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PubMed1985

Task-related coding of stimulus and response in cat motor cortex.

In a previous study in the cat, we have reported that motor cortex neurons discharging before the initiation of an aimed forearm response (lead cells) are better timed to movement of a display (stimulus) than to the response. The present study was done to distinguish the coding of stimulus and response features in the discharge patterns of such early activity in motor cortex. Single neurons were recorded in the arm area of motor cortex in three cats performing the same pair of responses (forearm flexion and extension) but to display movements in either of the two directions by changing display polarity. The modulation of lead cell activity was contingent on the occurrence of the learned motor response and timed to the stimulus in all conditions. The majority of lead cells (88%, n = 50) fell into one of two distinct classes. In one class of neurons, force-direction (56%, n = 32), activity was contingent on a single direction of forelimb response (flexion or extension) and was thus independent of the direction of the display stimulus. The only muscles whose patterns matched the activity of this class of response-related neurons were forelimb flexors and extensors. In these neurons, the onset of modulation was timed to one or the other of the two stimuli according to the stimulus direction which elicited the appropriate response. Thus, the display-related input to these neurons varied according to the response required. In the second class of neurons, stimulus-direction (32%, n = 18), modulation was associated with a specific stimulus direction rather than the response direction. The pattern of activity of these neurons was similar to the pattern of EMG signals of shoulder and neck muscles during the different task conditions. The contraction of proximal and axial muscles corresponded to a second response elicited by the stimulus, namely attempts at head rotation towards the moving display and was independent of the conditioned forelimb response in both time of onset and direction. To test the possibility that stimulus-direction neurons participated in the control of head rotation we trained two of the animals to also produce isometric changes in neck torque in the direction of the moving display without making the forelimb response. The activity of stimulus-direction neurons was similarly modulated during performance of the neck task. By contrast, force-direction neurons examined during the neck task were either unmodulated or discharged after the neck response.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1995

Post-spike facilitation of neck EMG by cat tectoreticulospinal neurones during orienting movements.

1. The activity of fourteen tectoreticulospinal neurones (TRSNs) was recorded intraaxonally in the caudal pons of alert cats during orienting movements towards visual stimuli. TRSN spikes were used to compute the spike-triggered average (STA) of rectified EMG of dorsal neck muscles. 2. Eight TRSNs for which 400-2532 spikes were available were analysed with the STA technique. When the STA was computed from all spikes, significant post-spike facilitation (PSF) was obtained for six of eighteen cell-muscle pairs investigated (5 TRSNs). The mean relative amplitude of PSFs was 7.4% (S.D. 3.7). The onset latencies ranged from 1.1 to 5.0 ms and mean duration was 11.4 +/- 3.1 ms (mean +/- S.D.). 3. Interspike interval distributions were unimodal, with modes between 2.7 and 12.7 ms. Spike trains of TRSNs that produced significant PSFs contained 5-13% of the interspike intervals < or = 5 ms and 22-37% of the intervals < or = 10 ms. To evaluate the contribution of short intervals to PSF, STAs were computed separately for spikes preceded by 'short' (< or = 5 or < or = 10 ms) and 'long' (> 5 or > 10 ms) intervals. 4. When computed from spikes preceded by 'long' intervals, PSF amplitudes were small (mean +/- S.D., 5.3 +/- 2.7%) and onset latencies measured by cusum ranged between 2.4 and 5.4 ms. This is longer than the estimated minimal latency of monosynaptic facilitatory effect on neck EMG (1.9-2.1 ms). 5. Relative amplitudes of PSF obtained with spikes preceded by 'short' intervals were much larger (mean +/- S.D., 14.8 +/- 7.4%), but cusums indicated negative latencies for four of six PSFs. The unrealistically short onset latencies could be accounted for by the summation of facilitation from the trigger spike with that of the preceding spikes. In four of five TRSNs a large increase of PSF amplitude (from 3.2 to 7.2 times the amplitude obtained from 'long' intervals) suggests the presence of frequency-dependent potentiation of synaptic transmission. 6. This study unequivocally demonstrates that some TRSNs produce significant post-spike facilitation of neck motoneurones. This facilitation could be mediated by monosynaptic tectomotoneuronal connections although a contribution by disynaptic connections cannot be definitively ruled out. The high instantaneous firing rates of TRSNs produce a potentiation of the otherwise weak facilitatory action of TRSNs that presumably contributes to a rapid recruitment of motoneurones during initiation of head orienting movements.

