scholarly journals Body side-specific control of motor activity during turning in a walking animal

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Matthias Gruhn ◽  
Philipp Rosenbaum ◽  
Till Bockemühl ◽  
Ansgar Büschges

Animals and humans need to move deftly and flexibly to adapt to environmental demands. Despite a large body of work on the neural control of walking in invertebrates and vertebrates alike, the mechanisms underlying the motor flexibility that is needed to adjust the motor behavior remain largely unknown. Here, we investigated optomotor-induced turning and the neuronal mechanisms underlying the differences between the leg movements of the two body sides in the stick insect Carausius morosus. We present data to show that the generation of turning kinematics in an insect are the combined result of descending unilateral commands that change the leg motor output via task-specific modifications in the processing of local sensory feedback as well as modification of the activity of local central pattern generating networks in a body-side-specific way. To our knowledge, this is the first study to demonstrate the specificity of such modifications in a defined motor task.

2020 ◽  
Author(s):  
Benjamin Parrell

AbstractReinforcement learning, the ability to change motor behavior based on external reward, has been suggested to play a critical role in early stages of speech motor development and is widely used in clinical rehabilitation for speech motor disorders. However, no current evidence exists that demonstrates the capability of reinforcement to drive changes in human speech behavior. Speech provides a unique test of the universality of reinforcement learning across motor domains: speech is a complex, high-dimensional motor task whose goals do not specify a task to be performed in the environment but ultimately must be self-generated by each speaker such that they are understood by those around them. Reinforcement learning may thus be more difficult for speech, given its high-dimensional and redundant motor system, while speech may also be particularly responsive to reinforcement given the ultimate goal is typically reliant on such feedback from our interlocutors. Across four experiments, we establish whether reinforcement learning alone is sufficient to drive changes in speech behavior and parametrically test two features known to affect reinforcement learning in reaching: how informative the reinforcement signal is as well as the availability of sensory feedback about the outcomes of one’s motor behavior. We show that reinforcement learning can alter speech behavior and that more informative reward signals lead to greater learning. Contrary to results from upper limb control, masking feedback about movement outcomes has no effect on speech learning. Our results suggest reinforcement learning is active in speech but may operate differently than in other motor domains.


2021 ◽  
pp. 1-17
Author(s):  
Benjamin Parrell

Abstract Reinforcement learning, the ability to change motor behavior based on external reward, has been suggested to play a critical role in early stages of speech motor development and is widely used in clinical rehabilitation for speech motor disorders. However, no current evidence exists that demonstrates the capability of reinforcement to drive changes in human speech behavior. Speech provides a unique test of the universality of reinforcement learning across motor domains: Speech is a complex, high-dimensional motor task whose goals do not specify a task to be performed in the environment but ultimately must be self-generated by each speaker such that they are understood by those around them. Across four experiments, we examine whether reinforcement learning alone is sufficient to drive changes in speech behavior and parametrically test two features known to affect reinforcement learning in reaching: how informative the reinforcement signal is as well as the availability of sensory feedback about the outcomes of one's motor behavior. We show that learning does occur and is more likely when participants receive auditory feedback that gives an implicit target for production, although they do not explicitly imitate that target. Contrary to results from upper limb control, masking feedback about movement outcomes has no effect on speech learning. Together, our results suggest a potential role for reinforcement learning in speech but that it likely operates differently than in other motor domains.


