scholarly journals Functional Integration Between Brain Regions at Rest Occurs in Multiple-Frequency Bands

2015 ◽  
Vol 5 (1) ◽  
pp. 23-34 ◽  
Author(s):  
Suril R. Gohel ◽  
Bharat B. Biswal
Keyword(s):  
Functional Integration ◽  
Brain Regions ◽  
Multiple Frequency ◽  
Frequency Bands

scholarly journals System Design and Calibration for Wideband Channel Sounding With Multiple Frequency Bands

IEEE Access ◽  
2017 ◽  
Vol 5 ◽  
pp. 781-793 ◽  
Author(s):  
Jinxing li ◽  
Youping Zhao ◽  
Cheng Tao ◽  
Bo Ai
Keyword(s):  
System Design ◽  
Multiple Frequency ◽  
Channel Sounding ◽  
Frequency Bands ◽  
Wideband Channel

scholarly journals Changes in Degree Centrality of Network Nodes in Different Frequency Bands in Parkinson’s Disease With Depression and Without Depression

2021 ◽  
Vol 15 ◽  
Author(s):  
Haiyan Liao ◽  
Jinyao Yi ◽  
Sainan Cai ◽  
Qin Shen ◽  
Qinru Liu ◽  
...  
Keyword(s):  
Basal Ganglia ◽  
Magnetic Resonance ◽  
Frequency Band ◽  
Limbic System ◽  
Resting State ◽  
Brain Regions ◽  
Degree Centrality ◽  
Functional Magnetic Resonance ◽  
Frequency Bands ◽  
Medial Frontal Gyrus

BackgroundDepression induces an early onset of Parkinson’s disease (PD), aggravates dyskinesia and cognitive impairment, and accelerates disease progression. However, it is very difficult to identify and diagnose PD with depression (PDD) in the early clinical stage. Few studies have suggested that the changes in neural networks are associated with PDD, while degree centrality (DC) has been documented to be effective in detecting brain network changes.ObjectivesThe objectives of this study are to explore DC changes between patients with PDD and without depression (PDND) and to find the key brain hubs involved with depression in PD patients.MethodsOne hundred and four PD patients and 54 healthy controls (HCs) underwent brain resting-state functional magnetic resonance imaging. The Data Processing and Analysis of Brain Imaging and Resting-State Functional Magnetic Resonance Data Analysis Toolkit were used for processing and statistical analysis. The DC value of each frequency band was calculated. One-way analysis of variance and a two-sample t-test for post hoc comparison were used to compare the differences of the DC values in different frequency bands among PDD, PDND, and healthy control group. Gaussian random field was used for multiple comparison correction. Pearson correlation analysis was performed between each individual’s DC map and clinical indicators.ResultsThe DC value of different brain regions changed in PDD and PDND in different frequency bands. The prefrontal lobe, limbic system, and basal ganglia were the main brain regions involved. PDD patients showed a wider range and more abnormal brain areas in the slow-4 frequency band (0.027–0.073 Hz) compared to the HCs. PDD showed a decreased DC value in the medial frontal gyrus, bilateral cuneus gyrus, right lingual gyrus, bilateral supplementary motor area (SMA), bilateral superior frontal gyrus, and left paracentral lobule, but an increased DC value in the bilateral brainstem, midbrain, bilateral parahippocampal gyrus, cerebellum, left superior temporal gyrus, bilateral insula, left fusiform gyrus, and left caudate nucleus in the traditional frequency band (0.01–0.08 Hz) compared to PDND patients. PDND patients displayed more abnormal functions in the basal ganglia in the slow-4 frequency band.ConclusionThe DC changes in PDD and PDND are frequency dependent and frequency specific. The medial frontal gyrus, SMA, and limbic system may be the key hubs for depression in PD.

scholarly journals Large-scale functional integration, rather than functional dissociation along dorsal and ventral streams, underlies visual perception and action

2019 ◽  
Author(s):  
Dipanjan Ray ◽  
Nilambari Hajare ◽  
Dipanjan Roy ◽  
Arpan Banerjee
Keyword(s):  
Visual Perception ◽  
Large Scale ◽  
Premotor Cortex ◽  
Functional Integration ◽  
Predictive Coding ◽  
Dorsal Stream ◽  
Brain Regions ◽  
Neural Pathways ◽  
Healthy Human ◽  
Mri Environment

