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Brain Topography

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https://www.readbyqxmd.com/read/30019114/resting-motor-threshold-mep-and-tep-variability-during-daytime
#1
Esther M Ter Braack, Annika A de Goede, Michel J A M van Putten
Humans show a variation in physiological processes during the day. To reliably assess (changes in) cortical excitability with transcranial magnetic stimulation (TMS), it is relevant to know the natural variation in TMS readouts during the day. In case of significant daytime variations, this should be taken into account when scheduling (follow-up) measurements. This study aims to evaluate the influence of the time of day on the resting motor threshold (RMT), motor evoked potential (MEP) and TMS evoked potential (TEP) in healthy controls...
July 17, 2018: Brain Topography
https://www.readbyqxmd.com/read/29987641/increased-early-sensitivity-to-eyes-in-mouthless-faces-in-support-of-the-lifted-model-of-early-face-processing
#2
Roxane J Itier, Frank Preston
The N170 ERP component is a central neural marker of early face perception usually thought to reflect holistic processing. However, it is also highly sensitive to eyes presented in isolation and to fixation on the eyes within a full face. The lateral inhibition face template and eye detector (LIFTED) model (Nemrodov et al. in NeuroImage 97:81-94, 2014) integrates these views by proposing a neural inhibition mechanism that perceptually glues features into a whole, in parallel to the activity of an eye detector that accounts for the eye sensitivity...
July 9, 2018: Brain Topography
https://www.readbyqxmd.com/read/29980967/high-frequency-oscillations-in-the-ripple-band-80-250-hz-in-scalp-eeg-higher-density-of-electrodes-allows-for-better-localization-of-the-seizure-onset-zone
#3
N Kuhnke, J Schwind, M Dümpelmann, M Mader, A Schulze-Bonhage, J Jacobs
High frequency oscillations (HFO) are known as markers of epileptic areas in intracranial EEG and possibly scalp EEG. We compared distributions of HFO in the ripple band (80-250 Hz) in intracranial and scalp EEG with either a conventional 10-20-montage (10-20-EEG) or a high density recording using 128 electrodes (HD-EEG). HFO were visually identified, in all intracranial EEG channels (80-500 Hz) and all channels of the 10-20-EEG (scalp EEG 80-250 Hz). For the HD-EEG, HFO were analyzed in regions of interest using areas with HFO as seen on the 10-20-EEG as well as areas in the clinically-defined seizure onset zone (SOZ)...
July 6, 2018: Brain Topography
https://www.readbyqxmd.com/read/29974288/longitudinal-assessment-of-hippocampal-atrophy-in-midlife-and-early-old-age-contrasting-manual-tracing-and-semi-automated-segmentation-freesurfer
#4
Mark A Fraser, Marnie E Shaw, Kaarin J Anstey, Nicolas Cherbuin
It is important to have accurate estimates of normal age-related brain structure changes and to understand how the choice of measurement technique may bias those estimates. We compared longitudinal change in hippocampal volume, laterality and atrophy measured by manual tracing and FreeSurfer (version 5.3) in middle age (n = 244, 47.2[1.4] years) and older age (n = 199, 67.0[1.4] years) individuals over 8 years. The proportion of overlap (Dice coefficient) between the segmented hippocampi was calculated and we hypothesised that the proportion of overlap would be higher for older individuals as a consequence of higher atrophy...
July 4, 2018: Brain Topography
https://www.readbyqxmd.com/read/29971634/efficient-mapping-of-the-motor-cortex-with-navigated-biphasic-paired-pulse-transcranial-magnetic-stimulation
#5
Minna Pitkänen, Elisa Kallioniemi, Gustaf Järnefelt, Jari Karhu, Petro Julkunen
Navigated transcranial magnetic stimulation (nTMS) can be applied to locate cortical muscle representations. Usually, single TMS pulses are targeted to the motor cortex with the help of neuronavigation and by measuring motor evoked potential (MEP) amplitudes from the peripheral muscles. The efficacy of single-pulse TMS to induce MEPs has been shown to increase by applying facilitatory paired-pulse TMS (ppTMS). Therefore, the aim was to study whether the facilitatory ppTMS could enable more efficient motor mapping...
