scholarly journals Decoding the orientation of contrast edges from MEG evoked and induced responses

2017 ◽  
Author(s):  
Dimitrios Pantazis ◽  
Mingtong Fang ◽  
Sheng Qin ◽  
Yalda Mohsenzadeh ◽  
Quanzheng Li ◽  
...  
Keyword(s):  
Oblique Effect ◽  
Gamma Oscillations ◽  
Dominant Frequency ◽  
Induced Responses ◽  
Early Visual Cortex ◽  
Orientation Information ◽  
Stimulus Features ◽  
Basic Stimulus ◽  
Multivariate Pattern ◽  
The Relationship

1AbstractVisual gamma oscillations have been proposed to subserve perceptual binding, but their strong modulation by diverse stimulus features confounds interpretations of their precise functional role. Overcoming this challenge necessitates a comprehensive account of the relationship between gamma responses and stimulus features. Here we used multivariate pattern analyses on human MEG data to characterize the relationships between gamma responses and one basic stimulus feature, the orientation of contrast edges. Our findings confirmed we could decode orientation information from induced responses in two dominant frequency bands at 24-32 Hz and 50-58 Hz. Decoding was higher for cardinal than oblique orientations, with similar results also obtained for evoked MEG responses. In contrast to multivariate analyses, orientation information was mostly absent in univariate signals: evoked and induced responses in early visual cortex were similar in all orientations, with only exception an inverse oblique effect observed in induced responses, such that cardinal orientations produced weaker oscillatory signals than oblique orientations. Taken together, our results showed multivariate methods are well suited for the analysis of gamma oscillations, with multivariate patterns robustly encoding orientation information and predominantly discriminating cardinal from oblique stimuli.

scholarly journals Validating Linear Systems Analysis for Laminar fMRI: Temporal Additivity for Stimulus Duration Manipulations

2020 ◽  
Author(s):  
Jelle A. van Dijk ◽  
Alessio Fracasso ◽  
Natalia Petridou ◽  
Serge O. Dumoulin
Keyword(s):  
Systems Theory ◽  
Linear Systems ◽  
Blood Oxygenation ◽  
Ultra High Field ◽  
Feedback Information ◽  
Oxygenation Level ◽  
Early Visual Cortex ◽  
Magnetic Resonance Imaging Mri ◽  
And Function ◽  
The Relationship

AbstractAdvancements in ultra-high field (7 T and higher) magnetic resonance imaging (MRI) scanners have made it possible to investigate both the structure and function of the human brain at a sub-millimeter scale. As neuronal feedforward and feedback information arrives in different layers, sub-millimeter functional MRI has the potential to uncover information processing between cortical micro-circuits across cortical depth, i.e. laminar fMRI. For nearly all conventional fMRI analyses, the main assumption is that the relationship between local neuronal activity and the blood oxygenation level dependent (BOLD) signal adheres to the principles of linear systems theory. For laminar fMRI, however, directional blood pooling across cortical depth stemming from the anatomy of the cortical vasculature, potentially violates these linear system assumptions, thereby complicating analysis and interpretation. Here we assess whether the temporal additivity requirement of linear systems theory holds for laminar fMRI. We measured responses elicited by viewing stimuli presented for different durations and evaluated how well the responses to shorter durations predicted those elicited by longer durations. We find that BOLD response predictions are consistently good predictors for observed responses, across all cortical depths, and in all measured visual field maps (V1, V2, and V3). Our results suggest that the temporal additivity assumption for linear systems theory holds for laminar fMRI. We thus show that the temporal additivity assumption holds across cortical depth for sub-millimeter gradient-echo BOLD fMRI in early visual cortex.

EEG-correlates of work efficiency level among young persons with stress-induced bruxism

2021 ◽  
pp. 25-29
Author(s):  
A. E. Barulin ◽  
S. V. Klauchek ◽  
A. E. Klauchek
Keyword(s):  
Regression Models ◽  
Alpha Rhythm ◽  
Negative Relationship ◽  
Maximum Amplitude ◽  
Dominant Frequency ◽  
Regression Equations ◽  
Microsoft Excel ◽  
The Subject ◽  
Males And Females ◽  
The Relationship

Purpose of the study. To establish the relationship between neurophysiological status and the level of efficiency in young people with bruxism.Materials and methods. Two groups of 64 and 53 subjects (males and females) aged 20–35 years old with bruxism and non-bruxers were formed according to questionnaire results and physical examination. The level of efficiency was assessed by the results of sensorimotor tracking of a moving object (the ‘Smile’ model). Spectral analysis was performed for evaluation of the baseline electroencephalograms. Microsoft Excel and Statistica 10.0 programs were used for statistical data processing.Results. The level of efficiency was statistically significantly lower in the hardest test of Smile model among the individuals with bruxism (p < 0.05). The bruxers also demonstrated a significantly lower dominant frequency and maximum amplitude of alpha-rhythm (p < 0.05), and significantly higher dominant frequency of beta2 rhythm (p < 0.05). The dominant frequency and the maximum amplitude of the alpha-rhythm are parameters corresponding to significant coefficients of the regression analysis. A negative relationship was found between the degree of error during sensorimotor tracking and the frequency and amplitude of alpha-rhythm.Conclusion. Regression models present the relationship between the level of efficiency and the alpha-rhythm severity. The regression equations make it possible to determine the functional state of the subject using an electroencephalogram.

