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PubMed1982

Localization of proprioceptive reflexes in the splenius muscle of the cat.

Activity of the cat splenius muscle was modulated by sinusoidal rotation of the head around the C1-C2 joint in decerebrate cats with labyrinth intact or with all semicircular canals plugged, or, in one intact and alert cat, by rotation of the body with the head fixed in space. EMG modulation, recorded from the areas of splenius innervated by the C1-C4 nerves, was due to the cervicocollic reflex. Modulation was not uniform, but decreased with progressively more caudal recording locations; with stimuli of small amplitude it was often possible to obtain modulation of the rostral part of the muscle only. The results demonstrate localization of proprioceptive reflexes, including the stretch reflex, within the splenius muscle.

Animals↗
PubMed1985

Localization of the spinal accessory motoneurons in the cervical cord in connection with the phrenic nucleus: an HRP study in cats.

The localization of the spinal accessory motoneurons (SAMNs) that innervate the accessory respiratory muscles, the sternocleidomastoid (SCM) and trapezius (TP) muscles, was identified in the cat using the horseradish peroxidase (HRP) method. In the cases of HRP bathing of the transected spinal accessory nerve (SAN), HRP-labeled motoneurons were observed ipsilaterally from the C1 to the rostral C6 segments of the spinal cord. Labeled neurons were located principally in the medial and central regions of the dorsomedial cell column of the ventral horn in the C1 segment, in the lateral region of the ventrolateral cell column in the C2-C4 segments, between the ventrolateral and ventromedial cell columns in the C5 segment and in the lateral region of the ventromedial cell column in the C6 segment. In the cases of HRP injection into either SCM or TP muscles, labeled SCM motoneurons were found in the C1-C3 segments of the spinal cord and labeled TP motoneurons were chiefly localized more caudally within the spinal accessory nucleus. The present study revealed that, in the C5 and C6 segments, the SAMNs have a very similar topographic localization to the phrenic nucleus in the ventral horn. This finding implicated the functional linkage of the SAMNs with the phrenic motoneurons in particular types of respiration.

Accessory Nerve↗
PubMed1991

Genioglossus EMG activity during rhythmic jaw movements in the anesthetized guinea pig.

The electromyograph (EMG) activity of the left anterior digastric and the genioglossus muscles was studied in ketamine-anesthetized guinea pigs under 3 separate jaw movement paradigms. The first paradigm has been previously named spontaneous rhythmic jaw movements. These jaw movements occur 1-2 h after the onset of ketamine anesthesia. After spontaneous rhythmic jaw movements began, a single dose of apomorphine caused a new, second jaw movement paradigm to occur, apomorphine-induced rhythmic jaw movements. The final paradigm, cortically-evoked rhythmic jaw movements, was elicited by electrical stimulation of the masticatory area of the cerebral cortex. Genioglossus EMG activity was complex and highly variable in spontaneous rhythmic jaw movements; however, apomorphine-induced jaw movements were characterized by simultaneously occurring rhythmic EMG bursts of approximately 230 ms duration in both the digastric and genioglossus muscles. In 4 of 5 animals, genioglossus muscle activity onset preceded digastric muscle activity onset by approximately 20 ms. These results support the hypothesis that apomorphine-induced rhythmic jaw movements are an analog of lapping in the awake animal. In cortically-evoked rhythmic jaw movements, both digastric and genioglossus EMG activity were time-locked to the cortical electrical stimulation, with an onset latency of approximately 11 ms for the digastric EMG activity and of 16 ms for the genioglossus EMG activity. These results support the hypothesis that both trigeminal and hypoglossal motoneuron pools are closely coupled in certain coordinative movement patterns.

Anesthesia, General↗
PubMed1992

Calbindin D-28k-immunoreactivity in rat muscle spindle; a light and electron microscopic study.

The localization of the vitamin D-dependent calcium-binding protein, calbindin D-28k (CaBP), was studied immunocytochemically in rat striated muscle. CaBP-like immunoreactivity was found in some of the intrafusal fibres in muscle spindles. The spindle capsule and the perineurial sheath of the nerve bundles were occasionally immunoreactive to CaBP. In electron microscope the labelling for CaBP was found diffusely in sarcoplasm, in Z-bands and inside the terminal cisternae of intrafusal muscle fibres. The present findings suggest that CaBP may have a role in maintaining the appropriate microenvironment in the intracapsular space of muscle spindle and that CaBP may be involved in the function of intrafusal muscle fibres.

Animals↗
PubMed1993

Organization of motor pools supplying axial muscles in the chicken.

