Spatially bivariate EEG-neurofeedback can manipulate interhemispheric inhibition.

Human behavior requires inter-regional crosstalk to employ the sensorimotor processes in the brain. Although external neuromodulation techniques have been used to manipulate interhemispheric sensorimotor activity, a central controversy concerns whether this activity can be volitionally controlled. Experimental tools lack the power to up- or down-regulate the state of the targeted hemisphere over a large dynamic range and, therefore, cannot evaluate the possible volitional control of the activity. We addressed this difficulty by using the recently developed method of spatially bivariate electroencephalography (EEG)-neurofeedback to systematically enable the participants to modulate their bilateral sensorimotor activities. Here, we report that participants learn to up- and down-regulate the ipsilateral excitability to the imagined hand while maintaining constant contralateral excitability; this modulates the magnitude of interhemispheric inhibition (IHI) assessed by the paired-pulse transcranial magnetic stimulation (TMS) paradigm. Further physiological analyses revealed that the manipulation capability of IHI magnitude reflected interhemispheric connectivity in EEG and TMS, which was accompanied by intrinsic bilateral cortical oscillatory activities. Our results show an interesting approach for neuromodulation, which might identify new treatment opportunities, e.g., in patients suffering from a stroke.

Use of common average reference and large-Laplacian spatial-filters enhances EEG signal-to-noise ratios in intrinsic sensorimotor activity.

BACKGROUND: Oscillations in the resting-state scalp electroencephalogram (EEG) represent various intrinsic brain activities. One of the characteristic EEG oscillations is the sensorimotor rhythm (SMR)-with its arch-shaped waveform in alpha- and betabands-that reflect sensorimotor activity. The representation of sensorimotor activity by the SMR depends on the signal-to-noise ratio achieved by EEG spatial filters. NEW METHOD: We employed simultaneous recording of EEG and functional magnetic resonance imaging, and 10-min resting-state brain activities were recorded in 19 healthy volunteers. To compare the EEG spatial-filtering methods commonly used for extracting sensorimotor cortical activities, we assessed nine different spatial-filters: a default reference of EEG amplifier system, a common average reference (CAR), small-, middle- and large-Laplacian filters, and four types of bipolar manners (C3-Cz, C3-F3, C3-P3, and C3-T7). We identified the brain region that correlated with the EEG-SMR power obtained after each spatial-filtering method was applied. Subsequently, we calculated the proportion of the significant voxels in the sensorimotor cortex as well as the sensorimotor occupancy in all significant regions to examine the sensitivity and specificity of each spatial-filter. RESULTS: The CAR and large-Laplacian spatial-filters were superior at improving the signal-to-noise ratios for extracting sensorimotor activity from the EEG-SMR signal. COMPARISON WITH EXISTING METHODS: Our results are consistent with the spatial-filter selection to extract task-dependent activation for better control of EEG-SMR-based interventions. Our approach has the potential to identify the optimal spatial-filter for EEG-SMR. CONCLUSIONS: Evaluating spatial-filters for extracting spontaneous sensorimotor activity from the EEG is a useful procedure for constructing more effective EEG-SMR-based interventions.

Scalp electroencephalograms over ipsilateral sensorimotor cortex reflect contraction patterns of unilateral finger muscles.

A variety of neural substrates are implicated in the initiation, coordination, and stabilization of voluntary movements underpinned by adaptive contraction and relaxation of agonist and antagonist muscles. To achieve such flexible and purposeful control of the human body, brain systems exhibit extensive modulation during the transition from resting state to motor execution and to maintain proper joint impedance. However, the neural structures contributing to such sensorimotor control under unconstrained and naturalistic conditions are not fully characterized. To elucidate which brain regions are implicated in generating and coordinating voluntary movements, we employed a physiologically inspired, two-stage method to decode relaxation and three patterns of contraction in unilateral finger muscles (i.e., extension, flexion, and co-contraction) from high-density scalp electroencephalograms (EEG). The decoder consisted of two parts employed in series. The first discriminated between relaxation and contraction. If the EEG data were discriminated as contraction, the second stage then discriminated among the three contraction patterns. Despite the difficulty in dissociating detailed contraction patterns of muscles within a limb from scalp EEG signals, the decoder performance was higher than chance-level by 2-fold in the four-class classification. Moreover, weighted features in the trained decoders revealed EEG features differentially contributing to decoding performance. During the first stage, consistent with previous reports, weighted features were localized around sensorimotor cortex (SM1) contralateral to the activated fingers, while those during the second stage were localized around ipsilateral SM1. The loci of these weighted features suggested that the coordination of unilateral finger muscles induced different signaling patterns in ipsilateral SM1 contributing to motor control. Weighted EEG features enabled a deeper understanding of human sensorimotor processing as well as of a more naturalistic control of brain-computer interfaces.

