scholarly journals Rotational dynamics in motor cortex are consistent with a feedback controller

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Hari Teja Kalidindi ◽  
Kevin P Cross ◽  
Timothy P Lillicrap ◽  
Mohsen Omrani ◽  
Egidio Falotico ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Recurrent Neural Networks ◽  
Sensory Feedback ◽  
Feedback Controller ◽  
Rotational Dynamics ◽  
Rotational Structure ◽  
Brain Areas ◽  
Neural Recordings ◽  
Neurophysiological Studies ◽  
Motor Actions

Recent studies have identified rotational dynamics in motor cortex (MC) which many assume arise from intrinsic connections in MC. However, behavioural and neurophysiological studies suggest that MC behaves like a feedback controller where continuous sensory feedback and interactions with other brain areas contribute substantially to MC processing. We investigated these apparently conflicting theories by building recurrent neural networks that controlled a model arm and received sensory feedback from the limb. Networks were trained to counteract perturbations to the limb and to reach towards spatial targets. Network activities and sensory feedback signals to the network exhibited rotational structure even when the recurrent connections were removed. Furthermore, neural recordings in monkeys performing similar tasks also exhibited rotational structure not only in MC but also in somatosensory cortex. Our results argue that rotational structure may also reflect dynamics throughout the voluntary motor system involved in online control of motor actions.

scholarly journals Rotational dynamics in motor cortex are consistent with a feedback controller

2020 ◽  
Author(s):  
Hari Teja Kalidindi ◽  
Kevin P. Cross ◽  
Timothy P. Lillicrap ◽  
Mohsen Omrani ◽  
Egidio Falotico ◽  
...  
Keyword(s):  
Neural Networks ◽  
Motor Cortex ◽  
Somatosensory Cortex ◽  
Sensory Feedback ◽  
Feedback Controller ◽  
Rotational Dynamics ◽  
Rotational Structure ◽  
List Type ◽  
Neurophysiological Studies ◽  
Recurrent Connections

SummaryRecent studies hypothesize that motor cortical (MC) dynamics are generated largely through its recurrent connections based on observations that MC activity exhibits rotational structure. However, behavioural and neurophysiological studies suggest that MC behaves like a feedback controller where continuous sensory feedback and interactions with other brain areas contribute substantially to MC processing. We investigated these apparently conflicting theories by building recurrent neural networks that controlled a model arm and received sensory feedback about the limb. Networks were trained to counteract perturbations to the limb and to reach towards spatial targets. Network activities and sensory feedback signals to the network exhibited rotational structure even when the recurrent connections were removed. Furthermore, neural recordings in monkeys performing similar tasks also exhibited rotational structure not only in MC but also in somatosensory cortex. Our results argue that rotational structure may reflect dynamics throughout voluntary motor circuits involved in online control of motor actions.HighlightsNeural networks with sensory feedback generate rotational dynamics during simulated posture and reaching tasksRotational dynamics are observed even without recurrent connections in the networkSimilar dynamics are observed not only in motor cortex, but also in somatosensory cortex of non-huma n primates as well as sensory feedback signalsResults highlight rotational dynamics may reflect internal dynamics, external inputs or any combination of the two.

scholarly journals Distinct roles for motor cortical and thalamic inputs to striatum during motor learning and execution

2019 ◽  
Author(s):  
Steffen B. E. Wolff ◽  
Raymond Ko ◽  
Bence P. Ölveczky
Keyword(s):  
Motor Cortex ◽  
Motor Learning ◽  
Learning Process ◽  
Brain Areas ◽  
Thalamic Neurons ◽  
Cortical Input ◽  
Motor Circuits ◽  
Motor Network ◽  
Motor Cortical ◽  
Cortical Inputs

