The impact of a regular blood donation on the hematology and EEG of healthy young male blood donors.

The aim of this study was to investigate the effect of 400 ml whole blood donation on the human electroencephalogram (EEG) and hematology, not earlier reported in the literature. EEG activity was recorded from ten male blood donors (experiment group) before, during and after blood donation (i.e., 400 ml whole blood withdrawal). EEG topography and regional spectral field powers analyses were carried out via fast Fourier transformation. The venous hemoglobin (Hb) concentration was measured with a hematology analyzer. In the control investigation, 12 male age-matched volunteers (control group) were kept in semi-sitting position for the duration of a blood donation without actually vena puncture. The volunteers had no prior experiences of blood donation. Within the experiment group, post-donation Hb concentration decreased by 3.7% compared with the pre-donation Hb values (P < 0.01). Before blood donation, Hb concentration in control group was significantly higher compared to the experiment group (P < 0.05). For the experiment group, the field power of alpha-1 (7.5-9.5 Hz) EEG during blood withdrawal was significantly lower compared to that after blood withdrawal (P < 0.05). In contrast for the control group, all seven bands of regional spectral field powers showed no significantly discrepancies in the three periods. Blood donation attenuates the alpha-1 at the parietal-frontal area on human EEG-DMN transiently with no lasting effect at post-donation period. The blood donation-related effects on brain function may be of little consequence due to slight hemodynamic change and the results may facilitate the opinion that blood donation is a safe process and that should not discourage volunteers.

Sensory handedness is not reflected in cortical responses after basic nerve stimulation: a MEG study.

Motor dominance is well established, but sensory dominance is much less clear. We therefore studied the cortical evoked magnetic fields using magnetoencephalography (MEG) in a group of 20 healthy right handed subjects in order to examine whether standard electrical stimulation of the median and ulnar nerve demonstrated sensory lateralization. The global field power (GFP) curves, as an indication of cortical activation, did not depict sensory lateralization to the dominant left hemisphere. Comparison of the M20, M30, and M70 peak latencies and GFP values exhibited no statistical differences between the hemispheres, indicating no sensory hemispherical dominance at these latencies for each nerve. Field maps at these latencies presented a first and second polarity reversal for both median and ulnar stimulation. Spatial dipole position parameters did not reveal statistical left-right differences at the M20, M30 and M70 peaks for both nerves. Neither did the dipolar strengths at M20, M30 and M70 show a statistical left-right difference for both nerves. Finally, the Laterality Indices of the M20, M30 and M70 strengths did not indicate complete lateralization to one of the hemispheres. After electrical median and ulnar nerve stimulation no evidence was found for sensory hand dominance in brain responses of either hand, as measured by MEG. The results can provide a new assessment of patients with sensory dysfunctions or perceptual distortion when sensory dominance occurs way beyond the estimated norm.

Replication and extension of the simplified modified rankin scale in 150 Chinese stroke patients.

BACKGROUND: Recently, a simplified modified Rankin Scale (mRS) questionnaire (smRSq) showed good reliability but has not been tested for its validity by its original creators. Our study aimed to test its reliability and validity in Chinese stroke patients. METHODS: Randomly chosen paired raters scored the smRSq, the conventional mRS, and the NIH Stroke Scale (NIHSS) face-to-face in 150 hospitalized stroke patients. Inter-rater reliability and concurrent validity were assessed for this translated questionnaire. RESULTS: For inter-rater reliability of the smRSq, the overall agreement among the raters was 84%, the κ was 0.79 (95% CI 0.72-0.87), and the κw was 0.91 (95% CI 0.88-0.94). For inter-rater reliability of the mRS, the overall agreement among the raters was 81%, the κ was 0.75 (95% CI 0.67-0.83), and the κw was 0.88 (95% CI 0.84-0.92). The agreement between the mRS and smRSq was 71%, κ = 0.63 (95% CI 0.54-0.71), and κw = 0.83 (95% CI 0.79-0.88). The correlation between the NIHSS and the smRSq (concurrent validity) was moderate (Spearman's correlation coefficient 0.70, p < 0.0001). CONCLUSIONS: Our results confirm the value of the smRSq in the assessment of stroke functional outcome in China. As this is a novel stroke tool, further validations are needed.

