scholarly journals Hybrid dedicated and distributed coding in PMd/M1 provides separation and interaction of bilateral arm signals

2021 ◽  
Vol 17 (11) ◽  
pp. e1009615
Author(s):  
Tanner C. Dixon ◽  
Christina M. Merrick ◽  
Joni D. Wallis ◽  
Richard B. Ivry ◽  
Jose M. Carmena
Keyword(s):  
Motor Cortex ◽  
Motor Planning ◽  
The Other ◽  
Contralateral Hemisphere ◽  
Population Response ◽  
Distributed Coding ◽  
Reaching Task ◽  
Population Responses ◽  
Functional Aspects ◽  
Organizational Principles

Pronounced activity is observed in both hemispheres of the motor cortex during preparation and execution of unimanual movements. The organizational principles of bi-hemispheric signals and the functions they serve throughout motor planning remain unclear. Using an instructed-delay reaching task in monkeys, we identified two components in population responses spanning PMd and M1. A “dedicated” component, which segregated activity at the level of individual units, emerged in PMd during preparation. It was most prominent following movement when M1 became strongly engaged, and principally involved the contralateral hemisphere. In contrast to recent reports, these dedicated signals solely accounted for divergence of arm-specific neural subspaces. The other “distributed” component mixed signals for each arm within units, and the subspace containing it did not discriminate between arms at any stage. The statistics of the population response suggest two functional aspects of the cortical network: one that spans both hemispheres for supporting preparatory and ongoing processes, and another that is predominantly housed in the contralateral hemisphere and specifies unilateral output.

scholarly journals Hybrid local and distributed coding in PMd/M1 provides separation and interaction of bilateral arm signals

2020 ◽  
Author(s):  
Tanner C. Dixon ◽  
Christina M. Merrick ◽  
Joni D. Wallis ◽  
Richard B. Ivry ◽  
Jose M. Carmena
Keyword(s):  
Motor Cortex ◽  
Motor Planning ◽  
Cortical Network ◽  
The Other ◽  
Contralateral Hemisphere ◽  
Population Response ◽  
Distributed Coding ◽  
Reaching Task ◽  
Population Responses ◽  
Organizational Principles

ABSTRACTPronounced activity is observed in both hemispheres of the motor cortex during preparation and execution of unimanual movements. The organizational principles of bi-hemispheric signals and the functions they serve throughout motor planning remain unclear. Using an instructed-delay reaching task in monkeys, we identified two components in population responses spanning PMd and M1. A ‘localized’ component, which confined activity within arm-specific sub-populations, emerged in PMd during preparation. It was most prominent following movement when M1 became strongly engaged, and principally involved the contralateral hemisphere. In contrast to recent reports, these localized signals solely accounted for divergence of arm-specific neural subspaces. The other ‘distributed’ component mixed signals for each arm within units, and the subspace containing it did not discriminate between arms at any stage. The statistics of the population response suggest two functional layers of the cortical network: one spanning hemispheres supporting preparatory and ongoing processes, and another specifying unilateral output.

scholarly journals Motor cortex signals for each arm are mixed across hemispheres and neurons yet partitioned within the population response

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Katherine Cora Ames ◽  
Mark M Churchland
Keyword(s):  
Motor Cortex ◽  
Muscle Activity ◽  
Population Level ◽  
The Other ◽  
Contralateral Hemisphere ◽  
Population Response

Motor cortex (M1) has lateralized outputs, yet neurons can be active during movements of either arm. What is the nature and role of activity across the two hemispheres? We recorded muscles and neurons bilaterally while monkeys cycled with each arm. Most neurons were active during movement of either arm. Responses were strongly arm-dependent, raising two possibilities. First, population-level signals might differ depending on the arm used. Second, the same population-level signals might be present, but distributed differently across neurons. The data supported this second hypothesis. Muscle activity was accurately predicted by activity in either the ipsilateral or contralateral hemisphere. More generally, we failed to find signals unique to the contralateral hemisphere. Yet if signals are shared across hemispheres, how do they avoid impacting the wrong arm? We found that activity related to each arm occupies a distinct subspace, enabling muscle-activity decoders to naturally ignore signals related to the other arm.

scholarly journals Sub-optimality in motor planning is not improved by explicit observation of motor uncertainty

