Motor cortical activity during drawing movements: single-unit activity during sinusoid tracing

1992 ◽  
Vol 68 (2) ◽  
pp. 528-541 ◽  
Author(s):  
A. B. Schwartz
Keyword(s):  
Average Rate ◽  
Discharge Rate ◽  
Arm Movement ◽  
Discharge Pattern ◽  
Movement Direction ◽  
Cortical Cells ◽  
Preferred Direction ◽  
Constant Direction ◽  
Motor Cortical ◽  
Tuning Function

1. This study examines the neuronal activity of motor cortical cells associated with the production of arm trajectories during drawing movements. Three monkeys were trained to perform two tasks. The first task ("center----out" task) required the animal to move its arm in different directions from a center start position to one of eight targets spaced at equal angular intervals and equal distances from the origin. Movements to each target were in a constant direction, and the average rate of neuronal discharge with movements to different targets varied in a characteristic pattern. A cosine tuning function was used to map each cell's discharge rate to the direction of arm movement. This function spanned all movement directions, with a peak firing rate in the cell's preferred direction. 2. The second task ("tracing" task) required the animal to trace curved figures consisting of sine waves of different spatial frequencies and amplitudes. Both the speed and direction changed continuously throughout these movements. The cosine tuning function derived from the center----out task was used to model the activity of the cell during the tracing of sinusoids in the second task. Sinusoidal data were divided into 20-ms bins; instantaneous direction, speed, and discharge rate were analyzed bin by bin. This provided a way to compare directly the tuning parameters during a task with constant direction to a task where the direction varied continuously. 3. Movement direction as it changed during the tracing task was an important factor in the discharge pattern of cells that had discharge patterns that could be represented by the cosine tuning function. 4. The modulation of discharge rate during figure tracing depended on both the cell's preferred direction and the orientation of the figure. The activity of cells with preferred directions perpendicular to the axis of the sinusoidal figure was most modulated, whereas the activity of those cells with preferred directions aligned to the figure's axis was least modulated. 5. The cells with modulated activity tended to have firing rates that differed from the predicted cosine tuning function during the sinusoidal movements for those portions of the trajectory where the movement direction was in the cell's preferred direction. 6. Finger speed during figure tracing varied inversely with path curvature with the same relation that has been found during human drawing. To assess the relation of instantaneous speed to discharge rate, the component of the discharge pattern related to direction was subtracted from the total discharge.(ABSTRACT TRUNCATED AT 400 WORDS)

Comparison of cerebellar and motor cortex activity during reaching: directional tuning and response variability

1993 ◽  
Vol 69 (4) ◽  
pp. 1136-1149 ◽  
Author(s):  
P. A. Fortier ◽  
A. M. Smith ◽  
J. F. Kalaska
Keyword(s):  
Motor Cortex ◽  
Response Curve ◽  
Reaching Movements ◽  
Movement Direction ◽  
Population Response ◽  
Cortical Cells ◽  
Cerebellar Neurons ◽  
Starting Position ◽  
Preferred Direction ◽  
Motor Cortical

1. The responses of 262 motor cortex cells and 223 cerebellar neurons were recorded during whole-arm reaching movements toward targets lights in eight evenly distributed directions radiating from a common central starting position. The reaching movements were followed by a 2-s target hold period where a fixed arm posture was actively maintained to stabilize the hand over the target light. 2. Cerebellar neurons had a higher mean tonic discharge rate while holding over the starting position (22.9 imp/s) than did motor cortex cells (12.5 imp/s). The mean population response curve describing the changes in activities with movement direction was likewise shifted toward higher frequencies in the cerebellum compared with the motor cortex, but the amplitude of the two curves was about equal. Therefore, the baseline discharges of cerebellar neurons were higher, but their changes in activity during movement were similar to those of motor cortical cells. 3. Motor cortex neurons were more strongly related to active maintenance of different arm postures than were cerebellar units. This was shown by a larger posture-related population response curve in the motor cortex (half-wave amplitude of cosine function was 11.2 imp/s, compared with 7.0 imp/s for cerebellar neurons), which represented the average response curve calculated from all the cells of the population. Furthermore, the motor cortex population had a higher percentage of single cells with tonic responses while the hand was held over different targets (tonic and phasic-tonic cells composed 57% of motor cortex population, compared with 38% of cerebellar population). Proportionately more cerebellar cells were phasically related to the movements. 4. The majority of motor cortex cells (58%) showed reciprocal changes relative to the center-hold time activity where the activity increased for movements in the preferred direction and decreased for movements in the opposite direction. Most of the remaining cells (40%) showed graded changes where the activity increased gradually as reaching was directed closer to the preferred direction. In contrast, the most common cerebellar response pattern was graded (38%). Only 26% were reciprocal and 18% were non-directional. The remaining 2% of motor cortical cells and 18% of cerebellar neurons could not be readily assigned to any of these three response classes. 5. Sector widths were calculated to measure the dispersion of individual cerebellar and motor cortical cell activities about the eight movement directions. Sector widths calculated from the absolute activities were always broader for cerebellar neurons (i.e., the cells were more broadly tuned).(ABSTRACT TRUNCATED AT 400 WORDS)

