Disruption of elaborated motor coordination after destruction of the parietal and premotor association areas of the dog

In experiments on seven dogs with a previously elaborated complex food-procuring reflex consisting of two instrumental movements, isolated damage of the parietal and premotor cortical areas deteriorated the achievement of exact movement--lifting and holding of the foreleg at the set level for a certain period of time. A second movement of lifting and holding the leg, similar to the first one, but with simultaneous lowering of the head during eating (altered inborn coordination) remained unaffected through the holding of the leg was also less stable. Successive damage of the parietal and premotor areas, worsening, but not significantly, the exact movement carried out in the natural posture, led to decomposition of the elaborated motor coordination revealed earlier (M. E. Ioffe, 1975) in case of the sensorimotor area damage. The role of the associative cortical areas in organization of elaborated coordination program is discussed.     

Contribution of the frontal lobe secondary motor area to organization of postural components in human voluntary movement

A total of 225 patients with local verified brain lesions were investigated with a view to identifying the brain regions contributing to organizing postural aspects of voluntary movement. Impaired postural adjustment movements associated with voluntary deep breathing were found in patients with damage primarily to the posterior section of the frontal lobe inferior convolution. Impaired activation of leg and trunk muscles accompanying arm movements were revealed in patients with damage chiefly to the posterior section of the superior convolution of the lobe, including the accessory motor area. It was deduced that postural movements differing in their functional purpose are controlled, like other learned tasks, by different sections of the secondary motor zone of the frontal lobe of the brain.Institute for Information Transmission Studies, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 20, No. 1, pp. 7–15, January–February, 1988.     

Distinct motor plans form and retrieve distinct motor memories for physically identical movements

We can adapt movements to a novel dynamic environment (e.g., tool use, microgravity, and perturbation) by acquiring an internal model of the dynamics. Although multiple environments can be learned simultaneously if each environment is experienced with different limb movement kinematics, it is controversial as to whether multiple internal models for a particular movement can be learned and flexibly retrieved according to behavioral contexts. Here, we address this issue by using a novel visuomotor task. While participants reached to each of two targets located at a clockwise or counter-clockwise position, a gradually increasing visual rotation was applied in the clockwise or counter-clockwise direction, respectively, to the on-screen cursor representing the unseen hand position. This procedure implicitly led participants to perform physically identical pointing movements irrespective of their intentions (i.e., movement plans) to move their hand toward two distinct visual targets. Surprisingly, if each identical movement was executed according to a distinct movement plan, participants could readily adapt these movements to two opposing force fields simultaneously. The results demonstrate that multiple motor memories can be learned and flexibly retrieved, even for physically identical movements, according to distinct motor plans in a visual space.     

Comparison of neural activity in the supplementary motor area and in the primary motor cortex in monkeys.

Neuronal activity recorded from the primary motor cortex (MI) and from the supplementary motor area (SMA) was compared in two monkeys trained to perform conditioned arm movements. A handle had to be held in a central waiting position until a visual go and cueing signal indicated to the monkey to move the handle either to a medial or to a lateral target zone (choice reaction time paradigm). Unit and representative electromyographic data were analyzed in relation either to the go signal or to movement onset. In 240 penetrations, 431 SMA neurons and 353 MI neurons were found with activity related to the task. The majority of neurons (303 in MI, 290 in SMA) displayed activity changes after the go signal and before movement onset. Of these "short-lead neurons", 71% in MI and 41% in SMA were clearly related to movement execution. The distribution of lead times in MI and SMA neurons was completely overlapping without any statistical difference among subgroups. The remaining neurons were as well related to the go signal as to movement onset, or were better related to the visual go signal. The response latencies to this signal were not statistically different in SMA and MI neurons. Activity changes during the waiting period was observed more frequently in SMA (47%) than in MI (32%); modulations restricted to the waiting period occurred in 14% of SMA neurons, but were exceptional in MI neurons (3%). It is concluded from these experiments that a surprisingly large proportion of SMA neurons have "MI-like" properties, in that they are temporally recruited together with MI neurons, with similar patterns of discharges during the task. This then suggests that the two interconnected areas operate in parallel. A population of SMA neurons is involved in some processing that is not as predominantly expressed in MI. This activity could relate to sensory, timing, or other higher-order aspects of response preparation, and/or motor functions such as postural stabilization.     

