Motor Facilitation Research Articles

Motor Patterns Induced in the Antenna of the Rock Lobster by Cuticular Vibration on the Cephalothorax

ABSTRACT In the rock lobster, Palinurus vulgaris, mechanical vibration applied to one point on the cuticle of the cephalothorax induced phasic sensory activity in numerous cuticular nerve branches innervating most of the carapace. The same vibratory stimulus produced two kinds of effect on the tonic activity of the motoneurones innervating the extensor and flexor muscles of the distal joints (J2 and J3) of the antenna: a reciprocal motor effect, decreasing the extensor motoneurone activity and increasing the flexor motoneurone discharge, or a diffuse facilitatory motor effect increasing both extensor and flexor motoneurone activity. The extensor and flexor excitatory motoneurones, like the inhibitory motoneurone common to the J2 and J3 extensor and flexor muscles, can be driven in a one-to-one manner by vibration at low frequency (5–10 Hz). Either motor effect of cuticular stimulation can be modified by other sensory stimuli, e.g. passive movements of the uropods. Cuticular vibration modulates the extensor and flexor resistance reflexes elicited by passive extension/flexion movements of the flagellum, the nature of this modulation depending upon which effect the vibratory stimulus alone produces. The functional significance of the cuticular motor effects is discussed.

Effects of topical cooling on isometric contractions of the human masseter muscle

Six adult males performed tooth clenching for 10 and 80 s at maximum voluntary contraction strength (MVC). Motor activity in the right and left masseter muscles was monitored by surface electromyography. Local temperatures of both cheeks were monitored by a thermocouple. MVC activity for 80s induced pain and fatigue in both muscles; 10s of clenching caused no muscle discomfort. Ice, subsequently applied to the right cheek for 30 min, lowered the temperature of the cheek and masseter muscle. The isometric MVC exercises were then repeated. During 10 s of isometric contraction, MVC motor activity in the cooled masseter muscle was significantly increased by 29 per cent; that of the non-cooled contralateral muscle was insignificantly reduced by 12 per cent. During 80 s of clenching, MVC motor activity in the cooled muscle was significantly increased by 30 per cent; that of the non-cooled muscle was insignificantly reduced by 4 per cent. MVC activity for 80 s by the cooled muscle caused no pain and fatigue, but the discomforts continued in the non-cooled muscle. Increased MVC alpha motor activity in the cooled masseter muscle might have resulted from motor facilitation that was mediated by cutaneous, muscular or mucosal cold receptors, or it might have been due to the absence of pain and fatigue.

Facilitation of monosynaptic reflexes by voluntary contraction of muscle in remote parts of the body. Mechanisms involved in the Jendrassik Manoeuvre.

The facilitation of the tendon reflex of quadriceps, induced by voluntary contraction of a muscle group in the upper limb, evolves in the three phases and depends on several factos. These include the strength and type (ballistic or ramp) of the contraction. In the absence of any electromyographic activity in the conditioning muscle (from a lesion of its nerve trunk or by blockage of conduction by injection of xylocaine), a voluntary attempt to contract it causes only a moderate facilitation of the quadriceps motor nucleus; while reflex activation of the conditioning muscles, by vibration or sudden stretching. causes a more marked facilitation. Thus, it is concluded that at least two distinct mechanisms act sequentially. First, a general motor facilitation of supraspinal origin induces the first moderate phase of facilitations (phase I). This early facilitation precedes the onset of electromyographic activity in the conditioning muscle. Secondly, the more marked facilitation (phase II) is related to the stimulation of afferents originating from the conditioning muscles, either by fusimotor excitation in voluntary contraction or by manoeuvres which stimulate the spindle receptors mechanically. To investigate the transmission pathways of these facilitations, the latencies of these two phases were compared at two distant motor nuclei, the trigeminal motor nucleus and the quadriceps nucleus, following voluntary contractions of the tibialis anterior. Since the facilitations of the trigeminal motor nucleus precede those of the quadriceps motor nucleus, a slowly-travelling rostro-caudal facilitation is postulated during phase II when the facilitation is related to afferents coming from the contracting muscle. A long loop, therefore, is postulated to interpret the second phase of the facilitation curves.

The Effectiveness of a Program of Oral Sensory-Motor Therapy with the Severely and Profoundly Developmentally Disabled

The efficacy of a program of oral-motor therapy designed to facilitate feeding patterns and thus produce increases in body weight in the severely developmentally disabled was explored. Twenty severely and profoundly retarded subjects with neuromotor disorders participated in a pretest / posttest control group design. The experimental group received a 9-week program of oral therapy designed to normalize oral motor functions and reduce pathological oral reflexes. Analysis of covariance revealed no statistically significant difference in body weight gains between the experimental and control group over the treatment period. A post hoc power analysis was computed and revealed a power of approximately .35, indicating a degree of insensitivity in the experimental manipulations and statistical analysis and suggesting the possibility of a Type II experimental error. The need for continued research in this area to establish the effectiveness of sensory and motor facilitation procedures in developing feeding patterns in the severely and profoundly disabled is discussed.

