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1.
Pedro Caldana Gordon Christoph Zrenner Debora Desideri Paolo Belardinelli Brigitte Zrenner André Russowsky Brunoni Ulf Ziemann 《Brain stimulation》2018,11(5):1024-1032
Background
Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique with potential for cost-effective therapeutic neuromodulation. Although positive therapeutic effects were found by stimulating the dorsolateral prefrontal cortex (DLPFC), few studies have investigated physiological effects of DLPFC-tDCS.Objectives
To investigate effects of tDCS with different parameter settings applied to the left DLPFC on cortical responses, measured by resting-state electroencephalography (rs-EEG) and transcranial magnetic stimulation (TMS)-evoked/induced EEG responses.Methods
22 healthy subjects underwent 5 tDCS sessions with different tDCS parameter settings in a double-blinded randomized crossover design (1: 1.5?mA, anode left-DLPFC, cathode right-DLPFC; 2: 1.5?mA, cathode left-DLPFC, anode right-DLPFC; 3: 0.5?mA, anode left-DLPFC, cathode right-DLPFC; 4: 1.5?mA, anode left-DLPFC, cathode left deltoid muscle; 5: sham stimulation). Rs-EEG and TMS-EEG were recorded before and after tDCS.Results
Rs-EEG power spectrum analysis showed no difference comparing baseline with post stimulation in any of the tDCS conditions. TMS-EEG evoked potential amplitude decreased in parietal cortex after 1.5?mA left-DLPFC anodal tDCS, and TMS-induced gamma and theta oscillations decreased after all conditions using left-DLPFC anodal tDCS. Left-DLPFC cathodal tDCS did not lead to significant change. None of the post-intervention changes was different when comparing the effects across conditions, including sham.Conclusions
Our study does not provide evidence that a single tDCS session results in significant changes in rs-EEG, using the current stimulation parameters. Significant changes in EEG responses to TMS pulses were observed following the anodal 1.5?mA tDCS interventions, although these changes were not statistically significant in a group comparison. 相似文献2.
Jose Gomez-Tames Atsushi Hamasaka Ilkka Laakso Akimasa Hirata Yoshikazu Ugawa 《Brain stimulation》2018,11(4):839-848
Background
Transcranial magnetic stimulation (TMS) activates target brain structures in a non-invasive manner. The optimal orientation of the TMS coil for the motor cortex is well known and can be estimated using motor evoked potentials. However, there are no easily measurable responses for activation of other cortical areas and the optimal orientation for these areas is currently unknown.Objective
This study investigated the electric field strength, optimal coil orientation, and relative locations to optimally stimulate the target cortex based on computed electric field distributions.Methods
A total of 518,616 stimulation scenarios were studied using realistic head models (2401 coil locations?×?12 coil angles?×?18 head models). Inter-subject registration methods were used to generate an atlas of optimized TMS coil orientations on locations on the standard brain.Results
We found that the maximum electric field strength is greater in primary somatosensory cortex and primary motor cortex than in other cortical areas. Additionally, a universal optimal coil orientation applicable to most subjects is more feasible at the primary somatosensory cortex and primary motor cortex. We confirmed that optimal coil angle follows the anatomical shape of the hand motor area to realize personalized optimization of TMS. Finally, on average, the optimal coil positions for TMS on the scalp deviated 5.5?mm from the scalp points with minimum cortex-scalp distance. This deviation was minimal at the premotor cortex and primary motor cortex.Conclusion
Personalized optimal coil orientation is preferable for obtaining the most effective stimulation. 相似文献3.
