scholarly journals Cyclic, condition-independent activity in primary motor cortex predicts corrective movement behavior

2018 ◽  
Author(s):  
Adam G. Rouse ◽  
Marc H. Schieber ◽  
Sridevi V. Sarma
Keyword(s):  
Motor Cortex ◽  
Neural Activity ◽  
Time Course ◽  
Primary Motor Cortex ◽  
Reaching Movements ◽  
Movement Behavior ◽  
Cyclic Activity ◽  
Cyclic Condition ◽  
Neuron Populations ◽  
Optimizing Control

AbstractReaching movements have previously been observed to have large condition-independent neural activity and cyclic neural dynamics. A new precision center-out task was used to test whether cyclic neural activity in the primary motor cortex (M1) occurred not only during initial reaching movements but also during subsequent corrective movements. Corrective movements were observed to be discrete with a time course and bell-shaped speed profile similar to the initial movements. Cyclic trajectories identified in the condition-independent neural activity were similar for initial and corrective submovements. The phase of the cyclic condition-independent neural activity predicted when peak movement speeds occurred, even when the subject made multiple corrective movements. Rather than being controlled as continuations of the initial reach, a discrete cycle of motor cortex activity encodes each corrective submovement.Significance StatementDuring a precision center-out task, initial and subsequent corrective movements occur as discrete submovements with bell-shaped speed profiles. A cycle of condition-independent activity in primary motor cortex neuron populations corresponds to each submovement whether initial or corrective, such that the phase of this cyclic activity predicts the time of peak speed. These submovements accompanied by cyclic neural activity offer important clues into how the we successfully execute precise, corrective reaching movements and may have implications for optimizing control of brain-computer interfaces.

scholarly journals Chronic Stability of Single-Channel Neurophysiological Correlates of Gross and Fine Reaching Movements in the Rat

2019 ◽  
Author(s):  
David T. Bundy ◽  
David J Guggenmos ◽  
Maxwell D Murphy ◽  
Randolph J. Nudo
Keyword(s):  
Motor Cortex ◽  
Local Field ◽  
Neural Activity ◽  
Local Field Potential ◽  
Primary Motor Cortex ◽  
Spectral Power ◽  
Premotor Cortex ◽  
Field Potential ◽  
Motor Recovery ◽  
Reaching Movements

AbstractFollowing injury to motor cortex, reorganization occurs throughout spared brain regions and is thought to underlie motor recovery. Unfortunately, the standard neurophysiological and neuroanatomical measures of post-lesion plasticity are only indirectly related to observed changes in motor execution. While substantial task-related neural activity has been observed during motor tasks in rodent primary motor cortex and premotor cortex, the long-term stability of these responses in healthy rats is uncertain, limiting the interpretability of longitudinal changes in the specific patterns of neural activity during motor recovery following injury. This study examined the stability of task-related neural activity associated with execution of reaching movements in healthy rodents. Rats were trained to perform a novel reaching task combining a ‘gross’ lever press and a ‘fine’ pellet retrieval. In each animal, two chronic microelectrode arrays were implanted in motor cortex spanning the caudal forelimb area (rodent primary motor cortex) and the rostral forelimb area (rodent premotor cortex). We recorded multiunit spiking and local field potential activity from 10 days to 7-10 weeks post-implantation to characterize the patterns of neural activity observed during each task component and analyzed the consistency of channel-specific task-related neural activity. Task-related changes in neural activity were observed on the majority of channels. While the task-related changes in multi-unit spiking and local field potential spectral power were consistent over several weeks, spectral power changes were more stable, despite the trade-off of decreased spatial and temporal resolution. These results show that rodent primary and premotor cortex are both involved in reaching movements with stable patterns of task-related activity across time, establishing the relevance of the rodent for future studies designed to examine changes in task-related neural activity during recovery from focal cortical lesions.

Comparison of Neural Activity in the Supplementary Motor Area and in the Primary Motor Cortex in Monkeys

1991 ◽  
Vol 8 (1) ◽  
pp. 27-44 ◽  
Author(s):  
Chen Dao-fen ◽  
B. Hyland ◽  
V. Maier ◽  
A. Palmeri ◽  
M. Wiesendanger
Keyword(s):  
Motor Cortex ◽  
Neural Activity ◽  
Primary Motor Cortex ◽  
Supplementary Motor Area ◽  
Motor Area

Time Course of Determination of Movement Direction in the Reaction Time Task in Humans

2001 ◽  
Vol 86 (3) ◽  
pp. 1195-1201 ◽  
Author(s):  
Martin Sommer ◽  
Joseph Classen ◽  
Leonardo G. Cohen ◽  
Mark Hallett
Keyword(s):  
Reaction Time ◽  
Motor Cortex ◽  
Time Course ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Movement Direction ◽  
Movement Onset ◽  
Thumb Movement