scholarly journals The Neural Representational Space of Social Memory

Open Mind ◽  
2019 ◽  
Vol 3 ◽  
pp. 1-12 ◽  
Author(s):  
Sarah L. Dziura ◽  
James C. Thompson
Keyword(s):  
Social Networks ◽  
Incidental Learning ◽  
Multivariate Pattern Analysis ◽  
Temporoparietal Junction ◽  
Representational Space ◽  
Analysis Technique ◽  
The Social ◽  
Multivariate Pattern ◽  
The Relationship ◽  
The Brain

Social functioning involves learning about the social networks in which we live and interact; knowing not just our friends, but also who is friends with our friends. This study utilized an incidental learning paradigm and representational similarity analysis (RSA), a functional MRI multivariate pattern analysis technique, to examine the relationship between learning social networks and the brain’s response to the faces within the networks. We found that accuracy of learning face pair relationships through observation is correlated with neural similarity patterns to those pairs in the left temporoparietal junction (TPJ), the left fusiform gyrus, and the subcallosal ventromedial prefrontal cortex (vmPFC), all areas previously implicated in social cognition. This model was also significant in portions of the cerebellum and thalamus. These results show that the similarity of neural patterns represent how accurately we understand the closeness of any two faces within a network. Our findings indicate that these areas of the brain not only process knowledge and understanding of others, but also support learning relations between individuals in groups.

scholarly journals Analisis Shear Strain dan Kerusakan Bangunan Akibat Gempa Bumi di Kecamatan Gading Cempaka dan Ratu Agung Kota Bengkulu

2018 ◽  
Vol 2 (2) ◽  
pp. 222-226
Author(s):  
Kurnia Lestari ◽  
Muchammad Farid ◽  
Afrizal Mayub
Keyword(s):  
Shear Strain ◽  
Land Surface ◽  
Amplification Factor ◽  
Dominant Frequency ◽  
Building Damage ◽  
Entire Area ◽  
Hvsr Method ◽  
Geological Formation ◽  
Formation Type ◽  
The Relationship

ABSTRACT  [The Analysis of Shear Strain and Building Damage due to Earthquake at Gading Cempaka and Ratu Agung District in Bengkulu City]. The aims of this research are to: (1) determine and mapping the distribution of shear strain values, (2) correlate between shear strains with building damage Gading Cempaka and Ratu Agung caused by earthwuake at sub district in Bengkulu city. Microtremor data were taken at 108 observation points then analyzed using HVSR method to obtain amplification factor and dominant frequency values..The result showed that shear strain value of Gading Cempaka and Ratu Agung sub district in Bengkulu city are relatively heterogeneous although in the same geological formation type. The earthquake in 2007 is estimated to be 3.38% potential to deform the land surface in the form of fractures and settlements and 96, 62% potentially experience shocks due to waves and vibrations due to earthquake. The earthquake of 2000 estimated that almost the entire area of Gading Cempaka and Ratu Agung has the potential to experience shocks due to waves and vibrations due to earthquake that is equal to 97% while potentially liquefaction (ambles) occurs by 3%. The correlation between shear strain with the damage of buildings due to earthquake shows the relationship is directly proportional to the function y = 15267x + 26.219 with the coefficient of resgression of    = 0.671. Keywords:  Earthquake;  HVSR method;  microtremor;  shear strain.

The Relationship Between Electrogram Cycle Length and Dominant Frequency in Patients with Persistent Atrial Fibrillation

2009 ◽  
Vol 20 (12) ◽  
pp. 1336-1342 ◽  
Author(s):  
SHELDON M. SINGH ◽  
E. KEVIN HEIST ◽  
JACOB S. KORUTH ◽  
CONOR D. BARRETT ◽  
JEREMY N. RUSKIN ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Cycle Length ◽  
Persistent Atrial Fibrillation ◽  
Dominant Frequency ◽  
The Relationship

Orientation Encoding and Viewpoint Invariance in Face Recognition: Inferring Neural Properties from Large-Scale Signals

2018 ◽  
Vol 24 (6) ◽  
pp. 582-608 ◽  
Author(s):  
Fernando M. Ramírez
Keyword(s):  
Face Recognition ◽  
Visual Processing ◽  
Large Scale ◽  
Bilateral Symmetry ◽  
Distributed Network ◽  
Face Area ◽  
Orientation Information ◽  
Orientation Perception ◽  
Multivariate Pattern