The dependence of glucose formation from lactate on the adenosine triphosphate content in the isolated perfused rat liver.

Bilateral intercollicular lesions in the chick abolish or depress notonly calling, but also those phases of behavior when calling would have been occurring. These include: long bouts of excited feeding immediately after food is made available;examining and pecking moving targets and novel objects; persistent scanning, and inhibitionof other behaviour in a novel environment. Deaf birds behave precisely like controls,so that possible auditory deficits are not involved. During calling phases significantvisual stimuli are treated as if they were startling or conspicuous. Conversely,continuousexamination of a stimulus causes calling to diminish or disappear even though responsecontinues; a brief period when the stimulus is not seen causes calling to begin againwhen it is once more perceived. In addition to the increased effectiveness of relevantvisual stimuli, motor facilitation is usual in calling phases, as is inhibition ofirrelevant responses. Emotioanl behaviour in man and other mammals is composed tocalling phases in the chick

Modulation of cortical and pyramidal tract induced motor responses by electrical stimulation of the basal ganglia

Two general mechanisms based on anatomical studies are possible for modulation of motor activity by the caudate nucleus and globus pallidus. These mechanisms are: (1) modulation of the output of cortical neurons that exert motor influences; and (2) modulation of subcortical neurons that exert motor influences. Differentiation between these two mechanisms was accomplished in the present study by two experimental approaches, both of which employed the conditioning-test paradigm. The first approach was an investigation of caudate nucleus or globus pallidus modulation (conditioning stimulus) of flexor responses of the anterior tibialis muscle elicited by electrical stimulation of the sensorimotor cortex (test stimulus) or pyramidal tract (test stimulus). These investigations were carried out in the intact and in decorticate cats. The second approach was an analysis of modulation of cortically induced pyramidal tract responses (direct and indirect, D-I potentials) by conditioning shock trains delivered to various loci within the caudate nucleus or globus pallidus. Both approaches were designed to determine which inhibitory and facilitatory motor influences of the basal ganglia occured at a cortical or subcortical level. Simultaneous stimulation of a locus within the caudate nucleus and the sensorimotor cortex evoked either an enhancement, reduction or no alteration of the cortically induced increase in flexor responses (measured by Ia afferent activity, EMG, myogram). In contrast, no inhibitory influences occurred from caudate nucleus stimulation upon pyramidal tract induced flexor responses in either the intact or decorticate preparation. Inhibitory loci were distributed toward the rostral portion of the caudate nucleus, whereas facilitatory loci were distributed throughout; this distribution was statistally sigificant (X 2; P < 0.01). Only enhancement or no influence upon cortical induced or pyramidal tract induced responses were obtained by conditioning stimuli to the globus pallidus. In the unanesthetized but immobilized cat, trains of shocks delivered to the caudate nucleus enhanced, reduced or had no influence upon the cortically evoked direct (D) and indirect (I) potentials recorded in the bulbar pyramidal tract. The distribution of facilitatory and inhibitory loci was organized in a similar fashion as in the anesthetized preparation. From these observations, a model was proposed in which the output of the caudate nucleus exerts both facilitatory or inhibitory modulation of the tonically active globus pallidus cells. The latter in turn predominantly or exclusively facilitate output of pyramidal tract neurons as well as the output of subcortical structures; both effects facilitate motor responses at the spinal level.

The effects of muting lesions on emotional behaviour and behaviour normally associated with calling.

Bilateral intercollicular lesions in the chick abolish or depress not only calling, but also those phases of behaviour when calling would have been occurring. These include: long bouts of excited feeding immediately after food is made available; examining and pecking moving targets and novel objects; persistent scanning, and inhibition of other behaviour in a novel environment. Deaf birds behave precisely like controls, so that possible auditory deficits are not involved. During calling phases significant visual stimuli are treated as if they were starting or conspicuous. Conversely, continuous examination of a stimulus causes calling to diminish or disappear even though response continues; a brief period when the stimulus is not seen causes calling to begin again when it is once more perceived. In addition to the increased effectiveness of relevant visual stimuli, motor facilitation is usual in calling phases, as is inhibition of irrelevant responses. Emotional behaviour in man and other mammals is compared to calling phases in the chick.

Path neuron system of medial forebrain bundle as a possible substrate for hypothalamic self-stimulation