Anesthetic block of pain-related cortical activity in patients with peripheral nerve injury measured by magnetoencephalography.

BACKGROUND: This study examined whether chronic neuropathic pain, modulated by a local anesthetic block, is associated with cortical magnetic field changes. METHODS: In a group of 20 patients with pain caused by unilateral traumatic peripheral nerve injury, a local block with lidocaine 1% was administered and the cortical effects were measured and compared with a control group. The global field power (GFP), describing distribution of cortical activation after median and ulnar nerve stimulation, was plotted and calculated. The effects on the affected hemisphere and the unaffected hemisphere (UH) before and after a block of the injured nerve were statistically evaluated. RESULTS: Major differences based on the GFP curves, at a component between 50 ms - 90 ms (M70), were found in patients: in the affected hemisphere the M70 GFP peak values were statistically significantly larger in comparison with the UH, and the GFP curves differed morphologically. Interestingly, the mean UH responses were reduced in comparison with the control group, a finding suggesting that the UH is also part of the cortical changes. At M70, the GFP curves and values in the affected hemisphere were modulated by a local block of the median or the ulnar nerve. The most likely location of cortical adaptation is in the primary somatosensory cortex. CONCLUSIONS: Cortical activation is enhanced in the affected hemisphere compared with the UH and is modulated by a local block. The UH in neuropathic pain changes as well. Evoked fields may offer an opportunity to monitor the effectiveness of treatments of neuropathic pain in humans.

Effect of homobaric pure oxygen on sensory gating in the human brain.

Sensory gating, a viable function of the brain, is an adaptive mechanism to prevent overstimulation of nervous system. The aim of this study was to examine the effect of homobaric pure (i.e. 100%) oxygen on the human brain at different periods of inhalation. EEG was recorded while an auditory paired-click sensory gating test was conducted during 4 study periods: before inhalation of pure oxygen (Before), inhalation of 100% oxygen (air in control group) for 20 min (Oxy20) and 50 min (Oxy50), 30 min after oxygen (air in control group) inhalation (After). Each of the auditory stimuli elicited 4 clear peaks at 20, 39, 55 and 100 ms in ERPs, demonstrating that sensory gating is a multi-stage process. Comparing the S1-S2 differences of field potentials between two groups, significant experimental effects (P < 0.05-0.01) were shown at Oxy50 and After periods mainly at the 20 and 100 ms peak in ERPs. Pure oxygen was experimentally shown, for the first time, to affect the human brain activation, at the beginning of early P20 sensory cortical activation and late N100 auditory perception. The effect found in this study shall encourage further investigation on the oxygen treatment in human brain.

Influence of propofol on the electroencephalogram default mode network in patients of advanced age.

OBJECTIVE: This study was performed to evaluate the effects of propofol on the electroencephalogram (EEG) default mode network (DMN) in patients of advanced age. METHODS: Fifteen men aged >60 years (mean, 70 years) were selected. Propofol target-controlled infusion was performed under EEG bispectral index monitoring. The propofol target effect-site concentration, blood pressure, heart rate, and distributions and powers of the EEG spectrum were recorded in an awake state and under anesthesia. The EEG included seven bands: delta (0.5-3.5 Hz), theta (4.0-7.0 Hz), alpha-1 (7.5-9.5 Hz), alpha-2 (10-12 Hz), beta-1 (13-23 Hz), beta-2 (24-34 Hz), and gamma (35-45 Hz). RESULTS: From an awake state to anesthesia, the brain topographic map showed that the energies of delta, theta, alpha-1, alpha-2, and beta-1 were concentrated in the frontoparietal site, and the power increased significantly. The energy distribution of beta-2 was significantly decreased and the power significantly reduced. The energy distribution of gamma in the temporal lobe was also markedly decreased and the power significantly reduced. CONCLUSIONS: This study revealed the changes in the spatial distribution and regional energy of the EEG DMD in men of advanced age from the awake state to the anesthetized state.