AbstractThe acquisition and execution of learned motor sequences are mediated by a distributed motor network, spanning cortical and subcortical brain areas. The sensorimotor striatum is an important cog in this network, yet how its two main inputs, from motor cortex and thalamus respectively, contribute to its role in motor learning and execution remains largely unknown. To address this, we trained rats in a task that produces highly stereotyped and idiosyncratic motor sequences. We found that motor cortical input to the sensorimotor striatum is critical for the learning process, but after the behaviors were consolidated, this corticostriatal pathway became dispensable. Functional silencing of striatal-projecting thalamic neurons, however, disrupted the execution of the learned motor sequences, causing rats to revert to behaviors produced early in learning and preventing them from re-learning the task. These results show that the sensorimotor striatum is a conduit through which motor cortical inputs can drive experience-dependent changes in subcortical motor circuits, likely at thalamostriatal synapses.

scholarly journals Locomotor adaptation is modulated by observing the actions of others

2015 ◽  
Vol 114 (3) ◽  
pp. 1538-1544 ◽  
Author(s):  
Mitesh Patel ◽  
R. Edward Roberts ◽  
Mohammed U. Riyaz ◽  
Maroof Ahmed ◽  
David Buckwell ◽  
...  
Keyword(s):  
Motor Behavior ◽  
Postural Sway ◽  
Mirror Neuron System ◽  
Action Observation ◽  
Mirror Neuron ◽  
Locomotor Adaptation ◽  
Neurophysiological Studies ◽  
Challenging Environment ◽  
Automatic Mechanism ◽  
Motor Actions

Observing the motor actions of another person could facilitate compensatory motor behavior in the passive observer. Here we explored whether action observation alone can induce automatic locomotor adaptation in humans. To explore this possibility, we used the “broken escalator” paradigm. Conventionally this involves stepping upon a stationary sled after having previously experienced it actually moving (Moving trials). This history of motion produces a locomotor aftereffect when subsequently stepping onto a stationary sled. We found that viewing an actor perform the Moving trials was sufficient to generate a locomotor aftereffect in the observer, the size of which was significantly correlated with the size of the movement (postural sway) observed. Crucially, the effect is specific to watching the task being performed, as no motor adaptation occurs after simply viewing the sled move in isolation. These findings demonstrate that locomotor adaptation in humans can be driven purely by action observation, with the brain adapting motor plans in response to the size of the observed individual's motion. This mechanism may be mediated by a mirror neuron system that automatically adapts behavior to minimize movement errors and improve motor skills through social cues, although further neurophysiological studies are required to support this theory. These data suggest that merely observing the gait of another person in a challenging environment is sufficient to generate appropriate postural countermeasures, implying the existence of an automatic mechanism for adapting locomotor behavior.

scholarly journals Brain Switch for Reflex Micturition Control Detected by fMRI in Rats

2009 ◽  
Vol 102 (5) ◽  
pp. 2719-2730 ◽  
Author(s):  
Changfeng Tai ◽  
Jicheng Wang ◽  
Tao Jin ◽  
Ping Wang ◽  
Seong-Gi Kim ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Brain Stem ◽  
Afferent Input ◽  
Brain Network ◽  
Retrosplenial Cortex ◽  
Switching Circuits ◽  
Neurophysiological Studies ◽  
Urine Storage ◽  
And Control ◽  
The Brain

The functions of the lower urinary tract are controlled by complex pathways in the brain that act like switching circuits to voluntarily or reflexly shift the activity of various pelvic organs (bladder, urethra, urethral sphincter, and pelvic floor muscles) from urine storage to micturition. In this study, functional magnetic resonance imaging (fMRI) was used to visualize the brain switching circuits controlling reflex micturition in anesthetized rats. The fMRI images confirmed the hypothesis based on previous neuroanatomical and neurophysiological studies that the brain stem switch for reflex micturition control involves both the periaqueductal gray (PAG) and the pontine micturition center (PMC). During storage, the PAG was activated by afferent input from the urinary bladder while the PMC was inactive. When bladder volume increased to the micturition threshold, the switch from storage to micturition was associated with PMC activation and enhanced PAG activity. A complex brain network that may regulate the brain stem micturition switch and control storage and voiding was also identified. Storage was accompanied by activation of the motor cortex, somatosensory cortex, cingulate cortex, retrosplenial cortex, thalamus, putamen, insula, and septal nucleus. On the other hand, micturition was associated with: 1) increased activity of the motor cortex, thalamus, and putamen; 2) a shift in the locus of activity in the cingulate and insula; and 3) the emergence of activity in the hypothalamus, substantia nigra, globus pallidus, hippocampus, and inferior colliculus. Understanding brain control of reflex micturition is important for elucidating the mechanisms underlying neurogenic bladder dysfunctions including frequency, urgency, and incontinence.

