles of the neck and back, during stimulation of the same 592 loci that formed the basis of the preceding article. 2. The thresholds of the responses were different for each group of muscles, with, on the average, the neck muscles being activated at the lowest range of currents, 13.8-16.5 microA; forelimb muscles at 16.9-17.9 microA; back muscles at 25.4-25.7 microA; and hindlimb muscles at 21.1-25.7 microA. 3. Whereas stimulation within the MRF evoked movement of the head only to the stimulated side (preceding article), analysis of the EMG responses showed there was frequently bilateral activation of the neck muscles. Similarly, even though stimulation produced predominantly ipsilateral elbow flexion and contralateral elbow extension, most loci caused cocontraction of antagonistic muscles at these joints. Cocontraction was also frequently observed for the hindlimbs. Reciprocal activation of antagonistic muscles was less frequent but was observed in the ipsilateral forelimb as well as in both hindlimbs; it was never observed in the contralateral forelimb. 4. Although excitatory responses were observed from widespread regions for all of the muscles under study, those regions of the MRF that evoked the strongest responses in each muscle showed a large degree of segregation. Muscles of the ipsilateral forelimb were most strongly activated from the rostrodorsal MRF, whereas muscles of the contralateral forelimb were most strongly effected by stimulation caudoventrally. Muscles of the hindlimbs were more strongly activated from the rostral brain stem, although with some exceptions. Responses in axial muscles were evoked from widespread regions of the brain stem but were concentrated further caudally than were the limb muscles. 5. Excitatory responses were much more prevalent than inhibitory responses and were evoked from all regions of the MRF, including the most caudal and ventral areas. The shortest latency responses in each track were, on the average, as follows: 6.6-8.8 ms for the neck; 11.2-13.4 ms for the forelimbs; 13.8-14.2 ms for the back; and 15.9-17.2 ms for the hindlimbs. Inhibitory responses were also evoked from widely distributed regions, which were intermingled with those loci evoking excitatory responses.(ABSTRACT TRUNCATED AT 400 WORDS)

Anatomy and physiology of saccadic long-lead burst neurons recorded in the alert squirrel monkey. I. Descending projections from the mesencephalon

1996 ◽  
Vol 76 (1) ◽  
pp. 332-352 ◽  
Author(s):  
C. A. Scudder ◽  
A. K. Moschovakis ◽  
A. B. Karabelas ◽  
S. M. Highstein
Keyword(s):  
Superior Colliculus ◽  
Brain Stem ◽  
Reticular Formation ◽  
Discharge Pattern ◽  
Reticular Nucleus ◽  
Medullary Reticular Formation ◽  
Burst Neurons ◽  
Nucleus Reticularis ◽  
Efferent Neurons ◽  
The Brain

1. The intra-axonal recording and horseradish peroxidase injection technique together with spontaneous eye movement monitoring has been employed in alert behaving monkeys to study the discharge pattern and axonal projections of mesencephalic saccade-related long-lead burst neurons (LLBNs). 2. Most of the recovered axons (N = 21) belonged to two classes of neurons. The majority (N = 13) were identified as efferents of the superior colliculus and had circumscribed movement fields typical of collicular saccade-related burst neurons. This discharge pattern, their responses to electrical stimulation of one or both superior colliculi, and their morphological appearance identified them as members of the T class of tectal efferent neurons. 3. Axons of these T cells deployed terminal fields within several saccade-related brain stem areas including the nucleus reticularis tegmenti pontis, which projects to the cerebellum; the nucleus reticularis pontis oralis and caudalis, which contains excitatory premotor burst neurons; the nucleus raphe interpositus, which contains omnipause neurons; the nucleus paragigantocellularis, which contains inhibitory premotor burst neurons, as well as other less differentiated parts of the brain stem reticular formation. 4. The other class of LLBNs (N = 4) had their somata in the medullary reticular formation just lateral to the interstitial nucleus of Cajal. They projected primarily to the raphe nuclei, the medullary reticular formation, and the paramedian reticular nucleus. Discharges were of the directional type with up ON directions (N = 3) and down ON directions (N = 1). 5. Other fibers, which project to pontine and medullary oculomotor structures but whose somata were not recovered (N = 4), illustrate that there are also other types of LLBNs that contribute to the generation and control of saccadic eye movements. 6. Our findings complement previous data about the axonal trajectories of T-type superior colliculus efferents. They also demonstrate the existence of LLBNs located in the mesencephalic reticular formation and their target areas in the brain stem. Implications of these findings for current concepts of oculomotor control are discussed.

