scholarly journals Postural Representations of the Hand in Primate Sensorimotor Cortex

2019 ◽  
Author(s):  
James M. Goodman ◽  
Gregg A. Tabot ◽  
Alex S. Lee ◽  
Aneesha K. Suresh ◽  
Alexander T. Rajan ◽  
...  
Keyword(s):  
Motor System ◽  
Sensory System ◽  
Reaching Movements ◽  
Hand Movements ◽  
Time Varying ◽  
Neural Responses ◽  
Neural Basis ◽  
Functional Roles ◽  
Hand Control ◽  
Dexterous Hand

SummaryDexterous hand control requires not only a sophisticated motor system but also a sensory system to provide tactile and proprioceptive feedback. To date, the study of the neural basis of proprioception in cortex has focused primarily on reaching movements, at the expense of hand-specific behaviors such as grasp. To fill this gap, we record both the time-varying hand kinematics and the neural activity evoked in somatosensory and motor cortices as monkeys grasp a variety of different objects. We find that neurons in somatosensory cortex, as well as in motor cortex, preferentially track postures of multi-joint combinations spanning the entire hand. This contrasts with neural responses during reaching movements, which preferentially track movement kinematics of the arm rather than its postural configuration. These results suggest different representations of arm and hand movements likely adapted to suit the different functional roles of these two effectors.

scholarly journals Rudimentary Dexterity Corresponds With Reduced Ability to Move in Synergy After Stroke: Evidence of Competition Between Corticoreticulospinal and Corticospinal Tracts?

2020 ◽  
Vol 34 (10) ◽  
pp. 904-914
Author(s):  
Merav R. Senesh ◽  
Karina Barragan ◽  
David J. Reinkensmeyer
Keyword(s):  
Motor System ◽  
Corticospinal Tract ◽  
Arm Movements ◽  
Hand Movements ◽  
Clinical Assessments ◽  
Corticospinal Tracts ◽  
Dexterous Hand ◽  
Moderate Range ◽  
Exclusive Or ◽  
At Will

Objective When a stroke damages the corticospinal tract (CST), it has been hypothesized that the motor system switches to using the corticoreticulospinal tract (CRST) resulting in abnormal arm synergies. Is use of these tracts mutually exclusive, or can the motor system spontaneously switch between them depending on the type of movement it wants to make? If the motor system can share control at will, then people with a rudimentary ability to make dexterous movements should be able to perform synergistic arm movements as well. Methods We analyzed clinical assessments of 319 persons’ abilities to perform “out-of-synergy” and “in-synergy” arm movements after chronic stroke using the Upper Extremity Fugl-Meyer (UEFM) scale. Results We identified a moderate range of arm impairment (UEFM = ~30-40) where subjects had a rudimentary ability to make out-of-synergy (~23%-50% on the out-of-synergy score) and dexterous hand movements (~3-10 blocks on Box and Blocks Test). Below this range persons could perform in-synergy but not out-of-synergy or dexterous movements. In the moderate range, however, scoring better on out-of-synergy movements correlated with scoring worse on in-synergy movements ( P = .001, r ≈ −0.6). Conclusion Rudimentary dexterity corresponded with reduced ability to move the arm in-synergy. This finding supports the idea that CST and CRST compete and has implications for rehabilitation therapy.

Natural scenes in tactile texture

2014 ◽  
Vol 111 (9) ◽  
pp. 1792-1802 ◽  
Author(s):  
Louise R. Manfredi ◽  
Hannes P. Saal ◽  
Kyler J. Brown ◽  
Mark C. Zielinski ◽  
John F. Dammann ◽  
...  
Keyword(s):  
Sensory System ◽  
Laser Doppler Vibrometer ◽  
Relevant Information ◽  
Biomechanical Properties ◽  
Natural Scenes ◽  
Textured Surfaces ◽  
Neural Responses ◽  
Texture Perception ◽  
Neural Basis ◽  
Surface Microgeometry

Sensory systems are designed to extract behaviorally relevant information from the environment. In seeking to understand a sensory system, it is important to understand the environment within which it operates. In the present study, we seek to characterize the natural scenes of tactile texture perception. During tactile exploration complex high-frequency vibrations are elicited in the fingertip skin, and these vibrations are thought to carry information about the surface texture of manipulated objects. How these texture-elicited vibrations depend on surface microgeometry and on the biomechanical properties of the fingertip skin itself remains to be elucidated. Here we record skin vibrations, using a laser-Doppler vibrometer, as various textured surfaces are scanned across the finger. We find that the frequency composition of elicited vibrations is texture specific and highly repeatable. In fact, textures can be classified with high accuracy on the basis of the vibrations they elicit in the skin. As might be expected, some aspects of surface microgeometry are directly reflected in the skin vibrations. However, texture vibrations are also determined in part by fingerprint geometry. This mechanism enhances textural features that are too small to be resolved spatially, given the limited spatial resolution of the neural signal. We conclude that it is impossible to understand the neural basis of texture perception without first characterizing the skin vibrations that drive neural responses, given the complex dependence of skin vibrations on both surface microgeometry and fingertip biomechanics.