AbstractVisual dual stream theory posits that two distinct neural pathways of specific functional significance originate from primary visual areas and reach the inferior temporal (ventral) and posterior parietal areas (dorsal). However, there are several unresolved questions concerning the fundamental aspects of this theory. For example, is the functional dissociation between ventral and dorsal stream driven by features in input stimuli or is it driven by categorical differences between visuo-perceptual and visuo-motor functions? Is the dual stream rigid or flexible? What is the nature of the interactions between two streams? We addressed these questions using fMRI recordings on healthy human volunteers and employing stimuli and tasks that can tease out the divergence between visuo-perceptual and visuo-motor models of dual stream theory. fMRI scans were repeated after seven practice sessions that were conducted in a non-MRI environment to investigate the effects of neuroplasticity. Brain activation analysis supports an input-based functional dissociation and existence of context-dependent neuroplasticity in dual stream areas. Intriguingly, premotor cortex activation was observed in the position perception task and distributed deactivated regions were observed in all perception tasks thus, warranting a network level analysis. Dynamic causal modelling (DCM) analysis incorporating activated and deactivated brain areas during perception tasks indicates that the brain dynamics during visual perception and actions could be interpreted within the framework of predictive coding. Effectively, the network level findings point towards the existence of more intricate context-driven functional networks selective of “what” and “where” information rather than segregated streams of processing along ventral and dorsal brain regions.

scholarly journals Design of Compact MIMO Multiband Antenna for Wireless Radio Communication Application

2021 ◽  
Vol 3 (3) ◽  
pp. 170-181
Author(s):  
C. Anand
Keyword(s):  
Dielectric Constant ◽  
Microstrip Antennas ◽  
Antenna Design ◽  
Multiple Frequency ◽  
Radio Communication ◽  
Frequency Bands ◽  
Multiband Antenna ◽  
Mimo Antenna ◽  
Antenna Performance ◽  
Simulation And Evaluation

Slot and patch modification for the design of a compact multiband antenna with Multi-Input-Multi-Output (MIMO) functionality is proposed in this paper. At various frequency bands, the antenna performance is obtained by modification and addition of slot and patch shapes in the design of the compact MIMO multiband antenna. Addition of slots or patches is done separately in the already existing multiband antenna designs. Whereas in this work, the addition of slot and patch are combined. Arlon Diclad 880 with a dielectric constant of 2.17 - 2.2 (εr) and height 0.75mm is used for the antenna design. The MIMO multiband antenna with the dimension of 12.5 mm × 7.5 mm is designed. On various millimeter-wave frequency bands ranging from 20 GHz to 40 GHz, the MIMO antenna can function as observed in the results of simulation and evaluation. This work shows that microstrip antennas can be added with slots and patches during their design and development, thereby enabling the antenna to operate under multiple frequency bands.

scholarly journals Reduced Brain Electric Activity and Functional Connectivity in Bipolar Euthymia: An sLORETA Source Localization Study

2019 ◽  
Vol 51 (3) ◽  
pp. 155-166
Author(s):  
Annamaria Painold ◽  
Pascal L. Faber ◽  
Eva Z. Reininghaus ◽  
Sabrina Mörkl ◽  
Anna K. Holl ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Large Scale ◽  
Time Course ◽  
Temporal Cortex ◽  
Electric Activity ◽  
Brain Regions ◽  
Frequency Bands ◽  
Head Surface ◽  
Density Values ◽  
Surface Eeg

Bipolar disorder (BD) is a chronic illness with a relapsing and remitting time course. Relapses are manic or depressive in nature and intermitted by euthymic states. During euthymic states, patients lack the criteria for a manic or depressive diagnosis, but still suffer from impaired cognitive functioning as indicated by difficulties in executive and language-related processing. The present study investigated whether these deficits are reflected by altered intracortical activity in or functional connectivity between brain regions involved in these processes such as the prefrontal and the temporal cortices. Vigilance-controlled resting state EEG of 13 euthymic BD patients and 13 healthy age- and sex-matched controls was analyzed. Head-surface EEG was recomputed into intracortical current density values in 8 frequency bands using standardized low-resolution electromagnetic tomography. Intracortical current densities were averaged in 19 evenly distributed regions of interest (ROIs). Lagged coherences were computed between each pair of ROIs. Source activity and coherence measures between patients and controls were compared (paired t tests). Reductions in temporal cortex activity and in large-scale functional connectivity in patients compared to controls were observed. Activity reductions affected all 8 EEG frequency bands. Functional connectivity reductions affected the delta, theta, alpha-2, beta-2, and gamma band and involved but were not limited to prefrontal and temporal ROIs. The findings show reduced activation of the temporal cortex and reduced coordination between many brain regions in BD euthymia. These activation and connectivity changes may disturb the continuous frontotemporal information flow required for executive and language-related processing, which is impaired in euthymic BD patients.

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