The reactions of the cat motor cortex neurons to electrical stimulation of the base of the forebrain as a conditioned signal for the reflex of placing the forelimb on a support]

Electrical stimulation of the globus pallidus (500 ms, 300 Hz) in the area restricted by the stereotaxic coordinates AP 14-AP 16, L5-L8 at the level of the anterior commissura (HO) evoked food reactions in the form of mouth opening, chewing, and licking in the absence of food. There were no visible motor effects in the case of electrical stimulation of the subcommissural area (H-2-H-4) corresponding to the ventral pallidum and substantia innominata. The conditioned forepaw placing reaction was elaborated with the basal forebrain stimulation used as a conditioned stimulus. After conditioning, the short (3-5 pulses) conditioned basal forebrain stimulation evoked a prolonged (up to 500-1000 ms) activation of neurons in the motor cortex. This activation did not change in the absence of the movement, i.e., after acute extinction of the contralateral forepaw placing or transfer of placing reaction to the ipsilateral forepaw.     

Parallel motor pathways from thoracic interneurons of the ventral giant interneuron system of the cockroach, Periplaneta americana

The data described here complete the principal components of the cockroach wind-mediated escape circuit from cercal afferents to leg motor neurons. It was previously known that the cercal afferents excite ventral giant interneurons which then conduct information on wind stimuli to thoracic ganglia. The ventral giant interneurons connect to a large population of interneurons in the thoracic ganglia which, in turn, are capable of exciting motor neurons that control leg movements. Thoracic interneurons that receive constant short latency inputs from ventral giant interneurons have been referred to as type A thoracic interneurons (TIAs). In this paper, we demonstrate that the motor response of TIAs occurs in adjacent ganglia as well as in the ganglion of origin for the TIA. We then describe the pathway from TIAs to motor neurons in both ganglia. Our observations reveal complex interactions between thoracic interneurons and leg motor neurons. Two parallel pathways exist. TIAs excite leg motor neurons directly and via local interneurons. Latency and amplitude of post-synaptic potentials (PSPs) in motor neurons and local interneurons either in the ganglion of origin or in adjacent ganglia are all similar. However, the sign of the responses recorded in local interneurons (LI) and motor neurons varies according to the TIA subpopulation based on the location of their cell bodies. One group, the dorsal posterior group, (DPGs) has dorsal cell bodies, whereas the other group, the ventral median cells, (VMC) has ventral cell bodies. All DPG interneurons either excited postsynaptic cells or failed to show any connection at all. In contrast, all VMC interneurons either inhibited postsynaptic cells or failed to show any connection. It appears that the TIAs utilize directional wind information from the ventral giant interneurons to make a decision on the optimal direction of escape. The output connections, which project not only to cells within the ganglion of origin but also to adjacent ganglia and perhaps beyond, could allow this decision to be made throughout the thoracic ganglia as a single unit. However, nothing in these connections indicates a mechanism for making appropriate coordinated leg movements. Because each pair of legs plays a unique role in the turn, this coordination should be controlled by circuits dedicated to each leg. We suggest that this is accomplished by local interneurons between TIAs and leg motor neurons.     

The conditioned avoidance reflex and intersignal movements: the correlation of the cardiac and motor components]

In five dogs correlation was studied of heart rate (HR) and motor component of conditioned avoidance reflex (CAR), elaborated by Petropavlovski? method. Stable CAR was expressed in lifting and long (not less than 5-10 sec) holding of the paw on definite height (5-10 cm) for the avoidance of painful electrocutaneous paw stimulation in response to conditioned acoustic stimulus. The level of defensive excitation, evaluated by heart rate change was maximum before the beginning of the conditioned motor reaction. Immediately after lifting and placing the paw in the zone of security a sharp decrease of defensive excitation level ("drive" reduction) took place. Intertrial motor reactions of two types were revealed. The first type imitated the conditioned motor reaction, the second one the usual phasic bending of the paw. Against the background of intertrial movement of the first, operant type a decrease of defensive motivation took similarity as it occurred against the background of CAR during the performance response.     