The effect of reference choices on the spatio-temporal analysis of brain evoked potentials: the use of infinite reference.

Reference is a very virtual issue in EEG and ERP. Understanding the difference of various references will make the applications more confident. In this work, somatosensory evoked potential (SEP) with stimulation on the right hand was studied. The SEP spatio-temporal analysis was conducted comparatively on six references, left mastoid (contralateral mastoid reference, CM), right mastoid (ipsilateral mastoid reference, IM), linked mastoids (LM), average reference (AR), vertex reference (Cz) and the infinity reference (IR) newly proposed in 2001. Among the six, CM is the one used in actual recordings, and the other five are obtained by off-line re-referencing. The comparison is conducted on four selected components (P30 ms, P40 ms, N90 ms and P230 ms) in both temporal and spatial aspects. The results show that references may have a distinct influence on the amplitudes of the scalp potentials, with relative error at some electrodes larger than 500%, and for some electrodes it may even change the polarity. Pair-wise multiple comparison (Tukey test) shows that the differences of peak values among various references are very significant (P<0.001) between Cz and IR\CM\IM\LM, and significant (P<0.01) between Cz and AR for component N90 ms; very significant (P<0.001) between Cz and IR\CM\IM\LM\AR, significant between IMLM and AR (P<0.01), CM and AR (P<0.05) for component P230 ms. The amplitude value order is CM/IM> or =LM>IR>AR>Cz. The two-ways (the six references vs. the four Peaks) repeated measures ANOVA test shows the effect of different references depends on various components; there is a statistically significant interaction between reference and the peak (P=<0.001). While for the spatial map of the potential amplitude, references will not affect the amplitude map shape if the color-bar is selected automatically, but if a fixed color-bar is chosen for data of various references, they may show some differences. These results mean a common reference is important for producing a comparable result between labs. As IR is theoretically a constant reference, we recommend it as the common choice in the future.

Review on Neural Correlates of Emotion Regulation and Music: Implications for Emotion Dysregulation.

Previous studies have examined the neural correlates of emotion regulation and the neural changes that are evoked by music exposure. However, the link between music and emotion regulation is poorly understood. The objectives of this review are to (1) synthesize what is known about the neural correlates of emotion regulation and music-evoked emotions, and (2) consider the possibility of therapeutic effects of music on emotion dysregulation. Music-evoked emotions can modulate activities in both cortical and subcortical systems, and across cortical-subcortical networks. Functions within these networks are integral to generation and regulation of emotions. Since dysfunction in these networks are observed in numerous psychiatric disorders, a better understanding of neural correlates of music exposure may lead to more systematic and effective use of music therapy in emotion dysregulation.

Time-frequency filtering of MEG signals with matching pursuit.

Time-frequency signal analysis based on various decomposition techniques is widely used in biomedical applications. Matching Pursuit is a new adaptive approach for time-frequency decomposition of such biomedical signals. Its advantage is that it creates a concise signal approximation with the help of a small set of Gabor atoms chosen iteratively from a large and redundant set. In this paper, the usage of Matching Pursuit for time-frequency filtering of biomagnetic signals is proposed. The technique was validated on artificial signals and its performance was tested for varying signal-to-noise ratios using both simulated and real MEG somatic evoked magnetic field data.

Anticipatory electroencephalography alpha rhythm predicts subjective perception of pain intensity.

