BDNF polymorphism and inter hemispheric balance of motor cortex excitability: a preliminary study

2021 ◽  
Author(s):  
Raffaele Dubbioso ◽  
Giovanni Pellegrino ◽  
Federico Ranieri ◽  
Giovanni Di Pino ◽  
Fioravante Capone ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Short Interval ◽  
Intracortical Inhibition ◽  
Val66met Polymorphism ◽  
Healthy Humans ◽  
Motor Cortex Excitability ◽  
Active Motor ◽  
Bdnf Val66met Polymorphism

Preclinical studies have demonstrated that Brain-Derived Neurotrophic Factor (BDNF) plays a crucial role in the homeostatic regulation of cortical excitability and excitation/inhibition balance. Using transcranial magnetic stimulation (TMS) techniques we investigated whether BDNF polymorphism could influence cortical excitability of the left and right primary motor cortex in healthy humans. Twenty-nine participants were recruited and genotyped for the presence of the BDNF Val66Met polymorphism, namely homozygous for the valine allele (Val/Val), heterozygotes (Val/Met), and homozygous for the methionine allele (Met/Met). Blinded to the latter, we evaluated inhibitory and facilitatory circuits of the left (LH) and right motor cortex (RH) by measuring resting (RMT) and active motor threshold (AMT), short interval intracortical inhibition (SICI) and intracortical facilitation (ICF). For each neurophysiological metric we also considered the inter-hemispheric balance expressed by the Laterality Index (LI). Val/Val participants (n= 21) exhibited an overall higher excitability of the LH compared to the RH, as probed by lower motor thresholds, lower SICI and higher ICF. Val/Val participants displayed positive LI, especially for AMT and ICF (all p< 0.05), indicating higher LH excitability and more pronounced inter-hemispheric excitability imbalance as compared to Met carriers. Our preliminary results suggest that BDNF Val66Met polymorphism might influence interhemispheric balance of motor cortex excitability.

Influence of Short-Interval Intracortical Inhibition on Short-Interval Intracortical Facilitation in Human Primary Motor Cortex

2010 ◽  
Vol 104 (3) ◽  
pp. 1382-1391 ◽  
Author(s):  
Yuichiro Shirota ◽  
Masashi Hamada ◽  
Yasuo Terao ◽  
Hideyuki Matsumoto ◽  
Shinya Ohminami ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Short Interval ◽  
Conditioning Stimulus ◽  
Intracortical Inhibition ◽  
Intracortical Facilitation ◽  
Paired Pulse ◽  
Active Motor ◽  
Second Peak ◽  
Pulse Stimulation

Using the paired-pulse paradigm, transcranial magnetic stimulation (TMS) has revealed much about the human primary motor cortex (M1). A preceding subthreshold conditioning stimulus (CS) inhibits the excitability of the motor cortex, which is named short-interval intracortical inhibition (SICI). In contrast, facilitation is observed when the first pulse (S1) is followed by a second one at threshold (S2), named short-interval intracortical facilitation (SICF). SICI and SICF have been considered to be mediated by different neural circuits within M1, but more recent studies reported relations between them. In this study, we performed triple-pulse stimulation consisting of CS-S1-S2 to further explore putative interactions between these two effects. Three intensities of CS (80–120% of active motor threshold: AMT) and two intensities of S2 (120 and 140% AMT) were combined. The SICF in the paired-pulse paradigm exhibited clear facilitatory peaks at ISIs of 1.5 and 3 ms. The second peak at 3 ms was significantly suppressed by triple-pulse stimulation using 120% AMT CS, although the first peak was almost unaffected. Our present results obtained using triple-pulse stimulation suggest that each peak of SICF is differently modulated by different intensities of CS. The suppression of the second peak might be ascribed to the findings in the paired-pulse paradigm that CS mediates SICI by inhibiting later I waves such as I3 waves and that the second peak of SICF is most probably related to I3 waves. We propose that CS might inhibit the second peak of SICF at the interneurons responsible for I3 waves.

scholarly journals Distributed cortical structural properties contribute to motor cortical excitability and inhibition

2017 ◽  
Author(s):  
Eran Dayan ◽  
Virginia López-Alonso ◽  
Sook-Lei Liew ◽  
Leonardo G. Cohen
Keyword(s):  
Motor Cortex ◽  
Structural Properties ◽  
Motor Function ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Short Interval ◽  
Intracortical Inhibition ◽  
Corticospinal Excitability ◽  
Support Vector

