scholarly journals Reliability of transcallosal inhibition measurements for the lower limb motor cortex in stroke

2021 ◽  
Vol 743 ◽  
pp. 135558
Author(s):  
Anjali Sivaramakrishnan ◽  
Sangeetha Madhavan
Keyword(s):  
Motor Cortex ◽  
Lower Limb ◽  
Transcallosal Inhibition

scholarly journals Ipsilateral Motor Pathways and Transcallosal Inhibition During Lower Limb Movement After Stroke

2021 ◽  
pp. 154596832199904
Author(s):  
Brice T. Cleland ◽  
Sangeetha Madhavan
Keyword(s):  
Lower Limb ◽  
Functional Outcomes ◽  
Motor Pathways ◽  
Movement Accuracy ◽  
Transcallosal Inhibition ◽  
Paretic Limb ◽  
Bilateral Lower Limb ◽  
Ankle Movement ◽  
Lower Limb Movement ◽  
Clinical Measures

Background Stroke rehabilitation may be improved with a better understanding of the contribution of ipsilateral motor pathways to the paretic limb and alterations in transcallosal inhibition. Few studies have evaluated these factors during dynamic, bilateral lower limb movements, and it is unclear whether they relate to functional outcomes. Objective Determine if lower limb ipsilateral excitability and transcallosal inhibition after stroke depend on target limb, task, or number of limbs involved, and whether these factors are related to clinical measures. Methods In 29 individuals with stroke, ipsilateral and contralateral responses to transcranial magnetic stimulation were measured in the paretic and nonparetic tibialis anterior during dynamic (unilateral or bilateral ankle dorsiflexion/plantarflexion) and isometric (unilateral dorsiflexion) conditions. Relative ipsilateral excitability and transcallosal inhibition were assessed. Fugl-Meyer, ankle movement accuracy, and walking characteristics were assessed. Results Relative ipsilateral excitability was greater during dynamic than isometric conditions in the paretic limb ( P ≤ .02) and greater in the paretic than the nonparetic limb during dynamic conditions ( P ≤ .004). Transcallosal inhibition was greater in the ipsilesional than contralesional hemisphere ( P = .002) and during dynamic than isometric conditions ( P = .03). Greater ipsilesional transcallosal inhibition was correlated with better ankle movement accuracy ( R2 = 0.18, P = .04). Greater contralateral excitability to the nonparetic limb was correlated with improved walking symmetry ( R2 = 0.19, P = .03). Conclusions Ipsilateral pathways have increased excitability to the paretic limb, particularly during dynamic tasks. Transcallosal inhibition is greater in the ipsilesional than contralesional hemisphere and during dynamic than isometric tasks. Ipsilateral pathways and transcallosal inhibition may influence walking asymmetry and ankle movement accuracy.

Cortical Control of Human Motoneuron Firing During Isometric Contraction

1997 ◽  
Vol 77 (6) ◽  
pp. 3401-3405 ◽  
Author(s):  
Stephan Salenius ◽  
Karin Portin ◽  
Matti Kajola ◽  
Riitta Salmelin ◽  
Riitta Hari
Keyword(s):  
Motor Cortex ◽  
Upper Limb ◽  
Isometric Contraction ◽  
Lower Limb ◽  
Biceps Brachii ◽  
Cortical Control ◽  
Lower Limb Muscles ◽  
Cortical Rhythms ◽  
Motor Unit Firing ◽  
Limb Muscles

Salenius, Stephan, Karin Portin, Matti Kajola, Riitta Salmelin, and Riitta Hari. Cortical control of human motoneuron firing during isometric contraction. J. Neurophysiol. 77: 3401–3405, 1997. We recorded whole scalp magnetoencephalographic (MEG) signals simultaneously with the surface electromyogram from upper and lower limb muscles of six healthy right-handed adults during voluntary isometric contraction. The 15- to 33-Hz MEG signals, originating from the anterior bank of the central sulcus, i.e., the primary motor cortex, were coherent with motor unit firing in all subjects and for all muscles. The coherent cortical rhythms originated in the hand motor area for upper limb muscles (1st dorsal interosseus, extensor indicis proprius, and biceps brachii) and close to the foot area for lower limb muscles (flexor hallucis brevis). The sites of origin corresponding to different upper limb muscles did not differ significantly. The cortical signals preceded motor unit firing by 12–53 ms. The lags were shortest for the biceps brachii and increased systematically with increasing corticomuscular distance. We suggest that the motor cortex drives the spinal motoneuronal pool during sustained contractions, with the observed cortical rhythmic activity influencing the timing of efferent commands. The cortical rhythms could be related to motor binding, but the rhythmic output may also serve to optimize motor cortex output during isometric contractions.