Background
the influence of pulse width, pulse waveform and current direction on transcranial magnetic stimulation (TMS) outcomes is of critical importance. However, their effects have only been investigated indirectly with motor-evoked potentials (MEP). By combining TMS and EEG it is possible to examine how these factors affect evoked activity from the cortex and compare that with the effects on MEP.Objective
we used a new controllable TMS device (cTMS) to vary systematically pulse width, pulse waveform and current direction and explore their effects on global and local TMS-evoked EEG response.Methods
In 19 healthy volunteers we measured (1) resting motor threshold (RMT) as an estimate of corticospinal excitability; (2) global mean field power (GMFP) as an estimate of global cortical excitability; and (3) local mean field power (LMFP) as an estimate of local cortical excitability.Results
RMT was lower with monophasic posterior-to-anterior (PA) pulses that have a longer pulse width (p?<?0.001). After adjusting for the individual motor threshold of each pulse type we found that (a) GMFP was higher with monophasic pulses (p?<?0.001); (b) LMFP was higher with longer pulse width (p?=?0.015); (c) early TEP polarity was modulated depending on the current direction (p?=?0.01).Conclusions
Despite normalizing stimulus intensity to RMT, we found that local and global responses to TMS vary depending on pulse parameters. Since EEG responses can vary independently of the MEP, titrating parameters of TMS in relation to MEP threshold is not a useful way of ensuring that a constant set of neurons is activated within a cortical area. 相似文献4.
Logan T. Dowdle Truman R. Brown Mark S. George Colleen A. Hanlon 《Brain stimulation》2018,11(4):789-796
Background
In the 20 years since our group established the feasibility of performing interleaved TMS/fMRI, no studies have reported direct comparisons of active prefrontal stimulation with a matched sham. Thus, for all studies there is concern about what is truly the TMS effect on cortical neurons.Objective
After developing a sham control for use within the MRI scanner, we used fMRI to test the hypothesis of greater regional BOLD responses for active versus control stimulation.Methods
We delivered 4 runs of interleaved TMS/fMRI with a limited field of view (16 slices, centered at AC-PC) to the left DLPFC (2 active, 2 control; counterbalanced) of 20 healthy individuals (F3; 20 pulses/run, interpulse interval:10–15sec, TR:1sec). In the control condition, 3?cm of foam was placed between the TMS coil and the scalp. This ensured magnetic field decay, but preserved the sensory aspects of each pulse (empirically evaluated in a subset of 10 individuals).Results
BOLD increases in the cingulate, thalamus, insulae, and middle frontal gyri (p?<?0.05, FWE corrected) were found during both active and control stimulation. However, relative to control, active stimulation caused elevated BOLD signal in the anterior cingulate, caudate and thalamus. No significant difference was found in auditory regions.Conclusion(s)
This TMS/fMRI study evaluated a control condition that preserved many of the sensory features of TMS while reducing magnetic field entry. These findings support a relationship between single pulses of TMS and activity in anatomically connected regions, but also underscore the importance of using a sham condition in future TMS/fMRI studies. 相似文献5.
Background
Responses to transcranial magnetic stimulation (TMS) are notoriously variable. Previous studies have observed a dependence of TMS-induced responses on ongoing brain activity, for instance sensorimotor rhythms. This suggests an opportunity for the development of more effective stimulation protocols through closed-loop TMS-EEG. However, it is not yet clear how features of ongoing activity affect the responses of cortical circuits to TMS.Objective/Hypothesis
Here we investigate the dependence of TMS-responses on power and phase of ongoing oscillatory activity in a computational model of TMS-induced I-waves.Methods
The model comprises populations of cortical layer 2/3 (L2/3) neurons and a population of cortical layer 5 (L5) neurons and generates I-waves in response to TMS. Oscillatory input to the L2/3 neurons induces rhythmic fluctuations in activity of L5 neurons. TMS pulses are simulated at different phases and amplitudes of the ongoing rhythm.Results
The model shows a robust dependence of I-wave properties on phase and power of ongoing rhythms, with the strongest response occurring for TMS at maximal L5 depolarization. The amount of phase-modulation depends on stimulation intensity, with stronger modulation for lower intensity.Conclusion
The model predicts that responses to TMS are highly variable for low stimulation intensities if ongoing brain rhythms are not taken into account. Closed-loop TMS-EEG holds promise for obtaining more reliable TMS effects. 相似文献6.