Neurofeedback of scalp bi-hemispheric EEG sensorimotor rhythm guides hemispheric activation of sensorimotor cortex in the targeted hemisphere.

Oscillatory electroencephalographic (EEG) activity is associated with the excitability of cortical regions. Visual feedback of EEG-oscillations may promote sensorimotor cortical activation, but its spatial specificity is not truly guaranteed due to signal interaction among interhemispheric brain regions. Guiding spatially specific activation is important for facilitating neural rehabilitation processes. Here, we tested whether users could explicitly guide sensorimotor cortical activity to the contralateral or ipsilateral hemisphere using a spatially bivariate EEG-based neurofeedback that monitors bi-hemispheric sensorimotor cortical activities for healthy participants. Two different motor imageries (shoulder and hand MIs) were selected to see how differences in intrinsic corticomuscular projection patterns might influence activity lateralization. We showed sensorimotor cortical activities during shoulder, but not hand MI, can be brought under ipsilateral control with guided EEG-based neurofeedback. These results are compatible with neuroanatomy; shoulder muscles are innervated bihemispherically, whereas hand muscles are mostly innervated contralaterally. We demonstrate the neuroanatomically-inspired approach enables us to investigate potent neural remodeling functions that underlie EEG-based neurofeedback via a BCI.

Two-stage regression of high-density scalp electroencephalograms visualizes force regulation signaling during muscle contraction.

OBJECTIVE: A critical feature for the maintenance of precise skeletal muscle force production by the human brain is its ability to configure motor function activity dynamically and adaptively in response to visual and somatosensory information. Existing studies have concluded that not only the sensorimotor area but also distributed cortical areas act cooperatively in the generation of motor commands for voluntary force production to the desired level. However, less attention has been paid to such physiological mechanisms in conventional brain-computer interface (BCI) design and implementation. We proposed a new, physiologically inspired two-stage decoding method to see its contribution on accuracy improvement of BCI. APPROACH: We performed whole-head high-density scalp electroencephalographic (EEG) recording during a right finger force-matching task at three strength levels (20%, 40%, and 60% maximal voluntary contraction following a resting state). A two-stage regression approach was employed that decodes muscle contraction level from EEG signals in the multi-level force-matching task and translates them into: (1) presence/absence of muscle contraction as a first stage; and (2) muscle contraction level as a second stage. Dimensionality reduction of the EEG signals, using principal component analysis, avoided multicollinearity during multiple regression, and data-driven stepwise multiple regression identified EEG components that were involved in the multi-level force-matching task. MAIN RESULTS: An alternatively tuned two-stage regressor accurately decoded muscle contraction level with online processing rather than the conventional decoders, and identified EEG components that were related to voluntary force production. Relaxation/contraction state-dependent EEG components were localized dominantly in the contralateral parieto-temporal regions, whereas multi-level force regulation-dependent EEG components came from the fronto-parietal regions. SIGNIFICANCE: Our findings identify respective cortical signalings during relaxation/contraction and multi-level force regulation using a sensor-based approach with EEG. Simulation-based assessment of the current physiologically inspired decoding technique proved improved accuracy in online BCI control.

Development of intra-operative assessment system for ossicular mobility and middle ear transfer function.

Objective measurements of the ossicular mobility have not been commonly performed during the surgery, and the assessment of ossicular mobility is made by palpation in most cases. Palpation is inherently subjective and may not always be reliable, especially in milder degrees of ossicular fixation and in the case of multiple fixation. Although several devices have been developed to quantitatively measure the ossicular mobility during surgery, they have not been widely used. In this study, a new system with a hand-held probe which enables intraoperative quantitative measurements of ossicular mobility has been developed. This system not only measures the ossicular mobility, but also investigates "local" transmission characteristics of the middle ear by directly applying vibration to the ossicles and measuring cochlear microphonic. The basic performance of this system was confirmed by measuring the mobility of artificial ossicles and cochlear microphonics in an animal experiment. Our system may contribute to selection of a better surgical method and reducing the risks of revision surgery.

