Neck muscle spindle activity in the decerebrate, unparalyzed cat: dynamics and influence of vestibular stimulation

1989 ◽  
Vol 62 (4) ◽  
pp. 917-923 ◽  
Author(s):  
J. Kasper ◽  
V. J. Wilson ◽  
Y. Yamagata ◽  
B. J. Yates
Keyword(s):  
Muscle Spindle ◽  
Muscle Spindles ◽  
Vestibular Stimulation ◽  
High Gain ◽  
Neck Muscles ◽  
Body Tilt ◽  
Whole Body ◽  
Neck Muscle ◽  
Response Dynamics ◽  
Decerebrate Cat

1. Using floating electrodes, we recorded from neck-muscle spindle afferents in the C2 dorsal root ganglion of the decerebrate cat. Nerves to dorsal neck muscles were cut so that the afferents presumably originated mainly from ventral and ventrolateral perivertebral muscles and sternocleidomastoid. One goal of our experiments was to study possible vestibular influence exerted on these spindles via the fusimotor system. Unparalyzed preparations were therefore used. 2. Stimuli consisted of sinusoidal rotations in vertical planes. Neck tilt stretched neck muscles, whereas whole-body tilt stimulated vestibular receptors. 3. For each afferent we first determined the most effective direction of neck tilt, then used stimuli oriented close to this direction to study response dynamics, particularly gain of responses to stimuli of different amplitudes (0.5-7.5 degrees). 4. Three-quarters of the afferents failed to respond to 0.5 degrees, 0.2-Hz neck rotations. Stimuli that were effective usually elicited responses that had low gain and were linear over the whole range of amplitudes. Only a few afferents had behavior typical of spindle primary afferents: high-gain responses to small sinusoidal stimuli, gain decreasing as stimulus amplitude increases. This prevalence of static spindle responses in the unparalyzed cat is in striking contrast to results obtained on neck-muscle spindles in paralyzed, decerebrate cats, and on hindlimb extensor muscle spindles in decerebrate, unparalyzed cats. 5. Paralysis produced by injection of Flaxedil changed the behavior of 2/4 spindle afferents tested, causing the appearance of high-gain responses to 0.5 degrees stimuli and of nonlinear behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

Responses of interneurons in the cat cervical cord to vestibular tilt stimulation

1986 ◽  
Vol 56 (4) ◽  
pp. 1147-1156 ◽  
Author(s):  
R. H. Schor ◽  
I. Suzuki ◽  
S. J. Timerick ◽  
V. J. Wilson
Keyword(s):  
Cervical Spinal Cord ◽  
Semicircular Canals ◽  
Body Tilt ◽  
Whole Body ◽  
Cervical Cord ◽  
Otolith Organs ◽  
Phase Lag ◽  
Response Dynamics ◽  
Decerebrate Cat ◽  
Propriospinal Neurons

The responses of interneurons in the cervical spinal cord of the decerebrate cat to whole-body tilt were studied with a goal of identifying spinal elements in the production of forelimb vestibular postural reflexes. Interneurons both in the cervical enlargement and at higher levels, from which propriospinal neurons have been identified, were examined, both in animals with intact labyrinths and in animals with nonfunctional semicircular canals (canal plugged). Most cervical interneurons responding to tilt respond best to rotations in vertical planes aligned within 30 degrees of the roll plane. Two to three times as many neurons are excited by side-up roll tilt as are excited by side-down roll. In cats with intact labyrinths, most responses have dynamics proportional either to (and in phase with) the position of the animal or to a sum of position and tilt velocity. This is consistent with input from both otolith organs and semicircular canals. In animals without functioning canals, the "velocity" response is absent. In a few cells (8 out of 76), a more complex response, characterized by an increasing gain and progressive phase lag, was observed. These response dynamics characterize the forelimb reflex in canal-plugged cats and have been previously observed in vestibular neurons in such preparations.