Animals↗

PubMed2004

Intratester and intertester reliability of neck isometric dynamometry.

OBJECTIVE: To evaluate the reproducibility of measurement for maximum voluntary isometric contractions of the cervical musculature in different movements. DESIGN: Repeated test-retest measurements. SETTING: A department of physiotherapy. PARTICIPANTS: Thirty-three healthy subjects (17 men, 16 women; age range, 19-63 y) for the intraexaminer study and 10 healthy subjects (4 men, 6 women; age range, 20-37 y) for the interexaminer study. INTERVENTIONS: Maximum isometric strength in sitting and standing for flexion, extension, lateral flexion, and rotation using a custom isomyometer device. Three tests, performed 5 to 8 days apart, to assess intraexaminer reliability. Two examiners, each performing 1 trial, measuring on the same day to assess interexaminer reliability. MAIN OUTCOME MEASURES: Intraexaminer and interexaminer reliability of neck muscle strength. RESULTS: The standing position showed better reproducibility than the sitting position. The intraclass correlation coefficient (ICC1,3) was above .84 for all tests in any movement and position and above .93 when the first test was excluded. The standard error (SE) of measurement (<16.5 N; <.13 N-m for rotation) and smallest detectable difference (SDD) (<20.1%) were also small. For interexaminer reliability, the ICC(2,1) ranged from.88 to.94 and the SE from 10.7 to 20.8 N (<1.15 N-m for rotation); the SDD was less than 29.8% (except right rotation, which was 38.8%). CONCLUSIONS: A reliable protocol for measuring neck strength has been developed. Standing position and a full practice session produces more reliable measurements.

Adult↗

PubMed1996

[Abnormal head drooping in facioscapulohumeral muscular dystrophy].

Diagnosis of facioscapulohumeral muscular dystrophy (FSHD) is based on its characteristic pattern of muscle wasting. Initial symptom is usually shoulder girdle and upper arm muscle wasting resulting in difficulty in arm-lifting. Patients are aware of progressive change of facial appearance caused by characteristic facial muscle weakness. Affection of other muscles is usually realized much later, but, there is a considerable variation in pattern and severity between individuals even in the same family so that several clinical subtypes such as jump form or scapuloperoneal syndrome have been proposed. Here we described three patients with FSHD showing conspicuous head-drooping caused by severe wasting of posterior neck muscles. These patients realized abnormal neck posture much earlier than appearance of obvious gait disability, while they show other characteristic FSHD features. Familial occurrence is observed in two cases, other affected members from both families do not show abnormal head drooping. Therefore we regarded this sign as another example of clinical heterogeneity of this genetic disorder.

Aged↗

PubMed1994

Speech production during mechanical ventilation in tracheostomized individuals.

This investigation provides the first detailed description of speech production during mechanical ventilation. Seven adults with tracheostomies served as subjects. Recordings were made of chest wall motions, neck muscle activity, tracheal pressure, air flow at the nose and mouth, estimated blood-gas levels, and the acoustic speech signal during performance of a variety of speech tasks. Results indicated that subjects spoke for short durations that spanned all phases of the ventilator cycle, altered laryngeal opposing pressures in response to the continually changing tracheal pressure wave, and expended relatively small volumes of gas for speech production. Speech was improved by making selected ventilator adjustments. Suggestions for clinical interventions are offered.

Adult↗

PubMed1997

[Studies on applied anatomy of canine larynx].

In order to carry out an experiment of canine laryngeal transplantation, neck dissections were performed in 10 canines in this study. Canine larynx-correlated neck muscles and the main arteries which supply the larynx and drainage veins were observed. The diameter of the vessel was measured and the major passages of the blood circulation were analysed. The arteries and veins, which should be anastomosed, were discussed. The results showed that the bilated cranial thyroid arteries arising from the common carotid and the external jugular veins (through the hyoid venous arch) were the major passages of blood circulation of the larynx. This finding suggested that the unilateral cranial thyroid artery can supply sufficient blood for the survival of a transplantated larynx.

