Influence of long-latency reflex modulation on the performance of quick adjustment movements

1997 ◽  
Vol 76 (4) ◽  
pp. 328-334 ◽  
Author(s):  
Tomohiro Kizuka ◽  
Takaaki Asami ◽  
Katsunori Tanii
Keyword(s):  
Reflex Modulation ◽  
Long Latency ◽  
Long Latency Reflex

scholarly journals Voluntary reaction time and long-latency reflex modulation

2015 ◽  
Vol 114 (6) ◽  
pp. 3386-3399 ◽  
Author(s):  
Christopher J. Forgaard ◽  
Ian M. Franks ◽  
Dana Maslovat ◽  
Laurence Chin ◽  
Romeo Chua
Keyword(s):  
Reaction Time ◽  
Reflex Modulation ◽  
Electromyographic Activity ◽  
Gain Modulation ◽  
Voluntary Activity ◽  
Reflex Mechanism ◽  
Voluntary Response ◽  
Long Latency ◽  
Reflex Gain ◽  
Long Latency Reflex

Stretching a muscle of the upper limb elicits short (M1) and long-latency (M2) reflexes. When the participant is instructed to actively compensate for a perturbation, M1 is usually unaffected and M2 increases in size and is followed by the voluntary response. It remains unclear if the observed increase in M2 is due to instruction-dependent gain modulation of the contributing reflex mechanism(s) or results from voluntary response superposition. The difficulty in delineating between these alternatives is due to the overlap between the voluntary response and the end of M2. The present study manipulated response accuracy and complexity to delay onset of the voluntary response and observed the corresponding influence on electromyographic activity during the M2 period. In all active conditions, M2 was larger compared with a passive condition where participants did not respond to the perturbation; moreover, these changes in M2 began early in the appearance of the response (∼50 ms), too early to be accounted for by voluntary overlap. Voluntary response latency influenced the latter portion of M2, with the largest activity seen when accuracy of limb position was not specified. However, when participants aimed for targets of different sizes or performed movements of various complexities, reaction time differences did not influence M2 period activity, suggesting voluntary activity was sufficiently delayed. Collectively, our results show that while a perturbation applied to the upper limbs can trigger a voluntary response at short latency (<100 ms), instruction-dependent reflex gain modulation remains an important contributor to EMG changes during the M2 period.

scholarly journals Long-latency reflexes for inter-effector coordination reflect a continuous state feedback controller

2018 ◽  
Vol 120 (5) ◽  
pp. 2466-2483 ◽  
Author(s):  
Frederic Crevecoeur ◽  
Isaac Kurtzer
Keyword(s):  
Feedback Control ◽  
State Feedback ◽  
Feedback Controller ◽  
State Feedback Control ◽  
Comprehensive Treatment ◽  
State Feedback Controller ◽  
Long Latency ◽  
Continuous State ◽  
Long Latency Reflex ◽  
Long Latency Reflexes

Successful performance in many everyday tasks requires compensating unexpected mechanical disturbance to our limbs and body. The long-latency reflex plays an important role in this process because it is the fastest response to integrate sensory information across several effectors, like when linking the elbow and shoulder or the arm and body. Despite the dozens of studies on inter-effector long-latency reflexes, there has not been a comprehensive treatment of how these reveal the basic control organization that sets constraints on any candidate model of neural feedback control such as optimal feedback control. We considered three contrasting ways that controllers can be organized: multiple independent controllers vs. a multiple-input multiple-output (MIMO) controller, a continuous feedback controller vs. an intermittent feedback controller, and a direct MIMO controller vs. a state feedback controller. Following a primer on control theory and review of the relevant evidence, we conclude that continuous state feedback control best describes the organization of inter-effector coordination by the long-latency reflex.

Intraoperative Long-Latency Reflex Activity in Idiopathic Scoliosis Demonstrates Abnormal Central Processing

Spine ◽  
1993 ◽  
Vol 18 (12) ◽  
pp. 1621-1626 ◽  
Author(s):  
J. Maguire ◽  
R. Madigan ◽  
S. Wallace ◽  
R. Leppanen ◽  
V. Draper
Keyword(s):  
Idiopathic Scoliosis ◽  
Reflex Activity ◽  
Central Processing ◽  
Long Latency ◽  
Long Latency Reflex

scholarly journals Stabilizing stretch reflexes are modulated independently from the rapid release of perturbation-triggered motor plans

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hyunglae Lee ◽  
Eric J. Perreault
Keyword(s):  
Motor Response ◽  
Spinal Reflexes ◽  
Reflex Response ◽  
Voluntary Activity ◽  
Motor Responses ◽  
Triggered Reaction ◽  
Triggered Reactions ◽  
Long Latency ◽  
Target Effect ◽  
Long Latency Reflex