Microstimulation of the medullary reticular formation during fictive locomotion

1994 ◽  
Vol 71 (1) ◽  
pp. 229-245 ◽  
Author(s):  
M. C. Perreault ◽  
S. Rossignol ◽  
T. Drew
Keyword(s):  
Reticular Formation ◽  
Afferent Feedback ◽  
Medial Longitudinal Fasciculus ◽  
Cycle Duration ◽  
Fictive Locomotion ◽  
Medullary Reticular Formation ◽  
Locomotor Rhythm ◽  
Locomotor Pattern ◽  
Latency Response ◽  
Excitatory Responses

1. The present study was designed to determine the effects of microstimulation of the medullary reticular formation (MRF) on the locomotor activity of the cat in the absence of phasic afferent feedback from the limbs. To this end, both short (33 ms) and long (200 ms) trains of stimuli (trains of 0.2-ms pulses at 330 Hz, 35 microA) were applied at 43 loci in the MRF (P:6–12 mm; L:0.5–1.5 mm), and in 3 loci in the medial longitudinal fasciculus (P7.5, L < 0.5 mm) during fictive locomotion in the decerebrate and paralyzed cat. The locomotor pattern was monitored by recording the activity of representative flexor and extensor muscle nerves from each of the four limbs. 2. Short trains of stimuli evoked transient excitatory and/or inhibitory responses in extensor and flexor nerves of each limb that were incorporated into the locomotor pattern. In the majority of sites, excitatory responses were obtained in the motor nerves to both flexor and extensor muscles of the fore- and hindlimbs. The exception to this rule was the ipsilateral triceps, in which the predominant response was inhibitory. The amplitude of these responses was dependent on the time of the locomotor cycle at which the stimulus was delivered, and it was always maximum during the period of activity of the respective nerve. 3. The shortest latency response in the nerves to different muscles of the forelimb averaged between 5.6 and 7.3 ms; for the hindlimbs the values were between 6.9 and 9.3 ms. 4. Changing the depth at which the stimulation was applied in any one trajectory usually produced changes only in the amplitude of the evoked responses but occasionally also caused a change in the sign of these responses, especially in the most ventral regions of the MRF. 5. At 72% of the loci (31/43), short trains of stimulation also changed the duration of the activity in the recorded nerves. These changes were often (20/31 loci) sufficiently strong to alter the duration of the overall locomotor cycle. If one considers only the largest changes produced at each locus, stimulation during the period of ipsilateral extensor activity produced an average reduction in the ipsilateral locomotor cycle duration of 12.8 +/- 8.8% (mean +/- SD), whereas stimulation when the ipsilateral flexor nerve was active produced an average increase in locomotor cycle duration of 27.1 +/- 20.8%. 6. Long trains of stimuli produced similar but larger effects than the shorter trains and always reset the locomotor rhythm.(ABSTRACT TRUNCATED AT 400 WORDS)

Phase-dependent responses evoked in limb muscles by stimulation of medullary reticular formation during locomotion in thalamic cats

1984 ◽  
Vol 52 (4) ◽  
pp. 653-675 ◽  
Author(s):  
T. Drew ◽  
S. Rossignol
Keyword(s):  
Reticular Formation ◽  
The Body ◽  
The Other ◽  
Step Cycle ◽  
Medullary Reticular Formation ◽  
Locomotor Rhythm ◽  
Extensor Muscles ◽  
Short Period ◽  
Flexor Muscles ◽  
Excitatory Responses

Electromyographic and kinematic responses of all four limbs were studied when loci within the medullary reticular formation (MRF) were stimulated (30-ms train of 0.2-ms pulses at 300 Hz, strength 35 microA) during treadmill locomotion in spontaneously walking thalamic cats. Responses could be evoked in flexor or extensor muscles of any given limb by such stimulation, depending on the time during the step cycle at which the stimulus was delivered. Stimulation normally excited flexor muscles but could either excite or inhibit extensor muscles depending on the exact position of the electrode. Excitatory responses in extensor muscles were often followed by a short period of inhibition of activity. The responses in muscles of the opposing limbs of the same girdle were, in general, reciprocally organized. For instance, a stimulus delivered during the swing phase of the ipsilateral limb normally evoked excitatory responses both in flexor muscles of that limb and in extensor muscles of the contralateral limb. The same stimulus delivered during the stance phase of the ipsilateral limb evoked excitatory responses in ipsilateral extensor muscles and in contralateral flexor muscles. Responses were also observed at the same time in fore- and hindlimbs that were well organized with respect to the locomotor cycle. Seventy-five percent of all responses occurred within 8-20 ms of the onset of the stimulus train. Responses evoked in muscles of the opposing limbs of one girdle (e.g., a flexor of one limb and an extensor of the other) had similar latencies, suggesting that the responses were synchronously organized on both sides of the body rather than one being a consequence of the other. Although the majority of responses in a given muscle were elicited during its period of activity, responses could occasionally be evoked when there was no activity in that muscle or could be absent despite activity in the muscle. The short trains of stimuli were normally potent enough to affect the limb trajectory, which reflected changes in the onset or the offset of the activity of most muscles. Thus the stimuli effectively changed both the duration of the period of activity in these muscles and the overall step cycle. Longer trains of stimuli (200 ms) markedly amplified these changes to the point of completely resetting the locomotor rhythm.(ABSTRACT TRUNCATED AT 400 WORDS)

