scholarly journals Motor Cortex Neural Correlates of Output Kinematics and Kinetics During Isometric-Force and Arm-Reaching Tasks

2005 ◽  
Vol 94 (4) ◽  
pp. 2353-2378 ◽  
Author(s):  
Lauren E. Sergio ◽  
Catherine Hamel-Pâquet ◽  
John F. Kalaska
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Isometric Force ◽  
Arm Movements ◽  
Population Level ◽  
Emg Activity ◽  
Hand Motion ◽  
Arm Reaching ◽  
Direction Of Movement ◽  
Isometric Forces

We recorded the activity of 132 proximal-arm-related neurons in caudal primary motor cortex (M1) of two monkeys while they generated either isometric forces against a rigid handle or arm movements with a heavy movable handle, in the same eight directions in a horizontal plane. The isometric forces increased in monotonic fashion in the direction of the force target. The forces exerted against the handle in the movement task were more complex, including an initial accelerating force in the direction of movement followed by a transient decelerating force opposite to the direction of movement as the hand approached the target. EMG activity of proximal-arm muscles reflected the difference in task dynamics, showing directional ramplike activity changes in the isometric task and reciprocally tuned “triphasic” patterns in the movement task. The apparent instantaneous directionality of muscle activity, when expressed in hand-centered spatial coordinates, remained relatively stable during the isometric ramps but often showed a large transient shift during deceleration of the arm movements. Single-neuron and population-level activity in M1 showed similar task-dependent changes in temporal pattern and instantaneous directionality. The momentary dissociation of the directionality of neuronal discharge and movement kinematics during deceleration indicated that the activity of many arm-related M1 neurons is not coupled only to the direction and speed of hand motion. These results also demonstrate that population-level signals reflecting the dynamics of motor tasks and of interactions with objects in the environment are available in caudal M1. This task-dynamics signal could greatly enhance the performance capabilities of neuroprosthetic controllers.

Changes in the Temporal Pattern of Primary Motor Cortex Activity in a Directional Isometric Force Versus Limb Movement Task

1998 ◽  
Vol 80 (3) ◽  
pp. 1577-1583 ◽  
Author(s):  
Lauren E. Sergio ◽  
John F. Kalaska
Keyword(s):  
Motor Cortex ◽  
Temporal Pattern ◽  
Primary Motor Cortex ◽  
Isometric Force ◽  
Limb Movement ◽  
Emg Activity ◽  
Limb Movements ◽  
Hand Motion ◽  
Burst Pattern ◽  
Spatial Coordinates

Sergio, Lauren E. and John F. Kalaska. Changes in the temporal pattern of primary motor cortex activity in a directional isometric force versus limb movement task. J. Neurophysiol. 80: 1577–1583, 1998. We recorded the activity of 75 proximal-arm-related cells in caudal primary motor cortex (MI) while a monkey generated either isometric forces or limb movements against an inertial load. The forces and movements were in eight directions in a horizontal plane. The isometric force generated at the hand increased monotonically in the direction of the target force level. The force exerted against the load in the movement task was more complex, including a transient decelerative phase during the movement as the hand approached the target. Electromyographic (EMG) activity of proximal-arm muscles reflected the task-dependent changes in dynamics, showing a ramp increase in activity during the isometric task and a reciprocal triphasic burst pattern in the movement task. A sliding 50-ms window analysis showed that the directionality of the EMG, when expressed in hand-centered spatial coordinates, remained stable throughout the isometric ramp but often showed a significant transient shift during the limb movements. Many cells in M1 showed corresponding significant changes in activity pattern and instantaneous directionality between the two tasks. This momentary dissociation of discharge from the directional kinematics of hand displacement is evidence that the activity of many single proximal-arm related M1 cells is not coupled only to the direction and velocity of hand motion.

scholarly journals Motor Cortical Activity During Drawing Movements: Population Representation During Spiral Tracing

1999 ◽  
Vol 82 (5) ◽  
pp. 2693-2704 ◽  
Author(s):  
Daniel W. Moran ◽  
Andrew B. Schwartz
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Prediction Interval ◽  
Premotor Cortex ◽  
Cortical Activity ◽  
Simultaneous Action ◽  
Emg Activity ◽  
Radius Of Curvature ◽  
Time Interval ◽  
Population Vector

