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Corticospinal excitability

Richard G Carson, Michelle L Rankin
There has been an explosion of interest in methods that may promote neural plasticity by indirectly stimulating tissue in damaged brains using transient magnetic fields or weak electrical currents. A major limitation of these approaches is that the induced variations in brain activity tend to be diffuse. Thus far it has proved extremely difficult to target pathways from the brain to specific muscles. This is a particular challenge for applications in rehabilitation. Stroke survivors often exhibit abnormal patterns of muscle activation, including diminished specificity and high levels of co-contraction...
2018: Frontiers in Psychology
Sara J Hussain, Leonardo Claudino, Marlene Bönstrup, Gina Norato, Gabriel Cruciani, Ryan Thompson, Christoph Zrenner, Ulf Ziemann, Ethan Buch, Leonardo G Cohen
Oscillatory activity within sensorimotor networks is characterized by time-varying changes in phase and power. The influence of interactions between sensorimotor oscillatory phase and power on human motor function, like corticospinal output, is unknown. We addressed this gap in knowledge by delivering transcranial magnetic stimulation (TMS) to the human motor cortex during electroencephalography recordings in 20 healthy participants. Motor evoked potentials, a measure of corticospinal excitability, were categorized offline based on the mu (8-12 Hz) and beta (13-30 Hz) oscillatory phase and power at the time of TMS...
October 11, 2018: Cerebral Cortex
Leonardo Botelho, Letícia Angoleri, Maxciel Zortea, Alicia Deitos, Aline Brietzke, Iraci L S Torres, Felipe Fregni, Wolnei Caumo
Background: There is limited evidence concerning the effect of intramuscular electrical stimulation (EIMS) on the neural mechanisms of pain and disability associated with chronic Myofascial Pain Syndrome (MPS). Objectives: To provide new insights into the EIMS long-term effect on pain and disability related to chronic MPS (primary outcomes). To assess if the neuroplasticity state at baseline could predict the long-term impact of EIMS on disability due to MPS we examined the relationship between the serum brain-derived-neurotrophic-factor (BDNF) and by motor evoked potential (MEP)...
2018: Frontiers in Human Neuroscience
Caleb T Sypkes, Vincenzo S Contento, Leah R Bent, Chris J McNeil, Geoffrey A Power
Torque depression (TD) is the reduction in steady-state isometric torque following active muscle shortening when compared to an isometric reference contraction at the same muscle length and activation level. Central nervous system excitability differs in the TD state. While torque production about a joint is influenced by both agonist and antagonist muscle activation, investigations of corticospinal excitability have focused on agonist muscle groups. Hence, it is unknown how the TD state affects spinal and supraspinal excitability of an antagonist muscle...
November 19, 2018: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Ahmad O Alokaily, Mathew Yarossi, Gerard G Fluet, Eugene Tunik, Sergei V Adamovich
Paired associative stimulation (PAS) has been shown to increase corticospinal excitability (CSE) providing a promising adjuvant therapeutic approach for stroke. Combining PAS with movement of the stimulated limb may further increase enhancement of CSE, however, individuals with moderate to severe stroke may not be able to engage in the necessary repetitive voluntary movements of the paretic limb. The objective of this study was to investigate the feasibility of contralaterally coordinated PAS (ccPAS) applied to the resting hand extensors during fast extension of the contralateral hand...
July 2018: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Shokoofeh Parvin, Mina Mehdinezhad, Aidin Taghiloo, Ruhollah Nourian, Mehdi M Mirbagheri
The purpose of this study was to investigate the therapeutic effects of neuro-navigated repetitive transcranial magnetic stimulation (rTMS) combined with occupational therapy (OT) on gait impairment of a child (male, age: 13.2) with spastic hemiplegic cerebral palsy (CP). The treatment included 4 days a week of rTMS sessions for 3 weeks and 4 days of rTMS and OT sessions per week for 3 weeks. Transcranial magnetic stimulation (TMS) was used to evaluate corticospinal tract (CST) activities and H-reflex test was used to assess reflex hyper-excitability...
July 2018: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Shokoofeh Parvin, Amin Shahrokhi, Abbas Tafakhori, Ashkan Irani, Mehrnaz Rasteh, Mehdi M Mirbagheri
The objective of this research was to study the therapeutic effects of repetitive transcranial magnetic stimulation (rTMS) on corticospinal tract (CST) activities, reflex hyper-excitability, muscle stiffness, and the clinical status of children with spastic hemiplegic cerebral palsy (CP). Three children participated in this study. The treatment lasted for 6 weeks. Two of the patients, the experimental group, received rTMS therapy 4 days a week during the first 3 weeks, and then received typical occupational therapy (OT) after each rTMS session during the second 3 weeks...