Motor cortical activity during drawing movements: population representation during sinusoid tracing

1993 ◽  
Vol 70 (1) ◽  
pp. 28-36 ◽  
Author(s):  
A. B. Schwartz
Keyword(s):  
Discharge Rate ◽  
Tangential Velocity ◽  
Passive Movement ◽  
Movement Direction ◽  
Precentral Gyrus ◽  
Population Response ◽  
Preferred Direction ◽  
Instantaneous Discharge ◽  
The Individual ◽  
Tuning Function

1. Monkeys were trained to trace sinusoids with their index fingers on a planar surface. During this task, both the direction and speed of movement varied continuously. Activity of individual units in the precentral gyrus contralateral to the moving arm was recorded as the task was performed. These cells responded to passive movement of the shoulder and/or elbow. The relation between discharge rate and movement direction for these individual cells could be described with a cosine tuning function. 2. Data recorded as the sinusoid was traced were divided into 100 bins as each cell was studied during the experiment. In each bin, the activity of a particular cell was represented by a vector. The vector ("cell vector") pointed in the direction of finger movement that corresponded to the highest rate of neuronal discharge. This direction, referred to as the preferred direction, corresponded to the peak of the cosine tuning function. The direction of the vector was constant between bins, but the magnitude of this cell's vector was a function of the instantaneous discharge rate. 3. This cell vector is a hypothetical contribution of a single cell to the population response comprised of 554 similarly derived vectors from different cells. The population response was represented as the vector that resulted from forming the sum of the vector contributions from the individual cells. A separate calculation was made for each bin, resulting in 100 population vectors for each sinusoid. 4. Within a given time series of population vectors, their lengths and directions varied in a consistent relation to the tangential velocity of the drawing movement.(ABSTRACT TRUNCATED AT 250 WORDS)

Self-Organization of Firing Activities in Monkey's Motor Cortex: Trajectory Computation from Spike Signals

1997 ◽  
Vol 9 (3) ◽  
pp. 607-621 ◽  
Author(s):  
Siming Lin ◽  
Jennie Si ◽  
A. B. Schwartz
Keyword(s):  
Motor Cortex ◽  
Cortical Neurons ◽  
Arm Movement ◽  
Neuronal Firing ◽  
Neural Representation ◽  
Population Vector ◽  
Vector Method ◽  
Preferred Direction ◽  
Motor Cortical ◽  
Self Organizing

The population vector method has been developed to combine the simultaneous direction-related activities of a population of motor cortical neurons to predict the trajectory of the arm movement. In this article, we consider a self-organizing model of a neural representation of the arm trajectory based on neuronal discharge rates. A self-organizing feature map (SOFM) is used to select the optimal set of weights in the model to determine the contribution of an individual neuron to an overall movement representation. The correspondence between movement directions and discharge patterns of the motor cortical neurons is established in the output map. The topology-preserving property of the SOFM is used to analyze the recorded data of a behaving monkey. The data used in this analysis were taken while the monkey was tracing spirals and doing center→out movements. The arm trajectory could be well predicted using such a statistical model based on the motor cortex neuronal firing information. The SOFM method is compared with the population vector method, which extracts information related to trajectory by assuming that each cell has a fixed preferred direction during the task. This implies that these cells are acting along lines labeled only for direction. However, extradirectional information is carried in these cell responses. The SOFM has the capability of extracting not only direction-related information but also other parameters that are consistently represented in the activity of the recorded population of cells.