An adrenergic basis for bulbar inhibition

1959 ◽  
Vol 197 (4) ◽  
pp. 835-838 ◽  
Author(s):  
J. I. Cranmer ◽  
A. W. Brann ◽  
L. M. N. Bach
Keyword(s):  
Reticular Formation ◽  
Intravenous Infusion ◽  
Regional Differences ◽  
Direct Injection ◽  
Inhibitory Effect ◽  
Direct Stimulation ◽  
Nucleus Reticularis ◽  
Nucleus Reticularis Gigantocellularis ◽  
Reticular Nuclei ◽  
Stimulation Of

Evidence has been obtained showing that intravenous infusion of Diebenzyline in cats anesthetized with Nembutal will consistently and completely abolish inhibition of the patellar reflex induced by direct stimulation of the bulbar reticular formation. The inhibition can always be restored by subsequent infusion of epinephrine. Parallel vasopressor effects can also be observed. Various techniques, including direct injection of Dibenzyline and epinephrine into the medulla through hollow electrodes, provided evidence that these drugs exerted depressant and enhancing effects, respectively, on the thresholds for bulbar inhibition. There appear to be regional differences in epinephrine sensitivity in the medulla. The area corresponding to the nucleus reticularis gigantocellularis appears to be more sensitive to epinephrine than surrounding reticular nuclei. The results suggest that locally released epinephrine activates the gigantocellularis nucleus which, in turn, develops a pattern of discharges leading to an inhibitory effect mediated by spinal projections. This mechanism may explain immobilization which frequently occurs in highly emotional situations.

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.

Activity of neurons in the medial pontomedullary reticular formation during orienting movements in alert head-free cats

1995 ◽  
Vol 74 (1) ◽  
pp. 73-95 ◽  
Author(s):  
T. Isa ◽  
K. Naito
Keyword(s):  
Reticular Formation ◽  
Head Movement ◽  
Light Emitting Diode ◽  
Firing Frequency ◽  
Head Movements ◽  
Medullary Reticular Formation ◽  
Nucleus Reticularis ◽  
Directional Preference ◽  
Alert Cats ◽  
Medullary Neurons

1. Single unit activities of 236 neurons were recorded in the medial pontomedullary reticular formation during visually triggered orienting gaze shifts in 10 alert cats under head-free conditions using movable tungsten-needle electrodes attached to the skull. The activities were analyzed mainly in relation to the head movement that was triggered by presentation of a light-emitting diode (LED) in one of eight directions separated radially by 45 deg after fixation of the center LED. Of these, 120 neurons were recorded in the pontine reticular formation, chiefly in the nucleus reticularis pontis caudalis, and the remaining 116 were in the medullary reticular formation, chiefly in the nucleus reticularis gigantocellularis. Activities of 65 pontine and 65 medullary neurons were modulated in relation to the dynamic phase of orienting movements ("orienting-related neurons"). Activities of the remaining neurons were modulated either irregularly or not at all during orienting movement ("irregular or no-response neurons"). Input from the contralateral superior colliculus and cerebral cortex and projections to the spinal cord were also investigated. 2. Among the orienting-related neurons, 62 pontine and 55 medullary neurons showed increases in activity preceding the onset of eye and head movement by 0-155 ms ("pretype"). Three pontine and 10 medullary neurons showed increases in activity only after the onset of movement ("posttype"). Of the pretype neurons, 61 pontine and 51 medullary neurons showed directional preference of activity ("directional" neurons). One pontine and four medullary neurons were classified as "omnidirectional" because these neurons increased activity preceding movements in all directions tested, and no directional preference was apparent. 3. In the pretype-directional cells, the average firing frequency during bursts was correlated with amplitude and angular velocity of head movements. Activities of the directional neurons during movements in the eight different directions could be well fitted with cosine functions in the majority of cases. The preferred directions of most pontine neurons and of about half the medullary neurons, as determined by first-degree sinusoidal regression analysis, were distributed around the ipsiversive horizontal axis. However, there were also a considerable number of neurons whose preferred directions were upward, downward, contraversive, or oblique in the medulla. 4. Among the directional cells preferring ipsiversive horizontal movements, 11 pontine neurons showed activity, the onset of which was locked to visual stimuli with latencies of 40-70 ms, in addition to phasic discharges locked to the onset of movement. This "stimulus-locked activity" was sometimes modulated depending on the attentional state of the animal.(ABSTRACT TRUNCATED AT 400 WORDS)

Sign in / Sign up

Export Citation Format

Share Document