scholarly journals Evidence accumulation relates to perceptual consciousness and monitoring

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Michael Pereira ◽  
Pierre Megevand ◽  
Mi Xue Tan ◽  
Wenwen Chang ◽  
Shuo Wang ◽  
...  
Keyword(s):  
Posterior Parietal Cortex ◽  
Detection Threshold ◽  
Task Demands ◽  
Neuron Activity ◽  
Neural Responses ◽  
Neuronal Responses ◽  
Neural Basis ◽  
Perceptual Consciousness ◽  
Evidence Accumulation ◽  
Posterior Parietal

AbstractA fundamental scientific question concerns the neural basis of perceptual consciousness and perceptual monitoring resulting from the processing of sensory events. Although recent studies identified neurons reflecting stimulus visibility, their functional role remains unknown. Here, we show that perceptual consciousness and monitoring involve evidence accumulation. We recorded single-neuron activity in a participant with a microelectrode in the posterior parietal cortex, while they detected vibrotactile stimuli around detection threshold and provided confidence estimates. We find that detected stimuli elicited neuronal responses resembling evidence accumulation during decision-making, irrespective of motor confounds or task demands. We generalize these findings in healthy volunteers using electroencephalography. Behavioral and neural responses are reproduced with a computational model considering a stimulus as detected if accumulated evidence reaches a bound, and confidence as the distance between maximal evidence and that bound. We conclude that gradual changes in neuronal dynamics during evidence accumulation relates to perceptual consciousness and perceptual monitoring in humans.

scholarly journals Dexterous Hand Control Through Fascicular Targeting (HAPTIX-DEFT)

2017 ◽  
Vol 42 (9) ◽  
pp. S8-S9 ◽  
Author(s):  
Jonathan Cheng ◽  
Stephen Helms Tillery ◽  
John Miguelez ◽  
John Lachapelle ◽  
Edward Keefer
Keyword(s):  
Hand Control ◽  
Dexterous Hand

Neural and genetic basis of dexterous hand movements

2018 ◽  
Vol 52 ◽  
pp. 25-32 ◽  
Author(s):  
Yutaka Yoshida ◽  
Tadashi Isa
Keyword(s):  
Genetic Basis ◽  
Hand Movements ◽  
Dexterous Hand

Dexterous Hand Movements and Their Recovery After Central Nervous System Injury

2019 ◽  
Vol 42 (1) ◽  
pp. 315-335 ◽  
Author(s):  
Tadashi Isa
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Large Scale ◽  
Therapeutic Strategies ◽  
Central Nervous System Injury ◽  
Hand Movements ◽  
Recovery Model ◽  
Cortical Motor ◽  
Hand Dexterity ◽  
Dexterous Hand

Hand dexterity has uniquely developed in higher primates and is thought to rely on the direct corticomotoneuronal (CM) pathway. Recent studies have shown that rodents and carnivores lack the direct CM pathway but can control certain levels of dexterous hand movements through various indirect CM pathways. Some homologous pathways also exist in higher primates, and among them, propriospinal (PrS) neurons in the mid-cervical segments (C3-C4) are significantly involved in hand dexterity. When the direct CM pathway was lesioned caudal to the PrS and transmission of cortical commands to hand motoneurons via the PrS neurons remained intact, dexterous hand movements could be significantly recovered. This recovery model was intensively studied, and it was found that, in addition to the compensation by the PrS neurons, a large-scale reorganization in the bilateral cortical motor-related areas and mesolimbic structures contributed to recovery. Future therapeutic strategies should target these multihierarchical areas.

scholarly journals Diabetes Mellitus-Related Dysfunction of the Motor System

2020 ◽  
Vol 21 (20) ◽  
pp. 7485
Author(s):  
Ken Muramatsu
Keyword(s):  
Motor Control ◽  
Motor Neurons ◽  
Motor System ◽  
Corticospinal Tract ◽  
Experimental Studies ◽  
Sensory System ◽  
Treatment Strategies ◽  
Motor Deficits ◽  
New Perspective ◽  
The Brain

