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PubMed1983

Infant lesion effect: II. Sparing and recovery of function after spinal cord damage in newborn and adult cats.

Considerable disagreement exists concerning the degree to which sparing and/or recovery of function occurs following CNS damage at birth rather than in adulthood. To study this question, the spinal cord was hemisected in neonatal and adult cats and the motor behavior of the two groups was compared when the neonatal operates matured and the adult operates recovered. Quantitative analysis of the motor behavior indicated that the effects were not uniform: in some aspects of motor behavior sparing of function was found in neonatal operates; in others, the adult operates displayed performance which was superior to the neonatal group. Both groups exhibited considerable recovery of locomotor function, but adult operates showed greater accuracy of limb placement during locomotion. Furthermore, the neonatal group had some deficits in locomotion and postural reflexes which were not seen at all in adult operates. There were, however, examples of greater recovery in neonatal operates, e.g. in ipsilateral hopping responses and in the reduced hypermetria of the proprioceptive placing reflexes. True sparing of function was manifested by the presence of tactile placing in neonatal operates which was always abolished permanently in adult operates. The characteristics of the performance suggested that although sparing of function had obviously occurred, the response had never matured fully. These results taken together indicate that the relationship between age at the time damage occurs and ultimate outcome in terms of motor behavior is complex: different motor patterns respond differently to the same lesion. True sparing of function may be restricted to motor patterns which are not directly affected by the lesion because they have not yet developed when the lesion is made.

Age Factors↗
PubMed1997

CAG repeat length and disease duration in Machado-Joseph disease: a new clinical classification.

To evaluate the clinical characteristics of Machado-Joseph disease (MJD) with reference to CAG repeat length and disease duration, we analyzed neurologic findings in 108 patients from 84 families. The majority of MJD patients presented with an ataxic gait as the initial symptom. Dysarthria and nystagmus were observed from an early stage. Bulging eyes, muscle atrophy and bradykinesia developed later. Patients with a shorter CAG repeat length or later onset had more frequent involvement of proprioceptive sensory deficit. Incidence of abnormal reflexes, tones, and proprioceptive sensation was not associated with disease duration, but with CAG repeat length. Based on these results, we propose a new clinical classification: type A (juvenile type), with hyperreflexia and dystonia, but without a proprioceptive sensory deficit; type C (adult type), with hyporeflexia and a proprioceptive sensory deficit, but without dystonia; and type B (intermediate type), the remaining patients with a mixed presentation.

Adult↗
PubMed1982

[Proprioceptive afferents of the transcortical reflex in motor epilepsy:localisation of their thalamic relay in the cat (author's transl)].

In the Cat with a penicillin motor focus, a transcortical reflex (RTC) can be triggered by stimulation of the muscle or the cutaneous branch of the radial nerve (DR - SR). We tried here to identify at a suprabulbar level, the proprioceptive pathway involved in triggering RTC. Cerebellar ablation did not modify the reflex. On the other hand reversibly inactivation of a rostral-dorso-medial part of VPL (VPLr) receiving short latency proprioceptive afferents, reversibly abolished the TRC elicited through DR stimulation, while SR stimulation was still effective. It is thus assumed that muscle and cutaneous afferents responsible for eliciting the RTC run in parallel pathways with distinct relay zones within the VPL nucleus.U

Afferent Pathways↗
PubMed1982

[Convergence of visual and neck proprioceptives on the vestibulo-ocular reflex arc and the "vestibulo-cerebellum" (author's transl)].

Linked to the vestibular reflex, ontologically the most primitive, nuchal and visual proprioceptive afferent impulses heighten perception of movement and the position of the head and body in space. The final goal of these reflexes appears to be maintenance of the visual axis and of posture. They are under cerebellar control which adapts responses according to sensory interactions, and probably increases reactions when a deficiency exists. Functional exploratory tests in patients with positional or postural vertigo should include the study of responses to separate or combined stimulation of these three types of receptor according to the three planes of the semicircular canals.

Animals↗
PubMedDate not supplied

Visual and vestibular reflexes that stabilize gaze in the chameleon.