Long descending fibers of the medial forebrain bundle terminate on path neurons in the lateral hypothalamic and preoptic regions. The axons of the path neurons bifurcate to project rostrally and caudally giving off many short collaterals to adjacent path neurons. Thus, the path neuron system of the medial forebrain bundle forms a series of reverberatory loops in the lateral hypothalamus. findings obtained by combining conditioning test stimulation and instrumental self-stimulation techniques in the rat indicate that (a) such neurons, which, like path neurons, give short excitatory collaterals to each other, are excited by lateral hypothalamic rewarding electrical pulses. Weak stimulation of the lateral hypothalamic self-stimulation loci results in poststimulatory excitability changes time course of which resembles the shape of excitatory postsynaptic potentials. The 0.5–0.6 msec long latencies correspond to the sum of the synaptic transmission time plus a few tenths of a msec required for the conduction of excitation in the collaterals between adjacent path neurons and for the electrotonic conduction of depolarization in the postsynaptic (i.e. synaptically activated) path neurons (Experiments 1 and 2). (b) Excitability curves obtained with more intense stimulation reflect definite signs of repeated synaptic activation (Experiment 1) and reverberation (Experiment 3). Rebound aftereffects recorded immediately after the end of rewarding intracranial stimulus trains also suggest that, during stimulation, reverberatory circuits are activated. However, a negative feedback inhibition which is also reflected by the excitability curves (Experiment 3) suppresses the reverberatory activity until the end of the rewarding stimulus train and a release occurs afterwards. The observations are interpreted as indicating that the excitation of the path neuron system of medial forebrain bundle is responsible for the lateral hypothalamic self-stimulation. With regard to the various psychological theories of reinforcement (the expectancy model and motor facilitation hypothesis of Milner, Miller's go mechanism, the postinhibitory rebound theory of Grastyán, drive-reduction and drive-induction theories) a possibility is also discussed that the path neuron system is capable to serve as an unitary anatomical substrate for reward.

THIRST MOTIVATION ASSOCIATED WITH THE SALT AROUSAL OF DRINKING.

Results represent two additional tests of the thirst deprivation trace hypothesis based upon more complex tasks. Tests are based upon the fact that thirst induced by a moderate dose of hypertonic saline (3.0 mEq of a 15% NaCl solution) injected subcutaneously develops rapidly, remains constant for a relatively long period of time (6–7 hr), and provides an opportunity to measure its facilitation (drive) on performance as a function of time independent of differences in consummatory activity. Data of the first experiment support the hypothesis and demonstrate that the facilitation of a previously learned response to depress a lever and obtain water when thirsty will increase as a function of time following the injection. In the second experiment on maze learning the effect did not appear in either measure, running time, or errors. These results indicate that the facilitatory effect is not a general one for complex measures of behavior but is specific to relatively simple motor responses and represents a motor facilitation component in drive.

Influence de la formation reticulaire et du cortex cerebral sur l'excitabilite motrice au cours de l'hypoxie

In curarised cats, acute progressive hypoxia (6.5% O 2 in N 2 induces reticular facilitation of motoneurons excitability. The delay of the onset and the manner of development of this phenomenon depend on three factors: early chemoreflex reticular excitation, direct excitation of reticular cells, and release of a corticofugal inhibitory influence. In the unanesthetised animal with a functional cortex, the onset and the manner of development of motor facilitation of reticular origin depend entirely on the last of these factors. 1. 1. In é preparations where telencephalic influence had been eliminated by a diencephalic transection of the brain stem ( tronc cérébral isolé preparation), acute progressive hypoxia (APH) produces progressive facilitation of the monosynaptic masseter reflex (cranial homologue of a monosynaptic extension reflex). 2. 2. After elimination of the aortic and carotid chemoreceptors, APH still produces motor facilitation, although it is less intense and more delayed than previously. At relatively high partial pressures of oxygen, the progressive facilitation of the motoneurons therefore arises from the increased discharge of the carotid and aortic chemoreceptors. At very low partial pressures of oxygen, however, the facilitatory reticular formation can be excited by another mechanism. Unit recording in an islet of é shows that this action consists of a direct humoral activation of reticular cells. 3. 3. In ordinary é preparations, the development of motor facilitation due to hypoxia is entirely different owing to the presence of a cortical control system. ( a) At a time corresponding to that when motor facilitation appears in diencephalic animals, a cortical arousal of chemoceptor origin is observed in the intact preparation. However, no appreciable motor facilitation can be observed at this time. ( b) When electrocortical activity ceases, reticular facilitation appears suddenly and immediately reaches its maximum value; its coincidence with the cessation of electrocortical activity can be regarded as statistically significant. ( c) When the arterial chemoreceptors are eliminated by transecting the IXth and Xth cranial nerves, the phase of cortical arousal does not appear; the sudden facilitation of reticular origin, however, still appears at the very moment when cortical electrical activity ceases. These results indicate that: ( a) in the é preparation with functional cortex, reticular activity is subject to tonic inhibitory control which ceases at the moment when cortical activity stops; ( b) reticular excitation provoked by intensification of chemoreceptor discharge is controlled in a phasic manner by the same cortical system; ( c) these conclusions are similar to those derived from a series of earlier investigations which demonstrated the existence of a feed-back system, comprising the ascending activating system, a diffuse cortical system and a cortico-reticular descending system; the static and dynamic properties of this system can account for both the motor and the cortical manifestations obtained during hypoxia. 4. 4. In the non-curarised é preparation or in a preparation with a transection at the level of D 2, acute progressive hypoxia gives rise to a series of movements beginning at the same time as cortical arousal and ceasing at the same time as the convulsions. Since the descending facilitatory reticular activity is not increased simultaneously, it appears that the latter is not necessary for the development even of intense motor activity. The functional consequences of this fact are considered in relation to homeostatic regulation.