Tilt responses of neurons in the caudal descending nucleus of the decerebrate cat: influence of the caudal cerebellar vermis and of neck receptors

1996 ◽  
Vol 75 (3) ◽  
pp. 1242-1249 ◽  
Author(s):  
V. J. Wilson ◽  
H. Ikegami ◽  
R. H. Schor ◽  
D. B. Thomson
Keyword(s):  
Head Rotation ◽  
Muscle Spindles ◽  
Vestibular Nuclei ◽  
Vestibular Stimulation ◽  
Cerebellar Vermis ◽  
Neck Muscle ◽  
Vestibular Input ◽  
Decerebrate Cat ◽  
Neck Rotation ◽  
Vertical Semicircular Canal

1. In decerebrate cats with intact cerebellums, we studied the responses of neurons in the caudal areas of the vestibular nuclei to natural vestibular stimulation in vertical planes and to neck rotation. The activity of most neurons was recorded in the caudal half of the descending nucleus. 2. One goal of our experiments was to compare the dynamic and spatial properties of responses to sinusoidal vestibular stimulation with those seen in previous experiments in which the caudal cerebellar vermis, including the nodulus and uvula, was removed. This part of the cerebellum receives vestibular input and projects to the caudal areas of the vestibular nuclei, suggesting that it could influence responses to stimulation of the labyrinth. 3. As in our previous experiments, most neurons could be classified as receiving predominant input either from the otoliths or from one vertical semicircular canal. When mean gain and phase and response vector orientations were compared, there were no obvious differences between the behavior of neurons in the partially decerebellate preparation and the one with the cerebellum intact, demonstrating that in the decerebrate cat the nodulus and uvula have little or no influence on the processing of vertical vestibular input in this region of the vestibular nuclei. 4. Only 23 of 74 (31%) of neurons tested responded to neck rotation. This contrasts with the much larger fractions that respond to this stimulus in Deiters' nucleus and in the rostral descending nucleus. We also recorded from neurons near the vestibular nuclei, mainly in the external cuneate nucleus. All of them (9 of 9) responded to neck rotation. 5. Responses to neck rotation also differed in their dynamics from those found more rostrally in the vestibular nuclei. Dynamics of more rostral neurons resemble those of neck muscle spindles, as do those of external cuneate neurons. The dynamics of caudal vestibular neurons, on the other hand, have a steeper gain slope and more advanced phases than do those of neurons in the more rostral vestibular nuclei. This suggests the possibility of involvement of additional receptors in the production of these responses. 6. In the more rostral vestibular nuclei, responses to vestibular and neck rotation are most often antagonistic, so that head rotation results in little or no response. This is not the case in the caudal areas of the vestibular nuclei, where less than half the neurons tested displayed antagonistic behavior. Further experiments are required to put the neck projection to the caudal vestibular nuclei in a functional context.

Interaction between acoustic startle and habituated neck postural responses in seated subjects

2007 ◽  
Vol 102 (4) ◽  
pp. 1574-1586 ◽  
Author(s):  
Jean-Sébastien Blouin ◽  
Gunter P. Siegmund ◽  
J. Timothy Inglis
Keyword(s):  
Startle Response ◽  
Acoustic Startle ◽  
Acoustic Startle Response ◽  
Neck Muscles ◽  
Whole Body ◽  
Neck Muscle ◽  
Postural Response ◽  
Root Mean Square Amplitude ◽  
Postural Responses ◽  
Spatial Changes

Postural and startle responses rapidly habituate with repeated exposures to the same stimulus, and the first exposure to a seated forward acceleration elicits a startle response in the neck muscles. Our goal was to examine how the acoustic startle response is integrated with the habituated neck postural response elicited by forward accelerations of seated subjects. In experiment 1, 14 subjects underwent 11 sequential forward accelerations followed by 5 additional sled accelerations combined with a startling tone (124-dB sound pressure level) initiated 18 ms after sled acceleration onset. During the acceleration-only trials, changes consistent with habituation occurred in the root-mean-square amplitude of the neck muscles and in the peak amplitude of five head and torso kinematic variables. The subsequent addition of the startling tone restored the amplitude of the neck muscles and four of the five kinematic variables but shortened onset of muscle activity by 9–12 ms. These shortened onset times were further explored in experiment 2, wherein 16 subjects underwent 11 acceleration-only trials followed by 15 combined acceleration-tone trials with interstimulus delays of 0, 13, 18, 23, and 28 ms. Onset times shortened further for the 0- and 13-ms delays but did not lengthen for the 23- and 28-ms delays. These temporal and spatial changes in EMG can be explained by a summation of the excitatory drive converging at or before the neck muscle motoneurons. The present observations suggest that habituation to repeated sled accelerations involves extinguishing the startle response and tuning the postural response to the whole body disturbance.

