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Nicholas W. Baumgartner, Anne M. Walk, Caitlyn G. Edwards, Alicia R. Covello, Morgan R. Chojnacki, Ginger E. Reeser, Andrew M. Taylor, Hannah D. Holscher and Naiman A. Khan

encompasses cognitive processes that are thought to drive goal-directed behavior. 17 The core processes thought to comprise cognitive control include attentional inhibition (the ability to resist distractions to maintain focus); working memory (the ability to store, maintain, and manipulate information to be

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Linda Paschen, Tim Lehmann, Miriam Kehne and Jochen Baumeister

monitoring of complex, goal-directed processes involved in perception, memory, and action ( 10 , 13 ). The 3 interrelated and interacting core domains of EF are inhibition, working memory, and cognitive flexibility ( 9 , 10 ). In this context, inhibition describes a deliberate suppression of distracting

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Ines Pfeffer and Tilo Strobach

, 2012 ; Miyake et al., 2000 ) systematized the complexity of different situations and processes involving the executive function construct primarily in three domains: inhibition , updating , and shifting . Inhibition is related to deliberate overriding of dominant or prepotent responses, updating

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J. Ty Hopkins and Christopher D. Ingersoll

Objectives:

To define the concept of arthrogenic muscle inhibition (AMI), to discuss its implications in the rehabilitation of joint injury, to discuss the neurophysiologic events that lead to AMI, to evaluate the methods available to measure AM1 and the models that might be implemented to examine AMI, and to review therapeutic interventions that might reduce AMI.

Data Sources:

The databases MEDLINE, SPORTDiscus, and CIHNAL were searched with the terms reflex inhibition, joint mechanoreceptor, Ib interneuron, Hoffmann reflex, effusion, and joint injury. The remaining citations were collected from references of similar papers.

Conclusions:

AMI is a limiting factor in the rehabilitation of joint injury. It results in atrophy and deficiencies in strength and increases the susceptibility to further injury. A therapeutic intervention that results in decreased inhibition, allowing for active exercise, would lead to faster and more complete recovery.

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Katherine G. Holste, Alia L. Yasen, Matthew J. Hill and Anita D. Christie

The purpose of this study was to assess the effect of a cognitive task on motor cortex excitability and inhibition. Transcranial magnetic stimulation of the motor cortex was performed on 20 healthy individuals (18–24 years; 9 females) to measure motor evoked potentials (MEPs) and cortical silent periods at baseline, during, and following a secondary cognitive task. The MEP amplitude increased from 0.50 ± 0.09–0.87 ± 0.50 mV during a secondary cognitive task (p = .04), and returned to baseline (0.48 ± 0.31 mV; p = .90) posttask. The CSP duration also increased from 93.48 ± 28.76–113.6 ± 33.68 ms (p = .001) during the cognitive task, and returned to baseline posttask (89.0 ± 6.9 ms; p = .88). In the presence of a cognitive task, motor cortex excitability and inhibition were both increased relative to baseline. The increase in inhibition may help to explain the motor deficits experienced while performing a secondary cognitive task.

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Luciana Brondino, Esther Suter, Hae-Dong Lee and Walter Herzog

Muscle inhibition (MI) in human knee extensors increases with increasing maximal voluntary force as a function of knee angle. It was speculated that this angle-dependent MI was modulated by force-dependent feedback, likely Golgi tendon organ pathways. Such angle-dependent MI is of clinical and theoretical importance. The purpose of this study was to determine MI in human elbow flexors for maximal voluntary contractions. Muscle inhibition, elbow flexor force, and electromyographic (EMG) activity were measured in 31 volunteers at elbow angles between 30º and 120º. MI and elbow flexor EMG were the same at all elbow angles. Maximal isometric forces were greatest at the 70º angle, and never fell below 70% of the peak force at any of the tested angles. From these results it is concluded that force-dependent modulation of MI did not occur in the elbow flexors, possibly because maximal isometric force remained relatively close (within 30%) to the peak force. In contrast, force-dependent modulation of MI occurred in the knee extensors at the most extended angles, when the average knee extensor force had dropped to 50% or less of the maximal knee extensor force. It is likely that human maximal voluntary contractions are not associated with a given activation. Rather, activation appears to be modulated by force-dependent feedback at force levels below 70% of the absolute peak force, which manifests itself in a change of MI that parallels the level of maximal isometric force in voluntary contractions.

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Steve Hansen, James L. Lyons and Katherine M. Keetch

This study examined the performance of the upper limbs during responses to previously cued and un-cued locations. Participants made unimanual and bimanual responses under homologous and non-homologous muscular control, within a cuetarget (Experiment 1; n = 10), and a target-target (Experiment 2; n = 10) aiming protocol. The inhibition of return (IOR) to a target location was expected to increase with (a) an increase in the organization of the movement response required, and (b) the decrease in the muscular coupling under which the bimanual movement was performed. IOR was observed in both experiments when participants completed their movements in either the unimanual or homologous conditions, but not in the non-homologous condition. In addition, reaction times were significantly shorter when a movement preceded the response than when no manual response was made to the initial visual cue. The results indicate that common processing delays in response to exogenously cued targets are dependent on the muscular control of those responses. Thus, this study provides evidence that IOR is moderated by the muscular control under which the bimanual movement was performed indicating an influential involvement of the motor system in both the movement planning and movement response to multiple target stimuli.

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Andrew L. McDonough and Joseph P. Weir

The purpose of this case study was to investigate reflex inhibition of the quadriceps femoris in a subject with postsurgical edema of the left knee. The subject was a 45-year-old male with a traumatic knee injury with resultant edema who underwent elective arthroscopic surgery. Reflex inhibition was assessed by H-reflex elicitation in the femoral nerve and surface electromyography of the quadriceps. To assess the degree of edema, direct circumferential measurements were taken. On the first presurgical visit, the left knee demonstrated mild edema with a decrease in H-reflex amplitudes. Two days after surgery, a further reduction in amplitudes and more swelling were demonstrated followed by an increase in amplitudes and a reduction in edema on the 28th postoperative day. These findings document a relationship between reflex inhibition and joint swelling that was previously described in experimental models where joint edema was simulated.

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Lori A. Bolgla and Douglas R. Keskula

Objective:

To provide information on research investigating the relationship between a knee effusion and quadriceps inhibition

Data Sources:

Peer-reviewed publications from 1965 to 1997 that investigated the effect of a knee effusion on quadriceps strength.

Study Selection:

The studies reviewed involved human subjects. Researchers have used active motion, electromyographic equipment, and isokinetics to measure changes in quadriceps strength after a knee effusion.

DataSynthesis:

Most studies reported that a knee effusion resulted in quadriceps inhibition and inferred that quadriceps inhibition would impair knee function.

Conclusions:

The authors believe that additional research is needed to better understand the effect of a knee effusion on knee function. Although a knee effusion might lead to quadriceps inhibition, other factors contribute to normal knee function and might allow enough compensation so that knee function is not affected significantly in the presence of certain effusions.

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Cheryl Glazebrook, Digby Elliott, James Lyons and Luc Tremblay

This study investigated inhibition of return in persons with and without Down syndrome (DS) when visual or verbal cues were used to specify a target in a crossmodal paradigm. Individuals with DS and without DS performed manual aiming movements to a target located in right or left hemispace. The target was specified by an endogenous visual or verbal stimulus. Both groups were significantly slower when responding to the same target as the previous trial when the target was cued in a different modality. Although participants with DS initiated and executed their movements more slowly, they demonstrated a similar pattern of inhibition as people without DS, suggesting that inhibitory processes are functioning normally in persons with DS.