Sensory control of leg movement in the stick insect Carausius morosus

Hind legs with crossed receptor-apodemes of the femoral chordotonal organ when making a step during walking often do not release the ground after reaching the extreme posterior position. After putting a clamp on the trochanter (stimulation of the campaniform sensilla) the leg is no longer protracted during walking. However, during searching-movements the same leg is moved very far forwards. The anatomical situation of the campaniform sensilla on the trochanter and the sensory innervation of the trochanter is described. After removal of the hair-rows and continuously stimulating the hair-plate at the thorax-coxa-joint the extreme anterior and posterior positions of the leg in walking are displaced in the posterior direction. Front and middle legs operated in this way sometimes do not release the ground at the end of retraction. In searching-movements the same leg is moved in a normal way. If only one side of a decerebrated animal goes over a step, then on the other side a compensatory effect is observed. The main source of this compensatory information appears to be the BF1-hair-plates. If the animal has to drag a weight the extreme anterior and posterior positions of the middle and hind legs are displaced in the anterior direction. Crossing the receptor-apodeme of the femoral chordotonal organ, when it causes the leg to remain in the protraction phase, displaces the extreme posterior position of the ipsilateral leg in front of the operated one in the posterior direction. Influences of different sources on the extreme posterior position can superimpose. A model is presented which combines both a central programme and peripheral sensory influence. The word programme used here means that it does not only determine the motor output but also determines the reactions to particular afferences. The fact that the reaction to a stimulus depends on the internal state of the CNS is also represented by the model.Supported by Deutsche Forschungsgemeinschaft     

Parallel motor pathways from thoracic interneurons of the ventral giant interneurons system of the cockroach,Periplaneta americana

The data described here complete the principal components of the cockroach wind-mediated escape circuit form cercal afferents to leg motor neurons. It was previously known that the cercal afferents excite ventral giant interneurons which then conduct information on wind stimuli to thoracic ganglia. The ventral giant interneurons connect to a large population of interneurons in the thoracic ganglia which, in turn, are capable of exciting motor neurons that control leg movements. Thoracic interneurons that receive constant short latency inputs from ventral giant interneurons have been referred to as type A thoracic interneurons (TI_As). In this paper, we demonstrate that the motor response of TI_As occurs in adjacent ganglia as well as in the ganglion of origin for the TI_A. We then describe the pathway from TI_As to motor neurons in both ganglia. Our observations reveal complex interactions between thoracic interneurons and leg motor neurons. Two parallel pathways exist. TI_As excite leg motor neurons directly and via local interneurons. Latency and amplitude of post-synaptic potentials (PSPs) in motor neurons and local interneurons either in the ganglion of origin or in adjacent ganglia are all similar. However, the sign of the responses recorded in local interneurons (LI) and motor neurons varies according to the TI_A subpopulation based on the location of their cell bodies. One group, the dorsal posterior group, (DPGs) has dorsal cell bodies, whereas the other group, the ventral median cells, (VMC) has ventral cell bodies. All DPG interneurons either excited postsynaptic cells or failed to show any connection at all. In contrast, all VMC interneurons either inhibited postsynaptic cells or failed to show any connection. It appears that the TI_As utilize directional wind information from the ventral giant interneurons to make a decision on the optimal direction of escape. The output connections, which project not only to cells within the ganglion of origin but also to adjacent ganglia and perhaps beyond, could allow this decision to be made throughout the thoracic ganglia as a single unit. However, nothing in these connections indicates a mechanism for making appropriate coordinated leg movements. Because each pair of legs plays a unique role in the turn, this coordination should be controlled by circuits didicated to each leg. We suggest that this is accomplished by local interneurons between TI_As and leg motor neurons.     

