Modulation of Excitability in the Cerebral Cortex Projecting to Upper Extremity Muscles by Rotational Positioning of the Forearm

Kosei, Mitsuhashi; Seki, Kazunori; Akamatsu, Chizuru; Handa, Yasunobu

doi:10.1620/tjem.212.221

Cited by 24 publications

(21 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, since we were concerned primarily with differences in reflex behavior between our subject populations, consistent changes in joint angle are less likely to have influenced our main conclusions. Nevertheless, posture does alter spinal (Hyngstrom et al 2007) and cortical (Mitsuhashi et al 2007) excitability and assessing these influences within each of our subject populations could lead to a better understanding of how these changes influence the coordination of multijoint reflexes within each. Similarly, since we chose perturbation parameters and experimental conditions that elicited consistent responses in both populations, we do not expect that a change in these parameters would have a substantial effect on our conclusions.…”

Section: Coordination Of Stretch Reflexes Following Strokementioning

confidence: 99%

Contributions of Altered Stretch Reflex Coordination to Arm Impairments Following Stroke

Trumbower

Ravichandran

Krutky

et al. 2010

Journal of Neurophysiology

View full text Add to dashboard Cite

Patterns of stereotyped muscle coactivation, clinically referred to as synergies, emerge following stroke and impair arm function. Although researchers have focused on cortical contributions, there is growing evidence that altered stretch reflex pathways may also contribute to impairment. However, most previous reflex studies have focused on passive, single-joint movements without regard to their coordination during volitional actions. The purpose of this study was to examine the effects of stroke on coordinated activity of stretch reflexes elicited in multiple arm muscles following multijoint perturbations. We hypothesized that cortical injury results in increased stretch reflexes of muscles characteristic of the abnormal flexor synergy during active arm conditions. To test this hypothesis, we used a robot to apply position perturbations to impaired arms of 10 stroke survivors and dominant arms of 8 healthy age-matched controls. Corresponding reflexes were assessed during volitional contractions simulating different levels of gravitational support, as well as during voluntary flexion and extension of the elbow and shoulder. Reflexes were quantified by average rectified surface electromyogram, recorded from eight muscles spanning the elbow and shoulder. Reflex coordination was quantified using an independent components analysis. We found stretch reflexes elicited in the stroke group were significantly less sensitive to changes in background muscle activation compared with those in the control group (P < 0.05). We also observed significantly increased reflex coupling between elbow flexor and shoulder abductor-extensor muscles in stroke subjects relative to that in control subjects. This increased coupling was present only during volitional tasks that required elbow flexion (P < 0.001), shoulder extension (P < 0.01), and gravity opposition (P < 0.01), but not during the "no load" condition. During volitional contractions, reflex amplitudes scaled with the level of impairment, as assessed by Fugl-Meyer scores (r(2) = 0.63; P < 0.05). We conclude that altered reflex coordination is indicative of motor impairment level and may contribute to impaired arm function following stroke.

show abstract

Section: Coordination Of Stretch Reflexes Following Strokementioning

confidence: 99%

Contributions of Altered Stretch Reflex Coordination to Arm Impairments Following Stroke

Trumbower

Ravichandran

Krutky

et al. 2010

Journal of Neurophysiology

View full text Add to dashboard Cite

show abstract

“…Thus, our data support previous work demonstrating that corticomotor excitability of a muscle can be influenced by the orientation of a joint that the muscle does not span. 4,6,27 …”

Section: Discussionmentioning

confidence: 99%

“…4 Also, when the forearm is fully supinated for a given static orientation of the shoulder and elbow, MEP amplitude recorded from the nonimpaired biceps is consistently greater relative to MEP amplitude recorded with the forearm oriented in neutral or fully pronated. 4,6 …”

Section: Introductionmentioning

confidence: 99%

Posture-Dependent Corticomotor Excitability Differs Between the Transferred Biceps in Individuals With Tetraplegia and the Biceps of Nonimpaired Individuals

