News in Motor Cortical Physiology

Physiology ◽  
1999 ◽  
Vol 14 (2) ◽  
pp. 64-68
Author(s):  
Apostolos P. Georgopoulos
Keyword(s):  
Motor Cortex ◽  
Isometric Force ◽  
Cortical Activity ◽  
Dynamic Parameters ◽  
Limb Position ◽  
Dual Relation ◽  
Motor Cortical ◽  
Static Conditions ◽  
Cortical Physiology

Motor cortical activity relates to static motor parameters (isometric force, limb position) under static conditions but predominantly to dynamic parameters (change of force, limb velocity) under dynamic conditions. This dual relation conceptually unifies the role of motor cortex in the control of isometric force and movement.

scholarly journals Disruption of cortical dopaminergic modulation impairs preparatory activity and delays licking initiation

2018 ◽  
Author(s):  
Ke Chen ◽  
Roberto Vincis ◽  
Alfredo Fontanini
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Motor Cortex ◽  
Neural Activity ◽  
Cortical Activity ◽  
Motor Deficits ◽  
Receptor Modulation ◽  
Dopaminergic Modulation ◽  
Preparatory Activity ◽  
Motor Cortical

ABSTRACTDysfunction of motor cortices is thought to contribute to motor disorders such as Parkinson’s disease (PD). However, little is known on the link between cortical dopaminergic loss, abnormalities in motor cortex neural activity and motor deficits. We address the role of dopamine in modulating motor cortical activity by focusing on the anterior lateral motor cortex (ALM) of mice performing a cued-licking task. We first demonstrate licking deficits and concurrent alterations of spiking activity in ALM of mice with unilateral depletion of dopaminergic neurons (i.e., mice injected with 6-OHDA into the medial forebrain bundle). Hemi-lesioned mice displayed delayed licking initiation, shorter duration of licking bouts, and lateral deviation of tongue protrusions. In parallel with these motor deficits, we observed a reduction in the prevalence of cue responsive neurons and altered preparatory activity. Acute and local blockade of D1 receptors in ALM recapitulated some of the key behavioral and neural deficits observed in hemi-lesioned mice. Altogether, our data show a direct relationship between cortical D1 receptor modulation, cue-evoked and preparatory activity in ALM, and licking initiation.SIGNIFICANCE STATEMENTThe link between dopaminergic signaling, motor cortical activity and motor deficits is not fully understood. This manuscript describes alterations in neural activity of the anterior lateral motor cortex (ALM) that correlate with licking deficits in mice with unilateral dopamine depletion or with intra-ALM infusion of dopamine antagonist. The findings emphasize the importance of cortical dopaminergic modulation in motor initiation. These results will appeal not only to researchers interested in cortical control of licking, but also to a broader audience interested in motor control and dopaminergic modulation in physiological and pathological conditions. Specifically, our data suggest that dopamine deficiency in motor cortex could play a role in the pathogenesis of the motor symptoms of Parkinson’s disease.

Role of motor cortex in coordinating multi-joint movements: Is it time for a new paradigm?

2000 ◽  
Vol 78 (11) ◽  
pp. 923-933 ◽  
Author(s):  
Stephen H Scott
Keyword(s):  
Motor Cortex ◽  
Neural Activity ◽  
Cortical Activity ◽  
Reaching Movements ◽  
Cortical Region ◽  
Joint Movement ◽  
Global Features ◽  
Motor Patterns ◽  
New Device ◽  
Motor Cortical

Reaching movements to spatial targets require motor patterns at the shoulder to be coordinated carefully with those at the elbow to smoothly move the hand through space. While the motor cortex is involved in this volitional task, considerable debate remains about how this cortical region participates in planning and controlling movement. This article reviews two opposing interpretations of motor cortical function during multi-joint movements. On the one hand, studies performed predominantly on single-joint movement generally support the notion that motor cortical activity is intimately involved in generating motor patterns at a given joint. In contrast, studies on reaching demonstrate correlations between motor cortical activity and features of movement related to the hand, suggesting that the motor cortex may be involved in more global features of the task. Although this latter paradigm involves a multi-joint motor task in which neural activity is correlated with features of movement related to the hand, this neural activity is also correlated to other movement variables. Therefore it is difficult to assess if and how the motor cortex contributes to the coordination of motor patterns at different joints. In particular, present paradigms cannot assess whether motor cortical activity contributes to the control of one joint or multiple joints during whole-arm tasks. The final point discussed in this article is the development of a new experimental device (KINARM) that can both monitor and manipulate the mechanics of the shoulder and elbow independently during multi-joint motor tasks. It is hoped that this new device will provide a new approach for examining how the motor cortex is involved in motor coordination.Key words: reaching movements, biomechanics, motor coordination, proximal arm.