Effects of neck and circumoesophageal connective lesions on posture and locomotion in the cockroach

Few studies in arthropods have documented to what extent local control centers in the thorax can support locomotion in absence of inputs from head ganglia. Posture, walking, and leg motor activity was examined in cockroaches with lesions of neck or circumoesophageal connectives. Early in recovery, cockroaches with neck lesions had hyper-extended postures and did not walk. After recovery, posture was less hyper-extended and animals initiated slow leg movements for multiple cycles. Neck lesioned individuals showed an increase in walking after injection of either octopamine or pilocarpine. The phase of leg movement between segments was reduced in neck lesioned cockroaches from that seen in intact animals, while phases in the same segment remained constant. Neither octopamine nor pilocarpine initiated changes in coordination between segments in neck lesioned individuals. Animals with lesions of the circumoesophageal connectives had postures similar to intact individuals but walked in a tripod gait for extended periods of time. Changes in activity of slow tibial extensor and coxal depressor motor neurons and concomitant changes in leg joint angles were present after the lesions. This suggests that thoracic circuits are sufficient to produce leg movements but coordinated walking with normal motor patterns requires descending input from head ganglia.Electronic Supplementary Material Supplementary material is available for this article at     

The assessment of preschool children's motor skills after familiarization with motor tests

This research study was conducted to establish the influence of familiarization on the information component of movement in a motor task for the assessment of preschool children's motor skills. The sample included 50 children whose mean age was 5.9 years (71.5 months). The experimental group consisted of 27 children who were 5.9 years (71.5 months) old, and the control group consisted of 23 children who were 5.9 years (71.5 months) old. The examinees performed 2 motor tasks, standing long jump (SJ, explosive strength) and standing on 1 leg on a beam "flamingo test" (FT, balance). The experimental group underwent a period of familiarization with the motor task in 3 sessions with 5 trials every 3 days. The results indicate statistically significant differences in the final testing between both groups of examinees; the experimental group mean was 112.73 cm, and the control group mean was 100.62 in the SJ test (p = 0.00), and the experimental group mean was 27.10 seconds and the control group mean was 15.01 seconds in the FT (for balance) (p = 0.00). The results obtained in this research indicate that children significantly improved the results in the motor test of strength and balance, being influenced by familiarization. It was confirmed that it was necessary for preschool children to be familiar with the test and it is not justified to use testing and assessment protocols and standards for adults. Physical educators and coaches, when testing preschool children, should introduce children to tests to obtain the best result.     

Abnormalities of mutual influences of the upper and lower limbs after a stroke

The common pattern of muscle activation and specifics of interlimb neuronal connections during the performance of rhythmic separate and simultaneous arm and leg movements in the lying position in healthy subjects, which reflected functionally significant interlimb neuronal interactions, were shown. The study was designed to investigate these mutual influences of the upper and lower limbs during the performance of similar motor tasks by stroke patients. Sixteen poststroke patients with different degrees of hemiparesis performed active and passive arm movements simultaneously with stepping leg movements or without them while lying supine. It was demonstrated that the patients had a disordered common pattern of distribution of muscle activity when they performed voluntary cyclic movements with both arms. Passive movements of both paretic and nonparetic arms led to different degrees of activation of their muscles, depending on the degree of paresis: in patients with mild paresis, muscle activation was similar to that in healthy subjects; in patients with severe paresis, it was insignificant. The loading of the nonparetic arm resulted in an increase in the activity in the paretic arm shoulder flexor muscles in patients with mild paresis (which was typical of healthy subjects), while loading did not influence significantly patients with severe paresis. The combination of cyclic arm movements and stepping leg movements in diagonal synergy decreased the activity in the proximal muscles of both arms, irrespective of the degree of paresis, as it was observed in healthy subjects. Simultaneous arm and leg movements did not change the muscle activity in nonparetic legs in either groups of patients, but the activity in the paretic leg muscles even decreased. The results obtained revealed important features of poststroke motor disturbances, which caused changes in interlimb interactions and largely depended on the degree of paresis. The data could be useful for developing new methods for the performance of rehabilitative procedures in poststroke patients.     