scholarly journals Reaching Movements With Similar Hand Paths But Different Arm Orientations. I. Activity of Individual Cells in Motor Cortex

1997 ◽  
Vol 77 (2) ◽  
pp. 826-852 ◽  
Author(s):  
Stephen H. Scott ◽  
John F. Kalaska
Keyword(s):  
Motor Cortex ◽  
Dynamic Range ◽  
Reaching Movements ◽  
Movement Direction ◽  
Electromyographic Activity ◽  
Cortical Cells ◽  
Directional Tuning ◽  
Level Of Activity ◽  
Motor Cortical ◽  
Significant Change

Scott, Stephen H. and John F. Kalaska. Reaching movements with similar hand paths but different arm orientations. I. Activity of individual cells in motor cortex. J. Neurophysiol. 77: 826–852, 1997. This study shows that the discharge of many motor cortical cells is strongly influenced by attributes of movement related to the geometry and mechanics of the arm and not only by spatial attributes of the hand trajectory. The activity of 619 directionally tuned cells was recorded from the motor cortex of two monkeys during reaching movements with the use of similar hand paths but two different arm orientations, in the natural parasagittal plane and abducted into the horizontal plane. Nearly all cells (588 of 619, 95%) showed statistically significant changes in activity between the two arm orientations [analysis of variance (ANOVA), P < 0.01]. A majority of cells showed a significant change in their overall level of activity (ANOVA, main effect of task, P < 0.01) between arm orientations before, during, and after movement. Many cells (433 of 619, 70%) also showed a significant change in the relation of their discharge with movement direction(ANOVA, task × direction interaction term, P < 0.01) during movement, including changes in the dynamic range of discharge with movement and changes in the directional preference of cells that were directionally tuned in both arm orientations. Similar effects were seen for the discharge of cells while the monkey maintained constant arm postures over the different peripheral targets with the use of different arm orientations. Repeated data files from the same cell with the use of the same arm orientation showed only small changes in the level of discharge or in directional tuning, suggesting that changes in cell discharge between arm orientations cannot be explained by random temporal variations in cell activity. The distribution of movement-related preferred directions of the whole sample differed between arm orientations, and also differed strongly between cells receiving passive input predominantly from the shoulder or elbow. The electromyographic activity of most prime mover muscles at the shoulder and elbow was also strongly affected by arm orientation, resulting in changes in overall level of activity and/or directional tuning that often resembled those of the proximal arm-related motor cortical cells. A mathematical model that represented movements in terms of movement direction centered on the hand could not account for any of the arm-orientation-related response changes seen in this task, whereas models in intrinsic parameter spaces of joint kinematics and joint torques predicted many of the effects.

Neuronal specification of direction and distance during reaching movements in the superior precentral premotor area and primary motor cortex of monkeys

1993 ◽  
Vol 70 (5) ◽  
pp. 2097-2116 ◽  
Author(s):  
Q. G. Fu ◽  
J. I. Suarez ◽  
T. J. Ebner
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Arm Movement ◽  
Movement Direction ◽  
Target Movement ◽  
Reaching Task ◽  
Premotor Area ◽  
Preferred Direction ◽  
The Mean ◽  
Time Periods