The primary motor cortex produces motor commands that include encoding the direction of movement. Excitability of the motor cortex in the reaction time (RT) task can be assessed using transcranial magnetic stimulation (TMS). To elucidate the timing of the increase in cortical excitability and of the determination of movement direction before movement onset, we asked six right-handed, healthy subjects to either abduct or extend their right thumb after a go-signal indicated the appropriate direction. Between the go-signal and movement onset, single TMS pulses were delivered to the contralateral motor cortex. We recorded the direction of the TMS-induced thumb movement and the amplitude of motor-evoked potentials (MEPs) from the abductor pollicis brevis and extensor pollicis brevis muscles. Facilitation of MEPs from the prime mover, as early as 200 ms before the end of the reaction time, preceded facilitation of MEPs from the nonprime mover, and both preceded measurable directional change. Compared with a control condition in which no voluntary movement was required, the direction of the TMS-induced thumb movement started to change in the direction of the intended movement as early as 90 ms before the end of the RT, and maximum changes were seen shortly before the end of reaction time. Movement acceleration also increased with maxima shortly before the end of the RT. We conclude that in concentric movements a change of the movement direction encoded in the primary motor cortex occurs in the 200 ms prior to movement onset, which is as early as increased excitability itself can be detected.

27. Attention-dependent modulation of neural activity in primary motor cortex

2009 ◽  
Vol 120 (1) ◽  
pp. e15
Author(s):  
A. Milnik ◽  
I. Nowak ◽  
N. Müller
Keyword(s):  
Motor Cortex ◽  
Neural Activity ◽  
Primary Motor Cortex

scholarly journals Vacillation, indecision and hesitation in moment-by-moment decoding of monkey motor cortex

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Matthew T Kaufman ◽  
Mark M Churchland ◽  
Stephen I Ryu ◽  
Krishna V Shenoy
Keyword(s):  
Motor Cortex ◽  
Neural Activity ◽  
Free Choice ◽  
Primary Motor Cortex ◽  
Brain State ◽  
Decision Task ◽  
Final Choice ◽  
The Rich ◽  
Individual Decisions ◽  
Monkey Motor Cortex

When choosing actions, we can act decisively, vacillate, or suffer momentary indecision. Studying how individual decisions unfold requires moment-by-moment readouts of brain state. Here we provide such a view from dorsal premotor and primary motor cortex. Two monkeys performed a novel decision task while we recorded from many neurons simultaneously. We found that a decoder trained using ‘forced choices’ (one target viable) was highly reliable when applied to ‘free choices’. However, during free choices internal events formed three categories. Typically, neural activity was consistent with rapid, unwavering choices. Sometimes, though, we observed presumed ‘changes of mind’: the neural state initially reflected one choice before changing to reflect the final choice. Finally, we observed momentary ‘indecision’: delay forming any clear motor plan. Further, moments of neural indecision accompanied moments of behavioral indecision. Together, these results reveal the rich and diverse set of internal events long suspected to occur during free choice.

Neural Activity in Primary Motor Cortex Related to Mechanical Loads Applied to the Shoulder and Elbow During a Postural Task

2001 ◽  
Vol 86 (4) ◽  
pp. 2102-2108 ◽  
Author(s):  
D. William Cabel ◽  
Paul Cisek ◽  
Stephen H. Scott
Keyword(s):  
Motor Cortex ◽  
Neural Activity ◽  
Primary Motor Cortex ◽  
Cell Activity ◽  
Motor Patterns ◽  
Mechanical Loads ◽  
Central Target ◽  
Extensor Torque ◽  
Vector Sum ◽  
Joint Loads

Whole-arm motor tasks performed by nonhuman primates have become a popular paradigm to examine neural activity during motor action, but such studies have traditionally related cell discharge to hand-based variables. We have developed a new robotic device that allows the mechanics of the shoulder and elbow joints to be manipulated independently. This device was used in the present study to examine neural activity in primary motor cortex (MI) in monkeys ( macaca mulatta) actively maintaining their hand at a central target as they compensated for loads applied to the shoulder and/or elbow. Roughly equal numbers of neurons were sensitive to mechanical loads only at the shoulder, only at the elbow, or loads at both joints. Neurons possessed two important properties. First, cell activity during multi-joint loads could be predicted from its activity during single-joint loads as a vector sum in a space defined by orthogonal axes for the shoulder and elbow. Second, most neurons were related to flexor torque at one joint coupled with extensor torque at the other, a distribution that paralleled the observed activity of forelimb muscles. These results illustrate that while MI activity may be described by independent axes representing each mechanical degree-of-freedom, neural activity is also strongly influenced by the specific motor patterns used to perform a given task.

scholarly journals Plastic Changes in Primate Motor Cortex Following Paired Peripheral Nerve Stimulation

2020 ◽  
Author(s):  
Bonne Habekost ◽  
Maria Germann ◽  
Stuart N Baker
Keyword(s):  
Motor Cortex ◽  
Task Performance ◽  
Nerve Stimulation ◽  
Neural Activity ◽  
Primary Motor Cortex ◽  
Index Finger ◽  
Paired Stimulation ◽  
Motor Cortical ◽  
Decoding Accuracy ◽  
Stimulation Of