UNLABELLED: This high-resolution electroencephalography (EEG) study tested the hypothesis that the suppression of rolandic alpha power before predictable painful stimulation affects the subject's subsequent evaluation of pain intensity, as a reflection of the influence of expectancy processes on painful stimulus processing. High-resolution EEG data were recorded (126 channels) from 10 healthy adult volunteers during the expectancy of a painful CO(2)-laser stimulation at the right wrist. Surface laplacian estimation enhanced the EEG spatial information content over 6 scalp regions of interest (left frontal, right frontal, left central, right central, left parietal, and right parietal areas). Spectral power was computed for 3 alpha sub-bands with reference to the individual alpha frequency peak (about 5-7 Hz for alpha 1, 7-9 Hz for alpha 2, and 9-11 Hz for alpha 3). The suppression of the alpha power before the painful stimulation [as reflected by the event-related desynchronization (ERD)] indexed the anticipatory cortical processes. Results showed maximum (negative) correlations between the alpha 2 and alpha 3 ERD amplitude at the left central area and the subjective evaluation of pain intensity (P < .001). The stronger the anticipatory alpha 2 and alpha 3 ERD, the higher the subjective evaluation of pain intensity. For alpha 3, that correlation was confirmed even when the effect of habituation across the recording session was taken into account. These results suggest that the anticipatory suppression of the alpha rhythms over the contralateral primary sensorimotor cortex predicts subsequent subjects' evaluation of pain intensity, in line with its crucial role for the discrimination of that intensity. PERSPECTIVE: This electroencephalographic study showed that anticipatory activation/deactivation of sensorimotor cortex roughly predicts subjective evaluation of pain. This motivates further investigation on possible implications for the understanding of central chronic pain. Chronic pain patients might exaggerate the anticipatory activation of sensorimotor cortex to negligible pain stimuli.

Cortical plasticity: effect of high and low intensity conditioning electrical stimulations (100 Hz) on SEPs to painful finger stimulation.

OBJECTIVE: To study the effect of high-frequency (100 Hz) repetitive conditioning electrical stimulation (CES, 10 min) on human somatosensory evoked potentials (SEPs) to evaluate if short-term cortical plasticity could be induced. METHODS: Painful electrical stimulations were applied to thumb (D1) and little finger (D5) fingertips, respectively. The 124-channel EEG was recorded from 10 healthy male volunteers. Peak stages around 34, 45, 212, 331 ms were analyzed with focal maximum amplitude (FA) and area magnitude (AM) of scalp field potential, topography, and equivalent current dipole source localisation, comparing before and after two-level CES (high- vs. low-level) applied to the He-Gu acupoint. RESULTS: After a high-level CES, the positive FA and AM of the current efflux showed a significant increase at the early phase 34 ms, and significantly decreased at 45 ms in D1 SEPs. The negative FA and AM of the current influx were significantly increased at late phase 350 ms of the D5 SEPs. Only 36 ms, the z-axis position of dipole was significantly changed from (x: -15.9 mm, y: 29.6 mm, z: 43.9 mm) to (x: -12.9 mm, y: 29.4mm, z: 51.5mm) for the D5 SEPs. CONCLUSIONS: The high-level CES significantly attenuated the subsequent cortical activation (45 ms peak for D1 stimulation). Both low- and high-level CES significantly enhanced the late activities (226, 350 ms) in D5 stimulation. This may be explained by pain sensation change at the level of subcortical cingulate cortex induced by the site-dependent post-effect of CES. SIGNIFICANCE: This study showed cortical plasticity induced by conditioning somatosensory stimulation.

Anticipation of somatosensory and motor events increases centro-parietal functional coupling: an EEG coherence study.

OBJECTIVE: Does functional coupling of centro-parietal EEG rhythms selectively increase during the anticipation of sensorimotor events composed by somatosensory stimulation and visuomotor task? METHODS: EEG data were recorded in (1) 'simultaneous' condition in which the subjects waited for somatosensory stimulation at left hand concomitant with a Go (or NoGo) visual stimulus triggering (50%) right hand movements and in (2) 'sequential' condition where the somatosensory stimulation was followed (+1.5 s) by a visuomotor Go/NoGo task. Centro-parietal functional coupling was modeled by spectral coherence. Spectral coherence was computed from Laplacian-transformed EEG data at delta-theta (2-7 Hz), alpha (8-14 Hz), beta 1 (15-21 Hz), beta 2 (22-33 Hz), and gamma (34-45 Hz) rhythms. RESULTS: Before 'simultaneous' sensorimotor events, centro-parietal coherence regions increased in both hemispheres and at all rhythms. In the 'sequential' condition, right centro-parietal coherence increased before somatosensory event (left hand), whereas left centro-parietal coherence increased before subsequent Go/NoGo event (right hand). CONCLUSIONS: Anticipation of somatosensory and visuomotor events enhances contralateral centro-parietal coupling of slow and fast EEG rhythms. SIGNIFICANCE: Predictable somatosensory and visuomotor events are anticipated not only by synchronization of cortical pyramidal neurons generating EEG power in parietal and primary sensorimotor cortical areas (Babiloni C, Brancucci A, Capotosto P, Arendt-Nielsen L, Chen ACN, Rossini PM. Expectancy of pain is influenced by motor preparation: a high-resolution EEG study of cortical alpha rhythms. Behav. Neurosci. 2005a;119(2):503-511; Babiloni C, Brancucci A, Pizzella V, Romani G.L, Tecchio F, Torquati K, Zappasodi F, Arendt-Nielsen L, Chen ACN, Rossini PM. Contingent negative variation in the parasylvian cortex increases during expectancy of painful sensorimotor events: a magnetoencephalographic study. Behav. Neurosci. 2005b;119(2):491-502) but also by functional coordination of these areas.