Patterns of muscular and motor cortical activity during a simple arm movement in the monkey

1981 ◽  
Vol 59 (7) ◽  
pp. 748-756 ◽  
Author(s):  
Y. Lamarre ◽  
G. Spidalieri ◽  
J. P. Lund
Keyword(s):  
Motor Cortex ◽  
Macaca Mulatta ◽  
Arm Movement ◽  
Cortical Activity ◽  
Macaque Monkeys ◽  
Direction Of Movement ◽  
Motor Cortical ◽  
Movement Parameters ◽  
Fusimotor System ◽  
Flexion And Extension

This article describes the behavior of motor cortex neurons recorded in macaque monkeys (Macaca mulatta) which had been trained to make extension and flexion movements about the elbow in response to auditory, visual, or somesthetic cues. The pattern of activity of 65% of those movement-related neurons which were recorded during both flexion and extension was reciprocally related to the direction of movement. However, the movements of extension and flexion were made by co-contraction of the biceps and triceps in a pattern that did not match that of the motor cortex neurons. The majority of motor cortex neurons had firing frequencies that were related to movement parameters but by their nature could not be directly involved in the control of α motoneurons in both directions of movement. We suggest that they could, instead, control the fusimotor system. It is more likely that α motoneurons are controlled by the 35% of motor cortex neurons that, like the muscles, do not show reciprocal patterns of activity for movements in opposite directions.

scholarly journals Cortical inhibition, facilitation and plasticity in late-life depression: effects of venlafaxine pharmacotherapy

2020 ◽  
Vol 46 (1) ◽  
pp. E88-E96
Author(s):  
Jennifer I. Lissemore ◽  
Benoit H. Mulsant ◽  
Tarek K. Rajji ◽  
Jordan F. Karp ◽  
Charles F. Reynolds III ◽  
...  
Keyword(s):  
Depressive Symptoms ◽  
Motor Cortex ◽  
Antidepressant Treatment ◽  
Short Interval ◽  
Late Life ◽  
Cortical Inhibition ◽  
Late Life Depression ◽  
Paired Pulse ◽  
Motor Cortical ◽  
Cortical Physiology

Background: Late-life depression is often associated with non-response or relapse following conventional antidepressant treatment. The pathophysiology of late-life depression likely involves a complex interplay between aging and depression, and may include abnormalities in cortical inhibition and plasticity. However, the extent to which these cortical processes are modifiable by antidepressant pharmacotherapy is unknown. Methods: Sixty-eight patients with late-life depression received 12 weeks of treatment with open-label venlafaxine, a serotonin-norepinephrine reuptake inhibitor (≤ 300 mg/d). We combined transcranial magnetic stimulation of the left motor cortex with electromyography recordings from the right hand to measure cortical inhibition using contralateral cortical silent period and paired-pulse short-interval intracortical inhibition paradigms; cortical facilitation using a paired-pulse intracortical facilitation paradigm; and short-term cortical plasticity using a paired associative stimulation paradigm. All measures were collected at baseline, 1 week into treatment (n = 23) and after approximately 12 weeks of treatment. Results: Venlafaxine did not significantly alter cortical inhibition, facilitation or plasticity after 1 or 12 weeks of treatment. Improvements in depressive symptoms during treatment were not associated with changes in cortical physiology. Limitations: The results presented here are specific to the motor cortex. Future work should investigate whether these findings extend to cortical areas more closely associated with depression, such as the dorsolateral prefrontal cortex. Conclusion: These findings suggest that antidepressant treatment with venlafaxine does not exert meaningful changes in motor cortical inhibition or plasticity in late-life depression. The absence of changes in motor cortical physiology, alongside improvements in depressive symptoms, suggests that age-related changes may play a role in previously identified abnormalities in motor cortical processes in late-life depression, and that venlafaxine treatment does not target these abnormalities.