Animals↗

PubMedDate not supplied

Transcranial magnetic stimulation and silent period in spasmodic torticollis.

OBJECTIVE: Our objective was to study the corticobulbar projections to neck muscles in cervical dystonia. DESIGN: We compared both the motor evoked potentials and the electromyographic silent period after transcranial magnetic stimulation from sternocleidomastoid and trapezius muscles in a group of 13 patients with spasmodic torticollis with those of 20 healthy volunteers. RESULTS: With the target muscle at rest, no changes of motor threshold, motor evoked potentials latency, and amplitude were observed in dystonic patients. With facilitation, the mean amplitude of the motor evoked potentials was increased in patients compared with controls, the significant difference being for the trapezius muscle, whereas the latency did not differ between groups. The cortical silent period was significantly shorter in dystonic patients than in healthy subjects in both muscles. The duration of the cortical silent period recorded from the sternocleidomastoid muscle showed a positive correlation with the degree of neurologic disability assessed by Tsui's scale. No abnormalities of both nerve conduction velocity and peripheral silent period by stimulation of accessory nerve were found. CONCLUSIONS: These results indicate an impairment of the mechanisms of inhibitory motor control in patients with spasmodic torticollis, which could be the result of a decrease of the basal ganglia inhibitory output over the motor cortex.

Adult↗

PubMed1995

Quantitation of the enflurane-sparing effect of alfentanil during general surgery.

The authors quantitated the enflurane-sparing effect of alfentanil during N2O/O2 anaesthesia in 50 patients undergoing body surface surgery and in 50 patients undergoing upper abdominal surgery. Patients were assigned to one of five treatment regimens (10 patients each group, double-blind administration) as follows: placebo bolus followed by placebo infusion (group I); or alfentanil bolus (30 micrograms kg-1) followed by infusion of placebo (group II) or alfentanil, at the rate of 10 (group III), 20 (group IV), or 40 (group V) micrograms kg-1 h-1. Anaesthesia was induced with thiopentone and vecuronium, and neuromuscular block was kept at 85-90% by continuous infusion of vecuronium. Increases in spontaneous electromyographic activity of neck muscles (NEMG) and in systolic blood pressure (SBP) served as criteria of inadequate anaesthesia. When such increases occurred, enflurane was given in 0.2% steps (end-tidal concentration) of 5 min each, until the increases were suppressed. The relationship between increases in NEMG and increases in SBP was inconsistent: only 10% of the increases occurred simultaneously. With alfentanil, the consumption of enflurane decreased by as much as 70% (P < 0.001) during superficial surgery and 50% (P < 0.05) during abdominal surgery.

Abdomen↗

PubMed2006

Effect of wearing a mouthguard on the vestibulocollic reflex.

It has been speculated that the use of a mouthguard improves athletic ability such as muscular strength and equilibrium. The postural system is equipped with response patterns that correct for unexpected perturbations. These responses are driven by immediate feedback from visual, vestibular, and somatosensory information. These are integrated by the central nervous system. We analysed the possibility that wearing a mouthguard influences vestibular information via the vestibulocollic reflex (VCR) in the sagittal plane. The input of the VCR is vestibular afferent activity and its output is neck muscle activation. With the subject in the supine position, the apparatus used in this study induces the VCR by subjecting the head to abrupt vertical acceleration by sudden free fall under the head's own weight. Surface electromyographic (EMG) recordings in the sternocleidomastoid muscles (SCM) of 14 participants were analysed. There were no significant differences in the amplitude of the VCR within the left and right SCM whether subjects were or were not wearing a mouthguard (P=0.3227 within left SCM; P=0.9686 within right SCM). These results suggest that wearing a mouthguard has no effect on the VCR in the sagittal plane when supine, and so that vestibular sensory information is unaffected by wearing a mouthguard, in this context. Further research is required to examine whether this also holds true in more functional, upright and dynamic body positions.

Adult↗

PubMed2004

The treatment of acute vertigo.