Intact skull chronic windows for mesoscopic wide-field imaging in awake mice.

BACKGROUND: Craniotomy-based window implants are commonly used for microscopic imaging, in head-fixed rodents, however their field of view is typically small and incompatible with mesoscopic functional mapping of cortex. NEW METHOD: We describe a reproducible and simple procedure for chronic through-bone wide-field imaging in awake head-fixed mice providing stable optical access for chronic imaging over large areas of the cortex for months. RESULTS: The preparation is produced by applying clear-drying dental cement to the intact mouse skull, followed by a glass coverslip to create a partially transparent imaging surface. Surgery time takes about 30min. A single set-screw provides a stable means of attachment (in relation to the measured lateral and axial resolution) for mesoscale assessment without obscuring the cortical field of view. COMPARISON WITH EXISTING METHODS: We demonstrate the utility of this method by showing seed-pixel functional connectivity maps generated from spontaneous cortical activity of GCAMP6 signals in both awake and anesthetized mice in longitudinal studies of up to 2 months in duration. CONCLUSIONS: We propose that the intact skull preparation described here may be used for most longitudinal studies that do not require micron scale resolution and where cortical neural or vascular signals are recorded with intrinsic sensors or in transgenic mice expressing genetically encoded sensors of activity.

Expectancy of pain is influenced by motor preparation: a high-resolution EEG study of cortical alpha rhythms.

This high-resolution electroencephalographic (EEG) study on alpha event-related desynchronization (ERD) evaluated whether anticipatory activity precedes a sensorimotor interaction induced by concomitant painful stimuli and sensorimotor demand. An omitted-stimulus paradigm induced the expectancy of the painful stimulation at the left hand. In the experimental condition, the painful stimulation was associated with a visual go/no-go task triggering right-hand movements. Two control conditions manipulated the painful sensorimotor interaction variable. Compared with the control conditions, the expectancy of the painful sensorimotor interaction increased the high-band alpha EEG oscillations over the right primary sensorimotor cortex contralateral to the nociceptive stimuli and, to a lesser extent, over the centroparietal midline. These findings suggest that concomitant painful stimuli and simple sensorimotor go/no-go demands affect anticipatory activity as revealed by alpha ERD.

Contingent negative variation in the parasylvian cortex increases during expectancy of painful sensorimotor events: a magnetoencephalographic study.

Previous evidence relating to somatosensory-evoked magnetic fields has shown that the human parasylvian cortex (PC) is affected by ongoing painful sensorimotor interactions. In the present magnetoencephalographic study, the activity of the PC was investigated to evaluate the hypothesis of anticipatory processes preceding painful sensorimotor interactions. Sensorimotor interactions were induced by warned painful electrical stimulations at the left hand concomitant with a motor task of the right hand. The anticipatory activity of the PC was probed via contingent negative variation. Compared with the control nonpainful condition, the anticipation of the painful sensorimotor interactions increased the PC activity over the hemisphere ipsilateral to the stimulation. Dipole modeling indicated that the center of gravity of the anticipatory activity in the PC was located in the secondary somatosensory cortex. These results suggest that anticipation of painful sensorimotor interactions engages the human PC, especially in the hemisphere ipsilateral to upcoming painful stimuli and contralateral to preparatory motor commands.