1. Single-unit neuronal activity was recorded in the primary motor and superior precentral premotor areas of two rhesus monkeys during an arm reaching task. The task involved moving a cursor displayed on a video terminal using a draftsman's arm-type manipulandum. From a centrally located start box the animal was required to move to 1 of 48 target boxes at eight different directions (0-360 degrees in 45 degrees intervals) and six distances (1.4-5.4 cm in 0.8-cm increments). Both direction and distance for the upcoming movement were unpredictable. 2. The activity of 197 arm movement-related cells was recorded and evaluated for each of the 48 targets. Histological examination showed the cells to be primarily in the primary motor cortex or in the premotor area around the superior precentral sulcus. Each cell's discharge was aligned on movement onset and averaged over five trials for each target. Movement kinematics including hand path velocity were also determined. The task time was divided into three epochs, a premovement period (PT), a movement period (MT), and total time (TT = PT+MT). For each epoch the average firing was correlated with the direction and distance of the movement using various regression procedures. 3. An analysis of variance (ANOVA) showed that the majority of neurons were modulated significantly by movement direction in each of the three time periods, PT (73.7%), MT (68.3%), and TT (78.5%). The relationship of the firing to direction was fit to a cosine tuning function for each significantly modulated cell. In 86.3% of the cells the firing was correlated significantly with a cosine function of movement direction in TT. A cell's preferred direction varied little for different movement distances. The mean difference in preferred direction for the smallest possible change in distance (0.8 cm) was 12.8 +/- 11.4 degrees (SD) and 17.1 +/- 14.7 degrees for the largest change in distance (4.0 cm). 4. Correlation analysis revealed that the activity of the majority of cells was modulated significantly by distance along at least one direction in each of the three time periods, PT (46.8%), MT (68.8%), and TT (67.7%). Subsequently, a univariate linear regression model was used to quantify a cell's discharge as a function of distance. For the regressions of firing with distance with a statistically significant correlation (r > 0.8), the mean slope was 3.59 +/- 0.17 spikes.s-1.cm-1 for the total time. The existence of a significant distance modulation was not invariably correlated with a cell's preferred movement direction.(ABSTRACT TRUNCATED AT 400 WORDS)

Cerebellar neuronal activity related to whole-arm reaching movements in the monkey

1989 ◽  
Vol 62 (1) ◽  
pp. 198-211 ◽  
Author(s):  
P. A. Fortier ◽  
J. F. Kalaska ◽  
A. M. Smith
Keyword(s):  
Reaction Time ◽  
Reaching Movements ◽  
Movement Direction ◽  
Sample Population ◽  
Response Patterns ◽  
Cortical Cells ◽  
Cerebellar Neurons ◽  
Starting Position ◽  
Preferred Direction ◽  
Arm Reaching

1. Three monkeys were trained to make whole-arm reaching movements from a common central starting position toward eight radially arranged targets disposed at 45 degrees intervals. A sample of 312 cerebellar neurons with proximal-arm receptive fields or discharge related to shoulder or elbow movements was studied in the task. The sample included 69 Purkinje cells, 115 unidentified cortical cells, 65 interpositus neurons, and 63 dentate units. 2. The reaching task was divided into three movement-related epochs: a reaction time, a movement time, and holding over the target. All neurons demonstrated significant changes in discharge during one or more of these three epochs. Almost all of the cells (95%) showed a significant change in activity during the movement, whereas 68-69% of the cells showed significant changes from premovement activity during the reaction time and holding periods. 3. During the combined reaction time-movement period, 231/312 cells were strongly active in the task. Of these, 151 cells (65.4%) demonstrated unimodal directional responses. Sixty-three had a reciprocal relation to movement direction, whereas 88 showed only graded increases or decreases in activity. A further 37 cells (16.0%) were nondirectional, with statistically uniform changes in discharge in all eight directions. The remaining 43 cells (18.6%) showed significant differences in activity for different directions of movement, but their response patterns were not readily classifiable. 4. The proportion of directional versus nondirectional cells was consistent across the four cell populations. However, graded response patterns were more common and reciprocal responses less common among Purkinje and dentate neurons than among unidentified cortical cells and interpositus neurons. 5. The distribution of preferred directions of the population of cerebellar neurons covered all possible movement directions away from the common central starting position in the horizontal plane. When the preferred direction of each cell in the sample population was aligned, the mean direction-related activity of the cerebellar population formed a bell-shaped tuning curve for the activity recorded during both the reaction time and the movement, as well as during the time the arm maintained a fixed posture over the targets. A vector representation also showed that the overall activity of the cerebellar population during normal reaching arm movements generated a signal that varied with movement direction. 6. These results demonstrate that the cerebellum generates a signal that varies with the direction of movement of the proximal arm during normal aimed reaching movements and is consistent with a role in the control of the activity of muscles or muscle groups generating these movements.