Spontaneous eye movements as well as visual, vestibular, and proprioceptive cervical reflexes which contribute to gaze stabilization were investigated in the chameleon using the magnetic search-coil technique. The oculomotor range of each eye was very large (180 deg horizontally x 80 deg vertically). Spontaneous ocular saccades were independent in the two eyes and could have very large amplitudes. The fast phases of nystagmus during the stabilization reflexes were also independent in the eyes. In the head-restrained condition, optokinetic nystagmus (OKN) had a low gain in both horizontal and vertical planes (0.35 at 5 deg/s) and showed little binocular interaction. The vestibulo-ocular reflex (VOR) exhibited a low gain (0.2-0.3 from 0.05-1 Hz) and a high-phase lead at low frequency (140 deg at 0.05 Hz). Rotation of the animal in the presence of a visible surround increased the overall gain of gaze stabilization to 0.4-0.5 (P < 0.01) and considerably reduced the phase lead (38 deg at 0.05 Hz). In the head-free condition, head and eye reflexes were active simultaneously during both optokinetic and vestibular stimulation, but nystagmic head movements appeared only occasionally with a rather loose eye-head coordination. During optokinetic stimulation, eye movements contributed more than head movements to gaze stabilization, whereas, during vestibular or visuo-vestibular stimulation, the relative contribution of eye and head responses varied with stimulus frequency. When the head was freed, overall gain for gaze stabilization increased from 0.35 to 0.45 (P < 0.05) for optokinetic stimulation at 5 deg/s and from 0.2-0.3 to 0.4-0.75 (P < 0.001) for vestibular stimulation at 0.05-1 Hz.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Reinforcement of tonic vibration reflex and exteroceptive vibration-induced flexion reflex in finger flexion muscles by forced respiration.

The effects of forced respiration on tonic vibration reflex (TVR) and exteroceptive vibration-induced flexion reflex (VFR) were studied in healthy man. vibration (100 Hz) applied to finger flexion muscles or the volar side of the middle finger induced a slowly augmenting facilitation of the TVR, which has mono-and polysynaptic components, and VFR, which is polysynaptic. Forced inspiration and forced expiration facilitated these slowly augmenting processes in both reflexes. Respiration reinforces both proprioceptive and exteroceptive reflexes elicited by vibration.

Adult↗
PubMed1998

Roles of eyes, leg proprioceptors and statocysts in the compensatory eye movements of freely walking land crabs (Cardisoma guanhumi)

The compound eyes, the canal organs of the statocysts and proprioceptors in the legs all generate compensatory eye movements in the horizontal plane in the land crab Cardisoma guanhumi. Frequency analyses of the compensatory eye reflexes elicited by each of these inputs show that visual (V) and proprioceptive (P) reflexes respond best below 0.1 Hz, while statocyst (S) reflexes only achieve a high gain above this frequency. They thus increase the range of frequencies over which compensation can occur. Eye and body movements were recorded in an arena under all possible combinations of crabs seeing or blind (V+ or V-), with or without statocysts (S+ or S-) and freely walking or passively transported on a trolley (P+ or P-). Intact crabs (V+S+P+) show good stabilisation of the eyes in space, the only movements with respect to external coordinates being saccadic resetting movements (fast phases of nystagmus). The eyes thus compensate well for body turns, but are unaffected by translatory movements of the body and turns that are not accompanied by a change in the orientation of the long axis of the body in space. In the absence of any one sense, compensation for rotation is significantly impaired, whether measured by the increase in the width of the histograms of changes in the angular positions of the eyes in space ( capdelta &phgr; E), by the mean angular velocity of the eyes (slope of regression line, mE) with respect to the angular velocity of the body (mB) or by response gain plotted against angular acceleration of body turn (a). The absence of two senses reduces the crab's ability to compensate still further, with the statocyst-only condition (V-S+P-) being little better than the condition when all three senses are absent (V-S-P-).Such multisensory control of eye compensation for body rotation is discussed both in terms of making use of every available cue for reducing retinal slip and in making available the information content of the optic flow field.

Journal Article↗
PubMed1994

Vestibular patients examined by posturography: sensory interaction testing.

Posturography (PG) examines the influence of vestibular disturbance on standing balance via the vestibulospinal reflex. Testing under several conditions, in which the sensory input by vision and proprioception is impeded from contributing in a normal way, evaluates the "sensory interaction." In a number of patients with known peripheral vestibular disorders, PG showed normal results, which indicate that, for these patients, the possible influence of the vestibular dysfunction has been cancelled at the central level (compensation). In the others, influence was seen in several degrees. The sensory interaction indicated that this group can be subdivided according to the sensory input that had the most influence in the balance performance in standing. The sensory contribution of vision and proprioception was mostly positive (i.e., enhancing the vestibular compensation). In some cases, there was a negative effect, indicating that the sensory input considered had a disturbing influence. No pattern of results could typify the several groups of peripheral vestibular disturbances. Posturography provides complementary information to the classically obtained diagnoses. The data of posturographic examination can provide useful information about the problem of falling in the elderly and give suggestions for adequate rehabilitation exercises.

Caloric Tests↗