Repeated paired stimulation of two peripheral nerves can produce lasting changes in motor cortical excitability, but little is known of the underlying neuronal basis. Here we trained two macaque monkeys to perform selective thumb and index finger abduction movements. Neural activity was recorded from the contralateral primary motor cortex during task performance, and following stimulation of the ulnar and median nerves, and the nerve supplying the extensor digitorum communis (EDC) muscle. Responses were compared before and after one hour of synchronous or asynchronous paired ulnar/median nerve stimulation. Task performance was significantly enhanced after asynchronous, and impaired after synchronous stimulation. The amplitude of short latency neural responses to median and ulnar nerve stimulation was increased after asynchronous stimulation; later components were reduced after synchronous stimulation. Synchronous stimulation increased neural activity during thumb movement and decreased it during index finger movement; asynchronous stimulation decreased activity during both movements. To assess how well neural activity could separate behavioral or sensory conditions, linear discriminant analysis was used to decode which nerve was stimulated, or which digit moved. Decoding accuracy for nerve stimulation was decreased after synchronous, and increased after asynchronous paired stimulation. Decoding accuracy for task performance was decreased after synchronous, but unchanged after asynchronous paired stimulation. Paired stimulation produces changes in motor cortical circuits which outlast the stimulation. Some of these changes depend on precise stimulus timing.

scholarly journals Microstimulation of dorsal premotor and primary motor cortex delays the volitional commitment to an action choice

2020 ◽  
Vol 123 (3) ◽  
pp. 927-935
Author(s):  
David Thura ◽  
Paul Cisek
Keyword(s):  
Motor Cortex ◽  
Neural Activity ◽  
Primary Motor Cortex ◽  
Premotor Cortex ◽  
Neural Substrates ◽  
Daily Basis ◽  
Decision Task ◽  
Movement Initiation ◽  
Deliberation Process ◽  
The Moment

Humans and other animals are faced with decisions about actions on a daily basis. These typically include a period of deliberation that ends with the commitment to a choice, which then leads to the overt expression of that choice through action. Previous studies with monkeys have demonstrated that neural activity in sensorimotor areas correlates with the deliberation process and reflects the moment of commitment before movement initiation, but the causal roles of these regions are challenging to establish. Here, we tested whether dorsal premotor (PMd) and primary motor cortex (M1) are causally involved in the volitional commitment to a reaching choice. We found that brief subthreshold microstimulation in PMd or M1 delayed commitment to an action but not the initiation of the action itself. Importantly, microstimulation only had a significant effect when it was delivered close to and before commitment time. These results are consistent with the proposal that PMd and M1 participate in the commitment process, which occurs when a critical firing rate difference is reached between cells voting for the selected option and those voting for the competing one. NEW & NOTEWORTHY The neural substrates of decisions between actions are typically investigated by correlating neural activity and subjects’ decision behavior, but this does not establish causality. In a reaching decision task, we demonstrate that subthreshold microstimulation of the monkey dorsal premotor cortex or primary motor cortex delays the deliberation duration if applied shortly before choice commitment. This result suggests a causal role of the sensorimotor cortex in the determination of decisions between actions.

Corticocortical and thalamocortical responses of neurons in the monkey primary motor cortex and their relation to a trained motor task

1994 ◽  
Vol 71 (2) ◽  
pp. 550-560 ◽  
Author(s):  
H. Aizawa ◽  
J. Tanji
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Motor Task ◽  
Reaching Movements ◽  
Response Latencies ◽  
Implanted Electrodes ◽  
Thalamic Stimulation ◽  
Primary Sensory Cortex ◽  
Activity Onset ◽  
Stimulation Of

1. We studied the responsiveness of neurons in the primary motor cortex (MI) of monkeys (Macacafuscata) to electrical stimulation of the supplementary motor area (SMA), primary sensory cortex (SI), and the ventral subnucleus of the thalamus (VPLo) with chronically implanted electrodes. 2. All neurons examined in this study were characterized by their relation to a motor task performed by the animals. They responded to stimulation of the cortical or thalamic area with excitation from one area alone (n = 128) or from multiple areas (n = 84) of all combinations. In a majority of neurons, response latencies to both cortical and thalamic stimulation were within 5 ms. 3. A vast majority of neurons (80%) that were active during a preparatory period for forthcoming reaching movements were activated by SMA stimulation. They were activated only infrequently by SI or thalamic stimulation. 4. Movement-related neurons (active immediately before and during reaching movements) were activated by thalamic, SI, or SMA stimulation or by any combination of those stimuli. More than half of the movement-related neurons activated exclusively by either thalamic or SMA stimulation exhibited activity onset times earlier than those observed in the earliest muscles. By contrast, most movement-related neurons that responded only to SI stimulation were late in their activity onset. 5. These findings suggest that the SMA input to MI is important in developing a preparatory type of activity in MI, whereas the thalamus (VPLo) provides substantial inputs in movement execution. The roles played by inputs from SI and SMA in relation to motor execution are debatable and are discussed here with reference to previous reports.

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