scholarly journals Motor cortex is an input-driven dynamical system controlling dexterous movement

2018 ◽  
Author(s):  
Britton Sauerbrei ◽  
Jian-Zhong Guo ◽  
Matteo Mischiati ◽  
Wendy Guo ◽  
Mayank Kabra ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Activity Patterns ◽  
Large Body ◽  
Cortical Activity ◽  
Brain Regions ◽  
External Input ◽  
Time Varying ◽  
Movement Initiation ◽  
Population Activity ◽  
Motor Cortical

AbstractSkillful control of movement is central to our ability to sense and manipulate the world. A large body of work in nonhuman primates has demonstrated that motor cortex provides flexible, time-varying activity patterns that control the arm during reaching and grasping. Previous studies have suggested that these patterns are generated by strong local recurrent dynamics operating autonomously from inputs during movement execution. An alternative possibility is that motor cortex requires coordination with upstream brain regions throughout the entire movement in order to yield these patterns. Here, we developed an experimental preparation in the mouse to directly test these possibilities using optogenetics and electrophysiology during a skilled reach-to-grab-to-eat task. To validate this preparation, we first established that a specific, time-varying pattern of motor cortical activity was required to produce coordinated movement. Next, in order to disentangle the contribution of local recurrent motor cortical dynamics from external input, we optogenetically held the recurrent contribution constant, then observed how motor cortical activity recovered following the end of this perturbation. Both the neural responses and hand trajectory varied from trial to trial, and this variability reflected variability in external inputs. To directly probe the role of these inputs, we used optogenetics to perturb activity in the thalamus. Thalamic perturbation at the start of the trial prevented movement initiation, and perturbation at any stage of the movement prevented progression of the hand to the target; this demonstrates that input is required throughout the movement. By comparing motor cortical activity with and without thalamic perturbation, we were able to estimate the effects of external inputs on motor cortical population activity. Thus, unlike pattern-generating circuits that are local and autonomous, such as those in the spinal cord that generate left-right alternation during locomotion, the pattern generator for reaching and grasping is distributed across multiple, strongly-interacting brain regions.

scholarly journals Multi-dimensional tuning in motor cortical neurons during active behavior

2020 ◽  
Author(s):  
Rachel C. Yuan ◽  
Sarah W. Bottjer
Keyword(s):  
Motor Cortex ◽  
Motor Skills ◽  
Cortical Neurons ◽  
Cortical Activity ◽  
Single Neurons ◽  
Active Behavior ◽  
Complex Motor ◽  
Freely Behaving ◽  
Motor Cortical ◽  
Complex Motor Skills

ABSTRACTA region within songbird cortex, AId (dorsal intermediate arcopallium), is functionally analogous to motor cortex in mammals and has been implicated in vocal learning during development. AId thus serves as a powerful model for investigating motor cortical contributions to developmental skill learning. We made extracellular recordings in AId of freely behaving juvenile zebra finches and evaluated neural activity during diverse motor behaviors throughout entire recording sessions, including song production as well as hopping, pecking, preening, fluff-ups, beak interactions with cage objects, scratching, and stretching. A large population of single neurons showed significant modulation of activity during singing relative to quiescence. In addition, AId neurons demonstrated heterogeneous response patterns that were evoked during multiple movements, with single neurons often demonstrating excitation during one movement type and suppression during another. Lesions of AId do not disrupt vocal motor output or impair generic movements, suggesting that the responses observed during active behavior do not reflect direct motor drive. Consistent with this idea, we found that some AId neurons showed differential activity during pecking movements depending on the context in which pecks occurred, suggesting that AId circuitry encodes diverse inputs beyond generic motor parameters. Moreover, we found evidence of neurons that did not respond during discrete movements but were nonetheless modulated during active behavioral states compared to quiescence. Taken together, our results support the idea that AId neurons are involved in sensorimotor integration of external sensory inputs and/or internal feedback cues to help modulate goal-directed behaviors.SIGNIFICANCE STATEMENTMotor cortex across taxa receives highly integrated, multi-modal information and has been implicated in both execution and acquisition of complex motor skills, yet studies of motor cortex typically employ restricted behavioral paradigms that target select movement parameters, preventing wider assessment of the diverse sensorimotor factors that can affect motor cortical activity. Recording in AId of freely behaving juvenile songbirds that are actively engaged in sensorimotor learning offers unique advantages for elucidating the functional role of motor cortical neurons. The results demonstrate that a diverse array of factors modulate motor cortical activity and lay important groundwork for future investigations of how multi-modal information is integrated in motor cortical regions to contribute to learning and execution of complex motor skills.