Accuracy of Quantification of Iodine and Hounsfield Unit Values on Virtual Monochromatic Imaging Using Dual-Energy Computed Tomography: Comparison of Dual-Layer Computed Tomography With Fast Kilovolt-Switching Computed Tomography.

OBJECTIVE: The aim of the study was to compare the accuracy of quantification of iodine and Hounsfield unit (HU) values on virtual monochromatic imaging (VMI) using dual-layer computed tomography (DLCT) and fast kilovolt-switching computed tomography (FKSCT). MATERIALS AND METHODS: This study was performed in 2 phantoms (large and small) using 16 rods representing different materials (iodine, calcium, blood, and adipose tissue) with different dimensions and concentrations. The absolute percentage errors (absolute ratio of measurement error to true iodine concentration) for iodine concentration and HU value on VMI at 50, 70, and 100 keV were compared between DLCT and FKSCT. The Mann-Whitney U test was used to assess statistical significance. RESULTS: Overall, the absolute percentage errors for iodine concentration and HU value on VMI were smaller for DLCT than for FKSCT. CONCLUSIONS: Overall, the accuracy of iodine and HU values was higher for DLCT than for FKSCT.

Identification of Multiple Forms of RNA Transcripts Associated with Human-Specific Retrotransposed Gene Copies.

The human genome contains thousands of retrocopies, mostly as processed pseudogenes, which were recently shown to be prevalently transcribed. In particular, those specifically acquired in the human lineage are able to modulate gene expression in a manner that contributed to the evolution of human-specific traits. Therefore, knowledge of the human-specific retrocopies that are transcribed or their full-length transcript structure contributes to better understand human genome evolution. In this study, we identified 16 human-specific retrocopies that harbor 5' CpG islands by in silico analysis and showed that 12 were transcribed in normal tissues and cancer cell lines with a variety of expression patterns, including cancer-specific expression. Determination of the structure of the transcripts associated with the retrocopies revealed that none were transcribed from their 5' CpG islands, but rather, from inside the 3' UTR and the nearby 5' flanking region of the retrocopies as well as the promoter of neighboring genes. The multiple forms of the transcripts, such as chimeric and individual transcripts in both the sense and antisense orientation, might have introduced novel post-transcriptional regulation into the genome during human evolution. These results shed light on the potential role of human-specific retrocopies in the evolution of gene regulation and genomic disorders.

Secreted calmodulin-like skin protein ameliorates scopolamine-induced memory impairment.

Humanin, a short bioactive peptide, inhibits cell death in a variety of cell-based death models through Humanin receptors in vitro. In vivo, Humanin ameliorates both muscarinic receptor antagonist-induced memory impairment in normal mice and memory impairment in Alzheimer's disease (AD)-relevant mouse models including aged transgenic mice expressing a familial AD-linked gene. Recently, calmodulin-like skin protein (CLSP) has been shown to be secreted from skin tissues, contain a region minimally similar to the core region of Humanin, and inhibit AD-related neuronal death through the heterotrimeric Humanin receptor on the cell surface in vitro. As CLSP is much more potent than Humanin and efficiently transported through blood circulation across the blood-brain barrier to the central nervous system, CLSP is considered as a physiological agonist that binds to the heterotrimeric Humanin receptor and triggers the Humanin-induced signals in central nervous system. However, it remains unknown whether CLSP ameliorates memory impairment in mouse dementia models as Humanin does. In this study, we show that recombinant CLSP, administered intracerebroventricularly or intraperitoneally, ameliorates scopolamine-induced dementia in mice.

Nuclear factor kappaB (NF-kappaB) activation primes cells to a pro-inflammatory polarized response to a Toll-like receptor 7 (TLR7) agonist.