Combining transcranial direct current stimulation with aerobic exercise to optimize cortical priming in stroke

2020 ◽  
Author(s):  
Anjali Sivaramakrishnan ◽  
Sangeetha Madhavan
Keyword(s):  
Reaction Time ◽  
Aerobic Exercise ◽  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Lower Limb ◽  
Synergistic Effects ◽  
Short Interval ◽  
Moderate Intensity ◽  
Direct Current Stimulation ◽  
Transcallosal Inhibition

Aerobic exercise (AE) and transcranial direct current stimulation (tDCS) are priming techniques that have been studied for their potential neuromodulatory effects on corticomotor excitability (CME), however the synergistic effects of AE and tDCS are not explored in stroke. Here we investigated the synergistic effects of AE and tDCS on CME, intracortical and transcallosal inhibition, and motor control for the lower limb in stroke. 26 stroke survivors participated in three sessions - tDCS, AE and AE + tDCS. AE included moderate intensity exercise and tDCS included 1 mA of anodal tDCS to the lower limb motor cortex with or without AE. Outcomes included measures of CME, short interval intracortical inhibition (SICI), ipsilateral silent period (iSP) (an index of transcallosal inhibition) for the tibialis anterior and ankle reaction time. Ipsilesional CME significantly decreased for AE compared to AE + tDCS and tDCS. No differences were noted in SICI, iSP measures or reaction time between all three sessions. Our findings suggest that a combination of exercise and tDCS, and tDCS demonstrate greater excitability of the ipsilesional hemisphere compared to exercise only, however these effects were specific to the descending corticomotor pathways. No additive priming effects of exercise and tDCS over tDCS was observed. Novelty: • An exercise and tDCS paradigm upregulated the descending motor pathways from the ipsilesional lower limb M1 compared to exercise. • Exercise or tDCS administered alone or in combination did not affect intracortical or transcallosal inhibition or reaction time.

Mirror Therapy in Lower Limb Amputees – A Look Beyond Primary Motor Cortex Reorganization

2011 ◽  
Vol 183 (11) ◽  
pp. 1051-1057 ◽  
Author(s):  
S. Seidel ◽  
G. Kasprian ◽  
J. Furtner ◽  
V. Schöpf ◽  
M. Essmeister ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Lower Limb ◽  
Primary Motor Cortex ◽  
Mirror Therapy ◽  
Lower Limb Amputees

Facilitatory I Wave Interaction in Proximal Arm and Lower Limb Muscle Representations of the Human Motor Cortex

2000 ◽  
Vol 83 (3) ◽  
pp. 1426-1434 ◽  
Author(s):  
Robert Chen ◽  
Rami Garg
Keyword(s):  
Motor Cortex ◽  
Lower Limb ◽  
Biceps Brachii ◽  
Conditioning Stimulus ◽  
Wave Interaction ◽  
Transcranial Electrical Stimulation ◽  
Lower Limb Muscle ◽  
Limb Muscle ◽  
Human Motor Cortex ◽  
Human Motor

Transcranial magnetic stimulation (TMS) of the human motor cortex elicits direct and indirect (I) waves in the corticospinal tract. Facilitatory I wave interaction has been demonstrated with a suprathreshold first stimulus (S1) followed by a subthreshold to threshold second stimulus (S2). Intracortical inhibition (ICI) and intracortical facilitation (ICF) can be studied by another paired TMS paradigm with a subthreshold conditioning stimulus (CS) followed by a suprathreshold test stimulus. Facilitatory I wave interaction in motor representations other than the hand area and its relationship to ICI and ICF has not been studied. We studied I wave interaction, ICI and ICF in an intrinsic hand muscle (abductor pollicis brevis, APB), in a proximal arm muscle (biceps brachii, BB) and in a lower limb muscle (tibialis anterior, TA) in 11 normal subjects. I wave facilitation was studied by paired TMS at 24 interstimulus intervals (ISIs) from 0.5 to 5.1 ms. For APB and TA, facilitation occurred in three distinct peaks at ISIs of 0.9–1.7, 2.5–3.5, and 4.1–5.1 ms. For BB, facilitation was significant for the first two peaks. The latencies of the peaks were similar among different muscles, but the magnitude of facilitation was much greater for APB and TA compared with BB. For all three muscles, changing the S2 to transcranial electrical stimulation (TES) resulted in much less facilitation of the first peak. For APB, there was significant I wave facilitation with S2 at 72% motor threshold (MT). The same stimulus used as the CS did not elicit ICF at ISI of 15 ms, suggesting that the threshold for eliciting I wave facilitation is lower than that for ICF. For BB and TA, there was no I wave facilitation with S2 at 90% of APB MT, and the same stimulus used as CS led to ICI. Thus in BB and TA the threshold for eliciting ICI is lower than that for I wave facilitation. We conclude that the circuits that mediate I wave interactions are present in the proximal arm and lower limb representations of the motor cortex. I wave facilitation occurs predominately in the cortex and may be primarily related to the monosynaptic corticomotoneuronal (CM) system. The reduced I wave facilitation for BB compared with APB and TA may be related to less extensive CM projection and involvement of other polysynaptic descending pathways. I wave facilitation, ICI, and ICF appears to be mediated by different neuronal circuits.

scholarly journals The effects of experimental knee pain on lower limb corticospinal and motor cortex excitability

2015 ◽  
Vol 17 (1) ◽  
Author(s):  
David Andrew Rice ◽  
Thomas Graven-Nielsen ◽  
Gwyn Nancy Lewis ◽  
Peter John McNair ◽  
Nicola Dalbeth
Keyword(s):  
Motor Cortex ◽  
Knee Pain ◽  
Lower Limb ◽  
Motor Cortex Excitability
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