Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Oscillatory potentials of the slow-sequence multifocal ERG in primates extracted using the Matching Pursuit method.

ABSTRACT: This study used the Matching Pursuit (MP) method, a time-frequency analysis, to identify and characterize oscillatory potentials (OPs) in the primate electroretinogram (ERG). When the slow-sequence mfERG from the macular region of the retina was matched with Gabor functions, OPs were identified in two distinct bands: a high-frequency band peaking around 150 Hz that contributes to early OPs, and a low-frequency band peaking around 80 Hz that contributes to both early and late OPs. Pharmacological blockade and experimental glaucoma studies showed that the high-frequency OPs depend upon sodium-dependent spiking activity of retinal ganglion cells, whereas the low-frequency OPs depend primarily upon non-spiking activity of amacrine cells, and more distal retinal activity.

SUBMITTER: Zhou W

PROVIDER: S-EPMC2072998 | biostudies-literature | 2007 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Oscillatory potentials of the slow-sequence multifocal ERG in primates extracted using the Matching Pursuit method.

Zhou Wei W Rangaswamy Nalini N Ktonas Periklis P Frishman Laura J LJ

Vision research 20070523 15

This study used the Matching Pursuit (MP) method, a time-frequency analysis, to identify and characterize oscillatory potentials (OPs) in the primate electroretinogram (ERG). When the slow-sequence mfERG from the macular region of the retina was matched with Gabor functions, OPs were identified in two distinct bands: a high-frequency band peaking around 150 Hz that contributes to early OPs, and a low-frequency band peaking around 80 Hz that contributes to both early and late OPs. Pharmacological ...[more]

PMID: 17512027

Similar Datasets

Multifocal ERG findings in carriers of X-linked retinoschisis.

Project description:To determine whether retinal dysfunction in obligate carriers of X-linked retinoschisis (XLRS) could be observed in local electroretinographic responses obtained with the multifocal electroretinogram (mfERG).Nine obligate carriers of XLRS (mean age, 46.2 years) were examined for the study. Examination of each carrier included an ocular examination and mfERG testing. For the mfERG, we used a 103-scaled hexagonal stimulus array that subtended a retinal area of approximately 40 degrees in diameter. The amplitudes and implicit times in each location for the mfERG were compared with the corresponding values determined for a group of 34 normally-sighted, age-similar control subjects.Mapping of 103 local electroretinographic response amplitudes and implicit times within a central 40 degrees area with the mfERG showed regions of reduced mfERG amplitudes and delayed implicit times in two of nine carriers.The mfERG demonstrated areas of retinal dysfunction in two carriers of XLRS. When present, retinal dysfunction was evident in the presence of a normal-appearing fundus. Multifocal ERG testing can be useful for identifying some carriers of XLRS.

| S-EPMC1784540 | biostudies-other

Assessing amblyopia treatment using multifocal visual evoked potentials.

Project description:BackgroundTo evaluate the effect of occlusion treatment for anisometropic amblyopia using multifocal visual evoked potentials (mfVEPs).MethodsThe patients for this study comprised 19 patients (mean age 6.05 ± 1.65 years) with anisometropic amblyopia underwent mfVEP analysis using the RETIscan® system before and after occlusion treatment. After dividing the area into six ring areas and four quadrants, we analyzed the amplitudes and latencies of the mfVEPs.ResultsThe amplitudes of ring 1 (central field) in amblyopic eyes after treatment were significantly higher than those in the other rings (p = 0.001). The mfVEP amplitudes in each of the six rings between amblyopic eyes and fellow eyes at diagnosis and after occlusion treatment showed no significant differences. In quadrant 1 the amplitudes of the amblyopic eyes and fellow eyes were significantly different at the time of diagnosis (p = 0.005), whereas after occlusion treatment there was no significant difference (p = 0.888). The amplitudes for each of the six rings at diagnosis and after occlusion treatment in amblyopic eyes versus fellow eyes showed no significant difference. There were also no differences in the amplitudes in each of the four quadrants at the time of diagnosis and after occlusion treatment in amblyopic eyes versus fellow eyes. No significant difference was found in the comparison of latency values in each of the six rings or in each of the four quadrants at diagnosis and after occlusion treatment in amblyopic eyes versus their fellow eyes.ConclusionsThe amplitudes of quadrant 1 in amblyopic eyes compared with those of the fellow eyes at diagnosis were increased after occlusion treatment. Changes of the difference between amblyopic eyes and fellow eyes in quadrant 1 after occlusion treatment could be a useful, objective method for monitoring improvement in visual acuity.

| S-EPMC6090668 | biostudies-literature

Multifocal visual evoked potentials in chronic inflammatory demyelinating polyneuropathy.