July 3, 2018: Brain Topography
https://www.readbyqxmd.com/read/29971633/robust-identification-of-rich-club-organization-in-weighted-and-dense-structural-connectomes
#6
Xiaoyun Liang, Chun-Hung Yeh, Alan Connelly, Fernando Calamante
The human brain is a complex network, in which some brain regions, denoted as 'hub' regions, play critically important roles. Some of these hubs are highly interconnected forming a rich-club organization, which has been identified based on the degree metric from structural connectomes constructed using diffusion tensor imaging (DTI)-based fiber tractography. However, given the limitations of DTI, the yielded structural connectomes are largely compromised, possibly affecting the characterization of rich-club organizations...
July 3, 2018: Brain Topography
https://www.readbyqxmd.com/read/29943242/accurate-coil-positioning-is-important-for-single-and-paired-pulse-tms-on-the-subject-level
#7
Annika A de Goede, Esther M Ter Braack, Michel J A M van Putten
Function-guided navigation is commonly used when assessing cortical excitability using transcranial magnetic stimulation (TMS). However, the required accuracy, stability and the effect of a change in coil positioning are not entirely known. This study investigates the accuracy of function-guided navigation for determining the hotspot. Furthermore, it evaluates the effect of a change in coil location on the single and paired pulse excitability measures: motor evoked potential (MEP) amplitude, TMS evoked potential (TEP) and long intracortical inhibition (LICI), and of a change in coil orientation on LICI...
June 25, 2018: Brain Topography
https://www.readbyqxmd.com/read/29934729/optical-mapping-of-brain-activation-and-connectivity-in-occipitotemporal-cortex-during-chinese-character-recognition
#8
Zhishan Hu, Juan Zhang, Tania Alexandra Couto, Shiyang Xu, Ping Luan, Zhen Yuan
In this study, functional near-infrared spectroscopy (fNIRS) was used to examine the brain activation and connectivity in occipitotemporal cortex during Chinese character recognition (CCR). Eighteen healthy participants were recruited to perform a well-designed task with three categories of stimuli (real characters, pseudo characters, and checkerboards). By inspecting the brain activation difference and its relationship with behavioral data, the left laterality during CCR was clearly identified in the Brodmann area (BA) 18 and 19...
June 22, 2018: Brain Topography
https://www.readbyqxmd.com/read/29934728/requirements-for-coregistration-accuracy-in-on-scalp-meg
#9
Rasmus Zetter, Joonas Iivanainen, Matti Stenroos, Lauri Parkkonen
Recent advances in magnetic sensing has made on-scalp magnetoencephalography (MEG) possible. In particular, optically-pumped magnetometers (OPMs) have reached sensitivity levels that enable their use in MEG. In contrast to the SQUID sensors used in current MEG systems, OPMs do not require cryogenic cooling and can thus be placed within millimetres from the head, enabling the construction of sensor arrays that conform to the shape of an individual's head. To properly estimate the location of neural sources within the brain, one must accurately know the position and orientation of sensors in relation to the head...
June 22, 2018: Brain Topography
https://www.readbyqxmd.com/read/29882034/two-stage-processing-of-aesthetic-information-in-the-human-brain-revealed-by-neural-adaptation-paradigm
#10
Miho Iwasaki, Yasuki Noguchi, Ryusuke Kakigi
Some researchers in aesthetics assume visual features related to aesthetic perception (e.g. golden ratio and symmetry) commonly embedded in masterpieces. If this is true, an intriguing hypothesis is that the human brain has neural circuitry specialized for the processing of visual beauty. We presently tested this hypothesis by combining a neuroimaging technique with the repetition suppression (RS) paradigm. Subjects (non-experts in art) viewed two images of sculptures sequentially presented. Some sculptures obeyed the golden ratio (canonical images), while the golden proportion were impaired in other sculptures (deformed images)...
June 7, 2018: Brain Topography
https://www.readbyqxmd.com/read/29860588/a-comparative-study-of-different-eeg-reference-choices-for-diagnosing-unipolar-depression
#11
Wajid Mumtaz, Aamir Saeed Malik
The choice of an electroencephalogram (EEG) reference has fundamental importance and could be critical during clinical decision-making because an impure EEG reference could falsify the clinical measurements and subsequent inferences. In this research, the suitability of three EEG references was compared while classifying depressed and healthy brains using a machine-learning (ML)-based validation method. In this research, the EEG data of 30 unipolar depressed subjects and 30 age-matched healthy controls were recorded...
