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Brain Topography

E Salari, Z V Freudenburg, M J Vansteensel, N F Ramsey
The sensorimotor cortex is responsible for the generation of movements and interest in the ability to use this area for decoding speech by brain-computer interfaces has increased recently. Speech decoding is challenging however, since the relationship between neural activity and motor actions is not completely understood. Non-linearity between neural activity and movement has been found for instance for simple finger movements. Despite equal motor output, neural activity amplitudes are affected by preceding movements and the time between movements...
September 20, 2018: Brain Topography
Jonas Kunst, Radek Marecek, Patricia Klobusiakova, Zuzana Balazova, Lubomira Anderkova, Nela Nemcova-Elfmarkova, Irena Rektorova
Using MRI, a characteristic pattern of grey matter (GM) atrophy has been described in the early stages of Alzheimer's disease (AD); GM patterns at different stages of Parkinson's disease (PD) have been inconclusive. Few studies have directly compared structural changes in groups with mild cognitive impairment (MCI) caused by different pathologies (AD, PD). We used several analytical methods to determine GM changes at different stages of both PD and AD. We also evaluated associations between GM changes and cognitive measurements...
September 11, 2018: Brain Topography
Luqing Wei, Nana Guo, Chris Baeken, Minghua Bi, Xiaowan Wang, Jiang Qiu, Guo-Rong Wu
Effortful control (EC), considered as one component of temperament, describes an individual's capacity for self-regulation. Previous neuroimaging studies have provided convergent evidence that individual differences in EC are determined by the functioning of neural systems subserving executive attention, primarily comprising the anterior cingulate cortex (ACC) and the lateral prefrontal cortex (PFC). Notwithstanding, as previous neuroimaging findings highlighted the structural neural bases of EC in adolescence, during which the PFC is prominently remodeled, the underlying neuroanatomical substrates of EC remain uncertain in young adults...
September 10, 2018: Brain Topography
Raffaella Franciotti, Nicola Walter Falasca, Dario Arnaldi, Francesco Famà, Claudio Babiloni, Marco Onofrj, Flavio Mariano Nobili, Laura Bonanni
Graph theory analysis on resting state electroencephalographic rhythms disclosed topological properties of cerebral network. In Alzheimer's disease (AD) patients, this approach showed mixed results. Granger causality matrices were used as input to the graph theory allowing to estimate the strength and the direction of information transfer between electrode pairs. The number of edges (degree), the number of inward edges (in-degree), of outgoing edges (out-degree) were statistically compared among healthy controls, patients with mild cognitive impairment due to AD (AD-MCI) and AD patients with mild dementia (ADD) to evaluate if degree abnormality could involve low and/or high degree vertices, the so called hubs, in both prodromal and over dementia stage...
August 25, 2018: Brain Topography
Won Hee Lee, Dominik Andreas Moser, Alex Ing, Gaelle Eve Doucet, Sophia Frangou
Metastability is currently considered a fundamental property of the functional configuration of brain networks. The present study sought to generate a normative reference framework for the metastability of the major resting-state networks (RSNs) (resting-state metastability dataset) and discover their association with demographic, behavioral, physical and cognitive features (non-imaging dataset) from 818 participants of the Human Connectome Project. Using sparse canonical correlation analysis, we found that the metastability and non-imaging datasets showed significant but modest interdependency...
August 22, 2018: Brain Topography
Daniela Calvetti, Annalisa Pascarella, Francesca Pitolli, Erkki Somersalo, Barbara Vantaggi
A recently proposed iterated alternating sequential (IAS) MEG inverse solver algorithm, based on the coupling of a hierarchical Bayesian model with computationally efficient Krylov subspace linear solver, has been shown to perform well for both superficial and deep brain sources. However, a systematic study of its ability to correctly identify active brain regions is still missing. We propose novel statistical protocols to quantify the performance of MEG inverse solvers, focusing in particular on how their accuracy and precision at identifying active brain regions...
August 18, 2018: Brain Topography
Yoon-Hee Cha, Guofa Shou, Diamond Gleghorn, Benjamin C Doudican, Han Yuan, Lei Ding
To determine intrinsic functional connectivity (IFC) related to symptom changes induced by rTMS in mal de debarquement syndrome (MdDS), a motion perceptual disorder induced by entrainment to oscillating motion. Twenty right-handed women (mean age: 52.9 ± 12.6 years; mean duration illness: 35.2 ± 24.2 months) with MdDS received five sessions of rTMS (1 Hz right DLPFC, 10 Hz left DLPFC) over consecutive days. High-density (128-channel) resting-state EEG were recorded prior to and following treatment sessions and analyzed using a group-level independent component (IC) analysis...