AbstractThe link between the local structure of the primary motor cortex and motor function has been well documented. However, motor function relies on a network of interconnected brain regions and the link between the structural properties characterizing these distributed brain networks and motor function remains poorly understood. Here, we examined whether distributed patterns of brain structure, extending beyond the primary motor cortex can help classify two forms of motor function: corticospinal excitability and intracortical inhibition. To this effect, we recorded high-resolution structural magnetic resonance imaging scans in 25 healthy volunteers. To measure corticospinal excitability and inhibition in the same volunteers we recorded motor evoked potentials (MEPs) elicited by single-pulse transcranial magnetic stimulation (TMS) and short-interval intracortical inhibition (SICI) in a separate session. Support vector machine (SVM) pattern classification was used to identify distributed multivoxel gray matter areas, which distinguished subjects who had lower and higher MEPs and SICIs. We found that MEP and SICI classification could be predicted based on a widely distributed, largely non-overlapping pattern of voxels in the frontal, parietal, temporal, occipital and cerebellar regions. Thus, structural properties distributed over the brain beyond the primary motor cortex relate to motor function.

scholarly journals Pathophysiology of Central Poststroke Pain

Stroke ◽  
2019 ◽  
Vol 50 (10) ◽  
pp. 2851-2857 ◽  
Author(s):  
Sung-Chun Tang ◽  
Lukas Jyuhn-Hsiarn Lee ◽  
Jiann-Shing Jeng ◽  
Sung-Tsang Hsieh ◽  
Ming-Chang Chiang ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Motor Cortex ◽  
Evoked Potential ◽  
Short Interval ◽  
Intracortical Inhibition ◽  
Contact Heat ◽  
Sensorimotor Interaction ◽  
Motor Cortex Excitability ◽  
Impaired Quality

Background and Purpose— Central poststroke pain (CPSP) is a disabling condition in stroke patients, and evidence suggests that altered corticospinal and motor intracortical excitability occurs in neuropathic pain. The objective of this study was to investigate changes in motor cortex excitability and sensorimotor interaction and their correlates with clinical manifestations and alterations in somatosensory systems in CPSP patients. Methods— Fourteen patients with CPSP but no motor weakness were compared with age- and sex-matched healthy controls for motor cortex excitability and sensorimotor interaction assessed by transcranial magnetic stimulation to measure resting motor thresholds, short-interval intracortical inhibition, intracortical facilitation, and afferent inhibitions. The sensory pathway was evaluated by quantitative sensory testing, contact heat evoked potential, and somatosensory evoked potentials. Clinical pain and quality of life were assessed with validated tools. Results— The duration of CPSP was 3.3±3.0 years (ranging 0.5–10 years), and pain significantly impaired quality of life. Compared with the unaffected hemisphere, the stroke hemisphere had higher thermal thresholds, lower contact heat evoked potential amplitudes, and prolonged cortical somatosensory evoked potential latencies. There was no difference in resting motor thresholds between the stroke and unaffected hemisphere or between patients and controls. CPSP patients had a reduction in short-interval intracortical inhibition in the stroke hemisphere compared with that in the unaffected hemispheres of patients and controls. No changes were noted in afferent inhibitions between the stroke and unaffected hemispheres. The short-interval intracortical inhibition of the stroke hemisphere was negatively correlated with self-rated health on a visual analog scale and positively correlated with cortical somatosensory evoked potential latencies. Conclusions— CPSP patients with intact corticospinal tracts showed reduced motor intracortical inhibition in the stroke hemisphere, suggesting defective gamma-aminobutyric acid-ergic inhibition. This disinhibition was associated with impaired quality of life and was related to dorsal column–medial lemniscus pathway dysfunction.

scholarly journals Expanding the parameter space of anodal transcranial direct current stimulation of the primary motor cortex

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Desmond Agboada ◽  
Mohsen Mosayebi Samani ◽  
Asif Jamil ◽  
Min-Fang Kuo ◽  
Michael A. Nitsche
Keyword(s):  
Motor Cortex ◽  
Parameter Space ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Anodal Tdcs ◽  
Stimulation Parameters ◽  
Motor Cortex Excitability ◽  
The Impact ◽  
Motor Cortex Plasticity

AbstractSize and duration of the neuroplastic effects of tDCS depend on stimulation parameters, including stimulation duration and intensity of current. The impact of stimulation parameters on physiological effects is partially non-linear. To improve the utility of this intervention, it is critical to gather information about the impact of stimulation duration and intensity on neuroplasticity, while expanding the parameter space to improve efficacy. Anodal tDCS of 1–3 mA current intensity was applied for 15–30 minutes to study motor cortex plasticity. Sixteen healthy right-handed non-smoking volunteers participated in 10 sessions (intensity-duration pairs) of stimulation in a randomized cross-over design. Transcranial magnetic stimulation (TMS)-induced motor-evoked potentials (MEP) were recorded as outcome measures of tDCS effects until next evening after tDCS. All active stimulation conditions enhanced motor cortex excitability within the first 2 hours after stimulation. We observed no significant differences between the three stimulation intensities and durations on cortical excitability. A trend for larger cortical excitability enhancements was however observed for higher current intensities (1 vs 3 mA). These results add information about intensified tDCS protocols and suggest that the impact of anodal tDCS on neuroplasticity is relatively robust with respect to gradual alterations of stimulation intensity, and duration.