Monkeys traced spirals on a planar surface as unitary activity was recorded from either premotor or primary motor cortex. Using the population vector algorithm, the hand's trajectory could be accurately visualized with the cortical activity throughout the task. The time interval between this prediction and the corresponding movement varied linearly with the instantaneous radius of curvature; the prediction interval was longer when the path of the finger was more curved (smaller radius). The intervals in the premotor cortex fell into two groups, whereas those in the primary motor cortex formed a single group. This suggests that the change in prediction interval is a property of a single population in primary motor cortex, with the possibility that this outcome is due to the different properties generated by the simultaneous action of separate subpopulations in premotor cortex. Electromyographic (EMG) activity and joint kinematics were also measured in this task. These parameters varied harmonically throughout the task with many of the same characteristics as those of single cortical cells. Neither the lags between joint-angular velocities and hand velocity nor the lags between EMG and hand velocity could explain the changes in prediction interval between cortical activity and hand velocity. The simple spatial and temporal relationship between cortical activity and finger trajectory suggests that the figural aspects of this task are major components of cortical activity.

Development of an Apparatus for Bilateral Rhythmical Training of Arm Movement Via Linear and Elliptical Trajectories of Various Directions

2014 ◽  
Vol 8 (3) ◽  
Author(s):  
Zlatko Matjačić ◽  
Matjaž Zadravec ◽  
Jakob Oblak
Keyword(s):  
Muscle Activation ◽  
Arm Movement ◽  
Emg Activity ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Arm Cycling ◽  
Arm Reaching ◽  
Direction Of Movement ◽  
Muscle Groups ◽  
Neurologically Intact

Clinical rehabilitation of individuals with various neurological disorders requires a significant number of movement repetitions in order to improve coordination and restoration of appropriate muscle activation patterns. Arm reaching movement is frequently practiced via motorized arm cycling ergometers where the trajectory of movement is circular thus providing means for practicing a single and rather nonfunctional set of muscle activation patterns, which is a significant limitation. We have developed a novel mechanism that in the combination with an existing arm ergometer device enables nine different movement modalities/trajectories ranging from purely circular trajectory to four elliptical and four linear trajectories where the direction of movement may be varied. The main objective of this study was to test a hypothesis stating that different movement modalities facilitate differences in muscle activation patterns as a result of varying shape and direction of movement. Muscle activation patterns in all movement modalities were assessed in a group of neurologically intact individuals in the form of recording the electromyographic (EMG) activity of four selected muscle groups of the shoulder and the elbow. Statistical analysis of the root mean square (RMS) values of resulting EMG signals have shown that muscle activation patterns corresponding to each of the nine movement modalities significantly differ in order to accommodate to variation of the trajectories shape and direction. Further, we assessed muscle activation patterns following the same protocol in a selected clinical case of hemiparesis. These results have shown the ability of the selected case subject to produce different muscle activation patterns as a response to different movement modalities which show some resemblance to those assessed in the group of neurologically intact individuals. The results of the study indicate that the developed device may significantly extend the scope of strength and coordination training in stroke rehabilitation which is in current clinical rehabilitation practice done through arm cycling.

scholarly journals Effective intracortical microstimulation parameters applied to primary motor cortex for evoking forelimb movements to stable spatial end points

2013 ◽  
Vol 110 (5) ◽  
pp. 1180-1189 ◽  
Author(s):  
Gustaf M. Van Acker ◽  
Sommer L. Amundsen ◽  
William G. Messamore ◽  
Hongyu Y. Zhang ◽  
Carl W. Luchies ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Large Scale ◽  
Primary Motor Cortex ◽  
Emg Activity ◽  
Intracortical Microstimulation ◽  
End Points ◽  
End Point ◽  
Motor Effects ◽  
Forelimb Movements ◽  
Stimulation Of

High-frequency, long-duration intracortical microstimulation (HFLD-ICMS) applied to motor cortex is recognized as a useful and informative method for corticomotor mapping by evoking natural-appearing movements of the limb to consistent stable end-point positions. An important feature of these movements is that stimulation of a specific site in motor cortex evokes movement to the same spatial end point regardless of the starting position of the limb. The goal of this study was to delineate effective stimulus parameters for evoking forelimb movements to stable spatial end points from HFLD-ICMS applied to primary motor cortex (M1) in awake monkeys. We investigated stimulation of M1 as combinations of frequency (30–400 Hz), amplitude (30–200 μA), and duration (0.5–2 s) while concurrently recording electromyographic (EMG) activity from 24 forelimb muscles and movement kinematics with a motion capture system. Our results suggest a range of parameters (80–140 Hz, 80–140 μA, and 1,000-ms train duration) that are effective and safe for evoking forelimb translocation with subsequent stabilization at a spatial end point. The mean time for stimulation to elicit successful movement of the forelimb to a stable spatial end point was 475.8 ± 170.9 ms. Median successful frequency and amplitude were 110 Hz and 110 μA, respectively. Attenuated parameters resulted in inconsistent, truncated, or undetectable movements, while intensified parameters yielded no change to movement end points and increased potential for large-scale physiological spread and adverse focal motor effects. Establishing cortical stimulation parameters yielding consistent forelimb movements to stable spatial end points forms the basis for a systematic and comprehensive mapping of M1 in terms of evoked movements and associated muscle synergies. Additionally, the results increase our understanding of how the central nervous system may encode movement.