June 2, 2018: Brain Topography
https://www.readbyqxmd.com/read/29846835/cerebral-imaging-markers-of-gba-and-lrrk2-related-parkinson-s-disease-and-their-first-degree-unaffected-relatives
#12
Avner Thaler, Efrat Kliper, Inbal Maidan, Talia Herman, Keren Rosenberg-Katz, Noa Bregman, Tanya Gurevich, Tamara Shiner, Jeffrey M Hausdorff, Avi Orr-Urtreger, Nir Giladi, Anat Mirelman
Cerebral atrophy has been detected in patients with Parkinson's disease (PD) both with and without dementia, however differentiation based on genetic status has thus far not yielded robust findings. We assessed cortical thickness and subcortical volumes in a cohort of PD patients and healthy controls carriers of the G2019S mutation in the LRRK2 gene and the common GBA mutations, in an attempt to determine whether genetic status influences structural indexes. Cortical thickness and subcortical volumes were computed and compared between six groups of participants; idiopathic PD, GBA-PD, LRRK2-PD, non-manifesting non-carriers (NMNC), GBA-non-manifesting carriers (NMC) and LRRK2-NMC utilizing the FreeSurfer software program...
May 30, 2018: Brain Topography
https://www.readbyqxmd.com/read/29845492/clinical-correlations-of-brain-lesion-location-in-multiple-sclerosis-voxel-based-analysis-of-a-large-clinical-trial-dataset
#13
Anna Altermatt, Laura Gaetano, Stefano Magon, Dieter A Häring, Davorka Tomic, Jens Wuerfel, Ernst-Wilhelm Radue, Ludwig Kappos, Till Sprenger
There is a limited correlation between white matter (WM) lesion load as determined by magnetic resonance imaging and disability in multiple sclerosis (MS). The reasons for this so-called clinico-radiological paradox are diverse and may, at least partly, relate to the fact that not just the overall lesion burden, but also the exact anatomical location of lesions predict the severity and type of disability. We aimed at studying the relationship between lesion distribution and disability using a voxel-based lesion probability mapping approach in a very large dataset of MS patients...
May 29, 2018: Brain Topography
https://www.readbyqxmd.com/read/29766384/increased-functional-meg-connectivity-as-a-hallmark-of-mri-negative-focal-and-generalized-epilepsy
#14
Yiwen Li Hegner, Justus Marquetand, Adham Elshahabi, Silke Klamer, Holger Lerche, Christoph Braun, Niels K Focke
Epilepsy is one of the most prevalent neurological diseases with a high morbidity. Accumulating evidence has shown that epilepsy is an archetypical neural network disorder. Here we developed a non-invasive cortical functional connectivity analysis based on magnetoencephalography (MEG) to assess commonalities and differences in the network phenotype in different epilepsy syndromes (non-lesional/cryptogenic focal and idiopathic/genetic generalized epilepsy). Thirty-seven epilepsy patients with normal structural brain anatomy underwent a 30-min resting state MEG measurement with eyes closed...
May 15, 2018: Brain Topography
https://www.readbyqxmd.com/read/29737438/variability-and-reliability-of-paired-pulse-depression-and-cortical-oscillation-induced-by-median-nerve-stimulation
#15
Hideaki Onishi, Naofumi Otsuru, Sho Kojima, Shota Miyaguchi, Kei Saito, Yasuto Inukai, Koya Yamashiro, Daisuke Sato, Hiroyuki Tamaki, Hiroshi Shirozu, Shigeki Kameyama
Paired-pulse depression (PPD) has been widely used to investigate the functional profiles of somatosensory cortical inhibition. However, PPD induced by somatosensory stimulation is variable, and the reasons for between- and within-subject PPD variability remains unclear. Therefore, the purpose of this study was to clarify the factors influencing PPD variability induced by somatosensory stimulation. The study participants were 19 healthy volunteers. First, we investigated the relationship between the PPD ratio of each component (N20m, P35m, and P60m) of the somatosensory magnetic field, and the alpha, beta, and gamma band changes in power [event-related desynchronization (ERD) and event-related synchronization (ERS)] induced by median nerve stimulation...