Intramuscular injections of the retrograde tracers 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) and horseradish peroxidase (HRP) were used to map the motor pools innervating axial muscles in the cervical and thoracic regions of the chicken. We found that motor pool position is well correlated with the muscle's embryonic origin, and not necessarily with its position. Muscles of myotomal (exclusively somitic) origin were innervated by medially positioned motoneurons in the median motor column, and the motor pools supplying these muscles were somatotopically organized. Muscles having a dual embryonic origin, from the somites and lateral plate, were innervated by motoneurons positioned further laterally within the median motor column. The relationship between motor pool position and embryonic origin of the muscle may be a general principle of ventral horn organization.

Aging↗
PubMed1976

Cyclic EEG and motility patterns during sleep in restrained infant rats.

When restrained in a quasi-fetal position, infant rats (2--3 weeks old) remain for an extended period in a sleep-like state as judged by polygraphic criteria. Moreover, they become very difficult to arouse by sensory stimuli, and show a level of spontaneous motility considerably higher than is normally found at this age during sleep. Phasic generalized body movements, which are often quite stereotyped, occur in trains at regular intervals, against a low background level of neck muscle tonus. The amplitude of the cortical EEG, especially in the delta band, is negatively correlated with the frequency of spontaneous motor burst activity. It is suggested that these REM-like "rapid body movements" in immature mammals may well represent a transitional stage between fetal behavior patterns and sleep motility in the adult organism.

Age Factors↗
PubMed1978

Sleep telemetry in the rat. II. Automatic identification and recording of vigilance states.

An identification system for the vigilance states of the rat is described which uses as inputs the cortical EEG, neck muscle EMG and motor activity, and which allows concomitant monitoring of feeding and drinking behaviour. State identification and data recording are performed in an on-line and an off-line stage which are designed to accommodate a large number of data for computer processing.

Animals↗
PubMed1979

In-phase brain activities during arousal and sleep.

EEG of sensorimotor area, EMG of neck muscles and unit activity in lateral geniculate (LG) nucleus, recorded in freely moving cats, were analysed for the presence of correlations between them. The 3 activities were first integrated with a 2 sec time constant, then a correlation coefficient was assessed between time-linked points of the 3 records for periods of 40 sec. The average vlaues of the correlation coefficients were found to increase from arousal through slow synchronized sleep (S sleep), reaching the highest value in REM sleep. The average of the values in REM was found to be significantly different from those in arousal and S sleep. These differences were statistically significant for the correlation coefficients between EEG and LG activities, as well as of EMG and LG. On the contrary, the correlation between EEG and EMG, which may be thought of as having more direct anatomical connections and a higher degree of physiological dependence, did not change as a function of the different physiological states.

Animals↗
PubMed1983

Alumina cream-induced focal motor epilepsy in cats. IV. Peduncular and midline tegmental lesions.

The effect of peduncular and midline tegmental lesions on EEG-EMG patterns of type B and C alumina cream-induced focal motor seizures was studied on cats with chronically implanted electrodes and cannula lesion systems. EEG patterns included number, amplitude and contralateral propagation of type B spikes and occurrence and duration of type C tonic-clonic discharges. EMG patterns included phasic multiple unit activity (EMG MUA) time locked to the onset of type B EEG spikes and time locked to the onset (contradversive OTCD) and end (clonic ETCD) of type C tonic-clonic EEG paroxysmal discharges. (1) Lesions of the middle third of the cerebral peduncle, ipsilateral to the cortical epileptogenic focus, blocked type B muscular convulsions and significantly decreased phasic EMG MUA at contralateral face, neck and limbs. (2) Bilateral peduncular lesions blocked clonic type C muscular convulsions and significantly decreased phasic clonic ETCD EMG MUA at the same body regions. (3) Midline tegmental lesions blocked phasic type C muscular convulsions and significantly decreased phasic contradversive OTCD EMG MUA at neck muscles. (4) Bilateral peduncular lesions significantly increased and midline tegmental lesions significantly decreased (below the previous interictal) contradversive OTCD EMG MUA. (5) Neither peduncular nor midline tegmental lesions significantly changed EEG patterns of type B and C seizures.

Aluminum Oxide↗
PubMed1986

Behavioral states in the chronic medullary and midpontine cat.