Lewis J. Kerwin Corey J. Keller Wei Wu Manjari Narayan Amit Etkin 《Brain stimulation》2018,11(3):536-544
Background
Transcranial magnetic stimulation (TMS)-evoked potentials (TEPs), recorded using electroencephalography (TMS-EEG), offer a powerful tool for measuring causal interactions in the human brain. However, the test-retest reliability of TEPs, critical to their use in clinical biomarker and interventional studies, remains poorly understood.Objective/Hypothesis
We quantified TEP reliability to: (i) determine the minimal TEP amplitude change which significantly exceeds that associated with simply re-testing, (ii) locate the most reliable scalp regions of interest (ROIs) and TEP peaks, and (iii) determine the minimal number of TEP pulses for achieving reliability.Methods
TEPs resulting from stimulation of the left dorsolateral prefrontal cortex were collected on two separate days in sixteen healthy participants. TEP peak amplitudes were compared between alternating trials, split-halves of the same run, two runs five minutes apart and two runs on separate days. Reliability was quantified using concordance correlation coefficient (CCC) and smallest detectable change (SDC).Results
Substantial concordance was achieved in prefrontal electrodes at 40 and 60?ms, centroparietal and left parietal ROIs at 100?ms, and central electrodes at 200?ms. Minimum SDC was found in the same regions and peaks, particularly for the peaks at 100 and 200?ms. CCC, but not SDC, reached optimal values by 60–100 pulses per run with saturation beyond this number, while SDC continued to improve with increased pulse numbers.Conclusion
TEPs were robust and reliable, requiring a relatively small number of trials to achieve stability, and are thus well suited as outcomes in clinical biomarker or interventional studies. 相似文献7.
Isabella Premoli Julia Király Florian Müller-Dahlhaus Carl M. Zipser Pierre Rossini Christoph Zrenner Ulf Ziemann Paolo Belardinelli 《Brain stimulation》2018,11(4):818-827
Background
Inhibition in the human motor cortex can be probed by means of paired-pulse transcranial magnetic stimulation (ppTMS) at interstimulus intervals of 2–3 ms (short-interval intracortical inhibition, SICI) or ～100?ms (long-interval intracortical inhibition, LICI). Conventionally, SICI and LICI are recorded as motor evoked potential (MEP) inhibition in the hand muscle. Pharmacological experiments indicate that they are mediated by GABAA and GABAB receptors, respectively.Objective/Hypothesis: SICI and LICI of TMS-evoked EEG potentials (TEPs) and their pharmacological properties have not been systematically studied. Here, we sought to examine SICI by ppTMS-evoked compared to single-pulse TMS-evoked TEPs, to investigate its pharmacological manipulation and to compare SICI with our previous results on LICI.Methods
PpTMS-EEG was applied to the left motor cortex in 16 healthy subjects in a randomized, double-blind placebo-controlled crossover design, testing the effects of a single oral dose 20?mg of diazepam, a positive modulator at the GABAA receptor, vs. 50?mg of the GABAB receptor agonist baclofen on SICI of TEPs.Results
We found significant SICI of the N100 and P180 TEPs prior to drug intake. Diazepam reduced SICI of the N100 TEP, while baclofen enhanced it. Compared to our previous ppTMS-EEG results on LICI, the SICI effects on TEPs, including their drug modulation, were largely analogous.Conclusions
Findings suggest a similar interaction of paired-pulse effects on TEPs irrespective of the interstimulus interval. Therefore, SICI and LICI as measured with TEPs cannot be directly derived from SICI and LICI measured with MEPs, but may offer novel insight into paired-pulse responses recorded directly from the brain rather than muscle. 相似文献8.