Dynamics and directional sensitivity of neck muscle spindle responses to head rotation

1987 ◽  
Vol 57 (6) ◽  
pp. 1716-1729 ◽  
Author(s):  
Y. S. Chan ◽  
J. Kasper ◽  
V. J. Wilson
Keyword(s):  
Muscle Spindle ◽  
Vertical Plane ◽  
Head Rotation ◽  
Type A ◽  
Directional Sensitivity ◽  
Neck Muscle ◽  
Type B ◽  
Response Dynamics ◽  
Dynamic Index ◽  
Response Vector

With the use of floating electrodes we recorded from the C2 dorsal root ganglion of decerebrate cats during sinusoidal and trapezoidal head rotation. Fifty-one spontaneously firing afferents were identified as muscle spindle endings. Some were identified by their excitatory response to injection of succinylcholine, others by the similarity of their behavior to that of endings excited by the drug. Because afferent input to the ganglion was restricted by sectioning most nerve trunks, most spindle endings were presumably located in ventral and ventrolateral perivertebral muscles. The firing of each spindle afferent was modulated most effectively by tilting the head in a specific direction; this direction was termed its response vector. Responses to sine waves and trapezoids were then studied with stimuli oriented as closely as possible to the vertical plane of this vector. Most spindle afferents could be classified in one of two categories. Those with high gain, pronounced nonlinearity, and high dynamic index were called type A. Those classified as type B had low gain, a fairly linear response, and low dynamic index. In response to small (0.5 degrees) stimuli, type A endings had phase leads of approximately 40 degrees at frequencies of sinusoidal stimulation of 0.02-0.1 Hz, increasing to approximately 80 degrees at 4 Hz; with larger (2.5 degrees) stimuli, phase was advanced by an additional 10-20 degrees at all frequencies. Phase of type B responses was less advanced than that of type A responses. Gain slopes of the two types of endings were similar. Bode plots of spindle afferents strongly resembled those of upper cervical neurons whose activity is modulated by head rotation. Each spindle afferent had a response vector whose direction remained stable with time, different frequencies of stimulation, and different stimulus amplitudes. The distribution of response vectors covered approximately 270 degrees, with a gap near nose down pitch. Changing initial head position usually had little effect on the direction of an afferent's response vector or on response dynamics. However, stimulation far from the best plane could transform a type A into a type B response. This raises the possibility that type B receptors could be type A receptors best stimulated by yaw and with only low sensitivity to stimulation in vertical planes. Type A receptors have all the properties of spindle primaries. The identification of type B receptors remains uncertain, because they may include secondary afferents as well as primaries stimulated far from their best three-dimensional vector.(ABSTRACT TRUNCATED AT 400 WORDS)

Responses of neurons of the cat central cervical nucleus to natural neck and vestibular stimulation

1996 ◽  
Vol 76 (4) ◽  
pp. 2786-2789 ◽  
Author(s):  
D. B. Thomson ◽  
N. Isu ◽  
V. J. Wilson
Keyword(s):  
Vestibular Nuclei ◽  
Vestibular Stimulation ◽  
Body Tilt ◽  
Whole Body ◽  
Vestibular Input ◽  
Preferred Direction ◽  
Central Cervical Nucleus ◽  
Neck Rotation ◽  
Vector Orientation ◽  
To Receive