scholarly journals Simultaneous Preparation of Multiple Potential Movements: Opposing Effects of Spatial Proximity Mediated by Premotor and Parietal Cortex

2009 ◽  
Vol 102 (4) ◽  
pp. 2084-2095 ◽  
Author(s):  
Peter Praamstra ◽  
Dimitrios Kourtis ◽  
Kianoush Nazarpour
Keyword(s):  
Motor Cortex ◽  
Distributed Control ◽  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Delay Period ◽  
Spatial Proximity ◽  
Frontoparietal Network ◽  
Neurophysiological Studies ◽  
Preparatory Activity ◽  
Posterior Parietal

Neurophysiological studies in monkey have suggested that premotor and motor cortex may prepare for multiple movements simultaneously, sustained by cooperative and competitive interactions within and between the neural populations encoding different actions. Here, we investigate whether competition between alternative movement directions, manipulated in terms of number and spatial angle, is reflected in electroencephalographic (EEG) measures of (pre)motor cortical activity in humans. EEG was recorded during performance of a center-out pointing task in which response signals were preceded by cues providing prior information in the form of arrows pointing to one or more possible movement targets. Delay-period activity in (pre)motor cortex was modulated in the predicted manner by the number of possible movement directions and by the angle separating them. Response latencies, however, were determined not only by the amplitude of movement-preparatory activity, but also by differences in the duration of stimulus evaluation against the visuospatial memory of the cue, reflected in EEG potentials originating from posterior parietal cortex (PPC). Specifically, the spatial proximity of possible movement targets was processed differently by (pre)motor and posterior parietal cortex. Spatial proximity enhanced the amplitude of (pre)motor cortex preparatory activity during the delay period but delayed evaluation of the response signal in the PPC, thus producing opposite effects on response latency. The latter finding supports distributed control of movement decisions in the frontoparietal network, revealing a feature of distributed control that is of potential significance for the understanding of distracter effects in reaching and pointing.

scholarly journals A curved manifold orients rotational dynamics in motor cortex

2021 ◽  
Author(s):  
David A. Sabatini ◽  
Matthew T. Kaufman
Keyword(s):  
Motor Cortex ◽  
State Space ◽  
Population Level ◽  
Pattern Generation ◽  
Rotational Dynamics ◽  
Simple Relationship ◽  
Time Varying ◽  
Neural Responses ◽  
Complex Time ◽  
Time Courses

SummaryControlling arm movements requires complex, time-varying patterns of muscle activity 1,2. Accordingly, the responses of neurons in motor cortex are complex, time-varying, and heterogeneous during reaching 2–4. When examined at the population level, patterns of neural activity evolve over time according to dynamical rules 5,6. During reaching, these rules have been argued to be “rotational” 7 or variants thereof 8,9, containing coordinated oscillations in the spike rates of individual neurons. While these models capture key aspects of the neural responses, they fail to capture others – accounting for only 20-50% of the neural response variance. Here, we consider a broader class of dynamical models. We find that motor cortex dynamics take an unexpected form: there were 3-4 rotations at fixed frequencies in M1 and PMd explaining more than 90% of neural responses, but these rotations occurred in different portions of state space when movements differ. These rotations appear to reflect a curved manifold of fixed points in state space, around which dynamics are locally rotational. These fixed-frequency rotations obeyed a simple relationship with movement: the orientation of rotations in motor cortex activity were related almost linearly to the movement the animal made, allowing linear decoding of reach kinematic time-courses on single trials. This model constitutes a fundamentally novel way to consider pattern generation: like placing a record player in a large bowl, the frequency of activity is fixed, but the location of motor cortex activity on a curved manifold sets the orientation of locally-rotational dynamics. This system simplifies motor control, helps reconcile conflicting frameworks for interpreting motor cortex, and enables greatly improved neural decoding.

scholarly journals Mouse Motor Cortex Coordinates the Behavioral Response to Unpredicted Sensory Feedback