Parietal Area 5 Activity Does Not Reflect the Differential Time-Course of Motor Output Kinetics During Arm-Reaching and Isometric-Force Tasks

2006 ◽  
Vol 95 (6) ◽  
pp. 3353-3370 ◽  
Author(s):  
Catherine Hamel-Pâquet ◽  
Lauren E. Sergio ◽  
John F. Kalaska
Keyword(s):  
Time Course ◽  
Posterior Parietal Cortex ◽  
Primary Motor Cortex ◽  
Isometric Force ◽  
Arm Movement ◽  
Population Level ◽  
Motor Output ◽  
Initial Increase ◽  
Related Area ◽  
Area 5

Many single-neuron recording studies have examined the degree to which the activity of primary motor cortex (M1) neurons is related to the kinematics and kinetics of various motor tasks. This has not been explored as extensively for arm movement-related neurons in posterior parietal cortex area 5. We recorded the activity of 78 proximal arm–related neurons in area 5 of two monkeys while they used their whole arm to make reaching movements toward eight targets on a horizontal plane against an inertial load or to generate isometric forces at the hand in the same eight horizontal directions. The overall range of measured output forces was similar in the two tasks. The forces increased monotonically in the desired direction in the isometric task. In the movement task, in contrast, they showed a rapid initial increase in the direction of movement, followed by a transient reversal of forces as the hand approached the target. Many task-related area 5 neurons were tuned for the direction of motor output in the tasks, but most area 5 neurons were more strongly active or exclusively active in the movement task than in the isometric task. Furthermore, their activity at either the single cell or population level did not reflect the transient reversal of output forces during movement. In contrast, M1 neuronal activity was typically strong in both tasks and showed task-related changes that reflected the differences in the time course and directionality of force outputs between both tasks, including the transient reversal of forces in the movement task. These results show that area 5 neurons are less strongly related to the time-course of task kinetics than M1 during isometric and arm-movement tasks.

Organization of the primate face motor cortex as revealed by intracortical microstimulation and electrophysiological identification of afferent inputs and corticobulbar projections

1988 ◽  
Vol 59 (3) ◽  
pp. 796-818 ◽  
Author(s):  
C. S. Huang ◽  
M. A. Sirisko ◽  
H. Hiraba ◽  
G. M. Murray ◽  
B. J. Sessle
Keyword(s):  
Motor Cortex ◽  
Single Neuron ◽  
Primary Motor Cortex ◽  
General Pattern ◽  
Emg Activity ◽  
Projection Neurons ◽  
Intracortical Microstimulation ◽  
Facial Musculature ◽  
The Face ◽  
Afferent Inputs

1. The technique of intracortical microstimulation (ICMS), supplemented by single-neuron recording, was used to carry out an extensive mapping of the face primary motor cortex. The ICMS study involved a total of 969 microelectrode penetrations carried out in 10 unanesthetized monkeys (Macaca fascicularis). 2. Monitoring of ICMS-evoked movements and associated electromyographic (EMG) activity revealed a general pattern of motor cortical organization. This was characterized by a representation of the facial musculature, which partially enclosed and overlapped the rostral, medial, and caudal borders of the more laterally located cortical regions representing the jaw and tongue musculatures. Responses were evoked at ICMS thresholds as low as 1 microA, and the latency of the suprathreshold EMG responses ranged from 10 to 45 ms. 3. Although contralateral movements predominated, a representation of ipsilateral movements was found, which was much more extensive than previously reported and which was intermingled with the contralateral representations in the anterior face motor cortex. 4. In examining the fine organizational pattern of the representations, we found clear evidence for multiple representation of a particular muscle, thus supporting other investigations of the motor cortex, which indicate that multiple, yet discrete, efferent microzones represent an essential organizational principle of the motor cortex. 5. The close interrelationship of the representations of all three muscle groups, as well as the presence of a considerable ipsilateral representation, may allow for the necessary integration of unilateral or bilateral activities of the numerous face, jaw, and tongue muscles, which is a feature of many of the movement patterns in which these various muscles participate. 6. In six of these same animals, plus an additional two animals, single-neuron recordings were made in the motor and adjacent sensory cortices in the anesthetized state. These neurons were electrophysiologically identified as corticobulbar projection neurons or as nonprojection neurons responsive to superficial or deep orofacial afferent inputs. The rostral, medial, lateral, and caudal borders of the face motor cortex were delineated with greater definition by ICMS and these electrophysiological procedures than by cytoarchitectonic features alone. We noted that there was an approximate fit in area 4 between the extent of projection neurons and field potentials anti-dromically evoked from the brain stem and the extent of positive ICMS sites.(ABSTRACT TRUNCATED AT 400 WORDS)