1. The central cervical nucleus (CCN) is known to receive neck and vestibular input and to project to the contralateral cerebellum and vestibular nuclei. To investigate the processing of neck and vestibular input by cells in the CCN, we studied their responses to sinusoidal neck rotation and to whole-body tilt in vertical planes in decerebrate, paralyzed cats. CCN neurons were identified by antidromic stimulation with electrodes placed in or near the contralateral restiform body. 2. For every neuron, we first identified the preferred direction of neck rotation (response vector orientation), then studied the neuron's dynamics with rotations in a plane close to this direction at 0.05-1 Hz. 3. Responses of CCN neurons to neck rotation resembled those of previously studied neck spindle primary afferents in terms of their dynamics and nonlinear responses to stimuli of differing amplitudes. They also resembled the neck responses of Deiters' neurons studied in similar preparations. 4. The activity of two-thirds of CCN neurons also was modulated by natural vestibular stimulation. Orientation and dynamics of vestibular responses were characterized in the same way as neck responses. Labyrinthine input originated predominantly from the contralateral vertical canals, and there was no evidence of otolith input. Neck and vestibular inputs were always antagonistic, but the gain of the vestibular response was lower than that of the neck response at all frequencies studied. 5. The quantitative aspects of the interaction between neck and vestibular inputs can be expected to vary with the type of preparation and with stimulus parameters, and its functional significance remains to be investigated.

Body position with respect to the head or body position in space is coded by lumbar interneurons

1985 ◽  
Vol 54 (1) ◽  
pp. 123-133 ◽  
Author(s):  
I. Suzuki ◽  
S. J. Timerick ◽  
V. J. Wilson
Keyword(s):  
Body Position ◽  
Polarization Vector ◽  
Head Rotation ◽  
Vestibular Stimulation ◽  
Body Tilt ◽  
Whole Body ◽  
Vestibular Response ◽  
Maximal Sensitivity ◽  
Frequency Of Stimulation ◽  
Decerebrate Cats

In decerebrate cats, we have studied the response of neurons in the L3-L6 segments of the spinal cord to stimulation of neck and vestibular receptors. Neck receptors were stimulated by head rotation in labyrinthectomized cats or by body rotation with the head fixed in labyrinth-intact cats. Vestibular receptors were stimulated by whole-body tilt in the latter preparation. Most neurons were located outside the motoneuron nuclei and were arbitrarily classified as interneurons. Combinations of roll and pitch stimuli at frequencies of 0.1 or 0.05 Hz were used to determine the horizontal component of the polarization vector, i.e., the best direction of tilt, for each neuron. Two types of stimuli were used; rotation of a fixed angle of tilt around the head or body ("wobble," Ref. 22) or sinusoidal stimuli in several planes. Polarization vectors of the responses to neck stimulation were widely distributed; different neurons responded best to roll, pitch, and angles in between. For every neuron, the amplitude of the response decreased as the cosine of the angle between the direction of maximal sensitivity and the plane of the stimulus. The direction of the vector remained stable as the frequency of stimulation was varied. Neurons with different vectors had similar dynamics that resembled those of cervical interneurons (27). Many neurons responded to both neck and vestibular stimulation, although the vestibular response usually had a much lower gain. Neck and vestibular vectors were approximately opposite in direction. We suggest that neck responses originate in receptors, probably spindles, in perivertebral muscles. Each of these muscles presumably is best stretched by a particular direction of pull. It seems likely that convergence from receptors in selected muscles determines the direction of a spinal neuron's vector. Vestibular responses probably are due mainly to activity in otolith afferents.

scholarly journals The vestibular system does not modulate fusimotor drive to muscle spindles in relaxed leg muscles of subjects in a near-vertical position

2016 ◽  
Vol 115 (5) ◽  
pp. 2529-2535 ◽  
Author(s):  
T. P. Knellwolf ◽  
E. Hammam ◽  
V. G. Macefield
Keyword(s):  
Muscle Spindle ◽  
Vestibular System ◽  
Human Subjects ◽  
Common Peroneal Nerve ◽  
Muscle Spindles ◽  
Vestibular Stimulation ◽  
Galvanic Vestibular Stimulation ◽  
Vertical Position ◽  
Leg Muscles ◽  
Postural Threat