TLR7 (Toll-like receptor 7) mediates anti-viral immunity by recognizing ssRNA (single-stranded RNA) viruses. Small-molecular-mass TLR7 agonists have been approved, or are being evaluated, for treatment of cancers or infectious diseases. Although TLR7 is predominantly expressed in a restricted set of immune cell types, including pDCs (plasmacytoid dendritic cells), it is also expressed in non-native expressing cells (e.g. hepatocytes) under certain circumstances. To elucidate the molecular basis of TLR7 induction by pro-inflammatory stimulation and the subsequent cellular responses in these non-native TLR7-expressing cell types, we first cloned and characterized the 5'-promoter region of TLR7. The proximal region of this promoter drives the transcription of the TLR7 gene. Pro-inflammatory stimuli activated TLR 7 transcription via a NF-kappaB (nuclear factor kappaB)-binding motif in this region, and this activation could be blocked by mutation of the NF-kappaB binding site or addition of NF-kappaB inhibitors. Further studies showed that pretreatment of the Hep3B hepatocytes with TNF-alpha (tumour necrosis factor-alpha) or IL-1 (interleukin-1) rendered them responsive to TLR7 activation by a TLR7 agonist. However, distinct from TLR7 activation in pDCs, which respond to stimulation with Th1 polarized cytokine production, TLR7 induction by pro-inflammatory signals in hepatocytes reconstitutes the NF-kappaB-dependent cascade but not the IRF7 (interferon regulatory factor 7)-dependent cascade, resulting in a pro-inflammatory polarized response rather than a Th1 polarized response. These results indicate that inflammatory stimulation is capable of priming cells to respond to TLR7 agonist with an immune response that differs from that in native TLR7-expressing cells.

Impaired microRNA processing causes corpus luteum insufficiency and infertility in mice.

The microRNA (miRNA) processing enzyme Dicer1 is required for zygotic and embryonic development, but the early embryonic lethality of Dicer1 null alleles in mice has limited our ability to address the role of Dicer1 in normal mouse growth and development. To address this question, we used a mouse mutant with a hypomorphic Dicer1 allele (Dicer(d/d)) and found that Dicer1 deficiency resulted in female infertility. This defect in female Dicer(d/d) mice was caused by corpus luteum (CL) insufficiency and resulted, at least in part, from the impaired growth of new capillary vessels in the ovary. We found that the impaired CL angiogenesis in Dicer(d/d) mice was associated with a lack of miR17-5p and let7b, 2 miRNAs that participate in angiogenesis by regulating the expression of the antiangiogenic factor tissue inhibitor of metalloproteinase 1. Furthermore, injection of miR17-5p and let7b into the ovaries of Dicer(d/d) mice partially normalized tissue inhibitor of metalloproteinase 1 expression and CL angiogenesis. Our data indicate that the development and function of the ovarian CL is a physiological process that appears to be regulated by miRNAs and requires Dicer1 function.

A crucial role of mitochondrial Hsp40 in preventing dilated cardiomyopathy.

Many heat-shock proteins (Hsp) are members of evolutionarily conserved families of chaperone proteins that inhibit the aggregation of unfolded polypeptides and refold denatured proteins, thereby remedying phenotypic effects that may result from protein aggregation or protein instability. Here we report that the mitochondrial chaperone Hsp40, also known as Dnaja3 or Tid1, is differentially expressed during cardiac development and pathological hypertrophy. Mice deficient in Dnaja3 developed dilated cardiomyopathy (DCM) and died before 10 weeks of age. Progressive respiratory chain deficiency and decreased copy number of mitochondrial DNA were evident in cardiomyocytes lacking Dnaja3. Profiling of Dnaja3-interacting proteins identified the alpha-subunit of DNA polymerase gamma (Polga) as a client protein. These findings suggest that Dnaja3 is crucial for mitochondrial biogenesis, at least in part, through its chaperone activity on Polga and provide genetic evidence of the necessity for mitochondrial Hsp40 in preventing DCM.

Tid1 negatively regulates the migratory potential of cancer cells by inhibiting the production of interleukin-8.