Project description:ObjectiveStudies using conventional full-field visual evoked potentials (ffVEP) have reported subtle abnormalities in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). We hypothesize that these abnormalities can be detected in the majority of CIDP patients using enhanced methods.MethodsWe performed a cross-sectional noninterventional study comparing 18 CIDP patients and 18 matched healthy controls using multifocal VEP (mfVEP) as a technique with enhanced sensitivity to detect conduction abnormalities across the spectrum of optic nerve fibers. Patients with confounding diseases (ophthalmologic, diabetes mellitus) were excluded.ResultsThe mean amplitude and latency, as well as the low-contrast visual acuity, did not differ between CIDP patients and controls. Subanalyses revealed latency differences concerning the superior sector of the visual field. Severity markers of CIDP (ODSS, motor nerve conduction velocity) were associated with mfVEP latency delay.InterpretationWe could not adduce evidence for clinically or diagnostically relevant visual pathway involvement in CIDP. The latency differences identified were very subtle and restricted to the superior visual field which cannot be readily explained biologically, anatomically, or pathologically. In summary, we conclude that our study revealed no relevant differences in mfVEP parameters between CIDP patients and controls.

| S-EPMC6093840 | biostudies-literature

Simultaneous spatio-temporal matching pursuit decomposition of evoked brain responses in MEG.

Project description:We present a novel approach to the spatio-temporal decomposition of evoked brain responses in magnetoencephalography (MEG) aiming at a sparse representation of the underlying brain activity in terms of spatio-temporal atoms. Our approach is characterized by three attributes which constitute significant improvements with respect to existing approaches: (1) the spatial and temporal decomposition is addressed simultaneously rather than sequentially, with the benefit that source loci and corresponding waveforms can be unequivocally allocated to each other, and, hence, allow a plausible physiological interpretation of the parametrized data; (2) it is free from severe a priori assumptions about the solution space; (3) it comprises an optimization technique for the use of very large spatial and temporal subdirectories to greatly reduce the otherwise enormous computational cost by making use of the Cauchy-Schwarz inequality. We demonstrate the efficiency of the approach with simulations and real MEG data obtained from a subject exposed to a simple auditory stimulus.

| S-EPMC5326632 | biostudies-literature

Orientational potentials extracted from protein structures improve native fold recognition.

Project description:We develop coarse-grained, distance- and orientation-dependent statistical potentials from the growing protein structural databases. For protein structural classes (alpha, beta, and alpha/beta), a substantial number of backbone-backbone and backbone-side-chain contacts stabilize the native folds. By taking into account the importance of backbone interactions with a virtual backbone interaction center as the 21st anisotropic site, we construct a 21 x 21 interaction scheme. The new potentials are studied using spherical harmonics analysis (SHA) and a smooth, continuous version is constructed using spherical harmonic synthesis (SHS). Our approach has the following advantages: (1) The smooth, continuous form of the resulting potentials is more realistic and presents significant advantages for computational simulations, and (2) with SHS, the potential values can be computed efficiently for arbitrary coordinates, requiring only the knowledge of a few spherical harmonic coefficients. The performance of the new orientation-dependent potentials was tested using a standard database of decoy structures. The results show that the ability of the new orientation-dependent potentials to recognize native protein folds from a set of decoy structures is strongly enhanced by the inclusion of anisotropic backbone interaction centers. The anisotropic potentials can be used to develop realistic coarse-grained simulations of proteins, with direct applications to protein design, folding, and aggregation.

| S-EPMC2280067 | biostudies-literature

Dissipative self-assembly of particles interacting through time-oscillatory potentials.

Project description:Dissipative self-assembly is the emergence of order within a system due to the continuous input of energy. This form of nonequilibrium self-organization allows the creation of structures that are inaccessible in equilibrium self-assembly. However, design strategies for dissipative self-assembly are limited by a lack of fundamental understanding of the process. This work proposes a novel route for dissipative self-assembly via the oscillation of interparticle potentials. It is demonstrated that in the limit of fast potential oscillations the structure of the system is exactly described by an effective potential that is the time average of the oscillatory potential. This effective potential depends on the shape of the oscillations and can lead to effective interactions that are physically inaccessible in equilibrium. As a proof of concept, Brownian dynamics simulations were performed on a binary mixture of particles coated by weak acids and weak bases under externally controlled oscillations of pH. Dissipative steady-state structures were formed when the period of the pH oscillations was smaller than the diffusional timescale of the particles, whereas disordered oscillating structures were observed for longer oscillation periods. Some of the dissipative structures (dimers, fibers, and honeycombs) cannot be obtained in equilibrium (fixed pH) simulations for the same system of particles. The transition from dissipative self-assembled structures for fast oscillations to disordered oscillating structures for slow oscillations is characterized by a maximum in the energy dissipated per oscillation cycle. The generality of the concept is demonstrated in a second system with oscillating particle sizes.

| S-EPMC4103377 | biostudies-literature

Multifocal visual evoked potentials are influenced by variable contrast stimulation in MS.