Neuron ◽  
2018 ◽  
Vol 99 (5) ◽  
pp. 1040-1054.e5 ◽  
Author(s):  
Matthias Heindorf ◽  
Silvia Arber ◽  
Georg B. Keller
Keyword(s):  
Motor Cortex ◽  
Behavioral Response ◽  
Sensory Feedback

1 Hz Repetitive Transcranial Magnetic Stimulation of the Primary Motor Cortex: Impact on Excitability and Task Performance in Healthy Subjects

2020 ◽  
Vol 81 (02) ◽  
pp. 147-154 ◽  
Author(s):  
Melina Engelhardt ◽  
Thomas Picht
Keyword(s):  
Motor Cortex ◽  
Healthy Subjects ◽  
Grip Force ◽  
Silent Period ◽  
Small Sample ◽  
Hemispheric Dominance ◽  
Finger Tapping ◽  
Cortical Silent Period ◽  
Brain Areas ◽  
Resting Motor Threshold

Abstract Objective Neuronavigated repetitive transcranial stimulation (rTMS) at a frequency of 1 Hz was shown to reduce excitability in underlying brain areas while increasing excitability in the opposite hemisphere. In stroke patients, this principle is used to normalize activity between the lesioned and healthy hemispheres and to facilitate rehabilitation. However, standardization is lacking in applied protocols, and there is a poor understanding of the underlying physiologic mechanisms. Furthermore, the influence of hemispheric dominance on the intervention has not been studied before. A systematic evaluation of the effects in healthy subjects would deepen the understanding of these mechanisms and offer insights into ways to improve the intervention. Methods Twenty healthy subjects underwent five 15-minute sessions of neuronavigated rTMS or sham stimulation over their dominant or nondominant motor cortex. Dominance was assessed with the Edinburgh Handedness Inventory. Changes in both hemispheres were measured using behavioral parameters (finger tapping, grip force, and finger dexterity) and TMS measures (resting motor threshold, recruitment curve, motor area, and cortical silent period). Results All subjects tolerated the stimulation well. A pronounced improvement was noted in finger tapping scores over the nonstimulated hemisphere as well as a nonsignificant reduction of the cortical silent period in the stimulated hemisphere, indicating a differential effect of the rTMS on both hemispheres. Grip force remained at the baseline level in the rTMS group while decreasing in the sham group, suggesting the rTMS counterbalanced the effects of fatigue. Lastly, dominance did not influence any of the observed effects. Conclusions This study shows the capability of the applied low-frequency rTMS protocol to modify excitability of underlying brain areas as well as the contralateral hemisphere. It also highlights the need for a better understanding of underlying mechanisms and the identification of predictors for responsiveness to rTMS. However, results should be interpreted with caution because of the small sample size.

Modularity and Modulation of Locomotor Circuits in Adult Vertebrates

2017 ◽  
pp. 535-544
Author(s):  
Abdeljabbar El Manira
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Continuous Change ◽  
Brain Areas ◽  
Motor Behaviors ◽  
External Cues ◽  
Motor Actions ◽  
Brain And Spinal Cord ◽  
The Brain

The compartmentalized organization of the nervous system entails that specific functions are localized in different brain areas and regions of the spinal cord. Dedicated microcircuits in each region/area generate relevant motor behaviors by virtue of their connectivity and dynamic computations, combined with their ability to integrate internal and external cues. The patterns of motor actions are often versatile, with continuous change in speed and coordination as circumstances demand. How this versatility is encoded within microcircuits in the brain and spinal cord is a question that has been difficult to address. Although many mechanisms can contribute, two important tenets underlying this versatility are the modularity and modulation of microcircuits.

scholarly journals Rapid Integration of Artificial Sensory Feedback during Operant Conditioning of Motor Cortex Neurons

Neuron ◽  
2017 ◽  
Vol 93 (4) ◽  
pp. 929-939.e6 ◽  
Author(s):  
Mario Prsa ◽  
Gregorio L. Galiñanes ◽  
Daniel Huber
Keyword(s):  
Motor Cortex ◽  
Operant Conditioning ◽  
Sensory Feedback
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