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Keiji Ota ◽  
Masahiro Shinya ◽  
Laurence T. Maloney ◽  
Kazutoshi Kudo
Keyword(s):  
Motor Planning ◽  
The Other ◽  
Insufficient Information ◽  
Reaching Task ◽  
Additional Information ◽  
Optimal Decisions ◽  
Decisions Under Risk ◽  
Motor Error ◽  
Better Than ◽  
Decision Tasks

Abstract To make optimal decisions under risk, one must correctly weight potential rewards and penalties by the probabilities of receiving them. In motor decision tasks, the uncertainty in outcome is a consequence of motor uncertainty. When participants perform suboptimally as they often do in such tasks, it could be because they have insufficient information about their motor uncertainty: with more information, their performance could converge to optimal as they learn their own motor uncertainty. Alternatively, their suboptimal performance may reflect an inability to make use of the information they have or even to perform the correct computations. To discriminate between these two possibilities, we performed an experiment spanning two days. On the first day, all participants performed a reaching task with trial-by-trial feedback of motor error. At the end of the day, their aim points were still typically suboptimal. On the second day participants were divided into two groups one of which repeated the task of the first day and the other of which repeated the task but were intermittently given additional information summarizing their motor errors. Participants receiving additional information did not perform significantly better than those who did not.

A Phonomotor Approach to Apraxia of Speech Treatment

2020 ◽  
Vol 29 (4) ◽  
pp. 2109-2130
Author(s):  
Lauren Bislick
Keyword(s):  
Phase I ◽  
Treatment Effects ◽  
Single Case ◽  
Motor Planning ◽  
The Other ◽  
Multimodal Approach ◽  
Apraxia Of Speech ◽  
Duration Of Treatment ◽  
Treatment Gains ◽  
Future Work

Purpose This study continued Phase I investigation of a modified Phonomotor Treatment (PMT) Program on motor planning in two individuals with apraxia of speech (AOS) and aphasia and, with support from prior work, refined Phase I methodology for treatment intensity and duration, a measure of communicative participation, and the use of effect size benchmarks specific to AOS. Method A single-case experimental design with multiple baselines across behaviors and participants was used to examine acquisition, generalization, and maintenance of treatment effects 8–10 weeks posttreatment. Treatment was distributed 3 days a week, and duration of treatment was specific to each participant (criterion based). Experimental stimuli consisted of target sounds or clusters embedded nonwords and real words, specific to each participants' deficit. Results Findings show improved repetition accuracy for targets in trained nonwords, generalization to targets in untrained nonwords and real words, and maintenance of treatment effects at 10 weeks posttreatment for one participant and more variable outcomes for the other participant. Conclusions Results indicate that a modified version of PMT can promote generalization and maintenance of treatment gains for trained speech targets via a multimodal approach emphasizing repeated exposure and practice. While these results are promising, the frequent co-occurrence of AOS and aphasia warrants a treatment that addresses both motor planning and linguistic deficits. Thus, the application of traditional PMT with participant-specific modifications for AOS embedded into the treatment program may be a more effective approach. Future work will continue to examine and maximize improvements in motor planning, while also treating anomia in aphasia.

scholarly journals Area-specific thalamocortical synchronization underlies the transition from motor planning to execution

2021 ◽  
Vol 118 (6) ◽  
pp. e2012658118
Author(s):  
Abdulraheem Nashef ◽  
Rea Mitelman ◽  
Ran Harel ◽  
Mati Joshua ◽  
Yifat Prut
Keyword(s):  
Primary Motor Cortex ◽  
Premotor Cortex ◽  
Cell Activity ◽  
Motor Planning ◽  
Simultaneous Recording ◽  
Delayed Response ◽  
Neural Responses ◽  
Cortical Cells ◽  
Reaching Task ◽  
Motor Thalamus

We studied correlated firing between motor thalamic and cortical cells in monkeys performing a delayed-response reaching task. Simultaneous recording of thalamocortical activity revealed that around movement onset, thalamic cells were positively correlated with cell activity in the primary motor cortex but negatively correlated with the activity of the premotor cortex. The differences in the correlation contrasted with the average neural responses, which were similar in all three areas. Neuronal correlations reveal functional cooperation and opposition between the motor thalamus and distinct motor cortical areas with specific roles in planning vs. performing movements. Thus, by enhancing and suppressing motor and premotor firing, the motor thalamus can facilitate the transition from a motor plan to execution.