Although motor deficits in humans with diabetic neuropathy have been extensively researched, its effect on the motor system is thought to be lesser than that on the sensory system. Therefore, motor deficits are considered to be only due to sensory and muscle impairment. However, recent clinical and experimental studies have revealed that the brain and spinal cord, which are involved in the motor control of voluntary movement, are also affected by diabetes. This review focuses on the most important systems for voluntary motor control, mainly the cortico-muscular pathways, such as corticospinal tract and spinal motor neuron abnormalities. Specifically, axonal damage characterized by the proximodistal phenotype occurs in the corticospinal tract and motor neurons with long axons, and the transmission of motor commands from the brain to the muscles is impaired. These findings provide a new perspective to explain motor deficits in humans with diabetes. Finally, pharmacological and non-pharmacological treatment strategies for these disorders are presented.

Precis of Vigor: Neuroeconomics of movement control

2020 ◽  
pp. 1-10
Author(s):  
Reza Shadmehr ◽  
Alaa A. Ahmed
Keyword(s):  
Decision Making ◽  
New York ◽  
Neural Circuits ◽  
Movement Control ◽  
Brain Structures ◽  
The Other ◽  
Neural Basis ◽  
Hand Control ◽  
Measured Activity ◽  
The Brain

Abstract Why do we run toward people we love, but only walk toward others? Why do people in New York seem to walk faster than other cities? Why do our eyes linger longer on things we value more? There is a link between how the brain assigns value to things, and how it controls our movements. This link is an ancient one, developed through shared neural circuits that on one hand teach us how to value things, and on the other hand control the vigor with which we move. As a result, when there is damage to systems that signal reward, like dopamine and serotonin, that damage not only affects our mood and patterns of decision making, but how we move. In this book, we first ask why in principle evolution should have developed a shared system of control between valuation and vigor. We then focus on the neural basis of vigor, synthesizing results from experiments that have measured activity in various brain structures and neuromodulators, during tasks in which animals decide how patiently they should wait for reward, and how vigorously they should move to acquire it. Thus, the way we move unmasks one of our well-guarded secrets: how much we value the thing we are moving toward.

scholarly journals A reduced somatosensory gating response in individuals with multiple sclerosis is related to walking impairment

2017 ◽  
Vol 118 (4) ◽  
pp. 2052-2058 ◽  
Author(s):  
David J. Arpin ◽  
James E. Gehringer ◽  
Tony W. Wilson ◽  
Max J. Kurz
Keyword(s):  
Multiple Sclerosis ◽  
Sensory Gating ◽  
Healthy Controls ◽  
Neural Responses ◽  
Neural Basis ◽  
Tactile Discrimination ◽  
Mobility Impairments ◽  
Gait Kinematics ◽  
Walking Performance ◽  
Somatosensory Gating

When identical stimuli are presented in rapid temporal succession, neural responses to the second stimulation are often weaker than those observed for the first. This phenomenon is termed sensory gating and is believed to be an adaptive feature that helps prevent higher-order cortical centers from being flooded with unnecessary information. Recently, sensory gating in the somatosensory system has been linked to deficits in tactile discrimination. Additionally, studies have linked poor tactile discrimination with impaired walking and balance in individuals with multiple sclerosis (MS). In this study, we examine the neural basis of somatosensory gating in patients with MS and healthy controls and assess the relationship between somatosensory gating and walking performance. We used magnetoencephalography to record neural responses to paired-pulse electrical stimulation applied to the right posterior tibial nerve. All participants also walked across a digital mat, which recorded their spatiotemporal gait kinematics. Our results showed the amplitude of the response to the second stimulation was sharply reduced only in controls, resulting in a significantly reduced somatosensory gating in the patients with MS. No group differences were observed in the amplitude of the response to the first stimulation nor the latency of the neural response to either the first or second stimulation. Interestingly, the altered somatosensory gating responses were correlated with aberrant spatiotemporal gait kinematics in the patients with MS. These results suggest that inhibitory GABA circuits may be altered in patients with MS, which impacts somatosensory gating and contributes to the motor performance deficits seen in these patients. NEW & NOTEWORTHY We aimed to determine whether somatosensory gating in patients with multiple sclerosis (MS) differed compared with healthy controls and whether a relationship exists between somatosensory gating and walking performance. We found reduced somatosensory gating responses in patients with MS, and these altered somatosensory gating responses were correlated with the mobility impairments. These novel findings show that somatosensory gating is impaired in patients with MS and is related to the mobility impairments seen in these patients.

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