1994 ◽  
Vol 189 (1) ◽  
pp. 285-292 ◽  
Author(s):  
A Büschges

The leg joints of invertebrates are governed by neural control loops that control their position and velocity during movements (for reviews, see Bassler, 1983, 1993). These neural control loops rely on sensory feedback about the position and velocity of the controlled leg joint. In invertebrates, this sensory feedback is provided by external (e.g. hair fields, hair rows) and/or internal sense organs (e.g. chordotonal organs). The femoral chordotonal organ (fCO) serves as the main proprioceptor in the control loop governing the femur-tibia (FT) joint of the insect leg. The fCO measures the position and movement of this joint (e.g. Bassler, 1965, 1993; Burns, 1974; Usherwood et al. 1968; Zill, 1985). Previous investigations have described the physiology of sensory cells within femoral chordotonal organs (e.g. stick insect, Hofmann et al. 1985; Hofmann and Koch, 1985; locust, Matheson, 1990; Matheson and Field, 1990). Numerous investigations have been undertaken into the central processing of sensory information provided by the fCO to gain an insight into the control of FT joint movement during different behavioural tasks, for example during resistance reflexes in the standing animal (locust, Burrows, 1987, 1988; Burrows et al. 1988; stick insect, Bassler, 1988; Buschges, 1989, 1990; Driesang and Buschges, 1993) or during active movements (stick insect, Bassler, 1988; Bassler and Buschges, 1990). Most previous studies have not, however, taken into account the morphological separation of the fCO into two distinct scoloparia in the legs of some species (stick insect, Fuller and Ernst, 1973; Hofmann et al. 1985; Hofmann and Koch, 1985; locust middle leg, Burns, 1974). It has been inferred that the whole fCO supplies position and velocity information about the FT joint. In contrast, recent studies of leg reflexes have shown that only its smaller scoloparium (Fig. 1A), containing approximately one-sixth of the total number of sensory neurones, provides the sensory information that is used by the FT control loop (locust, Field and Pfluger, 1989; stick insect, Kittmann and Schmitz, 1992). These studies did not show what types of sensory neurones are located in the ventral part of the fCO and thus contribute to the FT control loop. We have therefore investigated the physiology of sensory neurones that are located in the ventral scoloparium of the fCO.


1999 ◽  
Vol 13 (4) ◽  
pp. 234-244
Author(s):  
Uwe Niederberger ◽  
Wolf-Dieter Gerber

Abstract In two experiments with four and two groups of healthy subjects, a novel motor task, the voluntary abduction of the right big toe, was trained. This task cannot usually be performed without training and is therefore ideal for the study of elementary motor learning. A systematic variation of proprioceptive, tactile, visual, and EMG feedback was used. In addition to peripheral measurements such as the voluntary range of motion and EMG output during training, a three-channel EEG was recorded over Cz, C3, and C4. The movement-related brain potential during distinct periods of the training was analyzed as a central nervous parameter of the ongoing learning process. In experiment I, we randomized four groups of 12 subjects each (group P: proprioceptive feedback; group PT: proprioceptive and tactile feedback; group PTV: proprioceptive, tactile, and visual feedback; group PTEMG: proprioceptive, tactile, and EMG feedback). Best training results were reported from the PTEMG and PTV groups. The movement-preceding cortical activity, in the form of the amplitude of the readiness potential at the time of EMG onset, was greatest in these two groups. Results of experiment II revealed a similar effect, with a greater training success and a higher electrocortical activation under additional EMG feedback compared to proprioceptive feedback alone. Sensory EMG feedback as evaluated by peripheral and central nervous measurements appears to be useful in motor training and neuromuscular re-education.


2019 ◽  
Vol 122 (5) ◽  
pp. 2173-2186 ◽  
Author(s):  
Joscha Schmitz ◽  
Matthias Gruhn ◽  
Ansgar Büschges

Feedback from load and movement sensors can modify timing and magnitude of the motor output in the stepping stick insect. One source of feedback is stretch reception by the femoral chordotonal organ (fCO), which encodes such parameters as the femorotibial (FTi) joint angle, the angular velocity, and its acceleration. Stimulation of the fCO causes a postural resistance reflex, during quiescence, and can elicit the opposite, so-called active reaction (AR), which assists ongoing flexion during active movements. In the present study, we investigated the role of fCO feedback for the difference in likelihood of generating ARs on the inside vs. the outside during curve stepping. We analyzed the effects of fCO stimulation on the motor output to the FTi and the neighboring coxa-trochanter and thorax-coxa joints of the middle leg. In inside and outside turns, the probability for ARs increases with increasing starting angle and decreasing stimulus velocity; furthermore, it is independent of the total angular excursion. However, the transition between stance and swing motor activity always occurs after a specific angular excursion, independent of the turning direction. Feedback from the fCO also has an excitatory influence on levator trochanteris motoneurons (MNs) during inside and outside turns, whereas the same feedback affects protractor coxae MNs only during outside steps. Our results suggest joint- and body side-dependent processing of fCO feedback. A shift in gain may be responsible for different AR probabilities between inside and outside turning, whereas the general control mechanism for ARs is unchanged. NEW & NOTEWORTHY We show that parameters of movement feedback from the tibia in an insect during curve walking are processed in a body side-specific manner, and how. From our results it is highly conceivable that the difference in motor response to the feedback supports the body side-specific leg kinematics during turning. Future studies will need to determine the source for the inputs that determine the local changes in sensory-motor processing.


2009 ◽  
Vol 101 (3) ◽  
pp. 1690-1694 ◽  
Author(s):  
Laura Avanzino ◽  
Marco Bove ◽  
Andrea Tacchino ◽  
Carlo Trompetto ◽  
Carla Ogliastro ◽  
...  