Cutaneous Inputs Can Activate the Ipsilateral Primary Motor Cortex During Bimanual Sensory-Driven Movements in Humans

2004 ◽  
Vol 92 (6) ◽  
pp. 3200-3209 ◽  
Author(s):  
Satoshi Shibuya ◽  
Yukari Ohki
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Human Subjects ◽  
Random Sequence ◽  
Virtual Object ◽  
Active Motor ◽  
Finger Forces ◽  
The Right ◽  
Transient Force

Using transcranial magnetic stimulation (TMS), we examined whether sensory input from a finger affects activity of the ipsilateral primary motor cortex (M1) when human subjects hold a virtual object bimanually and whether this ipsilateral activation varies under different contexts. Subjects used both index fingers to hold two plates, which were subjected to unpredictable pulling loads from torque motors. Loads were delivered in a random sequence to either plate or concurrently to both, although the latter occurred most frequently. Finger forces vertical to the plates and surface electromyographs from the first dorsal interosseous muscles were recorded bilaterally during the task. TMS was sometimes applied over the finger area of the left M1 at variable times relative to load onset to examine cortical excitability. Strength of TMS was set around the active motor threshold of the right finger muscle while subjects waited for loading to the handheld plates. When one plate was singly loaded, the M1 contralateral to the loaded finger was activated, causing automatic force increases in the finger. In addition, the ipsilateral M1 was activated during such loading, associated with transient force increases in the contralateral nonloaded finger. Activations in the ipsilateral M1 were also observed during concurrent loading, when activations were stronger than those following single loading of the contralateral plate. Ipsilateral activations weakened when concurrent loading was less frequent. These results suggest interactions between bilateral sensorimotor cortices during bimanual coordinated movements, with strength varying by context.

scholarly journals Short-interval intracortical inhibition in human primary motor cortex: A multi-locus transcranial magnetic stimulation study

NeuroImage ◽  
2019 ◽  
Vol 203 ◽  
pp. 116194 ◽  
Author(s):  
Jaakko O. Nieminen ◽  
Lari M. Koponen ◽  
Niko Mäkelä ◽  
Victor Hugo Souza ◽  
Matti Stenroos ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Short Interval ◽  
Intracortical Inhibition

Event-related desynchronization reflects downregulation of intracortical inhibition in human primary motor cortex

2013 ◽  
Vol 110 (5) ◽  
pp. 1158-1166 ◽  
Author(s):  
Mitsuaki Takemi ◽  
Yoshihisa Masakado ◽  
Meigen Liu ◽  
Junichi Ushiba
Keyword(s):  
Motor Cortex ◽  
Motor Imagery ◽  
Sensorimotor Cortex ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Short Interval ◽  
Hand Movement ◽  
Intracortical Inhibition ◽  
Imagery Task ◽  
Event Related Desynchronization

There is increasing interest in electroencephalogram (EEG)-based brain-computer interface (BCI) as a tool for rehabilitation of upper limb motor functions in hemiplegic stroke patients. This type of BCI often exploits mu and beta oscillations in EEG recorded over the sensorimotor areas, and their event-related desynchronization (ERD) following motor imagery is believed to represent increased sensorimotor cortex excitability. However, it remains unclear whether the sensorimotor cortex excitability is actually correlated with ERD. Thus we assessed the association of ERD with primary motor cortex (M1) excitability during motor imagery of right wrist movement. M1 excitability was tested by motor evoked potentials (MEPs), short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF) with transcranial magnetic stimulation (TMS). Twenty healthy participants were recruited. The participants performed 7 s of rest followed by 5 s of motor imagery and received online visual feedback of the ERD magnitude of the contralateral hand M1 while performing the motor imagery task. TMS was applied to the right hand M1 when ERD exceeded predetermined thresholds during motor imagery. MEP amplitudes, SICI, and ICF were recorded from the agonist muscle of the imagined hand movement. Results showed that the large ERD during wrist motor imagery was associated with significantly increased MEP amplitudes and reduced SICI but no significant changes in ICF. Thus ERD magnitude during wrist motor imagery represents M1 excitability. This study provides electrophysiological evidence that a motor imagery task involving ERD may induce changes in corticospinal excitability similar to changes accompanying actual movements.

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