Discrete and Effortful Imagined Movements Do Not Specifically Activate the Autonomic Nervous System

Background

The autonomic nervous system (ANS) is activated in parallel with the motor system during cyclical and effortful imagined actions. However, it is not clear whether the ANS is activated during motor imagery of discrete movements and whether this activation is specific to the movement being imagined. Here, we explored these topics by studying the baroreflex control of the cardiovascular system.

Methodology/Principal Findings

Arterial pressure and heart rate were recorded in ten subjects who executed or imagined trunk or leg movements against gravity. Trunk and leg movements result in different physiological reactions (orthostatic hypotension phenomenon) when they are executed. Interestingly, ANS activation significantly, but similarly, increased during imagined trunk and leg movements. Furthermore, we did not observe any physiological modulation during a control mental-arithmetic task or during motor imagery of effortless movements (horizontal wrist displacements).

Conclusions/Significance

We concluded that ANS activation during motor imagery is general and not specific and physiologically prepares the organism for the upcoming effortful action.     

Unitary activity in the cat motor cortex during a conditioned postural adjustment reflex

Unitary activity in the motor cortex (area 4) during a conditioned postural adjustment reflex was investigated in cats. Responses of the overwhelming majority of neurons connected with conditioned-reflex placing movements were activational in type. They consisted of several components and preceded the movements themselves by 50–600 msec. During realization of incorrect responses to presentation of a differential stimulus and of "spontaneous" interstimulus movements, the unitary responses were similar in direction but differed in their lower intensity and, in most cases, they appeared simultaneously with these movements. In the course of extinction both the conditioned-reflex movements and the corresponding unitary responses disappeared simultaneously. The technique of formation of a conditioned postural adjustment reflex suggested in this paper can be used to from natural, well-coordinated forelimb movements in animals in response to conditioned stimulation which are necessary initial components of more complex behavioral motor responses.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 16, No. 6, pp. 745–753, November–December, 1984.     

Visually mediated motor planning in the escape response of Drosophila

A key feature of reactive behaviors is the ability to spatially localize a salient stimulus and act accordingly. Such sensory-motor transformations must be particularly fast and well tuned in escape behaviors, in which both the speed and accuracy of the evasive response determine whether an animal successfully avoids predation [1]. We studied the escape behavior of the fruit fly, Drosophila, and found that flies can use visual information to plan a jump directly away from a looming threat. This is surprising, given the architecture of the pathway thought to mediate escape [2, 3]. Using high-speed videography, we found that approximately 200 ms before takeoff, flies begin a series of postural adjustments that determine the direction of their escape. These movements position their center of mass so that leg extension will push them away from the expanding visual stimulus. These preflight movements are not the result of a simple feed-forward motor program because their magnitude and direction depend on the flies' initial postural state. Furthermore, flies plan a takeoff direction even in instances when they choose not to jump. This sophisticated motor program is evidence for a form of rapid, visually mediated motor planning in a genetically accessible model organism.     

Changes in electrical thresholds for evoking movements from the cat cerebral cortex following lesions of the sensori-motor area

We evaluated motor maps in the cerebral cortex and motor performance in cats before and after lesions of the forelimb representation in the primary motor area. After the lesion there was a reduction in the use of the affected forelimb and loss of accuracy in prehension tasks using the forelimb; some recovery occurred during the mapping study. Electrode tracts and lesion sites were located in cytoarchitectonically identified cortical areas 4gamma, 4delta, 6aalpha, 6agamma, 3a. The lesions were mainly in area 4gamma. In the lesioned hemisphere there were many points around the lesion site (in areas 4gamma and 3a) from which movements could not be evoked. In some areas distant from the lesion site (e.g. area 6agamma) the mean thresholds for evoking forelimb movements were significantly elevated. Mean thresholds for evoking hindlimb and facial movements were not different from before. In the contralateral hemisphere mean thresholds for evoking forelimb, but not hindlimb or facial movements, were significantly elevated in several sensorimotor areas (area 4gamma, 6agamma and 3a). Mean thresholds for evoking forelimb movements appeared to progressively increase during the time of study. Minimal currents required to evoke forelimb movements from the cerebral cortex increase (possibly progressively) following a lesion of the forelimb representation in the primary motor area, affecting many interconnected motor areas in the hemispheres ipsilateral and contralateral to the lesioned site. This increase in thresholds may play a role in the changes in cortical control of the affected and contralateral limbs following brain lesions and explain the increased sense of effort required to produce movements.     