Slow cortical potential shifts preceding sensorimotor interactions.

It is well known that synchronization of cortical neurons is modulated ("gating") by the chronological interaction between somatosensory and sensorimotor events. This study tested the hypothesis that the anticipatory processes for this interaction increase the synchronization of cortical neurons as revealed by negative event-related potentials (contingent negative variation, CNV). High-resolution electroencephalographic data (128 electrodes) were recorded in 14 subjects. In the "sensorimotor interaction" condition, the subjects were waiting for a galvanic somatosensory stimulation at the left hand concomitant with a Go or NoGo stimulus (50% of Go trials triggering right hand movements). In the control condition, the Go/NoGo stimulus followed the somatosensory stimulation of 1.5s. The electroencephalographic data were spatially enhanced by surface Laplacian estimation. In the control condition, the CNV was observed only in the foreperiod between the somatosensory stimulation and Go/NoGo task (i.e. no CNV before the somatosensory stimuli). It was spatially localized in the primary sensorimotor area contralateral to the possible motor response. In the "sensorimotor interaction" condition, the CNV preceded the concomitant somatosensory stimulation and Go/NoGo task and was distributed to the frontocentral midline other than the contralateral sensorimotor area. These results suggest that the anticipatory processes for sensorimotor interactions increase the synchronization of cortical neurons in the frontocentral midline, possibly due to mechanisms sub-serving top-down attentional processes.

Comparative cerebral responses to non-painful warm vs. cold stimuli in man: EEG power spectra and coherence.

AIMS: The cerebral processing of painful thermal (heat/cold) stimulation have been extensively studied, but little is known about cerebral activation to non-painful warm and cold stimuli. This study aimed to investigate the comparative EEG effects of warm vs. cold stimulus in man. MATERIALS AND METHODS: The left nondominant hands of 13 healthy male subjects were stimulated by non-painful warm (40-43 degrees C) and cold (12-15 degrees C) water. The somatic sensations were continuously assessed with an analogue visual scale device. EEG data (32 channels) recorded before, during and after the warm and cold stimulations were analysed quantitatively. RESULTS: No significant difference in intensity of sensation was found during warm and cold stimulations. Different patterns of EEG activity were superimposed on the similar background of EEG activation during and after warm and cold stimulations. Significant decrease of theta activity in contra-stimulus frontal region was observed during cold stimulation rather than warm stimulation. EEG power spectra in theta, alpha-1 and alpha-2 bands significantly increased after cold stimulation compared to baseline. EEG coherence in delta, alpha-1 and alpha-2 bands significantly increased in the contra-stimulus hemisphere during stimulations. CONCLUSION: This suggests that similar neural networks may process somatic warm and cold sensory inputs differently and the differential EEG patterns may be encoded by the qualities of thermal stimuli.

A comparative study of different references for EEG spectral mapping: the issue of the neutral reference and the use of the infinity reference.

Based on EEG data recorded from 11 subjects with eyes open and the left mastoid (M) reference, three data sets were generated by re-referencing to the conventional linked mastoids (L), average (A) and the new 'infinity' (I) reference provided by the reference electrode standardization technique (REST, Yao 2001 Physiol. Meas. 22 693-711). The EEG power in the alpha frequency band with the four different references was calculated and compared with respect to the total energy and spatial amplitude weight centre (AWC) coordinates, to compare the effects of different references on power mapping in the frequency domain. Compared with the I reference, the AWCs of the EEG with the M reference show significant shifts to the right, frontal and superficial positions, the L reference significant shifts to frontal and superficial positions, and the A reference shifts the AWC significantly to a deeper position. Furthermore, the power maps of the M and L references have larger total power than the I reference, while that of the A reference has the smallest total power. These results confirm that different choices of reference electrodes result in systematic changes in the distribution of EEG frequency power, and in order to reduce the effect of such systematic shifts on the explanation of EEG mappings, a common reference is necessary for EEG research. We recommend the I reference for objective use in cross-laboratory studies and clinical practices, as it is far from all the other electrodes and can act as a neutral reference.