Vertigo and dizziness are very common symptoms in the general population. The aim of this paper is to describe the physical and pharmacological treatment of symptoms characterized by sudden onset of rotatory vertigo. Acute vertigo can be subdivided into two main groups: (1) spontaneous vertigo and (2) provoked vertigo, usually by postural changes, generally called paroxysmal positional vertigo (PPV). Sudden onset of acute vertigo is usually due to acute spontaneous unilateral vestibular failure. It can be also fluctuant as, e.g., in recurrent attacks of Ménière's disease. Pharmacotherapy of acute spontaneous vertigo includes Levo-sulpiride i.v., 50 mg in 250 physiologic solution, once or twice a day, methoclopramide i.m., 10 mg once or twice a day, or triethilperazine rectally, once or twice a day, to reduce neurovegetative symptoms; diazepam i.m., 10 mg once or twice a day, to decrease internuclear inhibition, sulfate magnesium i.v., two ampoules in 500 cc physiological solution, twice a day, or piracetam i.v., one ampoule in 500 cc physiological solution, twice a day, to decrease vestibular damage. At the onset of the acute symptoms, patients must lie on their healthy side with the head and trunk raised 20 degrees. The room must be quiet but not darkened. If the patient is able to swallow without vomiting, it is important to reduce nystagmus and stabilize the visual field with gabapentine, per os, 300 mg twice or three times a day. The first step of the physical therapy of acute vertigo is vestibular electrical stimulation, that is to say, a superficial paravertebral electrical stimulation of neck muscles, aimed to reduce antigravitary failure and to increase proprioceptive cervical sensory substitution. PPV is a common complaint and represents one of the most common entities in peripheral vestibular pathology. While the clinical picture is well known and widely described, the etiopathogenesis of PPV is still a matter of debate. Despite the different interpretation of PPV etiopathogenesis, the maneuvers described by Semont, Epley, or Lempert and their modifications are undoubtedly effective. For this reason the first therapeutic approach in acute provoked vertigo must be by means of one of these kinds of treatments.

Acute Disease↗

PubMed1993

Asymmetries in ocular and cervical responses to sagittal vestibular stimulations.

In rabbits and cats vestibulo-ocular reflex (VOR) and vestibulo-ocular reflex (VCR) were tested in frontal and sagittal planes. The VOR evoked by pitching the animals in side down position showed asymmetric responses with peak eye velocity higher in upward direction than in downward one. This asymmetry was abolished when pitching the animal in upright position. This indicate that the otolithic coactivation, occurring in upright position, symmetrizes canal-induced vertical responses. Vestibulo-ocular reflex evoked by rolling the animals was also symmetric, no matter the animal position was. The electromyographic response of neck muscles to sagittal VCR showed an asymmetric behaviour as far as the timing of extensor and flexor activation was concerning. In fact, the increase of extensor muscle activity was steeper than the decrease and the activation peak was more leading than the inhibition peak. The flexor muscles showed an opposite behaviour. This flexion-extension asymmetry was present either with or without otolithic coactivation. On the contrary, the EMG responses to frontal VCR were much more symmetric. It can be suggested that the upward preponderance is present in the sagittal vestibular circuitry to enhance the upward VCR against a gravity load which opposes head stability during downward head displacements. On the contrary, at level of the eye, in which the gravity does not oppose the responses, the canal-induced vertical asymmetry is cancelled by the otolithic coactivation.

Animals↗

PubMed1985

A quantitative analysis of the geometry of cat motoneurons innervating neck and shoulder muscles.