May 8, 2018: Brain Topography
https://www.readbyqxmd.com/read/29700719/influence-of-time-series-normalization-number-of-nodes-connectivity-and-graph-measure-selection-on-seizure-onset-zone-localization-from-intracranial-eeg
#16
Pieter van Mierlo, Octavian Lie, Willeke Staljanssens, Ana Coito, Serge Vulliémoz
We investigated the influence of processing steps in the estimation of multivariate directed functional connectivity during seizures recorded with intracranial EEG (iEEG) on seizure-onset zone (SOZ) localization. We studied the effect of (i) the number of nodes, (ii) time-series normalization, (iii) the choice of multivariate time-varying connectivity measure: Adaptive Directed Transfer Function (ADTF) or Adaptive Partial Directed Coherence (APDC) and (iv) graph theory measure: outdegree or shortest path length...
April 26, 2018: Brain Topography
https://www.readbyqxmd.com/read/29704076/spatio-temporal-reconstruction-of-neural-sources-using-indirect-dominant-mode-rejection
#17
Alireza Talesh Jafadideh, Babak Mohammadzadeh Asl
Adaptive minimum variance based beamformers (MVB) have been successfully applied to magnetoencephalogram (MEG) and electroencephalogram (EEG) data to localize brain activities. However, the performance of these beamformers falls down in situations where correlated or interference sources exist. To overcome this problem, we propose indirect dominant mode rejection (iDMR) beamformer application in brain source localization. This method by modifying measurement covariance matrix makes MVB applicable in source localization in the presence of correlated and interference sources...
July 2018: Brain Topography
https://www.readbyqxmd.com/read/29671156/alteration-and-role-of-interhemispheric-and-intrahemispheric-connectivity-in-motor-network-after-stroke
#18
Jungsoo Lee, Eunhee Park, Ahee Lee, Won Hyuk Chang, Dae-Shik Kim, Yun-Hee Kim
This study investigated local and global changes in the motor network using longitudinal resting-state functional magnetic resonance imaging (rs-fMRI). Motor impairment was measured in 81 stroke patients using Fugl-Meyer assessment on the same day as rs-fMRI acquisition at both 2 weeks and 3 months post-stroke. The relationships between network measures and motor function scores were assessed. With regard to local connectivity, interhemispheric connectivity was noticeably altered at each time point. Interhemispheric connectivity was also related to residual motor function and improvement in motor function...
July 2018: Brain Topography
https://www.readbyqxmd.com/read/29663098/alterations-in-normal-aging-revealed-by-cortical-brain-network-constructed-using-ibaspm
#19
Wan Li, Chunlan Yang, Feng Shi, Qun Wang, Shuicai Wu, Wangsheng Lu, Shaowu Li, Yingnan Nie, Xin Zhang
Normal aging has been linked with the decline of cognitive functions, such as memory and executive skills. One of the prominent approaches to investigate the age-related alterations in the brain is by examining the cortical brain connectome. IBASPM is a toolkit to realize individual atlas-based volume measurement. Hence, this study seeks to determine what further alterations can be revealed by cortical brain networks formed by IBASPM-extracted regional gray matter volumes. We found the reduced strength of connections between the superior temporal pole and middle temporal pole in the right hemisphere, global hubs as the left fusiform gyrus and right Rolandic operculum in the young and aging groups, respectively, and significantly reduced inter-module connection of one module in the aging group...
July 2018: Brain Topography
https://www.readbyqxmd.com/read/29497874/visualizing-the-human-subcortex-using-ultra-high-field-magnetic-resonance-imaging
#20
REVIEW
M C Keuken, B R Isaacs, R Trampel, W van der Zwaag, B U Forstmann
With the recent increased availability of ultra-high field (UHF) magnetic resonance imaging (MRI), substantial progress has been made in visualizing the human brain, which can now be done in extraordinary detail. This review provides an extensive overview of the use of UHF MRI in visualizing the human subcortex for both healthy and patient populations. The high inter-subject variability in size and location of subcortical structures limits the usability of atlases in the midbrain. Fortunately, the combined results of this review indicate that a large number of subcortical areas can be visualized in individual space using UHF MRI...
July 2018: Brain Topography
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