Abstract Responses elicited after the shortest latency spinal reflexes but prior to the onset of voluntary activity can display sophistication beyond a stereotypical reflex. Two distinct behaviors have been identified for these rapid motor responses, often called long-latency reflexes. The first is to maintain limb stability by opposing external perturbations. The second is to quickly release motor actions planned prior to the disturbance, often called a triggered reaction. This study investigated their interaction when motor tasks involve both limb stabilization and motor planning. We used a robotic manipulator to change the stability of the haptic environment during 2D arm reaching tasks, and to apply perturbations that could elicit rapid motor responses. Stabilizing reflexes were modulated by the orientation of the haptic environment (field effect) whereas triggered reactions were modulated by the target to which subjects were instructed to reach (target effect). We observed that there were no significant interactions between the target and field effects in the early (50–75 ms) portion of the long-latency reflex, indicating that these components of the rapid motor response are initially controlled independently. There were small but significant interactions for two of the six relevant muscles in the later portion (75–100 ms) of the reflex response. In addition, the target effect was influenced by the direction of the perturbation used to elicit the motor response, indicating a later feedback correction in addition to the early component of the triggered reaction. Together, these results demonstrate how distinct components of the long-latency reflex can work independently and together to generate sophisticated rapid motor responses that integrate planning with reaction to uncertain conditions.

Firing patterns of human flexor carpi radialis motor units during the stretch reflex

1985 ◽  
Vol 53 (5) ◽  
pp. 1179-1193 ◽  
Author(s):  
B. Calancie ◽  
P. Bawa
Keyword(s):  
Motor Unit ◽  
Stretch Reflex ◽  
Latency Period ◽  
Response Probability ◽  
Short Latency ◽  
Single Motor Unit ◽  
Single Motor ◽  
Motoneuron Pool ◽  
Long Latency ◽  
Long Latency Reflex

Single motor unit and gross surface electromyographic responses to torque motor-produced wrist extensions were studied in human flexor carpi radialis muscle. Surface EMG typically showed two "periods" of reflex activity, at a short and long latency following stretch, but both periods occurring before a subject's voluntary reaction to the stretch. The amplitude of EMG activity in both reflex periods increased monotonically with an increase in the torque load. The amplitude of the short-latency reflex response was very dependent on the motoneuron pool excitability, or preload. The amplitude of the long-latency reflex response also varied with the preload, but could, in addition, be modulated by the subject's preparatory set for a voluntary response to the imposed displacement. When a single motor unit that was not tonically active began to fire during the stretch reflex, it did so primarily during the long-latency period. When caused to fire repetitively by voluntary facilitation of the motoneuron pool, that same unit now showed activity during both periods of the stretch reflex. Further increases in either motoneuron pool facilitation or in perturbation strength resulted in a monotonic increase in response probability of a single motor unit during the short-latency period. However, the response probability of a single unit during the long-latency reflex period did not always vary in a monotonic way with increases in either torque load or motoneuron pool facilitation. For an additional series of experiments, the subject was instructed on how to respond voluntarily to the upcoming wrist perturbation. The three instructions to the subject had no effect on the response probability of a single motor unit during either the background or short-latency periods of the stretch reflex. However, prior instruction clearly affected a unit's response probability during the long-latency reflex period. Changes in the firing rate of motor units, and in the recruitment or derecruitment of nontonic units, contributed to this modulation of reflex activity during the long-latency period.

scholarly journals Task-dependent coordination of rapid bimanual motor responses

2012 ◽  
Vol 107 (3) ◽  
pp. 890-901 ◽  
Author(s):  
Michael Dimitriou ◽  
David W. Franklin ◽  
Daniel M. Wolpert
Keyword(s):  
Sensory Information ◽  
Optimal Feedback Control ◽  
Single Trial ◽  
Mechanical Perturbation ◽  
Contralateral Limb ◽  
Motor Responses ◽  
Bimanual Task ◽  
Rapid Responses ◽  
Long Latency ◽  
Long Latency Reflex

Optimal feedback control postulates that feedback responses depend on the task relevance of any perturbations. We test this prediction in a bimanual task, conceptually similar to balancing a laden tray, in which each hand could be perturbed up or down. Single-limb mechanical perturbations produced long-latency reflex responses (“rapid motor responses”) in the contralateral limb of appropriate direction and magnitude to maintain the tray horizontal. During bimanual perturbations, rapid motor responses modulated appropriately depending on the extent to which perturbations affected tray orientation. Specifically, despite receiving the same mechanical perturbation causing muscle stretch, the strongest responses were produced when the contralateral arm was perturbed in the opposite direction (large tray tilt) rather than in the same direction or not perturbed at all. Rapid responses from shortening extensors depended on a nonlinear summation of the sensory information from the arms, with the response to a bimanual same-direction perturbation (orientation maintained) being less than the sum of the component unimanual perturbations (task relevant). We conclude that task-dependent tuning of reflexes can be modulated online within a single trial based on a complex interaction across the arms.

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