Tid1 is the human homologue of the Drosophila tumor suppressor, Tid56. Reducing the expression of Tid1 in MDA-MB231 breast cancer cells enhanced their migration without affecting their survival or growth rate. From microarray screening, we discovered that after Tid1 depletion, the mRNA level of interleukin-8 (IL-8) was significantly increased in these cancer cells, which consequently increased secretion of IL-8 protein by 3.5-fold. The enhanced migration of these Tid1-knockdown cells was blocked by reducing the IL-8 expression or by adding an IL-8 neutralizing antibody to the culture medium, suggesting that enhancement of cell motility in these Tid1-deficient cells is dependent on the de novo synthesis of IL-8. Subsequently, we found that abrogating the nuclear factor kappaB binding site in the IL-8 promoter completely blocked the Tid1 depletion-induced IL-8 expression in the breast cancer cells. As increased IL-8 levels are known to promote tumor metastasis, we tested the effect of Tid1 knockdown on tumor metastasis and found that Tid1 depletion enhanced the metastasis of breast cancer cells in animals. Together, these results indicate that Tid1 negatively regulates the motility and metastasis of breast cancer cells, most likely through attenuation of nuclear factor kappaB activity on the promoter of the IL8 gene.

Big mitogen-activated protein kinase 1/extracellular signal-regulated kinase 5 signaling pathway is essential for tumor-associated angiogenesis.

Although big mitogen-activated protein kinase 1 (BMK1) has been shown to be critical for embryonic angiogenesis, the role of BMK1 in tumor-associated neovascularization is poorly understood. Exogenous tumors were established in BMK1+/+, BMK1flox/+, or BMK1flox/flox mice carrying the Mx1-Cre transgene. Induced deletion of host BMK1 gene significantly reduced the volumes of B16F10 and LL/2 tumor xenografts in BMK1flox/flox mice by 63% and 72%, respectively. Examining the tumors in these induced BMK1-knockout animals showed a significant decrease in vascular density. Localized reexpression of BMK1 in BMK1-knockout mice by administration of adenovirus encoding BMK1 restored tumor growth and angiogenesis to the levels observed in wild-type mice. These observations were further supported by in vivo Matrigel plug assays in which vascular endothelial growth factor- and basic fibroblast growth factor-induced neovacularization was impaired by removing BMK1. Through screening with the Pepchip microarray, we discovered that in BMK1-knockout endothelial cells, phosphorylation of ribosomal protein S6 (rpS6) at Ser235/236 was mostly abrogated, and this BMK1-dependent phosphorylation required the activity of p90 ribosomal S6 kinase (RSK). Immunofluorescent analysis of tumor vasculature from BMK1-knockout and control animals revealed a strong correlation between the presence of BMK1 and the phosphorylation of rpS6 in tumor-associated endothelial cells of blood vessels. As both RSK and rpS6 are known to be important for cell proliferation and survival, which are critical endothelial cell functions during neovascularization, these findings suggest that the BMK1 pathway is crucial for tumor-associated angiogenesis through its role in the regulation of the RSK-rpS6 signaling module.

Role of the BMK1/ERK5 signaling pathway: lessons from knockout mice.

Mitogen-activated protein (MAP) kinase cascades play a central role in mediating extracellular stimuli-induced intracellular signaling during cell activation. The fourth and least studied mammalian MAP kinase pathway, big MAP kinase 1 (BMK1), also known as extracellular signal regulated kinase 5 (ERK5), is activated in response to growth factors and stress. Activation of this signaling pathway has been implicated not only in physiological functions such as cell survival, proliferation and differentiation but also in pathological processes such as carcinogenesis, cardiac hypertrophy and atherosclerosis. In recent years a series of gene-targeted mice lacking components within the BMK1 cascade have been generated, which have enabled us to investigate the role of the BMK1 pathway within different tissues. Analyses of these knockout mice have led to major discoveries in the role of BMK1 signaling in angiogenesis and in cardiac development. Moreover, studies using conditional BMK1 knockout mice, which circumvent the early embryonic lethality of BMK1 knockouts, have unveiled the importance of BMK1 in endothelial survival and maintenance of vascular integrity during adulthood. Here we summarize current understanding of the function of BMK1, as well as include new data generated from a series of tissue-specific BMK1 knockout mice in an attempt to dissect the role of the BMK1 pathway in various cell types in animals.

Targeted deletion of BMK1/ERK5 in adult mice perturbs vascular integrity and leads to endothelial failure.