Viewpoint-invariant face recognition is thought to be subserved by a distributed network of occipitotemporal face-selective areas that, except for the human anterior temporal lobe, have been shown to also contain face-orientation information. This review begins by highlighting the importance of bilateral symmetry for viewpoint-invariant recognition and face-orientation perception. Then, monkey electrophysiological evidence is surveyed describing key tuning properties of face-selective neurons—including neurons bimodally tuned to mirror-symmetric face-views—followed by studies combining functional magnetic resonance imaging (fMRI) and multivariate pattern analyses to probe the representation of face-orientation and identity information in humans. Altogether, neuroimaging studies suggest that face-identity is gradually disentangled from face-orientation information along the ventral visual processing stream. The evidence seems to diverge, however, regarding the prevalent form of tuning of neural populations in human face-selective areas. In this context, caveats possibly leading to erroneous inferences regarding mirror-symmetric coding are exposed, including the need to distinguish angular from Euclidean distances when interpreting multivariate pattern analyses. On this basis, this review argues that evidence from the fusiform face area is best explained by a view-sensitive code reflecting head angular disparity, consistent with a role of this area in face-orientation perception. Finally, the importance is stressed of explicit models relating neural properties to large-scale signals.

Removing vibrator‐induced correlation artifacts by filtering in frequency‐uncorrelated time space

Geophysics ◽  
1992 ◽  
Vol 57 (7) ◽  
pp. 916-926 ◽  
Author(s):  
David A. Okaya ◽  
Eleni Karageorgi ◽  
Thomas V. McEvilly ◽  
Peter E. Malin
Keyword(s):  
Dominant Frequency ◽  
Two Dimensional ◽  
Spectral Filtering ◽  
Linear Rate ◽  
First Order ◽  
Fourier Frequency ◽  
Time Space ◽  
Extended Range ◽  
Energy Application ◽  
The Relationship

Vibrator‐to‐ground coupling can produce resonance‐induced energy that propagates with the primary sweep and produces serious artifacts in the correlated seismogram due to the frequency structure of this offending energy. For sweeps linearly increasing in frequency, the resulting artifact is observed (uncorrelated) to increase in frequency at a linear rate differing from the original sweep. Upon crosscorrelation with the pilot sweep, the artifact‐producing energy becomes distributed over an extended range of time while the normal reflected sweep is compressed, by design, into a narrow correlation wavelet. The resulting traces thus exhibit strong amplitudes that increase monotonically in dominant frequency. Display of individual uncorrelated seismograms using a Fourier frequency‐uncorrelated time (F-T) transformation reveals the relationship between the primary sweep and the induced artifact. “Surgical” filtering in this new F-T space provides for a first‐order removal of both the artifact and the energy in sweep harmonics as induced by the stong first arrivals. Two‐dimensional (2-D) spectral filtering of the modulus of the (complex) 2-D transform of the F-T data provides better rejection of the unwanted energy. Application of this trace‐by‐trace filtering process to a badly contaminated crustal-scale multichannel CDP profile in the southern San Joaquin Valley, California, reveals significant reflections from the middle and lower crust that were obscured in the unfiltered profile.

Mating call characteristics of hybrid toads (Bufo americanus × B. fowleri) at Long Point, Ontario

1982 ◽  
Vol 60 (12) ◽  
pp. 3293-3297 ◽  
Author(s):  
David M. Green
Keyword(s):  
Pulse Rate ◽  
Dominant Frequency ◽  
Pulse Number ◽  
Bufo Americanus ◽  
Call Duration ◽  
Mating Call ◽  
Intermediate Morphology ◽  
Laryngeal Cartilages ◽  
Northern Shore ◽  
The Relationship

The mating calls of the toads Bufo americanus, B. fowled, and their natural hybrids were recorded in May 1981 at Long Point, Ontario, on the northern shore of Lake Erie. The calls of the two species differed substantially in pulse rate and call duration but much less so in terms of dominant frequency. The numbers of pulses per call were not significantly different. Calls of hybrids were intermediate in character. Values for pulse rate, call duration, and dominant frequency agreed with those previously described. The relationship between pulse rate and call duration is hyperbolic as pulse number appears to be relatively constant. The differences in the calls of B. americanus and B. fowled appear to be fundamentally due to mechanical properties of the pulse modulating apparatus of the larynx. The characteristics of the calls of the hybrids may be due to intermediate morphology of the laryngeal cartilages that modulate the pulses of a call.

scholarly journals Development of an on-site system for measuring the low-frequency noise and complainant’s responses

2018 ◽  
Vol 37 (2) ◽  
pp. 373-384
Author(s):  
Hiroshi Sato ◽  
Jongkwan Ryu ◽  
Kenji Kurakata
Keyword(s):  
Time Trends ◽  
Sound Pressure ◽  
Low Frequency ◽  
Dominant Frequency ◽  
Pressure Level ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Measurement Results ◽  
Frequency Components ◽  
The Relationship

An on-site system for measuring low-frequency noise and complainant's responses to the low-frequency noise was developed to confirm whether the complainant suffer from the environmental noise with low-frequency components. The system suggests several methods to find the dominant frequency and major sound pressure level spectrum of the noise causing annoyance. This method can also yield a quantified relationship (correlation coefficient and percentage of response to the noise) between physical noise properties and the complainant’s responses. The advantage of this system is that it can easily find the relationship between the complainant’s response to the acoustic event of the houses and the physical characteristics of the low-frequency noise, such as the time trends and frequency characteristics. This paper describes the developed system and provides an example of the measurement results.

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