Dynamical Organization of Directional Tuning in the Primate Premotor and Primary Motor Cortex

2003 ◽  
Vol 89 (2) ◽  
pp. 1136-1142 ◽  
Author(s):  
Yoram Ben-Shaul ◽  
Eran Stark ◽  
Itay Asher ◽  
Rotem Drori ◽  
Zoltan Nadasdy ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Hand Movement ◽  
Movement Direction ◽  
Cortical Surface ◽  
Preferred Direction ◽  
Preparation Period ◽  
Direction Of Movement ◽  
The Mean ◽  
Movement Parameters

Although previous studies have shown that activity of neurons in the motor cortex is related to various movement parameters, including the direction of movement, the spatial pattern by which these parameters are represented is still unresolved. The current work was designed to study the pattern of representation of the preferred direction (PD) of hand movement over the cortical surface. By studying pairwise PD differences, and by applying a novel implementation of the circular variance during preparation and movement periods in the context of a center-out task, we demonstrate a nonrandom distribution of PDs over the premotor and motor cortical surface of two monkeys. Our analysis shows that, whereas PDs of units recorded by nonadjacent electrodes are not more similar than expected by chance, PDs of units recorded by adjacent electrodes are. PDs of units recorded by a single electrode display the greatest similarity. Comparison of PD distributions during preparation and movement reveals that PDs of nearby units tend to be more similar during the preparation period. However, even for pairs of units recorded by a single electrode, the mean PD difference is typically large (45° and 75° during preparation and movement, respectively), so that a strictly modular representation of hand movement direction over the cortical surface is not supported by our data.

Systematic Changes in Directional Tuning of Motor Cortex Cell Activity With Hand Location in the Workspace During Generation of Static Isometric Forces in Constant Spatial Directions

1997 ◽  
Vol 78 (2) ◽  
pp. 1170-1174 ◽  
Author(s):  
Lauren E. Sergio ◽  
John F. Kalaska
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Discharge Rate ◽  
Cell Activity ◽  
Force Production ◽  
Static Force ◽  
Force Output ◽  
Directional Tuning ◽  
Cortex Cell ◽  
Isometric Forces

Sergio, Lauren E. and John F. Kalaska. Systematic changes in directional tuning of motor cortex cell activity with hand location in the workspace during generation of static isometric forces in constant spatial directions. J. Neurophysiol. 78: 1170–1174, 1997. We examined the activity of 46 proximal-arm-related cells in the primary motor cortex (MI) during a task in which a monkey uses the arm to exert isometric forces at the hand in constant spatial directions while the hand is in one of nine different spatial locations on a plane. The discharge rate of all 46 cells was significantly affected by both hand location and by the direction of static force during the final static-force phase of the task. In addition, all cells showed a significant interaction between force direction and hand location. That is, there was a significant modulation in the relationship between cell activity and the direction of exerted force as a function of hand location. For many cells, this modulation was expressed in part as a systematic arclike shift in the cell's directional tuning at the different hand locations, even though the direction of static force output at the hand remained constant. These effects of hand location in the workspace indicate that the discharge of single MI cells does not covary exclusively with the level and direction of force output at the hand. Sixteen proximal-arm-related muscles showed similar effects in the task, reflecting their dependence on various mechanical factors that varied with hand location. The parallel changes found for both MI cell activity and muscle activity for static force production at different hand locations are further evidence that MI contributes to the transformation between extrinsic and intrinsic representations of limb movement.

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