The geometry of the somata and dendritic trees of motoneurons innervating neck and shoulder muscles was investigated by using intracellular injections of HRP. In general, these motoneurons did not belong to a homogeneous population of motoneurons. Differences in average primary dendritic diameter, number of primary dendrites, and other measures of dendritic tree size were found between different neck and shoulder motoneuron groups. Several indices of proximal dendritic tree size (number of primary dendrites, sum of dendritic diameters, Rall's dendritic trunk parameter, and the sum of dendritic holes) were weakly correlated with the diameter or surface area of the soma. Some of these correlations depended on the muscle supplied by the motoneuron. The total combined dendritic length ranged from 66,660 to 95,390 microns. There was a weak, but positive, correlation between the diameter of primary dendrites and combined dendritic length. This relationship varied from motoneuron to motoneuron. The diameters of all dendrites of three trapezius motoneurons were examined in detail. The total dendritic surface area examined ranged from 415,000 to 488,100 microns 2 and represented approximately 99% of the total neuronal surface area. Last-order dendrites showed a high degree (39.9%) of taper. Dendritic tapering, by itself, was a major factor in the decrease of the (sum of dendritic diameters)3/2 measured at progressively distal sites from the soma. Although few parent and daughter dendrites obeyed the "three-halves law," the average exponent was 1.57. The diameters of primary dendrites and dendritic surface area were weakly correlated. The correlation between dendritic diameter and combined dendritic length or surface area improved if the weighted average of the diameter of second-order dendrites was used as a measure of dendrite size. Second-order dendrites, whose branches terminated in different regions of the spinal cord, showed different relationships between dendritic diameter and combined dendritic length or surface area. Comparisons between the motoneurons examined in the present study and motoneurons innervating other muscles indicate that, although all spinal motoneurons share several common features (e.g., long dendrites, dendritic tapering), each motoneuron group has a set of unique features (e.g., soma shape, relationship between primary dendrite diameter and dendritic surface area). Thus, the rules governing motoneuron dendritic geometry are not fixed but depend on the species of the motoneuron.

Animals↗

PubMed1981

[Electroencephalographic study of sleep in Sea of Azov porpoises].

ECoG of both hemispheres, EMG of neck muscles, ECG and respiration rate were recorded in 3 free swimming Black Sea porpoises. The sleep characteristics in the porpoises were similar to those in the bottlenose dolphins which have been investigated earlier. Unihemispheric slow sleep was the main type of the porpoise sleep. Paradoxical sleep has not yet been found in them. All ther types of the porpoise sleep occurred during swimming and therefore could not serve to spare energy and to immobilize the animal. The experiments with nembutal and diazepam administration suggest that the functional necessity of the unihemispheric sleep results from the impossibility of maintaining dolphins' respiration during bilateral delta-sleep.

Animals↗

PubMedDate not supplied

Features indicative of cervical abnormality. A factor to be reckoned with in clinical headache work and research?

The current criteria for cervicogenic headache (CEH) contain an anamnestic and a physical examination part. The latter consists of: 1) range of motion in the cervical spine (1+); 2) mechanical precipitation of head pain (uppermost score: 1.5+). These two factors are included in "Features indicative of cervical abnormality", outlined in the present context, with a view to possibly facilitating CEH diagnosis. These "features" have a wider scope, containing not only the two original factors (1 and 2), but also three additional factors--their relative contribution to the totality also given in parentheses: 3) facet joint tenderness (0.5+); 4) neck muscle tenderness (0.5+); and 5) skin-roll test (1.0+). The sum of the solitary features is, accordingly, 4.5+. An extra 0.5+ can be added if there is extreme positivity of one of the factors, i.e., a maximum of 5.0+. This coarse system concerning cervical function has also been tested out in 1834 parishioners in the Vågå study of headache epidemiology (irrespective of headache diagnoses). The mean number of features increased with increasing intensity of head pain (by a factor of almost 3). In headache-free individuals (n.=246), the mean was 0.42+, against a mean in the whole series of 0.79+. Reproducibility tests demonstrated relatively high consistency.

Cervical Vertebrae↗

PubMed2006

The association between the cervical spine, the stomatognathic system, and craniofacial pain: a critical review.

AIMS: Craniofacial pain is a term that encompasses pain in the head, face, and related structures. Multiple etiologies and factors may be related to craniofacial pain; however, the association between the cervical spine and its related structures and craniofacial pain is still a topic of debate. The objective of this critical review was to present and analyze the evidence of the associations between the cervical spine, stomatognathic system, and craniofacial pain. METHODS: A search of the databases Medline, PubMed, Embase, Web of Sciences, Cochrane Library, Cinahl, and HealthStar was conducted for all publications related to the topic in the English and Spanish languages. Relevant information was also derived from reference lists of the retrieved publications. The key words used in the search were cervical spine, cervical vertebrae, neck pain, neck injuries, neck muscles, craniofacial pain, orofacial pain, facial pain, temporomandibular joint pain, and temporomandibular joint disorders. RESULTS: The search provided information referring to the biomechanical, anatomical, and pathological association between craniofacial pain, the stomatognathic system and the cervical spine. CONCLUSION: The information provided by this review suggests an association between the cervical spine, stomatognathic system, and craniofacial pain, but most of this information is not conclusive and was derived from poor-quality studies (levels 3b, 4, and 5 based on Sackett's classification). Better designed studies are needed in order to clarify the real influence that the cervical spine has in relation to the stomatognathic system and craniofacial pain.