August 11, 2018: Brain Topography
Hanna Kaltiainen, Liisa Helle, Mia Liljeström, Hanna Renvall, Nina Forss
Mild traumatic brain injury (mTBI) patients continue to pose a diagnostic challenge due to their diverse symptoms without trauma-specific changes in structural imaging. We addressed here the possible early changes in spontaneous oscillatory brain activity after mTBI, and their feasibility as an indicator of injury in clinical evaluation. We recorded resting-state magnetoencephalography (MEG) data in both eyes-open and eyes-closed conditions from 26 patients (11 females and 15 males, aged 20-59) with mTBI 6 days-6 months after the injury, and compared their spontaneous oscillatory activity to corresponding data from 139 healthy controls...
August 10, 2018: Brain Topography
Fadi N Karameh, Ziad Nahas
Model-based network discovery measures, such as the brain effective connectivity, require fitting of generative process models to measurements obtained from key areas across the network. For distributed dynamic phenomena, such as generalized seizures and slow-wave sleep, studying effective connectivity from real-time recordings is significantly complicated since (i) outputs from only a subnetwork can be practically measured, and (ii) exogenous subnetwork inputs are unobservable. Model fitting, therefore, constitutes a challenging blind module identification or model inversion problem for finding both the parameters and the many unknown inputs of the subnetwork...
August 4, 2018: Brain Topography
Dror Haor, Roman Joffe, Reuven Shavit, Ziv Peremen, Yaki Stern, Amir B Geva
Electroencephalogram (EEG) has evolved to be a well-established tool for imaging brain activity. This progress is mainly due to the development of high-resolution (HR) EEG methods. One class of HR-EEG is the cortical potential imaging (CPI), which aims to estimate the potential distribution on the cortical surface, which is much more informative than EEG. Even though these methods exhibit good performance, most of them have inherent inaccuracies that originate from their operating principles that constrain the solution or require a complex calculation process...
August 3, 2018: Brain Topography
Chany Lee, Chang-Hwan Im
The finite element method (FEM) is a numerical method that is often used for solving electroencephalography (EEG) forward problems involving realistic head models. In this study, FEM solutions obtained using three different mesh structures, namely coarse, densely refined, and adaptively refined meshes, are compared. The simulation results showed that the accuracy of FEM solutions could be significantly enhanced by adding a small number of elements around regions with large estimated errors. Moreover, it was demonstrated that the adaptively refined regions were always near the current dipole sources, suggesting that selectively generating additional elements around the cortical surface might be a new promising strategy for more efficient FEM-based EEG forward analysis...
August 2, 2018: Brain Topography
Yajing Pang, Heng Chen, Yuyan Chen, Qian Cui, Yifeng Wang, Zhiqiang Zhang, Guangming Lu, Huafu Chen
White matter (WM) fibers underpin individual differences in extraversion and neuroticism. These personality traits are associated with integration of emotion, cognition, and behavior, which rely on a large-scale brain network. Thus, research at network level is needed to characterize neural underpinnings of extraversion and neuroticism. We performed diffusion tensor imaging on 68 healthy individuals and combined a WM network with graph theory analysis to investigate the connectivity of the whole-brain network and individual regions associated with extraversion and neuroticism...
July 25, 2018: Brain Topography
Alexandra Morris, Mathura Ravishankar, Lena Pivetta, Asadur Chowdury, Dimitri Falco, Jessica S Damoiseaux, David R Rosenberg, Steven L Bressler, Vaibhav A Diwadkar
We investigated the flexible modulation of undirected functional connectivity (uFC) of brain pathways during simple uni-manual responding. Two questions were central to our interests: (1) does response hand (dominant vs. non-dominant) differentially modulate connectivity and (2) are these effects related to responding under varying motor sets. fMRI data were acquired in twenty right-handed volunteers who responded with their right (dominant) or left (non-dominant) hand (blocked across acquisitions). Within acquisitions, the task oscillated between periodic responses (promoting the emergence of motor sets) or randomly induced responses (disrupting the emergence of motor sets)...
July 21, 2018: Brain Topography
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
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
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
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
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
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
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...
September 2018: Brain Topography
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