Takahiro Matsuoka’s research while affiliated with National Institutes of Health and other places

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Publications (5)


Fig. 1 Schematic representation of MRI lesion sites. Patient numbers correspond with those in the Table 1. 
Fig. 2 Experimental paradigm. Top = the motor task consisted in brisk finger extensions at a rate of 1 per second. Bottom = EMG of bilateral forearm extensors (left and right extensor digitorum communis muscles, lEDC and rEDC) was monitored throughout all imaging procedures. Two representative traces are shown. Left = control subject, right = stroke patient. Absence of mirror activity in the hand at rest was required for all trials that entered the final analysis (PET, EEG). 
Fig. 3 Results of EEG spectral power analysis (TRPow). Grand average. Cortical activation (TRPow decreases, given in per cent with positive sign) is colour-coded in red. Top = control group, Bottom = stroke patients. The beta frequency band (16–20 and 22–26 Hz) is known to be particularly sensitive to variation of motor parameters in sensorimotor tasks. In this band, the main result was enhancement of activity in the CON-H of stroke patients, extending from the central region (dotted horizontal line) into the frontal and prefrontal cortex. In the alpha band, the results were more variable and only the global decrease of activation in the 11–13 Hz band was statistically significant. At 8–10 Hz, no significant differences were found. Right-hand side of each map = right-hand side of the brain. 
Fig. 4 Time-course analysis of spectral power in the beta band (16–20 Hz) in controls ( top row ) and stroke patients ( bottom ) (ERD). Grand average ( n = 11 for each group). The curves depict the temporal evolution of ERD from 384 ms before to 384 ms after EMG onset in the central region of the lesioned (FC3) and the contralesional (FC4) central region. In normal subjects, a clear dominance of activation in the left central region (FC3 > FC4) is seen throughout the movement. In patients, the dominant activation occurs in the contralesional central region (FC4 > FC3). The topographic maps (activation coded in red) illustrate for five time points how ERD evolves in the central region (right in the map corresponds to right in the patient’s brain). Note that activation of the contralesional central region in patients occurs already in the preparation phase before movement and increases slightly during movement execution. The duration of a typical EMG burst was between 200 and 350 ms. The power values on the y -axis are given relative to baseline (rest). Bottom = map orientation and electrode specifications. 
Fig. 5 Summary of functional connectivity analysis (EEG, TRCoh). Grand average ( n = 11 for each group). Coherence is coded in colored links with red indicating high TRCoh increases (‘enhanced synchrony’) during movement. Top = in control subjects maximal functional coupling regularly occurred between the left central region and the left frontal and mesial frontocentral cortex as well as between left central and right central electrodes (11–13, 16–20, 22–26 Hz). Bottom = in patients the main difference to the normal coherence pattern was a convergence of functional links over the contralesional (right) central region. This was most prominent in the beta frequency range (16–20 Hz), indicating functional integration of the contralesional central region in the reorganized cortical network subserving motor control of the recovered hand. The dotted line indicates the anterior–posterior position of the electrodes T4, C4, Cz, C3, T3. Right-hand side of each map = right-hand side of the brain. 

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Multimodal imaging of brain reorganization in motor areas of the contralesional hemisphere of well recovered patients after capsular stroke
  • Article
  • Full-text available