July 2018: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Olivia M Lapenta, Elisabetta Ferrari, Paulo S Boggio, Luciano Fadiga, Alessandro D'Ausilio
Observing others' actions desynchronizes electroencephalographic (EEG) rhythms and modulates corticospinal excitability as assessed by transcranial magnetic stimulation (TMS). However, it remains unclear if these measures reflect similar neurofunctional mechanisms at the individual level. In the present study, a within-subject experiment was designed to assess these two neurophysiological indexes and to quantify their mutual correlation. Participants observed reach-to-grasp actions directed towards a small (precision grip) or a large object (power grip)...
2018: PloS One
Arthur R Chaves, Elizabeth M Wallack, Liam P Kelly, Ryan W Pretty, Hailey D Wiseman, Alice Chen, Craig S Moore, Mark Stefanelli, Michelle Ploughman
OBJECTIVES: Investigate whether asymmetrical corticospinal excitability exists in Multiple Sclerosis (MS) and its association with MS symptoms. METHODS: Bilateral resting and active motor thresholds (RMT, AMT) were gathered using transcranial magnetic stimulation among 82 MS patients. Corticospinal excitability (CSE) asymmetry was expressed as the ratio between weaker and stronger sides' RMT and AMT. Stronger and weaker side was determined by pinch and grip strength...
November 6, 2018: Behavioural Brain Research
Chelsea L Gordon, Marco Iacoboni, Ramesh Balasubramaniam
Corticospinal excitability (CSE) in humans measured with Transcranial Magnetic Stimulation (TMS) is generally increased by the perception of other people's actions. This perception can be unimodal (visual or auditory) or multimodal (visual and auditory). The increase in TMS-measured CSE is typically prominent for muscles involved in the perceived action (muscle specificity). There are two main classes of accounts for this phenomenon. One suggests that the motor system mirrors the actions that the observer perceives (the resonance account)...
2018: Frontiers in Neuroscience
C Latella, A M Goodwill, M Muthalib, A M Hendy, B Major, K Nosaka, W P Teo
Differences in the neural mechanisms underpinning eccentric (ECC) and concentric (CON) contractions exist; however, the acute effects of fatiguing muscle contractions on intracortical and corticospinal excitability are not well understood. Therefore, we compared maximal ECC and CON contractions of the right biceps brachii (BB) muscle for changes in corticospinal excitability, short- (SICI) and long-interval intracortical inhibition (LICI) and intracortical facilitation (ICF) up to 1 h post-exercise. Fourteen right-handed adults (11M/3F; 26...
November 7, 2018: Scandinavian Journal of Medicine & Science in Sports
Elizabeth Salmon Powell, Radha Korupolu, Philip M Westgate, Cheryl Carrico, Lakshmi Reddy, Lumy Sawaki
BACKGROUND: Non-invasive transcranial direct current stimulation has been shown to modulate cortical excitability in various studies. Similarly, recent preliminary studies suggest that transcutaneous spinal direct current stimulation (tsDCS) may engender a modulation effect on spinal and cortical neurons. OBJECTIVE: The purpose of this study was to evaluate the dose-response effects of tsDCS in healthy subjects and thereby lay groundwork for expanding treatment options for patients with spinal cord injury (SCI)...
October 31, 2018: NeuroRehabilitation
Davis A Forman, Michael Monks, Kevin E Power
The purpose of the present study was to examine corticospinal excitability to the biceps and triceps brachii during arm cycling and an intensity-matched tonic contraction using stimulus response curves (SRCs) elicited via transcranial magnetic stimulation (TMS). Corticospinal excitability was assessed using TMS elicited motor-evoked potentials (MEPs) at eight different stimulation intensities (85-190% of MEP threshold). MEPs were recorded during arm cycling at two different positions, mid-elbow flexion (6 o'clock relative to a clock face) and mid-elbow extension (12 o'clock relative to a clock face), in addition to an intensity-matched (12 o'clock) tonic contraction...