Kinematic Coordinates In Which Motor Cortical Cells Encode Movement Direction

2000 ◽  
Vol 84 (5) ◽  
pp. 2191-2203 ◽  
Author(s):  
Robert Ajemian ◽  
Daniel Bullock ◽  
Stephen Grossberg
Keyword(s):  
Cellular Response ◽  
Muscle Activation ◽  
Primary Motor Cortex ◽  
Joint Angle ◽  
Movement Direction ◽  
Mathematical Framework ◽  
Coordinate Systems ◽  
Sensorimotor Transformation ◽  
Cortical Cells ◽  
Preferred Direction

During goal-directed reaching in primates, a sensorimotor transformation generates a dynamical pattern of muscle activation. Within the context of this sensorimotor transformation, a fundamental question concerns the coordinate systems in which individual cells in the primary motor cortex (MI) encode movement direction. This article develops a mathematical framework that computes, as a function of the coordinate system in which an individual cell is hypothesized to operate, the spatial preferred direction (pd) of that cell as the arm configuration and hand location vary. Three coordinate systems are explicitly modeled: Cartesian spatial, shoulder-centered, and joint angle. The computed patterns of spatial pds are distinct for each of these three coordinate systems, and experimental approaches are described that can capitalize on these differences to compare the empirical adequacy of each coordinate hypothesis. One particular experiment involving curved motion was analyzed from this perspective. Out of the three coordinate systems tested, the assumption of joint angle coordinates best explained the observed cellular response properties. The mathematical framework developed in this paper can also be used to design new experiments that are capable of disambiguating between a given set of specified coordinate hypotheses.

Comparing information about arm movement direction in single channels of local and epicortical field potentials from monkey and human motor cortex

2004 ◽  
Vol 98 (4-6) ◽  
pp. 498-506 ◽  
Author(s):  
Carsten Mehring ◽  
Martin Paul Nawrot ◽  
Simone Cardoso de Oliveira ◽  
Eilon Vaadia ◽  
Andreas Schulze-Bonhage ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Arm Movement ◽  
Movement Direction ◽  
Single Channels ◽  
Field Potentials ◽  
Human Motor Cortex ◽  
Human Motor

Neuronal Activity in Somatosensory Cortex of Monkeys Using a Precision Grip. I. Receptive Fields and Discharge Patterns

1999 ◽  
Vol 81 (2) ◽  
pp. 825-834 ◽  
Author(s):  
Iran Salimi ◽  
Thomas Brochier ◽  
Allan M. Smith
Keyword(s):  
Receptive Field ◽  
Somatosensory Cortex ◽  
Neuronal Activity ◽  
Single Cells ◽  
Precision Grip ◽  
Receptive Fields ◽  
Pressure Change ◽  
Discharge Pattern ◽  
Cortical Cells ◽  
Discharge Patterns

Neuronal activity in somatosensory cortex of monkeys using a precision grip. I. Receptive fields and discharge patterns. Three adolescent Macaca fascicularis monkeys weighing between 3.5 and 4 kg were trained to use a precision grip to grasp a metal tab mounted on a low friction vertical track and to lift and hold it in a 12- to 25-mm position window for 1 s. The surface texture of the metal tab in contact with the fingers and the weight of the object could be varied. The activity of 386 single cells with cutaneous receptive fields contacting the metal tab were recorded in Brodmann’s areas 3b, 1, 2, 5, and 7 of the somatosensory cortex. In this first of a series of papers, we describe three types of discharge pattern, the receptive-field properties, and the anatomic distribution of the neurons. The majority of the receptive fields were cutaneous and covered less than one digit, and a χ2 test did not reveal any significant differences in the Brodmann’s areas representing the thumb and index finger. Two broad categories of discharge pattern cells were identified. The first category, dynamic cells, showed a brief increase in activity beginning near grip onset, which quickly subsided despite continued pressure applied to the receptive field. Some of the dynamic neurons responded to both skin indentation and release. The second category, static cells, had higher activity during the stationary holding phase of the task. These static neurons demonstrated varying degrees of sensitivity to rates of pressure change on the skin. The percentage of dynamic versus static cells was about equal for areas 3b, 2, 5, and 7. Only area 1 had a higher proportion of dynamic cells (76%). A third category was identified that contained cells with significant pregrip activity and included cortical cells with both dynamic or static discharge patterns. Cells in this category showed activity increases before movement in the absence of receptive-field stimulation, suggesting that, in addition to peripheral cutaneous input, these cells also receive strong excitation from movement-related regions of the brain.

Sign in / Sign up

Export Citation Format

Share Document