Martin Sommer Matteo Ciocca Raffaella Chieffo Paul Hammond Andreas Neef Walter Paulus John C. Rothwell Ricci Hannah 《Brain stimulation》2018,11(3):558-565
Background
Biphasic pulses produced by most commercially available TMS machines have a cosine waveform, which makes it difficult to study the interaction between the two phases of stimulation.Objective
We used a controllable pulse TMS (cTMS) device delivering quasi-rectangular pulse outputs to investigate whether monophasic are more effective than biphasic pulses.Methods
Temporally symmetric (“biphasic”) or highly asymmetric (“monophasic”) charge-balanced biphasic stimuli were used to target the hand area of motor cortex in the anterior-posterior (AP) or posterior-anterior (PA) initial current direction.Results
We observed the lowest motor thresholds and shortest motor evoked potential (MEP) latencies with initial PA pulses, and highest thresholds and longest latencies with AP pulses. Increasing pulse symmetry tended to increase threshold with a PA direction whereas it lowered thresholds and shortened latencies with an AP direction. Furthermore, it steepened the MEP input-output curve with both directions.Conclusions
“Biphasic” TMS pulses can be viewed as two monophasic pulses of opposite directions, each stimulating a different set of interneurons with different thresholds (PA?<?AP). At threshold, the reverse phase of an initially PA pulse increases threshold compared with “monophasic” stimulation. At higher intensities, the reverse phase begins to activate AP-sensitive neurones and increase the effectiveness of stimulation above that of a “monophasic” PA pulse. “Biphasic” stimulation with initially AP pulses is dominated at threshold by activation produced by the lower threshold reverse (PA) phase.Significance
The effects of biphasic stimulation are best understood as the summed output of two independent sets of directionally selective neural populations. 相似文献9.
Background
Transcranial direct current stimulation (tDCS) has been found to improve working memory (WM) performance in healthy participants following a single session. However, results are mixed and the overall effect size is small. Interpretation of these results is confounded by heterogeneous study designs, including differences in tDCS dose (current intensity) and sham conditions used.Aims
We systematically investigated the effect of tDCS dose on working memory using behavioural and neurophysiological outcomes.Methods
In a single-blind parallel group design, 100 participants were randomised across five groups to receive 15?min of bifrontal tDCS at different current intensities (2?mA, 1?mA, and three sham tDCS conditions at 0.034?mA, 0.016?mA, or 0?mA). EEG activity was acquired while participants performed a WM task prior to, during, and following tDCS. Response time, accuracy and an event-related EEG component (P3) were evaluated.Results
We found no significant differences in response time or performance accuracy between current intensities. The P3 amplitude was significantly lower in the 0?mA condition compared to the 0.034?mA, 1?mA and 2?mA tDCS conditions. Changes in WM accuracy were moderately correlated with changes in frontal P3 amplitude (channel Fz) following tDCS compared to baseline levels (r?=?0.34).Conclusions
Working memory was not significantly altered by tDCS, regardless of dose. The P3 amplitude showed that stimulation at 1?mA, 2?mA and a sham condition (0.034?mA) had biological effects, with the largest effect size for 1?mA stimulation. These findings indicate higher sensitivity of neurophysiological outcomes to tDCS and suggests that sham stimulation previously considered inactive may alter neuronal function. 相似文献10.