April 2006

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348 Reads

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447 Citations

Brain

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Khalaf Bushara

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Alexandra Sailer

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Mark Hallett

Clinical recovery after stroke can be significant and has been attributed to plastic reorganization and recruitment of novel areas previously not engaged in a given task. As equivocal results have been reported in studies using single imaging or electrophysiological methods, here we applied an integrative multimodal approach to a group of well-recovered chronic stroke patients (n = 11; aged 50-81 years) with left capsular lesions. Focal activation during recovered hand movements was assessed with EEG spectral analysis and H2(15)O-PET with EMG monitoring, cortico-cortical connectivity with EEG coherence analysis (cortico-cortical coherence) and corticospinal connectivity with transcranial magnetic stimulation (TMS). As seen from comparisons with age-matched controls, our patients showed enhanced recruitment of the lateral premotor cortex of the lesioned hemisphere [Brodmann area (BA) 6], lateral premotor and to a lesser extent primary sensorimotor and parietal cortex of the contralesional hemisphere (CON-H; BA 4 and superior parietal lobule) and left cerebellum (patients versus controls, Z > 3.09). EEG coherence analysis showed that after stroke cortico-cortical connections were reduced in the stroke hemisphere but relatively increased in the CON-H (ANOVA, contrast analysis, P < 0.05), suggesting a shift of functional connectivity towards the CON-H. Nevertheless, fast conducting corticospinal transmission originated exclusively from the lesioned hemisphere. No direct ipsilateral motor evoked potentials (MEPs) could be elicited with TMS over the contralesional primary motor cortex (iM1) in stroke patients. We conclude that (i) effective recovery is based on enhanced utilization of ipsi- and contralesional resources, (ii) basic corticospinal commands arise from the lesioned hemisphere without recruitment of ('latent') uncrossed corticospinal tract fibres and (iii) increased contralesional activity probably facilitates control of recovered motor function by operating at a higher-order processing level, similar to but not identical with the extended network concerned with complex movements in healthy subjects.

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TABLE 1. Peak EMG amplitude, coefficient of variation of inter-tapping intervals and discrepancy for the different movement rates 
FIG. 1. Electrode locations, and each region of interest (ROI; A) and connection of interest (COI; B). ROI was used to compute the event-related band-power (ERpow) and COI for the event-related correlation (ERcor). Effect of volume conduction from occipital area was removed by partial-out of the signals at the OZ electrode shown by gray shading.  
FIG. 3. ERpow (top) and ERcor (bottom) are presented in time-frequency maps for the 2-Hz movement; movements were performed every 0.5 s. Red or blue color indicates an increase or decrease in ERpow and ERcor. x axis is expressed in real-time scale from 600 to 500 ms. The EMG onset is illustrated by black arrowhead. Temporal behaviors of ERpow and ERcor differ among the alpha (8 –12 Hz), beta1 (16 –20 Hz), beta2 (24 –28 Hz), and gamma (32– 40 Hz) bands. Note that a reduction in ERpow indicates increased activation. Maps were obtained by the average across 8 subjects.  
FIG. 2. A: timing of electromyogram (EMG) onset relative to tone onset is presented by means of histograms. Timing of EMG onset concentrates around tone onset (between 0.25 and 0.25 cycle) for slow rates (0.5–1 Hz) but is organized with about half-cycle phase lag (between 0.75 and 0.25 cycle) for fast rates (2– 4 Hz). B: distribution of phase shift from tone to EMG onset for 6 rates shown with cumulative density analysis. For slow rates (0.5–1 Hz), phase shift from tone to EMG onset distributes within 0.25 and 0.25 cycle: synchronization. In contrast, for fast rates (2– 4 Hz), it distributes from 0.75 to 0.25 cycle: syncopation. C: mean phase shift of 8 subjects in 6 rates. A main effect of RATE was observed (P 0.001 by 1-factorial ANOVA). A post hoc t-test with Bonferroni's correction showed a significant difference (P 0.05) for all pairwise combination between slow (0.5–1 Hz) and fast (2– 4 Hz) rates: 0.5–2, 0.5–3, 0.5– 4, 0.75–2, 0.75–3, 0.75– 4, 1–2, 1–3, and 1– 4 Hz. However, within the slow or fast rate group, no difference was found. Bars indicate SD  
Movement Rate Effect on Activation and Functional Coupling of Motor Cortical Areas