Peterson¹,

Rogers

Bednar

et al. 2016

Neurorehabil Neural Repair

View full text Add to dashboard Cite

Background Following biceps transfer to enable elbow extension in individuals with tetraplegia, motor re-education may be facilitated by greater corticomotor excitability. Arm posture modulates corticomotor excitability of the nonimpaired biceps. If arm posture also modulates excitability of the transferred biceps, posture may aid in motor re-education. Objective Our objective was to determine whether multi-joint arm posture affects corticomotor excitability of the transferred biceps similar to the nonimpaired biceps. We also aimed to determine whether corticomotor excitability of the transferred biceps is related to elbow extension strength and muscle length. Methods Corticomotor excitability was assessed in seven arms of individuals with tetraplegia and biceps transfer using transcranial magnetic stimulation (TMS) and compared to biceps excitability of nonimpaired individuals. Single-pulse TMS was delivered to the motor cortex with the arm in functional postures at rest. Motor evoked potential (MEP) amplitude was recorded via surface electromyography. Elbow moment was recorded during maximum isometric extension trials and muscle length was estimated using a biomechanical model. Results Arm posture modulated corticomotor excitability of the transferred biceps differently than the nonimpaired biceps. Elbow extension strength was positively related and muscle length was unrelated, respectively, to MEP amplitude across the arms with biceps transfer. Conclusions Corticomotor excitability of the transferred biceps is modulated by arm posture and may contribute to strength outcomes after tendon transfer. Future work should determine whether modulating corticomotor excitability via posture promotes motor re-education during the rehabilitative period following surgery.

show abstract

“…The RT of the EMG burst was affected by arm position (Furubayashi & Kasai, 1990), and the MEP amplitude in the hand muscles was affected by forearm position (Mitsuhashi, Seki, Akamatsu, & Handa, 2007), indicating that proprioceptive afferent feedback affects excitability of the motor system. However, corticospinal excitability in the hand muscles decreased during eye movement with visual occlusion irrespective of the forearm position in the present study.…”

Section: Proprioceptive Feedbackmentioning

confidence: 99%

Corticospinal Excitability in the Hand Muscles is Decreased During Eye Movement with Visual Occlusion

et al. 2016

View full text Add to dashboard Cite

Corticospinal excitability in the hand muscles decreases during smooth pursuit eye movement. The present study tested a hypothesis that the decrease in corticospinal excitability in the hand muscles at rest during eye movement is not caused by visual feedback but caused by motor commands to the eye muscles. Healthy men (M age = 28.4 yr., SD = 5.2) moved their eyes to the right with visual occlusion (dark goggles) while their arms and hands remained at rest. The motor-evoked potential in the hand muscles was suppressed by 19% in the third quarter of the eye-movement period, supporting a view that motor commands to the eye muscles are the cause of the decrease in corticospinal excitability in the hand muscles. The amount of the suppression was not significantly different among the muscles, indicating that modulation of corticospinal excitability in one muscle induced by eye movement is not dependent on whether eye movement direction and the direction of finger movement when the muscle contracts are identical. Thus, the finding failed to support a hypothetical view that motor commands to the eye muscles concomittantly produce motor commands to the hand muscles. Moreover, the amount of the suppression was not significantly different between the forearm positions, indicating that the suppression was not affected by proprioception of the forearm muscles when visual feedback is absent.

show abstract

Modulation of Excitability in the Cerebral Cortex Projecting to Upper Extremity Muscles by Rotational Positioning of the Forearm

Cited by 24 publications

References 10 publications

Contributions of Altered Stretch Reflex Coordination to Arm Impairments Following Stroke

Contributions of Altered Stretch Reflex Coordination to Arm Impairments Following Stroke

Posture-Dependent Corticomotor Excitability Differs Between the Transferred Biceps in Individuals With Tetraplegia and the Biceps of Nonimpaired Individuals

Corticospinal Excitability in the Hand Muscles is Decreased During Eye Movement with Visual Occlusion

Contact Info

Product

Resources

About