November 3, 2018: Neuroscience Letters
Julia Birchenall, Maxime Térémetz, Pauline Roca, Jean-Charles Lamy, Catherine Oppenheim, Marc A Maier, Jean-Louis Mas, Catherine Lamy, Jean-Claude Baron, Påvel G Lindberg
OBJECTIVES: In this longitudinal pilot study, we investigated how manual dexterity recovery was related to corticospinal tract (CST) injury and excitability, in six patients undergoing conventional rehabilitation. METHODS: Key components of manual dexterity, namely finger force control, finger tapping rate and independence of finger movements, were quantified. Structural MRI was obtained to calculate CST lesion load. CST excitability was assessed by measuring rest motor threshold (RMT) and the amplitude of motor evoked potentials (MEPs) using transcranial magnetic stimulation (TMS)...
October 31, 2018: Neurophysiologie Clinique, Clinical Neurophysiology
Joshua C Weavil, Markus Amann
The corticospinal pathway is considered the primary conduit for voluntary motor control in humans. The efficacy of the corticospinal pathway to relay neural signals from higher brain areas to the locomotor muscle, i.e., corticospinal excitability, is subject to alterations during exercise. While the integrity of this motor pathway has historically been examined during single-joint contractions, a small number of investigations have recently focused on whole body exercise, such as cycling or rowing. Although differences in methodologies employed between these studies complicate the interpretation of the existing literature, it appears that the net excitability of the corticospinal pathway remains unaltered during fatiguing whole body exercise...
2018: Progress in Brain Research
Fatemeh Khademi, Vladislav Royter, Alireza Gharabaghi
BACKGROUND: Intrinsic motor cortex activity modifies corticospinal excitability (CSE) in accordance with both oscillatory power fluctuations and phase-specific modulation along the oscillatory beta cycle, particularly in the 16-17 Hz frequency bin. OBJECTIVE: To determine the magnitude of CSE and the relevance of stimulation timing for input gain mediated by either oscillatory power or phase. METHODS: We applied single-pulse transcranial magnetic stimulation (TMS) over the primary motor cortex of healthy subjects at rest during electroencephalography recordings...
October 26, 2018: Brain Stimulation
Kensho Takahashi, Kenji Kato, Nobuaki Mizuguchi, Junichi Ushiba
BACKGROUND: Physical motor exercise aided by an electroencephalogram (EEG)-based brain-computer interface (BCI) is known to improve motor recovery in patients with stroke. In such a BCI paradigm, event-related desynchronization (ERD) in the alpha and beta bands extracted from EEG recorded over the primary sensorimotor area (SM1) is often used, since ERD has been suggested to be associated with an increase of corticospinal excitability. Recently, we demonstrated a novel online lock-in amplifier (LIA) algorithm to estimate the amplitude modulation of motor-related SM1 ERD...
November 1, 2018: Journal of Neuroengineering and Rehabilitation
Eman M Khedr, Bastawy Al Fawal, Ahmed M Abdelwarith, Mostafa Saber, Abeer Abdel Hady Tony, Ahmed El-Bassiony, John C Rothwell
OBJECTIVES: It has recently been suggested that drug-induced tardive syndromes (TS) might be due to maladaptive plasticity, which increases motor excitability in cerebral cortex and basal ganglia. In order to test this hypothesis, we performed the first measurements of cortical excitability in TS. METHODS: Motor cortex excitability was examined using transcranial magnetic stimulation (TMS) in 22 TS patients and compared with that in 20 age and sex-matched healthy individuals...
October 23, 2018: Neurophysiologie Clinique, Clinical Neurophysiology
Stefania C Ficarella, Lorella Battelli
In everyday life, environmental cues are used to predict and respond faster to upcoming events. Similarly, in cueing paradigms (where, on cued trials, a cued target requires a speeded response), cues are known to speed up response times (RTs), suggesting that motor preparation has occurred. However, some studies using short cue-target intervals (<300 ms) have found slower RTs on cued, compared to uncued trials (namely, the "paradoxical warning cost"). One explanation of this paradoxical effect is proactive inhibition, a motor gating mechanism that prevents false alarms, also called "the default state of executive control...
2018: Frontiers in Psychology
Per Aagaard
Neuromuscular activity is suppressed during maximal eccentric (ECC) muscle contraction in untrained subjects owing to attenuated levels of central activation and reduced spinal motor neuron (MN) excitability indicated by reduced electromyography signal amplitude, diminished evoked H-reflex responses, increased autogenic MN inhibition, and decreased excitability in descending corticospinal motor pathways. Maximum ECC muscle force recorded during maximal voluntary contraction can be increased by superimposed electrical muscle stimulation only in untrained individuals and not in trained strength athletes, indicating that the suppression in MN activation is modifiable by resistance training...
July 2018: Journal of Sport and Health Science
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