Big mitogen-activated protein kinase 1 (BMK1), also known as ERK5, is a member of the MAPK family. Genetic ablation of BMK1 in mice leads to embryonic lethality, precluding the exploration of pathophysiological roles of BMK1 in adult mice. We generated a BMK1 conditional mutation in mice in which disruption of the BMK1 gene is under the control of the inducible Mx1-Cre transgene. Ablation of BMK1 in adult mice led to lethality within 2-4 weeks after the induction of Cre recombinase. Physiological analysis showed that the blood vessels became abnormally leaky after deletion of the BMK1 gene. Histological analysis revealed that, after BMK1 ablation, hemorrhages occurred in multiple organs in which endothelial cells lining the blood vessels became round, irregularly aligned, and, eventually, apoptotic. In vitro removal of BMK1 protein also led to the death of endothelial cells partially due to the deregulation of transcriptional factor MEF2C, which is a direct substrate of BMK1. Additionally, endothelial-specific BMK1-KO leads to cardiovascular defects identical to that of global BMK1-KO mutants, whereas, surprisingly, mice lacking BMK1 in cardiomyocytes developed to term without any apparent defects. Taken together, the data provide direct genetic evidence that the BMK1 pathway is critical for endothelial function and for maintaining blood vessel integrity.

Tid1, a cochaperone of the heat shock 70 protein and the mammalian counterpart of the Drosophila tumor suppressor l(2)tid, is critical for early embryonic development and cell survival.

Tid1 is the mammalian counterpart of the Drosophila tumor suppressor Tid56 and is also a DnaJ protein containing a conserved J domain through which it interacts with the heat shock protein 70 (Hsp70) family of chaperone proteins. We generated a Tid1 conditional mutation in mice, and the subsequent global removal of the Tid1 protein was achieved by crossing these conditional knockout mice with general deletor mice. No Tid1(-/-) embryos were detected as early as embryonic day 7.5 (E7.5). Nonetheless, Tid1-deficient blastocysts were viable, hatched, formed an inner cell mass and trophectoderm, and implanted (E4.5), suggesting that the homozygous mutant embryos die between E4.5 and E7.5. To assess the function of Tid1 in embryonic cells, mouse embryonic fibroblasts with the homologous Tid1 floxed allele were produced. Tid1 removal in these cells led to massive cell death. The death of Tid1-deficient cells could be rescued by ectopic expression of wild-type Tid1 but not by expression of the Tid1 protein that had a mutated J domain and was thus incapable of binding to Hsp70. We propose that Tid1 is critical for early mammalian development, most likely for its function in sustaining embryonic-cell survival, which requires its association with Hsp70.

Pathophysiologic characteristics of the activity-stress paradigm in animal models: inhibitory effect of glucose on these responses.

This review provides a discussion of the pathophysiologic significance of animal models of the activity-stress paradigm and the role of plasma glucose level in the appearance of physical stress responses of those models. Many research reports have demonstrated that animal models exposed to activity-stress are useful as a "symptomatic model" of anorexia nervosa and obsessive-compulsive disorder as well as peptic ulcer. Our findings show that a decrease in plasma glucose concentration is an important factor in determining the activity-stress-induced physical responses. Further investigation of the pathophysiology of activity-stressed animal models may contribute to the development of new therapeutics for diseases such as anorexia nervosa and obsessive-compulsive disorder.

ADP-ribosylation factor 4 small GTPase mediates epidermal growth factor receptor-dependent phospholipase D2 activation.

The epidermal growth factor receptor (EGFR) plays a critical role in the development, proliferation, and differentiation of cells of epithelial and mesenchymal origin. These EGFR-dependent cellular processes are mediated by a repertoire of intracellular signaling pathways triggered by the activation of the EGFR cytoplasmic domain, which originates from ligand binding of its extracellular domain. To understand the molecular mechanisms by which the intracellular domain of EGFR transmits mitogenic messages to the downstream signaling pathways, we used the cytoplasmic region of EGFR as bait in yeast two-hybrid screening. We found that ADP-ribosylation factor 4 (ARF4) interacts with the intracellular part of EGFR and mediates the EGF-dependent cellular activation of phospholipase D2 (PLD2) but does not mediate the activation of PLD1. In addition, ARF4-mediated PLD2 activation leads to dramatic activation of the transcription factor activator protein 1 (AP-1), and, importantly, ARF4 activity is required for EGF-induced activation of cellular AP-1. Our findings indicate that ARF4 is a critical molecule that directly regulates cellular PLD2 activity and that this ARF4-mediated PLD2 activation stimulates AP-1-dependent transcription in the EGF-induced cellular response.