Andrea Guerra Antonio Suppa Matteo Bologna Valentina D&#x;Onofrio Edoardo Bianchini Peter Brown Vincenzo Di Lazzaro Alfredo Berardelli 《Brain stimulation》2018,11(4):734-742
Background
Transcranial Alternating Current Stimulation (tACS) consists in delivering electric current to the brain using an oscillatory pattern that may entrain the rhythmic activity of cortical neurons. When delivered at gamma frequency, tACS modulates motor performance and GABA-A-ergic interneuron activity.Objective
Since interneuronal discharges play a crucial role in brain plasticity phenomena, here we co-stimulated the primary motor cortex (M1) in healthy subjects by means of tACS during intermittent theta-burst stimulation (iTBS), a transcranial magnetic stimulation paradigm known to induce long-term potentiation (LTP)-like plasticity.Methods
We measured and compared motor evoked potentials before and after gamma, beta and sham tACS-iTBS. While we delivered gamma-tACS, we also measured short-interval intracortical inhibition (SICI) to detect any changes in GABA-A-ergic neurotransmission.Results
Gamma, but not beta and sham tACS, significantly boosted and prolonged the iTBS-induced after-effects. Interestingly, the extent of the gamma tACS-iTBS after-effects correlated directly with SICI changes.Conclusions
Overall, our findings point to a link between gamma oscillations, interneuronal GABA-A-ergic activity and LTP-like plasticity in the human M1. Gamma tACS-iTBS co-stimulation might represent a new strategy to enhance and prolong responses to plasticity-inducing protocols, thereby lending itself to future applications in the neurorehabilitation setting. 相似文献11.
Malte Wöstmann Johannes Vosskuhl Jonas Obleser Christoph S. Herrmann 《Brain stimulation》2018,11(4):752-758
Background
Spatial attention relatively increases the power of neural 10-Hz alpha oscillations in the hemisphere ipsilateral to attention, and decreases alpha power in the contralateral hemisphere. For gamma oscillations (>40?Hz), the opposite effect has been observed. The functional roles of lateralised oscillations for attention are currently unclear.Hypothesis
If lateralised oscillations are functionally relevant for attention, transcranial stimulation of alpha versus gamma oscillations in one hemisphere should differentially modulate the accuracy of spatial attention to the ipsi-versus contralateral side.Methods
20 human participants performed a dichotic listening task under continuous transcranial alternating current stimulation (tACS, vs sham) at alpha (10?Hz) or gamma (47?Hz) frequency. On each trial, participants attended to four spoken numbers on the left or right ear, while ignoring numbers on the other ear. In order to stimulate a left temporo-parietal cortex region, which is known to show marked modulations of alpha power during auditory spatial attention, tACS (1?mA peak-to-peak amplitude) was applied at electrode positions TP7 and FC5 over the left hemisphere.Results
As predicted, unihemispheric alpha-tACS relatively decreased the recall of targets contralateral to stimulation, but increased recall of ipsilateral targets. Importantly, this spatial pattern of results was reversed for gamma-tACS.Conclusions
Results provide a proof of concept that transcranially stimulated oscillations can enhance spatial attention and facilitate attentional selection of speech. Furthermore, opposite effects of alpha versus gamma stimulation support the view that states of high alpha are incommensurate with active neural processing as reflected by states of high gamma. 相似文献12.
Michele Dileone Laura Mordillo-Mateos Antonio Oliviero Guglielmo Foffani 《Brain stimulation》2018,11(4):676-688
Background
Transcranial static magnetic field stimulation (tSMS) was recently added to the family of inhibitory non-invasive brain stimulation techniques. However, the application of tSMS for 10–20?min over the motor cortex (M1) induces only short-lasting effects that revert within few minutes.Objective
We examined whether increasing the duration of tSMS to 30?min leads to long-lasting changes in cortical excitability, which is critical for translating tSMS toward clinical applications.Methods
The study comprised 5 experiments in 45 healthy subjects. We assessed the impact of 30-min-tSMS over M1 on corticospinal excitability, as measured by the amplitude of motor evoked potentials (MEPs) and resting motor thresholds (RMTs) to single-pulse transcranial magnetic stimulation (TMS) (experiments 1–2). We then assessed the impact of 30-min-tSMS on intracortical excitability, as measured by short-interval intracortical facilitation (SICF) and short-interval intracortical inhibition (SICI) using paired-pulse TMS protocols (experiments 2–4). We finally assessed the impact of 10-min-tSMS on SICF and SICI (experiment 5).Results
30-min-tSMS decreased MEP amplitude compared to sham for at least 30?min after the end of the stimulation. This long-lasting effect was associated with increased SICF and reduced SICI. 10-min-tSMS –previously reported to induce a short-lasting decrease in MEP amplitude– produced the opposite changes in intracortical excitability, decreasing SICF while increasing SICI.Conclusions
These results suggest a dissociation of intracortical changes in the consolidation from short-lasting to long-lasting decrease of corticospinal excitability induced by tSMS. The long-lasting effects of 30-min-tSMS open the way to the translation of this simple, portable and low-cost technique toward clinical trials. 相似文献13.