It has been shown that sinusoidal galvanic vestibular stimulation (sGVS) has no effect on the firing of spontaneously active muscle spindles in either relaxed or voluntarily contracting human leg muscles. However, all previous studies have been conducted on subjects in a seated position. Given that independent vestibular control of muscle spindle firing would be more valuable during postural threat, we tested the hypothesis that this modulation would become apparent for subjects in a near-vertical position. Unitary recordings were made from 18 muscle spindle afferents via tungsten microelectrodes inserted percutaneously into the common peroneal nerve of awake human subjects laying supine on a motorized tilt table. All recorded spindle afferents were spontaneously active at rest, and each increased its firing rate during a weak static contraction. Sinusoidal bipolar binaural galvanic vestibular stimulation (±2 mA, 100 cycles) was applied to the mastoid processes at 0.8 Hz. This continuous stimulation produced a sustained illusion of “rocking in a boat” or “swinging in a hammock.” The subject was then moved into a near-vertical position (75°), and the stimulation repeated. Despite robust vestibular illusions, none of the fusimotor-driven spindles exhibited phase-locked modulation of firing during sinusoidal GVS in either position. We conclude that this dynamic vestibular stimulus was insufficient to modulate the firing of fusimotor neurons in the near-vertical position. However, this does not mean that the vestibular system cannot modulate the sensitivity of muscle spindles via fusimotor neurons in free unsupported standing, when reliance on proprioceptive feedback is higher.

scholarly journals Neck Muscle Vibration and Spatial Orientation During Stepping in Place in Humans

2002 ◽  
Vol 88 (5) ◽  
pp. 2232-2241 ◽  
Author(s):  
Marco Bove ◽  
Gregoire Courtine ◽  
Marco Schieppati
Keyword(s):  
The Body ◽  
Body Orientation ◽  
Body Tilt ◽  
Whole Body ◽  
Neck Muscle ◽  
Body Rotation ◽  
Erect Posture ◽  
Proprioceptive Input ◽  
Neck Muscle Vibration ◽  
Stepping In Place

Unilateral long-lasting vibration was applied to the sternomastoid muscle to assess the influence of asymmetric neck proprioceptive input on body orientation during stepping-in-place. Blindfolded subjects performed 3 sequences of 3 trials, each lasting 60 s: control, vibration applied during stepping (VDS), and vibration applied before stepping (VBS). VDS caused clear-cut whole body rotation toward the side opposite to vibration. The body rotated around a vertical axis placed at about arm's length from the body. The rotation did not begin immediately on switching on the vibrator. The delay varied from subject to subject from a few seconds to about 10 s. Once initiated, the angular velocity of rotation was remarkably constant (about 1°/s). In VBS, at the beginning of stepping, subjects rotated for a while as if their neck were still vibrated. At a variable delay, the direction of rotation reversed, and the effects were opposite to those observed during VDS. Under no condition did head rotation, head roll, or lateral body tilt accompany rotation. The results confirm and extend the notion that the neck proprioceptive input plays a major role in body orientation during locomotion. The body rotation does not seem to depend on the same mechanisms that modify the erect posture; rather, the asymmetric neck input would seem to modify the egocentric body-centered coordinate system.

Response of vestibular neurons to head rotations in vertical planes. II. Response to neck stimulation and vestibular-neck interaction

1988 ◽  
Vol 60 (5) ◽  
pp. 1765-1778 ◽  
Author(s):  
J. Kasper ◽  
R. H. Schor ◽  
V. J. Wilson
Keyword(s):  
Head Rotation ◽  
The Body ◽  
Head Movements ◽  
Body Tilt ◽  
Whole Body ◽  
Frequency Range ◽  
Vestibular Input ◽  
Response Dynamics ◽  
Neck Input ◽  
Wide Range