Behavioral state organization was studied in the caudal portion of chronically maintained cats with transections at the ponto-medullary junction or midpontine level. The cats spent most of their time in a 'quiescent state.' This state was periodically interrupted by 'phasic activations.' During quiescence, ECG and reticular unit activity rates were low and regular. EMG levels resembled those seen during non-REM sleep in intact cats. During phasic activations, unit activity in the nucleus gigantocellularis and neck EMG activity increased to levels seen in the intact cat during active waking. Gross postural changes, vestibular slow phase head nystagmus and head shake reflexes could be observed at these times. No periods of neck muscle atonia were observed in either state. No periods of brain-stem controlled rapid eye movements (REMs) occurred. Unit activity patterns similar to those seen in the intact cat during REM sleep were never observed. Physostigmine administration did not produce REM sleep signs, but rather, triggered an aroused state. Phasic activations occurred in a regular ultradian rhythm, with a period similar to that seen in the REM sleep cycle. We conclude that the chronic medullary cat retains primitive aroused and quiescent states, but does not have any of the local signs of REM sleep. However, the medulla does have the capability of generating ultradian rhythmicities which may contribute to the control of the basic rest activity cycle and the REM, non-REM sleep cycle.

Animals↗
PubMed1989

Lability of the postauricular and inion microreflexes, studied in the normal human subject.

Experiments have been carried out to investigate the lability of 2 brain-stem microreflexes, viz., the postauricular and inion responses to auditory stimulation. The size of the postauricular response was reduced by conditioning auditory or median nerve stimulation. Both forms of conditioning stimulus also induced a reduction in ongoing EMG activity in postauricular muscles, which suggests that there may be a direct inhibitory effect on facial nerve motoneurones. The effectiveness of conditioning auditory stimulation in blocking the response to a subsequent auditory testing stimulus was related to the size of the response evoked by the conditioning stimulus, which suggests that part of the inhibitory effect may be due to afterhyperpolarization or a feedback type of inhibition which is dependent on motoneurone activation. By contrast, auditory and median nerve stimulation were not found to have an inhibitory effect on the inion response.

Acoustic Stimulation↗
PubMed1983

Central projection of nuchal group I muscle afferent fibers of the cat.

To investigate the central projection of nuchal group I afferent fibers of nerves which supply the complexus (COM), biventer cervicis (BV), splenius (SP), and occipitoscapularis (OCC) muscles, experiments were conducted on cats anesthetized with chloralose-urethane. A total of 246 neurons was found to respond to electrical stimulation of those nerves. Of these neurons, 99.2% were located in the ipsilateral external cuneate nucleus (ECN) and 0.8% in the ipsilateral main cuneate nucleus. Ninety-seven neurons responded only to the BIV, 88 neurons only to the SP, and 56 neurons to the OCC alone. The number of monosynaptically activated neurons from group I fibers were found to be 26 in 97 neurons which responded to the BIV, 20 in 88 neurons responded to the SP, and 8 in 56 neurons which responded to the OCC. The ECN contains these neurons organized in a somatotopic manner. Neurons from distal muscle (the OCC) project to medial parts and from proximal muscle (the BIV) to more lateral parts of the nucleus. Forty-three of the 143 neurons in the ECN (30.1%) were activated antidromically to electrical stimulation of the ipsilateral inferior peduncle and anterior lobules IV and V of the cerebellum. Thalamic responses from nuchal muscle afferent fibers were recorded in a very narrow region of nucleus ventralis posterolateralis (VPL) which is situated dorsolaterally to the forelimb muscle afferent (deep radial nerve) projection area. The cortical evoked potentials from these nerve stimulations were observed in the anterior suprasylvian gyrus, areas 2 or 5, which we regarded as a transitional area between the second somatosensory and association areas, and the postcruciate dimple (PCD) or area 3a. Cortical potentials in the PCD were reduced after lesion of the VPL, where the focal potentials evoked by nuchal muscle afferent stimulation were recorded.

Afferent Pathways↗
PubMed1985

Dynamic properties of fiber bundles from the rat sternomastoid muscle.

The sternomastoid muscle of the rat can be subdivided into a "white" and "red" portion. The red portion predominantly contains type IIA fibers and the white portion type IIB fibers. Fiber bundles were dissected from the two parts of the muscle and their dynamic properties determined; both showed "fast-twitch" type characteristics. Small, but significant, differences were found in their isometric properties. Their force-velocity relationships were identical, although the maximum speed of sarcomere shortening (about 40 microns s-1) was significantly less than that of other fast-twitch rat muscles. Other differences in the respective force-length relations at different temperatures were noted. The desirability of pursuing these investigations on identified single fibers is emphasized.