scholarly journals Motor cortical dynamics are shaped by multiple distinct subspaces during naturalistic behavior

2020 ◽  
Author(s):  
Matthew G. Perich ◽  
Sara Conti ◽  
Marion Badi ◽  
Andrew Bogaard ◽  
Beatrice Barra ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Somatosensory Cortex ◽  
Sensory Information ◽  
Cortical Activity ◽  
The Body ◽  
Cortical Dynamics ◽  
Object Interaction ◽  
Driven System ◽  
Flexible Integration ◽  
Motor Cortical

ABSTRACTBehavior relies on continuous influx of sensory information about the body and the environment. In primates, cortex integrates somatic feedback to accurately reach and manipulate objects. Yet, in many experimental regimes motor cortex seems paradoxically to operate as a feedforward, rather than feedback-driven, system. Here, we recorded simultaneously from motor and somatosensory cortex as monkeys performed a naturalistic reaching and object interaction behavior. We studied how unexpected feedback from behavioral errors influences cortical dynamics. Motor cortex generally exhibited robust feedforward dynamics, yet displayed feedback-driven dynamics surrounding correction of behavioral errors. We then decomposed motor cortical activity into orthogonal subspaces capturing communication with somatosensory cortex or behavior-generating dynamics. During error correction, the communication subspace became feedback-driven, while the behavioral subspace maintained feedforward dynamics. We therefore demonstrate that cortical activity is compartmentalized within distinct subspaces that shape the population dynamics, enabling flexible integration of salient inputs with ongoing activity for robust behavior.

Motor Cortical Activity during Interception of Moving Targets.

2001 ◽  
Vol 13 (3) ◽  
pp. 306-318 ◽  
Author(s):  
Nicholas L. Port ◽  
Wolfgang Kruse ◽  
Daeyeol Lee ◽  
Apostolos P. Georgopoulos
Keyword(s):  
Motor Cortex ◽  
Cortical Neurons ◽  
Primary Motor Cortex ◽  
Movement Time ◽  
Hand Movement ◽  
Cortical Activity ◽  
Target Motion ◽  
Moving Target ◽  
Movement Initiation ◽  
Motor Cortical

The single-unit activity of 831 cells was recorded in the arm area of the motor cortex of tow monkeys while the monkeys intercepted a moving visual stimulus (interception task) or remained immobile during presentation of the same moving stimulus (no-go task). The moving target traveled on an oblique path from either lower corner of a screen toward the vertical meridian, and its movement time (0.5,1.0, or 1.5 sec) and velocity profile (accelerating, decelerating, or constant velocity) were pseudorandomly varied. The moving target had to be intercepted within 130 msec of target arrival at an interception point. By comparing motor cortical activity at the single-neuron tasks, we tested whether information about parameters of moving target is represented in the primary motor cortex to generate appropriate motor responses. A substantial number of neurons displayed modulation of their activity during the no-go task, and this activity was often affected by the stimulus parameters. These results suggest a role of motor cortex in specifying the timing of movement initiation based on information about target motion. In addition, there was a lack of systematic relation between the onset times of neural activity in the interception and no-go task, suggesting that processing of information concerning target motion and generation of hand movement occurs in parallel. Finally, the activity in the most motor cortical neurons was modulated according to an estimate of the time-to-target interception, raising the possibility that time-to-interception may be coded in the motor cortical activity.