Project description:ObjectiveTo test the hypothesis that patients with multiple sclerosis (MS) with intereye asymmetry on low contrast letter acuity, and thickness of the retinal nerve fiber layer (RNFL), would exhibit corresponding changes in cortical timing and amplitude responses on pattern reversal multifocal visual evoked potentials (mfVEP), contingent upon variable stimulus contrast.MethodsIn a cross-sectional study, we investigated a cohort of 11 normal subjects and 40 patients with MS, 21 of whom had a history of acute optic neuritis (MS-AON) with an intereye asymmetry with respect to RNFL thickness, and on low contrast letter acuity performance. Pattern reversal mfVEP was performed at high (100%), low (33.3%), and very low (14.2%) Michelson-contrast levels.ResultsCompared to baseline measures at 100% contrast, the mean amplitude of the mfVEP was reduced in MS-AON eyes, upon pattern-reversal stimulation at the 2 lower contrast levels (p < 0.0001). With respect to changes in timing responses, the intereye asymmetry was increased in the MS-AON patients upon lower contrast pattern-reversal stimulation (p < 0.0001 for 33.3% compared to 100%, and p < 0.001 for 14.2% compared to 100%). The fellow eye in 12 (57%; p < 0.001) of the patients with an abnormal eye, and a history of AON, revealed abnormal amplitude and timing responses upon low contrast stimulation (signifying unmasking of occult damage).ConclusionsOur findings support the hypothesis that mfVEP metric abnormalities are contingent upon contrast magnitude during pattern reversal stimulation. Further, this paradigm was capable of unmasking occult abnormalities in a significant number of apparently unaffected eyes.

| S-EPMC4098874 | biostudies-literature

Digestion treatment of uscfDNA extracted by QiaM Method

Project description:We report the application of an uscfDNA-oriented sequencing pipeline profiling the cell-free DNA populations in plasma. The uscfDNA sequencing pipeline include two uscfDNA-optimized extraction methods (QiaM and SPRI) and one control extraction method (QiaC). Final libraries are made with a single-stranded library prepartion kit. We generate genome-wide maps revealing the presence of an uscfDNA population (25-99bp) in addition to the mncfDNA (100-250bp).

2022-05-10 | GSE202431 | GEO

Digestion treatment of uscfDNA extracted by SPRI Method

2022-05-10 | GSE202432 | GEO

Oscillatory characteristics of the visual mismatch negativity: what evoked potentials aren't telling us.

Project description:The visual mismatch negativity (vMMN) response is typically examined by subtracting the average response to a deviant stimulus from the response to the standard. This approach, however, can omit a critical element of the neural response, i.e., the non-phase-locked ("induced") oscillatory activity. Recent investigations of the oscillatory characteristics of the auditory mismatch negativity (aMMN) identified a crucial role for theta phase locking and power. Oscillatory characteristics of the vMMN from 39 healthy young adults were investigated in order to establish whether theta phase locking plays a similar role in the vMMN response. We explored changes in phase locking, overall post-stimulus spectral power as well as non-phase-locked spectral power compared to baseline (-300 to 0 ms). These were calculated in the frequency range of 4-50 Hz and analysed using a non-parametric cluster based analysis. vMMN was found intermittently in a broad time interval 133-584 ms post-stimulus and was associated with an early increase in theta phase locking (75-175 ms post-stimulus) that was not accompanied by an increase in theta power. Theta phase locking in the absence of an increase in theta power has been associated with the distribution and flow of information between spatially disparate neural locations. Additionally, in the 450-600 ms post-stimulus interval, deviant stimuli yielded a stronger decrease in non-phase-locked alpha power than standard stimuli, potentially reflecting a shift in attentional resources following the detection of change. The examination of oscillatory activity is crucial to the comprehensive analysis of a neural response to a stimulus, and when combined with evoked potentials (EPs) provide a more complete picture of neurocognitive processing.

| S-EPMC3729976 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data