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Biomedical subjects

Z Afelt

Publications and source records attributed to Z Afelt.

14 recordsLinked to original sources
PubMed1985

The use of chronic polyelectromyography in neurophysiological and behavioural experiments.

A method of electromyography (EMG) recording is described which makes it possible to follow simultaneously the activity of 4 muscles in awake, unrestrained rats and cats for 3-5 months. The implantable recording array consists of a percutaneous connector, steel wire spiral leads contained in silicone tubing and bipolar platinum electrodes embedded in silicone platelets. These electrode probes can be fixed onto the surface of various muscles without direct injury to the muscle and, at the same time, without electrical interference from neighbouring muscles. In most rats, EMG activity was recorded bilaterally from the soleus and tibialis anterior muscles. This method has so far been employed for assessing the muscle activity in experiments on reflex muscle atrophy, unilateral hindlimb deafferentation, disuse muscle atrophy induced by limb immobilization and compensatory muscle hypertrophy. A simple computer program has been used to evaluate the resting, postural activity. Objective information about muscle coordination, patterns of locomotor and reflex activity, muscle use and disuse under specific experimental conditions can only be obtained in awake, unrestrained laboratory animals by recording electromyographic (EMG) activity in chronic experiments. For this purpose we developed a method of chronic polyelectromyography allowing recording from 4 muscles in rats and cats (Hník et al. 1978) for several months. The method is briefly reviewed here, together with some applications to animal experiments.

Animals↗
PubMed1984

Stretch--induced inhibition of spontaneous EMG activity in extensor muscles of the rat caused by chronic deafferentation.

Stretching the chronically deafferented soleus muscle has recently been found to inhibit spontaneous EMG activity recorded by silicone-plate electrodes in this muscle. In order to ascertain whether this stretch-induced inhibition (SII) of EMG activity is not restricted exclusively to the soleus, a study was made of SII in the gastrocnemius muscle employing either concentric EMG needles or bipolar "fish-hook" electrodes. The results showed that SII of spontaneous EMG activity can be demonstrated in the soleus and gastrocnemius muscles (both extensor muscles) several days after dorsal rhizotomy L1-S1, employing all three modes of EMG recording in awake rats (namely, silicone-plate electrodes, concentric electrodes and bipolar "fish-hook" electrodes). It is suggested that ventral root afferents may be involved in this phenomenon.

Afferent Pathways↗
PubMed1983

Stepping frequency and stride length in animal locomotion: a new method of investigation.

A new method of investigating animal locomotion is presented which allows for the simultaneous measurement of the basic overground locomotion parameters: swing and stance durations, stride lengths, velocity of movement, gait diagrams and temporal relationships between all animal limbs. The measurements and recordings are given in detail to exemplify the application of the method in dogs.

Animals↗
PubMed1983

Speed control in animal locomotion: transitions between symmetrical and nonsymmetrical gaits in the dog.

Transitions between symmetrical and nonsymmetrical gaits as a speed control mechanism in dog locomotion were investigated. The external locomotion parameters such as swing and stance durations as well as stride length were measured in freely moving animals and were used to determine the spatial and temporal phase shifts between limb movements. The typical transition from trot to gallop and two kinds of gallop-trot transitions are described in detail. Such transitions occur usually in one or two steps and are linked with step length momentary changes within one diagonal pair of limbs. An example of walk to trot transition is also shown. This transition also occurred abruptly in one step and rapid leaps of the phase shift during walk - trot transitions were caused by a momentary decrease of the hindlimb step lengths. Finally, correlation between the external parameters of locomotion and the speed is discussed.

Acceleration↗
PubMed1978

Chronic polyelectromyography in awake, unrestrained animals.

A procedure is described for making an implantable electrode array for recording EMG activity in muscles of awake, unrestrained animals (rats and cats) at rest, during rhythmic activity and in response to various reflexogenic stimuli. The electrode array consists of a percutaneous connector (covered with Dow-Corning Silastic Medical Adhesive), steel wire spiral leads contained in silicone tubing and silicone plate probes with platinum electrodes. These plate probes can be fixed either to the bone underneath the muscle, slipped under the fascia, or fixed between muscles. EMG records are presented of postural activity and ambulation in rats, mastication in cats and unilateral and bilateral spinal and supraspinal reflex responses in rat hind limb muscles up to 6 months after implantation. The advantages (and drawbacks) of this technique and its possible uses in neurophysiology are enumerated in the discussion.

Animals↗
PubMed1976

Functional significance of the ventral and lateral funiculi in the frog's spinal cord.

The spinal cord was transected at the level of calamus scriptorius either completely (spinal preparation) or partially (funicular preparation). In the operated frogs and in normal controls cranial and peripheral receptive fields were stimulated by natural stimuli. Results indicated that the information necessary for somatic activation of the protective flight ascends in the dorsolateral funiculus, which can be characterized as an ascending part of the reflex arc of somatotopically guided avoidance behavior. The tectal region is apparently a center of responses. The information necessary for activating different patterns of locomotion adequate to environmental conditions goes unilaterally through the ventral and ventrolateral funiculus. A diminished specificity of these motor patterns observed after injury of the ventrolateral funiculus seems to be related to a reduced feedback from the periphery. Lacking of aquatic pattern of limb movements (even when terrestrial patterns of locomotion were undisturbed), and drowning in water seem to be related to an injury of a vestibulo-spinal system in the ventral funiculus. It is concluded that the ventrolateral area of the frog spinal cord, i.e., the area between median fissure and dorsal root, forms a closed system providing afferent and efferent information sufficient to evoke normal behavior.

Animals↗
PubMed1975

Limb coordinations during locomotion in cats and dogs.

The relations among swing, stance and step durations for the fore and hind limbs were investigated. Registration of the swing and stance phases was performed by the opening and closing of an electrical circuit as the cat moved along the conductive pathway. In the walking animal, longer swing and shorter stance durations for hind limbs, in comparison with the fore limbs, were observed. However, during trotting phases, these differences were insignificant. The correlations between swing and stance durations were found for both fore and hind limbs. As the walking animal moved faster, swing and stance durations became shorter.

Animals↗
PubMed1975

Limb coordinations during locomotion in amygdalar, rubral and funicular cats.

The registration of the step phases and the relations between them for all of the four limbs were described in the amygdalar, rubral and funicular cats. The evident changes in motor behavior observed after damage of the amygdala and red nucleus did not result from coordination disorders. Conversely, the damage of the medial part of the lateral funiculus in the dorsally hemisected spinal cord disturbed the coordination between fore and hind limbs.

Amygdala↗
PubMed1974

Functional significance of ventral descending tracts of the spinal cord in the cat.

Cats with an incomplete transection of the spinal cord at the Th10-12 level (various parts of the ventral and lateral funiculi intact) were examined 3-18 months after the operation. The walking, standing and righting reflexes were preserved in all the preparations with ventral funiculus spared. However, these reactions were altered in comparison with normal animals.

Animals↗