Yeowool Huh Dahee Jung Taeyoon Seo Sukkyu Sun Su Hyun Kim Hyewhon Rhim Sooyoung Chung Chong-Hyun Kim Youngwoo Kwon Marom Bikson Yong-an Chung Jeansok J. Kim Jeiwon Cho 《Brain stimulation》2018,11(5):1151-1160
Background
The bursting pattern of thalamocortical (TC) pathway dampens nociception. Whether brain stimulation mimicking endogenous patterns can engage similar sensory gating processes in the cortex and reduce nociceptive behaviors remains uninvestigated.Objective
We investigated the role of cortical parvalbumin expressing (PV) interneurons within the TC circuit in gating nociception and their selective response to TC burst patterns. We then tested if transcranial magnetic stimulation (TMS) patterned on endogenous nociceptive TC bursting modulate nociceptive behaviors.Methods
The switching of TC neurons between tonic (single spike) and burst (high frequency spikes) firing modes may be a critical component in modulating nociceptive signals. Deep brain electrical stimulation of TC neurons and immunohistochemistry were used to examine the differential influence of each firing mode on cortical PV interneuron activity. Optogenetic stimulation of cortical PV interneurons assessed a direct role in nociceptive modulation. A new TMS protocol mimicking thalamic burst firing patterns, contrasted with conventional continuous and intermittent theta burst protocols, tested if TMS patterned on endogenous TC activity reduces nociceptive behaviors in mice.Results
Immunohistochemical evidence confirmed that burst, but not tonic, deep brain stimulation of TC neurons increased the activity of PV interneurons in the cortex. Both optogenetic activation of PV interneurons and TMS protocol mimicking thalamic burst reduced nociceptive behaviors.Conclusions
Our findings suggest that burst firing of TC neurons recruits PV interneurons in the cortex to reduce nociceptive behaviors and that neuromodulation mimicking thalamic burst firing may be useful for modulating nociception. 相似文献14.
Pengcheng Sun Heng Li Zhuofan Lu Xiaofan Su Zengguang Ma Jianpin Chen Liming Li Chuanqing Zhou Yao Chen Xinyu Chai 《Brain stimulation》2018,11(4):667-675
Background
Electrical stimulation has been widely used in many ophthalmic diseases to modulate neuronal activities or restore partial visual function. Due to the different processing pathways and mechanisms, responses to visual and electrical stimulation in the primary visual cortex and higher visual areas might be different. This differences would shed some light on the properties of cortical responses evoked by electrical stimulation.Objective
This study's goal was to directly compare the cortical responses evoked by visual and electrical stimulation and investigate the cortical processing of visual information and extrinsic electrical signal.Methods
Optical imaging of intrinsic signals (OIS) was used to probe the cortical hemodynamic responses in 11 cats. Transcorneal electrical stimulation (TES) through an ERG-jet contact lens electrode was used to activate visual cortices. Full-field and peripheral drifting gratings were used as the visual stimuli.Results
The response latency evoked by TES was shorter than that responding to visual stimulation (VS). Cortical responses evoked by VS were retinotopically organized, which was consistent with previous studies. On the other hand, the cortical region activated by TES was preferentially located in the secondary visual cortex (Area 18), while the primary visual cortex (Area 17) was activated by a higher current intensity. Compared with the full-field VS, the cortical response in Area 18 to TES with a current intensity above 1.2?mA was significantly stronger.Conclusion
According to our results, we provided some evidence that the cortical processing of TES was influenced by the distribution of the electrical field in the retina and the activating threshold of different retinal ganglion cells. 相似文献15.