1. We have studied the responses of neurons in the lateral and descending vestibular nuclei of decerebrate cats to stimulation of neck receptors, produced by rotating the body in vertical planes with the head stationary. The responses to such neck stimulation were compared with the responses to vestibular stimulation produced by whole-body tilt, described in the preceding paper. 2. After determining the optimal vertical plane of neck rotation (response vector orientation), the dynamics of the neck response were studied over a frequency range of 0.02-1 Hz. The majority of the neurons were excited by neck rotations that brought the chin toward the ipsilateral side; most neurons responded better to roll than to pitch rotations. The typical neck response showed a low-frequency phase lead of 30 degrees, increasing to 60 degrees at higher frequencies, and a gain that increased about threefold per decade. 3. Neck input was found in about one-half of the vestibular-responsive neurons tested with vertical rotations. The presence of a neck response was correlated with the predominant vestibular input to these neurons; neck input was most prevalent on neurons with vestibular vector orientations near roll and receiving convergent vestibular input, either input from both ipsilateral vertical semicircular canals, or from canals plus the otolith organs. 4. Neurons with both vestibular and neck responses tend to have the respective orientation vectors pointing in opposite directions, i.e., a head tilt that produces an excitatory vestibular response would produce an inhibitory neck response. In addition, the gain components of these responses were similar. These results suggest that during head movements on a stationary body, these opposing neck and vestibular inputs will cancel each other. 5. Cancellation was observed in 12 out of 27 neurons tested with head rotation in the mid-frequency range. For most of the remaining neurons, the response to such a combined stimulus was greatly attenuated: the vestibular and neck interaction was largely antagonistic. 6. Neck response dynamics were similar to those of the vestibular input in many neurons, permitting cancellation to take place over a wide range of stimulus frequencies. Another pattern of interaction, observed in some neurons with canal input, produced responses to head rotation that had a relatively constant gain and remained in phase with position over the entire frequency range; such neurons possibly code head position in space.

Three-dimensional sensitivity and caudal projection of neck spindle afferents

1988 ◽  
Vol 59 (5) ◽  
pp. 1497-1509 ◽  
Author(s):  
J. Kasper ◽  
R. H. Schor ◽  
B. J. Yates ◽  
V. J. Wilson
Keyword(s):  
Muscle Spindle ◽  
Three Dimensional ◽  
Dorsal Column ◽  
Head Movements ◽  
Three Dimensions ◽  
Neck Muscle ◽  
Decerebrate Cat ◽  
Caudal Projection ◽  
Propriospinal Neurons ◽  
Response Vector

1. We recorded from neck muscle spindle afferents in the C2 dorsal root ganglion of the decerebrate cat using floating electrodes. The afferents presumably innervated mainly ventral and ventrolateral perivertebral muscles, and sternocleidomastoid. Stimuli consisted of combinations of rotatory head movements about the roll/pitch or pitch/yaw axes. An important difference from our earlier experiments (10) was the addition of yaw movement to the stimulus paradigm making possible a three-dimensional analysis of afferent behavior. 2. For each afferent we determined the most effective direction of tilt (orientation of the response vector) in three dimensions by using sinusoidal stimuli that combined pitch and roll, or pitch and yaw, or by measuring the gains to responses to roll, pitch, and yaw rotation. 3. Most afferents were sensitive to rotation around all three axes; pitch and yaw were usually more effective than roll. There was no indication of clustering of response vectors, as might be expected if the receptors were located in a small number of muscles each of which has receptors aligned in a homogeneous direction. 4. The responses of afferents were further studied using sinusoidal and trapezoidal stimuli aligned as closely as possible with the orientation of their response vector. The availability of the yaw stimulus made receptor classification based on response linearity, gain, and dynamic index more reliable than in our earlier experiments (10). 5. Muscle spindle responses were divided into three categories: A, B, and ambiguous. The evidence suggests that category A are probably spindle primary receptors and category B are secondaries. Ambiguous receptors have intermediate properties. 6. The caudal projection of spindle afferents was examined by delivering antidromic stimuli with a movable electrode on the surface of the ipsilateral dorsal column. Eighteen percent of the afferents projected to C4, and 14% as far as C5. Long caudal projections can be found in A, B, and ambiguous receptors with a range of directional sensitivities. 7. The evidence suggests that C2 spindle afferents make synapses in the midcervical segments with interneurons and propriospinal neurons that are part of the intraspinal pathway of the tonic neck reflex.

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