January 2003

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106 Reads

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113 Citations

Journal of Neurophysiology

We investigated changes in the activation and functional coupling of bilateral primary sensorimotor (SM1) and supplementary motor (SMA) areas with different movement rates in eight normal volunteers. An auditory-cued repetitive right-thumb movement was performed at rates of 0.5, 0.75, 1, 2, 3, and 4 Hz. As a control condition, subjects listened to pacing tones with no movements. Electroencephalogram (EEG) was recorded from 28 scalp electrodes and electromyogram was obtained from the hand muscles. The event-related changes in EEG band-power (ERpow: activation of each area) and correlation (ERcor: functional coupling between each pair of cortical areas) were computed every 32 ms. Modulations of ERpow and ERcor were inspected in alpha (8-12 Hz) and beta (16-20 Hz) bands. Motor cortical activation and coupling was greater for faster movements. With increasing movement rate, the timing relationship between movement and tone switched from synchronization (for 0.5-1 Hz) to syncopation (for 3-4 Hz). The results suggested that for slow repetitive movements (0.5-1 Hz), each individual movement is separately controlled, and EEG activation and coupling of the motor cortical areas were immediately followed by transient deactivation and decoupling, having clear temporal modulation locked to each movement. In contrast, for fast repetitive movements (3-4 Hz), it appears that the rhythm is controlled and the motor cortices showed sustained EEG activation and continuous coupling.


Generators of Movement-Related Cortical Potentials: fMRI-Constrained EEG Dipole Source Analysis

October 2002

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44 Reads

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85 Citations

NeuroImage

To clarify the precise location and timing of the mo tor cortical activation in voluntary movement, dipole source analysis integrating multiple constraints wa conducted for the movement-related cortical potentia (MRCP). Six healthy subjects performed single self paced extensions of the right index finger at about 15-intervals during EEG and event-related fMRI acquisi tions. EEG was recorded from 58 scalp electrodes, and fMRI of the entire brain was obtained every 2.6 s. Coordinates of the two methods were coregistered us ing anatomical landmarks. During dipole source mod eling, a realistic three-layer head model was used as a volume conductor. To identify the number of uncorre lated source s in the MRCP, principal component (PC analysis was performed, which was consistent with the existence of six sources in the left (Lt SM1) and right (Rt SMI) sensorimotor and medial frontocentral (MFC) areas. After dipoles were seeded at the acti vated spots revealed by fMRI, dipole orientations were fixed based on the interpretation of the topography of distribution of the PC. The strength of the six dipoles (three dipoles in Lt SMI, two in Rt SMI, and one in MFC) was then computed over time. Within the bilat eral SM1, activation of the precentral gyrus occurs bilaterally with similar strength from -1.2 s, followed by that of the precentral bank from -0.5 s with con tralateral preponderance. Subsequently, the postcen tral bank becomes active only on the contralateral side at 0.1 s after movement. Activation of the MFC shows timing similar to that of the bilateral precentral gyri These deduced patterns of activation are consis tent with previous studies of electrocorticography in humans.


Information flow from the sensorimotor cortex to muscle in humans

January 2001

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27 Reads

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124 Citations

Clinical Neurophysiology

To investigate the physiologic mechanism of human electroencephalogram-electromyogram (EEG-EMG) coherence, the directed transfer function (DTF) based on a multivariate autoregressive (MVAR) model was computed. Fifty-six channel EEG and EMG of the right abductor pollicis brevis muscle during a weak tonic contraction were recorded in 6 normal volunteers. The EEG over the left sensorimotor area and the rectified EMG were used to compute coherence and DTF. EEG-EMG coherence was observed at the peak frequency of 15-29 Hz (mean 18.5 Hz). The peak frequency of DTF from EEG to EMG was 12-27 Hz (mean 17.8 Hz). DTF from EEG to EMG was significantly larger than that from EMG to EEG at 19-30 and 45-50 Hz (P<0.05). The present findings suggest that the EEG-EMG coupling mechanism for the 19 Hz or higher frequency might differ from that for the lower frequency. Directional information flow from EEG to EMG in the former frequency range likely reflects the motor control command. The finding of the directional information flow from EEG to EMG within the gamma band indicates that 40 Hz EEG-EMG coherence is not specific to the muscle Piper rhythm which is seen only with strong contraction.