One-hertz repetitive transcranial magnetic stimulation (1Hz-rTMS) over ipsilateral motor cortex is able to modify up to 30 min the motor performance of repetitive finger opposition movements paced with a metronome at 2 Hz. We investigated whether the long-lasting rTMS effect on motor behavior can be modulated by subsequent engagement of the contralateral sensorimotor system. Motor task was performed in different experimental conditions: immediately after rTMS, 30 min after rTMS, or when real rTMS was substituted with sham rTMS. Subjects performing the motor task immediately after rTMS showed modifications in motor behavior ≤30 min after rTMS. On the other hand, when real rTMS was substituted with sham stimulation or when subjects performed the motor task 30 min after the rTMS session, the effect was no longer present. These findings suggest that the combination of ipsilateral 1Hz-rTMS and voluntary movement is crucial to endure the effect of rTMS on the movement itself, probably acting on synaptic plasticity-like mechanism. This finding might provide some useful hints for neurorehabilitation protocols.


2005 ◽  
Vol 93 (3) ◽  
pp. 1127-1135 ◽  
Author(s):  
Ansgar Büschges

It is well established that locomotor patterns result from the interaction between central pattern generating networks in the nervous system, local feedback from sensory neurons about movements and forces generated in the locomotor organs, and coordinating signals from neighboring segments or appendages. This review addresses the issue of how the movements of multi-segmented locomotor organs are coordinated and provides an overview of recent advances in understanding sensory control and the internal organization of central pattern generating networks that operate multi-segmented locomotor organs, such as a walking leg. Findings from the stick insect and the cat are compared and discussed in relation to new findings on the lamprey swimming network. These findings support the notion that common schemes of sensory feedback are used for generating walking and that central neural networks controlling multi-segmented locomotor organs generally encompass multiple central pattern generating networks that correspond with the segmental structure of the locomotor organ.


2017 ◽  
Vol 118 (4) ◽  
pp. 2296-2310 ◽  
Author(s):  
Charalampos Mantziaris ◽  
Till Bockemühl ◽  
Philip Holmes ◽  
Anke Borgmann ◽  
Silvia Daun ◽  
...  

To efficiently move around, animals need to coordinate their limbs. Proper, context-dependent coupling among the neural networks underlying leg movement is necessary for generating intersegmental coordination. In the slow-walking stick insect, local sensory information is very important for shaping coordination. However, central coupling mechanisms among segmental central pattern generators (CPGs) may also contribute to this. Here, we analyzed the interactions between contralateral networks that drive the depressor trochanteris muscle of the legs in both isolated and interconnected deafferented thoracic ganglia of the stick insect on application of pilocarpine, a muscarinic acetylcholine receptor agonist. Our results show that depressor CPG activity is only weakly coupled between all segments. Intrasegmental phase relationships differ between the three isolated ganglia, and they are modified and stabilized when ganglia are interconnected. However, the coordination patterns that emerge do not resemble those observed during walking. Our findings are in line with recent studies and highlight the influence of sensory input on coordination in slowly walking insects. Finally, as a direct interaction between depressor CPG networks and contralateral motoneurons could not be observed, we hypothesize that coupling is based on interactions at the level of CPG interneurons. NEW & NOTEWORTHY Maintaining functional interleg coordination is vitally important as animals locomote through changing environments. The relative importance of central mechanisms vs. sensory feedback in this process is not well understood. We analyzed coordination among the neural networks generating leg movements in stick insect preparations lacking phasic sensory feedback. Under these conditions, the networks governing different legs were only weakly coupled. In stick insect, central connections alone are thus insufficient to produce the leg coordination observed behaviorally.


1992 ◽  
Vol 9 (4) ◽  
pp. 343-352
Author(s):  
Geert J.P. Savelsbergh ◽  
J. Bernard Netelenbos

Spatial information for the execution of motor behavior is acquired by orienting eye and head movements. This information can be found in our direct field of view as well as outside this field. Auditory information is especially helpful in directing our attention to information outside our initial visual field of view. Two topics on the effect of an auditory loss are discussed. Experimental evidence is provided which shows that deaf children have problems in orienting to visual stimuli situated outside their field of view. An overview is given from several studies in which the eye and head movements of deaf children are analyzed. Second, it is suggested that specific visual localization problems are partly responsible for deaf children’s characteristic lag in motor development. The latter is illustrated in two studies involving the gross motor task of ball catching.


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