Platelet and Shear Rate Promote Tumor Cell Adhesion to Human Endothelial Extracellular Matrix - Absence of a Role for Platelet Cyclooxygenase

1989 ◽  
Vol 61 (03) ◽  
pp. 485-489 ◽  
Author(s):  
Eva Bastida ◽  
Lourdes Almirall ◽  
Antonio Ordinas
Keyword(s):  
Cell Adhesion ◽  
Shear Rate ◽  
Tumor Cell ◽  
Umbilical Vein ◽  
Blood Platelets ◽  
Flow Conditions ◽  
Tumor Cell Adhesion ◽  
Rate Dependent ◽  
Static Conditions

SummaryBlood platelets are thought to be involved in certain aspects of malignant dissemination. To study the role of platelets in tumor cell adherence to vascular endothelium we performed studies under static and flow conditions, measuring tumor cell adhesion in the absence or presence of platelets. We used highly metastatic human adenocarcinoma cells of the lung, cultured human umbilical vein endothelial cells (ECs) and extracellular matrices (ECM) prepared from confluent EC monolayers. Our results indicated that under static conditions platelets do not significantly increase tumor cell adhesion to either intact ECs or to exposed ECM. Conversely, the studies performed under flow conditions using the flat chamber perfusion system indicated that the presence of 2 × 105 pl/μl in the perfusate significantly increased the number of tumor cells adhered to ECM, and that this effect was shear rate dependent. The maximal values of tumor cell adhesion were obtained, in presence of platelets, at a shear rate of 1,300 sec-1. Furthermore, our results with ASA-treated platelets suggest that the role of platelets in enhancing tumor cell adhesion to ECM is independent of the activation of the platelet cyclooxygenase pathway.

Baboon Fibrinogen Adsorption and Platelet Adhesion to Polymeric Materials

1991 ◽  
Vol 65 (05) ◽  
pp. 608-617 ◽  
Author(s):  
Joseph A Chinn ◽  
Thomas A Horbett ◽  
Buddy D Ratner
Keyword(s):  
Platelet Adhesion ◽  
Coagulation Factor ◽  
Polymeric Materials ◽  
Platelet Suspension ◽  
Perfusion Chamber ◽  
Static Conditions ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Fibrinogen Adsorption

SummaryThe role of fibrinogen in mediating platelet adhesion to polymers exposed to blood plasma was studied by comparison of the effect of plasma dilution on fibrinogen adsorption and platelet adhesion, and by the use of coagulation factor deficient plasmas. Polyetherurethane substrates were first preadsorbed with dilute plasma, then contacted with washed platelets suspended in a modified, apyrase containing Tyrode’s buffer. Platelet adhesion was studied under static conditions in Multiwell dishes, and also under shearing conditions using a parallel plate perfusion chamber. Fibrinogen adsorption and platelet adhesion were measured using 125I radiolabeled baboon fibrinogen and min radiolabeled baboon platelets, respectively. Surfaces were characterized by electron spectroscopy for chemical analysis (ESCA).When fibrinogen adsorption to Biomer was measured after 2 h contact with a series of dilute plasma solutions under static conditions, a peak in adsorption was observed from 0.26% plasma, i.e., adsorption was greater from 0.26% plasma than from either more or less dilute plasma. A peak in subsequent platelet adhesion to the plasma preadsorbed surfaces, measured after 2 h static incubation with washed platelets, was also observed but occurred on Biomer preadsorbed with 1.0% plasma.When fibrinogen adsorption was measured after 5 min contact under shearing conditions, the fibrinogen adsorption peak occurred on surfaces that had been exposed to 1.0% plasma. A peak in platelet adhesion to these preadsorbed surfaces, measured after 5 min contact with the platelet suspensions under shearing conditions, was observed on Biomer preadsorbed with 0.1% plasma. Shifts between the positions of the peaks in protein adsorption and platelet adhesion occurred on other polymers tested as well.Platelet adhesion was almost completely inhibited when baboon and human plasmas lacking fibrinogen (i. e., serum, heat defibrinogenated plasma, and congenitally afibrinogénémie plasma) were used. Platelet adhesion was restored to near normal when exogenous fibrinogen was added to fibrinogen deficient plasmas. Adhesion was also inhibited completely when a monoclonal antibody directed against the glycoprotein IIb/IIIa complex was added to the platelet suspension. Platelet adhesion to surfaces preadsorbed to von Willebrand factor deficient plasma was the same as to surfaces preadsorbed with normal plasma.While it appears that surface bound fibrinogen does mediate the initial attachment of platelets to Biomer, the observation that the fibrinogen adsorption and platelet adhesion maxima do not coincide exactly also suggests that the degree of subsequent platelet adhesion is dictated not only by the amount of surface bound fibrinogen but also by its conformation.

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