Elisa Kallioniemi Petri Savolainen Gustaf Järnefelt Päivi Koskenkorva Jari Karhu Petro Julkunen 《Brain stimulation》2018,11(2):322-326
Background
Transcranial magnetic stimulation (TMS) induced I-wave behavior can be demonstrated at neuronal population level using paired-pulses and by observing short-interval cortical facilitation (SICF). Advancements in stimulator technology have made it possible to apply biphasic paired-pulses to induce SICF.Objective
Our aim was to characterize the SICF I-wave interaction by biphasic paired-pulses with the ultimate objective to enhance TMS effects via SICF in various TMS-applications.Methods
We used biphasic paired-pulses in 15 volunteers to characterize corticospinal SICF using various 1.2–8.0ms inter-stimulus intervals, and measuring SICF input-output response.Results
SICF interaction with the first I-wave (I1) was observed in the output responses (motor evoked potentials; MEPs) in all subjects. Most subjects (≥80%) also exhibited later SICF I-wave interaction. SICF at I1 was present at all applied intensities below 140% of resting motor threshold. At I2, we observed SICF only with intensities just above motor threshold.Conclusions
Biphasic paired-pulses can reliably induce SICF shown by the facilitatory I-wave interaction, and could therefore be applied with repetitive bursts to enhance responsiveness to TMS. 相似文献16.
Aron T. Hill Nigel C. Rogasch Paul B. Fitzgerald Kate E. Hoy 《Brain stimulation》2018,11(5):1033-1043
Background
Previous research has typically focussed on the neuromodulatory effects of direct currents applied over single regions of the cortex. However, complex processes such as working memory (WM) strongly rely on activations across a wider neural network and therefore might benefit from stimulation administered over multiple cortical targets.Objective
We examined the neurobiological and cognitive effects of High-Definition transcranial direct current stimulation (HD-tDCS) montages that either targeted the dorsolateral prefrontal cortex (DLPFC) alone, or simultaneously stimulated the DLPFC and parietal cortex (DLPFC + PC).Methods
In a within-subjects design, 16 healthy participants completed three experimental sessions in which they received HD-tDCS over either the DLPFC, the DLPFC + PC or sham stimulation. Changes in cortical reactivity were examined using transcranial magnetic stimulation combined with electroencephalography (TMS-EEG), while oscillatory power was measured via EEG recorded during n-back tasks. WM performance was also examined across several separate tasks.Results
Stimulation using both the DLPFC or DLPFC + PC montages modulated cortical reactivity, as indexed by potentiation of the P60 TMS-evoked potential. However, only the dual-site DLPFC + PC stimulation produced a reduction in the amplitude of the N100 component, relative to baseline. Increases in theta and gamma power were also observed following this montage, when compared to baseline, but were not present following HD-tDCS over the DLPFC alone. Despite these neurophysiological changes, WM performance was not significantly modulated by HD-tDCS, regardless of stimulation montage.Conclusion
These results provide important initial insight into the behavioural and biological effects of stimulation over key cortical regions linked to WM and attest to the sensitivity of TMS-EEG and EEG in detecting subtle neurophysiological changes induced by HD-tDCS. 相似文献17.
Background
Alpha (8–14?Hz) oscillatory power is linked to cortical excitability and corresponding modulations of sensory evoked potentials and perceptual detection performance. In somatosensory cortex (S1), negative linear and inverted U-shape relationships exist, whereas its effect on the primary motor cortex (M1) is hardly known.Objective
We used real-time EEG-triggered transcranial magnetic stimulation (TMS) of M1 to characterize the relationship between spontaneous sensorimotor mu-alpha power fluctuations at rest and corticospinal excitability.Methods
In 16 subjects, mu-alpha power was continuously monitored over the left sensorimotor cortex, and each 10%-percentile bin of the individual mu-alpha power distribution was repeatedly targeted in pseudorandomized order by single-pulse TMS of left M1, measuring motor evoked potentials (MEP) in the contralateral hand.Results
We found a weak positive relationship between mu-alpha power and MEP amplitude.Conclusion
Sensorimotor mu-alpha power may reflect a net facilitation or disinhibition of M1, possibly resulting from mu-alpha based suppression of excitatory and inhibitory input from S1. 相似文献18.
