Systematic Changes in Motor Cortex Cell Activity With Arm Posture During Directional Isometric Force Generation

Sergio, Lauren E.; Kalaska, John

doi:10.1152/jn.00016.2002

Cited by 120 publications

(96 citation statements)

References 67 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The shifts appeared consistent when the arm was rotated around an axis that was perpendicular to the work plane (Caminiti et al, 1991;Sergio and Kalaska, 2003;Morrow et al, 2007). However, the use of a larger rotation of the hand (180°) enabled dissociation between the external, muscle, and hand-orientation representations that was difficult to obtain in previous studies.…”

Section: Discussionmentioning

confidence: 83%

See 1 more Smart Citation

Coordinate Transformation is First Completed Downstream of Primary Motor Cortex

Yanai¹,

Adamit²,

Israel³

et al. 2008

J. Neurosci.

View full text Add to dashboard Cite

It was suggested previously that the transformation of action to muscle-based coding is completed in the primary motor cortex (M1). This is consistent with a predominant direct pathway leading from M1 to motoneurons. Accordingly, spinal segmental interneurons that are located downstream to M1 are expected to show muscle-like coding properties. We addressed this hypothesis using simultaneous recording of cortical and spinal activity in primates performing an isometric wrist task with multiple targets and two hand postures. Here we show that while the motor cortex follows an intermediate coordinate frame, spinal interneurons already follow a muscle-like coordinate frame. We thus suggest that the final steps in coordinate transformation of motor commands take place downstream of M1 via corticospinal interactions.

show abstract

Section: Discussionmentioning

confidence: 83%

“…A dynamic index (DI) was computed to quantify posture-related changes in the level of force-direction firing of single-cells (Sergio and Kalaska, 2003): DI ϭ (DRp Ϫ DRs)/(DRp ϩ DRs). DRp and DRs were defined as the difference between the maximal versus minimal targetrelated firing in pronation and supination, respectively.…”

Section: Methodsmentioning

confidence: 99%

Coordinate Transformation is First Completed Downstream of Primary Motor Cortex

Yanai¹,

Adamit²,

Israel³

et al. 2008

J. Neurosci.

View full text Add to dashboard Cite

show abstract

“…22 Cortical neurons discharge at different rates depending on the direction, acceleration, and force of movement into space for reaching or stepping. 23 With new demands and training, these neurons can represent different movements. Sensory feedback, such as proprioception, has a crucial effect on motor ability at cortical and spinal levels as it reshapes sensorimotor integration.…”

Section: Neuroscientific Bases For Rehabilitationmentioning

confidence: 99%

Strategies for stroke rehabilitation

Dobkin

2004

The Lancet Neurology

621

370

View full text Add to dashboard Cite

Rehabilitation after hemiplegic stroke has typically relied on the training of patients in compensatory strategies. The translation of neuroscientific research into care has led to new approaches and renewed promise for better outcomes. Improved motor control can progress with task-specific training incorporating increased use of proximal and distal movements during intensive practice of real-world activities. Functional gains are incorrectly said to plateau by 3-6 months. Many patients retain latent sensorimotor function that can be realised any time after stroke with a pulse of goal-directed therapy. The amount of practice probably best determines gains for a given level of residual movement ability. Clinicians should encourage patients to build greater strength, speed, endurance, and precision of multijoint movements on tasks that increase independence and enrich daily activity. Imaging tools may help clinicians determine the capacity of residual networks to respond to a therapeutic approach and help establish optimal dose-response curves for training. Promising adjunct approaches include practice with robotic devices or in a virtual environment, electrical stimulation to increase cortical excitability during training, and drugs to optimise molecular mechanisms for learning. Biological strategies for neural repair may augment rehabilitation in the next decade.Rehabilitation of patients with hemiplegia after stroke has been limited for decades by a lack of theory-driven strategies leading to successful clinical trials with improvement in motor skills for daily activities. Recent therapeutic approaches have begun to build on methods to manipulate the remarkable adaptability or plasticity of the brain in response to task-specific practice, drugs, robotic trainers, and other ways to augment motor learning. 1 In this review, I offer conceptual bases for a clinical science of neurorehabilitation and emphasise mechanisms and procedures to improve walking and arm movement to lessen disability and limitations in daily life. One goal is to diminish the pessimism of physicians regarding the effect of additional rehabilitation and to provide them with sensible advice to offer patients who seek to improve motor skills at any time after stroke. Patients with sensorimotor and visual-field loss are much more dependent on carers than those with pure motor impairments, but even the latter may walk too slowly to participate in out-of-home activities or may be unable to integrate the use of an affected arm into personal care.Rehabilitation for hemiplegic stroke includes organised multidisciplinary, supportive services that begin 48 h after onset in stable patients. Inpatient and outpatient rehabilitation works to the advantage of patients and families in a general sense, but the effectiveness of each component of care falls short of evidence-based practice standards. The training of patients to compensate with the unaffected arm or leg has been a mainstay of rehabilitation. Physical, occupational, and speech therapists ...

show abstract

“…In particular, the direction of end effector movement is represented using population codes [1,2] defined over neurons tuned to particular preferred directions (see next section for details). In contrast, the lower level system comprising the motor cortex (M1), the spinal cord (SC) and intermediate systems represents posture-dependent muscle force signals needed to execute the actions [16,17,20]. Thus, with reference to sequential actions, the overall system implements a convenient division of labor, where motor sequences such as writing letters or words, drawing shapes, playing key sequences, etc., are learned as action programs at an abstract, posture-and effector-independent kinematic level in the PFC/PM/SMA system, and are then "translated" into sequences of motor commands by M1 [3], possibly guided by the basal ganglia and cerebellum [23,30,31].…”

Section: Background and Motivationmentioning

confidence: 99%

“…Experiments with primates have shown that complex voluntary movements are encoded at multiple levels in the cortex, brainstem and the spinal cord [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. However, the overall process by which such movements are generated remains a subject of significant debate [16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Learning Complex Population-Coded Sequences

Byadarhaly

Perdoor

Vasa

et al. 2009

Artificial Neural Networks – ICANN 2009

View full text Add to dashboard Cite

Abstract. The sequential structure of complex actions is apparently learned at an abstract "cognitive" level in several regions of the frontal cortex, independent of the control of the immediate effectors by the motor system. At this level, actions are represented in terms of kinematic parameters -especially direction of end effector movement -and encoded using population codes. Muscle force signals are generated from this representation by downstream systems in the motor cortex and the spinal cord. In this paper, we consider the problem of learning population-coded kinematic sequences in an abstract neural network model of the medial frontal cortex. For concreteness, the sequences are represented as line drawings in a two-dimensional workspace. Learning such sequences presents several challenges because of the internal complexity of the individual sequences and extensive overlap between sequences. We show that, by using a simple module-selection mechanism, our model is capable of learning multiple sequences with complex structure and very high cross-sequence similarity.

show abstract

Systematic Changes in Motor Cortex Cell Activity With Arm Posture During Directional Isometric Force Generation

Cited by 120 publications

References 67 publications

Coordinate Transformation is First Completed Downstream of Primary Motor Cortex

Coordinate Transformation is First Completed Downstream of Primary Motor Cortex

Strategies for stroke rehabilitation

Learning Complex Population-Coded Sequences

Contact Info

Product

Resources

About