Biomechanical Phenomena↗

PubMedDate not supplied

[Reliability of manual medical examination techniques of the cervical spine. Study of quality assurance in manual diagnosis].

OBJECTIVE: Chiropractic techniques are of particular importance for the examination of the cervical spine. The aim of this study was to assess interexaminer reliability of examination techniques of the cervical spine in subjects with and without musculoskeletal distortions of the neck. The interrater method was used with five independent examiners. METHOD: Twenty patients suffering from neck diseases and 20 asymptomatic subjects of similar age and gender were randomized and assessed by five examiners blind to patient histories. Statistical analysis was carried out using multiple logistic regression and the calculation of kappa. RESULTS: Compared to asymptomatic subjects, patients experienced pain significantly often when pressure was applied to the cervical zygapophysial joints and the superficial neck muscles (p < or = 0.05 and p < or = 0.01). In addition, segmental function tests induced kinesialgia significantly more often in patients than in asymptomatic subjects (p < or = 0.05 and p < or = 0.01). A significant relationship was not found between the patient's health status and the findings from muscle palpation and functional examination of the motion segments. The assessment of agreement within examiners beyond chance had to be calculated, aside from for few exceptions, little to moderate (0.2 < kappa < or = 0.6). CONCLUSIONS: Chiropractic techniques are an essential part of every examination of the cervical spine. The clinical impact has not been scientifically established until up to now. Based on our findings and literature, we conclude that interexaminer reliability of manual diagnosis in the examination of the cervical spine should be improved by standardizing the examination process and setting guidelines for documentation and evaluation criteria. Controlled and frequently repeated training sessions also contribute to the reproducibility of findings from manual examinations.

Adult↗

PubMed2004

Hindlimb suspension inhibits air-righting due to altered recruitment of neck and back muscles in rats.

Effects of 9-week hindlimb suspension and 8-week recovery on air-righting reaction in response to drop from a supine position were studied in adult rats. The righting time in rats at the end of suspension (approximately 220 ms) was longer than the age-matched controls (approximately 120 ms, p <0.05). The unloading-related change in righting time was accompanied by lowered activities of electromyogram (EMG) and altered recruitment of both neck and back muscles at a specific stage of drop. After 8 weeks of reambulation, righting time recovered toward the control level (approximately 153 ms, p <0.05), but the EMG activity of back muscle was still less than controls. In contrast, the EMG of neck muscle during fall was even increased. The differences in the characteristics of the muscle fibers between two groups were minor. It is suggested that inhibition of recruitment, rather than the changes in the fiber characteristics, of neck and back muscles is one of the major causes of the slow air-righting.

Adaptation, Physiological↗

PubMed2001

Cerebral representations for egocentric space: Functional-anatomical evidence from caloric vestibular stimulation and neck vibration.

The internal representation of space involves the integration of different sensory inputs-visual, somatosensory/proprioceptive, vestibular-yielding reference frames which are not based on individual peripheral sensory codes, being organized instead in ego-centred (e.g. head, trunk, arm) and object- or environment-centred coordinates. Lateralized or direction-specific stimulation of peripheral sensory systems, such as caloric vestibular stimulation (CVS), posterior neck muscle mechanical vibration (NV) and optokinetic stimulation, can induce a distortion of egocentric coordinates, causing, for example, a deviation of the subjective straight ahead in pointing tasks. Appropriate forms of this stimulation can also temporarily improve a variety of pathological manifestations of unilateral neglect. We used PET measurements of regional cerebral blood flow changes in normal volunteers to measure the brain responses shared by CVS and NV. We show that somatosensory areas of the perisylvian cortex including the insula and retroinsular cortex, the temporoparietal junction and somatosensory area II receive signals from both sensory channels. We propose that these anatomical sites contribute to egocentric representation of space.

Adult↗