Samuel S. Shin Vijai Krishnan William Stokes Courtney Robertson Pablo Celnik Yanrong Chen Xiaolei Song Hanzhang Lu Peiying Liu Galit Pelled 《Brain stimulation》2018,11(6):1306-1313
Background
Therapeutic strategies for traumatic brain injury (TBI) in the last three decades have failed to show significant benefit in large scale studies. Given the multitude of pathological mechanisms involved in TBI, strategies focusing on multimodality regimen have gained interest as promising future interventions.Hypothesis
We hypothesized that combining noninvasive transcranial magnetic stimulation (TMS) with rehabilitative training in an environmental enrichment (EE) can facilitate post-TBI recovery in rats via cortical excitability and reorganization.Methods
We subjected rats to controlled cortical impact, and then assigned them to one of four groups: 1. No treatments (TBI), 2. EE after injury (TBI + EE), 3. TMS for one week (TBI + TMS), and 4. TMS for one week combined with EE (TBI + TMS/EE). For TMS, a 10 Hz repetitive TMS protocol was used.Results
At 7 days, TBI + TMS and TBI + TMS/EE groups had significantly increased primary somatosensory cortex local field potential (LFP) compared to TBI and TBI + EE groups (P < 0.05). Also, TBI + TMS/EE group had significantly improved performance on beam walk test compared to TBI group (P < 0.005). At 6 weeks, there was significantly higher response in TBI + TMS/EE group compared to TBI + TMS for somatosensory cortex LFP (P < 0.05), bicep motor evoked potentials (MEP) (P < 0.05), challenge ladder test performance (P < 0.01), and fMRI responses to tactile forepaw stimulation.Conclusions
We demonstrate here for the first time the mechanism by which combined therapy using TMS and EE after TBI leads to functional improvement, possibly via cortical excitability and reorganization. 相似文献19.
Tamara Gedankien Peter J. Fried Alvaro Pascual-Leone Mouhsin M. Shafi 《Clinical neurophysiology》2017,128(12):2419-2427
Objective
We studied the correlation between motor evoked potentials (MEPs) and early TMS-evoked EEG potentials (TEPs) from single-pulse TMS before and after intermittent Theta Burst Stimulation (iTBS) to the left primary motor cortex (M1) in 17 healthy older participants.Methods
TMS was targeted to the hand region of M1 using a MRI-guided navigated brain stimulation system and a figure-of-eight biphasic coil. MEPs were recorded from the right first dorsal interosseous muscle using surface EMG. TEPs were extracted from a 61-channel EEG recording. Participants received 90 single TMS pulses at 120% of resting motor threshold before and after iTBS.Results
Across all participants, the change in N15-P30 TEP and MEP amplitudes were significantly correlated (r = 0.69; p < 0.01). Average TEP responses did not change significantly after iTBS, whereas MEP amplitudes showed a significant increase.Conclusions
Changes in corticospinal reactivity and cortical reactivity induced by iTBS are related. However, the effect of iTBS on TEPs, unlike MEPs, is not straightforward.Significance
Our findings help elucidate the relationship between changes in cortical and corticospinal excitability in healthy older individuals. Going forward, TEPs may be used to evaluate the effects of theta-burst stimulation in non-motor brain regions. 相似文献20.
Xiaoming Du Laura M. Rowland Ann Summerfelt Andrea Wijtenburg Joshua Chiappelli Krista Wisner Peter Kochunov Fow-Sen Choa L. Elliot Hong 《Brain stimulation》2018,11(5):1071-1079