Ultrastructural features of the sensori-motor cortex of the primate

1979 ◽  
Vol 285 (1006) ◽  
pp. 123-139 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Motor Cortex ◽  
Thin Layer ◽  
Liquid Helium ◽  
Thermal Insulation ◽  
Solid Surfaces ◽  
The Other ◽  
Experimental Chamber ◽  
Short Discussion ◽  
Inside Wall

cooled to 2°K or lower. Rollin (1936) found that the thermal insulation of vessels containing liquid helium was much worse below than above the A point. He explained his observation by assuming the existence of a thin layer of liquid helium on the inside wall of the connecting tube, and thought it probable that the change in thermal conductivity of this film at the A point gave rise to the anomalous effects observed. As the result of more recent (unpublished) experiments Rollin and Simon* have put forward the other explanation that the film creeps up the tube and evaporates eventually. It is obvious that all these phenomena may have a common explanation and it was the object of the experiments described in this paper and the following paper to investigate the behaviour of He 11 in contact with solid surfaces systematically. The phenomena had to be investigated from various aspects and this made experiments necessary which varied in purpose and character to some extent. For simplicity’s sake we will therefore give, together with the description of each experiment, a short discussion and summarize at the end of the second paper all results in a general discussion on the whole phenomenon. All experiments were carried out in the same cryostat; and for different experiments only the experimental chamber and the experimental arrangement in it were altered.

Interaction Between Finger Opposition Movements and Aftereffects of 1Hz-rTMS on Ipsilateral Motor Cortex

2009 ◽  
Vol 101 (3) ◽  
pp. 1690-1694 ◽  
Author(s):  
Laura Avanzino ◽  
Marco Bove ◽  
Andrea Tacchino ◽  
Carlo Trompetto ◽  
Carla Ogliastro ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Motor Performance ◽  
Magnetic Stimulation ◽  
Voluntary Movement ◽  
Motor Behavior ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Motor Task ◽  
The Other ◽  
Experimental Conditions ◽  
Opposition Movements

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.

scholarly journals Motor Cortex Embeds Muscle-like Commands in an Untangled Population Response

Neuron ◽  
2018 ◽  
Vol 97 (4) ◽  
pp. 953-966.e8 ◽  
Author(s):  
Abigail A. Russo ◽  
Sean R. Bittner ◽  
Sean M. Perkins ◽  
Jeffrey S. Seely ◽  
Brian M. London ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Population Response

scholarly journals An Automated Test of Rat Forelimb Supination Quantifies Motor Function Loss and Recovery After Corticospinal Injury

2016 ◽  
Vol 31 (2) ◽  
pp. 122-132 ◽  
Author(s):  
Anil Sindhurakar ◽  
Samuel D. Butensky ◽  
Eric Meyers ◽  
Joshua Santos ◽  
Thelma Bethea ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Large Scale ◽  
Hand Function ◽  
Partial Recovery ◽  
Reaching Task ◽  
Single Pellet ◽  
Before And After ◽  
Drug Doses ◽  
Injury And Repair ◽  
Large Deficit

Background. Rodents are the primary animal model of corticospinal injury and repair, yet current behavioral tests do not show the large deficits after injury observed in humans. Forearm supination is critical for hand function and is highly impaired by corticospinal injury in both humans and rats. Current tests of rodent forelimb function do not measure this movement. Objective. To determine if quantification of forelimb supination in rats reveals large-scale functional loss and partial recovery after corticospinal injury. Methods. We developed a knob supination device that quantifies supination using automated and objective methods. Rats in a reaching box have to grasp and turn a knob in supination in order to receive a food reward. Performance on this task and the single pellet reaching task were measured before and after 2 manipulations of the pyramidal tract: a cut lesion of 1 pyramid and inactivation of motor cortex using 2 different drug doses. Results. A cut lesion of the corticospinal tract produced a large deficit in supination. In contrast, there was no change in pellet retrieval success. Supination function recovered partially over 6 weeks after injury, and a large deficit remained. Motor cortex inactivation produced a dose-dependent loss of knob supination; the effect on pellet reaching was more subtle. Conclusions. The knob supination task reveals in rodents 3 signature hand function changes observed in humans with corticospinal injury: (1) large-scale loss with injury, (2) partial recovery in the weeks after injury, and (3) loss proportional to degree of dysfunction.

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