Changes in electrical thresholds for evoking movements from the cat cerebral cortex following lesions of the sensori-motor area

We evaluated motor maps in the cerebral cortex and motor performance in cats before and after lesions of the forelimb representation in the primary motor area. After the lesion there was a reduction in the use of the affected forelimb and loss of accuracy in prehension tasks using the forelimb; some recovery occurred during the mapping study. Electrode tracts and lesion sites were located in cytoarchitectonically identified cortical areas 4γ, 4δ, 6aα, 6aγ, 3a. The lesions were mainly in area 4γ. In the lesioned hemisphere there were many points around the lesion site (in areas 4γ and 3a) from which movements could not be evoked. In some areas distant from the lesion site (e.g. area 6aγ) the mean thresholds for evoking forelimb movements were significantly elevated. Mean thresholds for evoking hindlimb and facial movements were not different from before. In the contralateral hemisphere mean thresholds for evoking forelimb, but not hindlimb or facial movements, were significantly elevated in several sensorimotor areas (area 4γ, 6aγ and 3a). Mean thresholds for evoking forelimb movements appeared to progressively increase during the time of study. Minimal currents required to evoke forelimb movements from the cerebral cortex increase (possibly progressively) following a lesion of the forelimb representation in the primary motor area, affecting many interconnected motor areas in the hemispheres ipsilateral and contralateral to the lesioned site. This increase in thresholds may play a role in the changes in cortical control of the affected and contralateral limbs following brain lesions and explain the increased sense of effort required to produce movements.     

Real-time gait assessment utilizing a new way of accelerometry

Real-time registration of body segment angles is essential in artificial body position control. A new method is presented for the real-time calculation of the lower extremity angles using data obtained from pairs of two one-dimensional accelerometers. It is shown that, assuming rigid-body dynamics and simple hinge joints, relative angles (i.e. angles between segments) can be calculated without integration, thereby solving the problem of integration drift normally associated with accelerometry. During the stance phase of walking, the relative angles can be transformed to absolute angles (i.e. relative to the gravitational field direction) for the different leg segments. The feasibility of relative angle calculation is demonstrated by calculation of the knee angle of a healthy subject. Stability and resolution were demonstrated with measurements during standing. Measurements during standing up, sitting down and walking showed that shock (heel-strike) and skin movements, due to movements of the underlying muscle tissue, are the main error sources. Additional signal processing, e.g. low-pass filtering, can be used to diminish this error. The accuracy of the knee angle found is shown to be high enough to be used in a feedback controller for functional electrostimulation of the lower extremities.     

Role of different projection areas of the motor cortex in reorganization of the innate head-forelimb coordination in dogs

Dogs were trained to perform the forelimb tonic flexion in order to lift a cup with meat from a bottom of the foodwell and hold it during eating with the head bent down to the cup. It is known that conditioning of the instrumental reaction is based on reorganization of the innate head-forelimb coordination into the opposite one. In untrained dogs, the forelimb flexion is accompanied by the anticipatory lifting of the head bent down to the foodwell. The following lowering of the head leads to an extension of the flexed forelimb. Tonic forelimb flexion is possible if the head is in the up position. Simultaneous holding of the flexed forelimb and lowered head providing food reinforcement is achieved only by learning. It was shown earlier that the lesion of the motor cortex contralateral to the "working" forelimb led to a prolonged disturbance of the elaborated coordination and reappearance of the innate coordination. In the present work we studied the influence of local lesions of the projection areas in the motor cortex, such as a "working" forelimb area, bilateral representation of the neck, and the medial part of the motor cortex, on the learned instrumental feeding reaction. It was found that only the lesion of the forelimb but not neck projection led to a disturbance of the learned head-forelimb movement coordination.