Animals↗
PubMed1985

Central nervous system axonal regeneration into sciatic nerve grafts: physiological properties of the grafts and histologic findings in the neuraxis.

Autologous nerve grafts were implanted extraspinally between the medulla and the ipsilateral cervical spinal cord in adult rats. Four to eight months after implantation, electrical stimulation of the grafts evoked EMG activity in a variety of head and neck muscles in 8/10 rats. In 5/10 rats, electrical stimulation of the graft during inspiration potentiated or inhibited EMG activity in each of the diaphragms. After the recordings were completed, the grafts were cut and their ends soaked in horseradish peroxidase (HRP). The average count of HRP-labeled neurons, both in the spinal cord and brain stem, was 969 (252 to 1961). Most labeled neurons were located within +/- 2 mm of the implant sites, with labeling seen in neurons as far as 9 mm away. In the brain stem, 20 different nuclei were labeled. Among them were the reticular formation, raphe complex, cranial nerve nuclei, the subceruleus, ventrolateral pontine tegmentum regions, and contralateral red nucleus. These results in adult rats showed that (i) CNS axons elongating within peripheral nerve grafts were able to conduct action potentials and maintain functional synapses on CNS neurons; (ii) newly growing neurons were situated in close proximity to the nerve graft; and (iii) many different kinds of central neurons, including monoaminergic and descending spinal tract neurons, can elongate their axons into peripheral nerve grafts.

Animals↗
PubMed1990

A model of muscular control of upper airway geometry.

Some disorders of the upper airway in humans are marked by decreased cross-sectional area and increased airway wall compliance. Based on our observations from studies performed in the isolated upper airway of dogs, we hypothesized that the size, and perhaps the geometry, of the airway was altered by changes in the relative activation levels of various muscle pairs. This could be accomplished either by altering the intensity of the neuromuscular input, or by activating muscle pairs which have different geometric orientation to the airway. We developed an analytic relationship to allow us to vary the stimulus level driving any one of six muscle pairs, each with a different anatomic orientation, to evaluate the relationship between those parameters and upper airway volume. With data generated from bilateral electrical stimulation of upper airway muscles, we described a shape factor which allowed us to predict the maximum force produced at optimal length. These findings were applied to a length/tension curve common to striated muscle to allow us to examine the muscle behavior at lengths other than optimal. The position of each muscle was described in spherical coordinates relative to an elastic cylinder, which represented the isolated, sealed upper airway. These coordinates defined the direction in which the force generated by each muscle pair would be applied. Three compliance constants determined the change in airway dimensions produced by the muscle force. This system and its variables were used to calculate the change in volume of the sealed upper airway chamber resulting from muscle contraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Coactivation of jaw muscles: recruitment order and level as a function of bite force direction and magnitude.

The aim of this study was to obtain insight into the coactivation behaviour of the jaw muscles under various a priori defined static loading conditions of the mandible. As the masticatory system is mechanically redundant, an infinite number of recruitment patterns is theoretically possible to produce a certain bite force. Using a three-component force transducer and a feedback method, subjects could be instructed to produce a bite force of specific direction and magnitude under simultaneous registration of the EMG activity of anterior and posterior temporal, masseter and digastric muscles on each side. Forces were measured at the second premolars. Vertical, anterior, posterior, lateral and medial force directions were examined; in each direction force levels between 50 N and maximal voluntary force were produced. The results show that for all muscles the bite force-EMG relationship obeys a straight-line fit for forces exceeding 50 N. The relationship varies with bite force direction, except in the case of the digastric muscles. Variation is small for the anterior temporal and large for the posterior temporal and masseter muscles. The relative activation of muscles for a particular force in a particular direction in unique, despite the redundancy.

Adult↗
PubMed1978

On the production of low tongue tip /s/: a case report.

X-ray motion pictures and electromyography were combined to record tongue movement and tongue muscle activity of a normal speaker during /s/ production. The /s/ was in /i/, /alpha/, and /u/ vowel environments and in two and three consonant clusters. Lead pellets attached to the tongue tip and dorsum were tracked by frame-by-frame analysis of the X-ray film. Recordings from the tongue muscles were graphed and compared with the movement data. Results demonstrate that this subject produces /s/ with the tongue tip down behind the lower incisors and the blade elevated toward the alveolar ridge. EMG data from the tongue shows that the tongue tip depression is not passive but is an active part of the motor strategy used by this subject to elevate the tongue body. These findings suggest that speech pathologists might well include the tip-down strategy of /s/ production in the therapeutic process as an alternative to the tip-up /s/.

Action Potentials↗