Functional coupling of human right and left cortical motor areas demonstrated with partial coherence analysis

July 2000

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56 Reads

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143 Citations

Neuroscience Letters

Although a linear correlation between oscillatory activities in the right and left motor cortices during movements has been shown in monkeys, there has been a debate whether scalp-recorded EEG coherence in human reflects a similar association. By applying partial coherence analysis, we demonstrated that interhemispheric coherence during movements cannot be explained by contamination from the occipital alpha rhythm or common reference signal. A significant increase of net interhemispheric communication in the beta1 band was shown during movements. We propose that the partial coherence method can be a useful tool to measure cortico-cortical functional coupling reliably.

Citations (5)


... Cortico-cortical functional connectivity between lower limb motor cortices increased during the adaptation and post-adaptation periods for the random force condition but showed decreased functional connectivity during the adaptation period for the constant force condition. This is partially consistent with previous upper limb studies that reported increased interhemispheric beta band coherence between motor cortices during complex bimanual motor learning task and decreased interhemispheric coherence after successful learning of the task (Andres et al. 1999;Mima et al. 2000;Gross et al. 2005). For the random force condition, CNS may enhance interhemispheric connectivity between the motor areas as individuals may need to consistently adjust motor commands to both the non-paretic leg, through which the constraint force was delivered, and the paretic leg, through which the counteracting propulsion force was generated, in response to random levels of force applied. ...

Reference:

Cortical drive may facilitate enhanced use of the paretic leg induced by random constraint force to the non-paretic leg during walking in chronic stroke
Functional coupling of human right and left cortical motor areas demonstrated with partial coherence analysis
  • Citing Article
  • July 2000

Neuroscience Letters

... Additionally, CMC in the gamma band (31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45) has been reported [42,50,51]. It is believed that the cortical mu rhythm contributes to the CMC at ~ 20 Hz [45,52]. Mu rhythm is a sensorimotor oscillation that arises from a mixture of frequencies with different neurophysiological origins. ...

Information flow from the sensorimotor cortex to muscle in humans
  • Citing Article
  • January 2001

Clinical Neurophysiology

... In line, we showed that the observed intersubject difference in high-gamma peaks was driven by differences in movement rate, where with faster movements individual peaks blurred and the probability to exhibit only one high-gamma peak increased. This contrasts with observations for power at lower frequencies: beta-band power modulations have still been observed at a movement frequency of 4 Hz (Toma et al., 2002). Hence, for faster repeating movements, high-gamma oscillations may code the overall motor action rather than every single movement separately. ...

Movement Rate Effect on Activation and Functional Coupling of Motor Cortical Areas

Journal of Neurophysiology

... Similarly, when examining the results in source space, no statistical difference between conditions was found, although the "movlook" condition, which may be associated with hand/arm movement MRCPs, appears to be located more frontally, and contralateral to the movement. Previous studies by 87 have identified the primary sensorimotor, premotor and medial frontocentral areas as generators of the hand/arm movement MRCPs. While the observed tendency suggests a relationship with the additional hand/arm attempted movement, the variability across participants does not allow for highlighting significant differences. ...

Generators of Movement-Related Cortical Potentials: fMRI-Constrained EEG Dipole Source Analysis
  • Citing Article
  • October 2002

NeuroImage

... Psychotropic medication was an exclusion criterion in all three groups. The number of recruited stroke survivors was based on prior comparable observational studies (Gerloff et al., 2006;Quandt et al., 2019). All participants were right-handed according to the Edinburgh Handedness Inventory. ...

Multimodal imaging of brain reorganization in motor areas of the contralesional hemisphere of well recovered patients after capsular stroke

Brain