Biomedical subjects

John C Gore

Publications and source records attributed to John C Gore.

75 records · Page 5Linked to original sources

PubMed2002

A method for determinism in short time series, and its application to stationary EEG.

A novel method for detecting determinism in short time series is developed and applied to investigate determinism in stationary electroencephalogram (EEG) recordings. This method is based on the observation that the trajectory of a time series generated from a differentiable dynamical system behaves smoothly in an embedded state space. The angles between two successive tangent vectors in the trajectory reconstructed from the time series is calculated as a function of time. The irregularity of the angle variations obtained from the time series is estimated using second-order difference plots, and compared with that of the corresponding surrogate data. Using this method, we demonstrate that scalp EEG recordings from normal subjects do not exhibit a low-dimensional deterministic structure. This method can be useful for analyzing determinism in short time series, such as those from physiological recordings.

Adult↗

PubMed2002

A functional magnetic resonance imaging study of language processing and its cognitive correlates in prematurely born children.

OBJECTIVE: Abnormalities in brain structure, cognition, and behavior have been described in children born prematurely. However, no direct in vivo evidence has yet demonstrated abnormal neural processing in these children. Our aim was to compare brain activity associated with phonologic and semantic processing of language between term and preterm children using functional magnetic resonance imaging (fMRI). METHODS: fMRI scans were acquired during a passive language comprehension task in 26 preterm children at 8 years of age and in 13 term community control children who were comparable in age, sex, maternal education, and minority status. IQ was assessed using a standard measure of intelligence. RESULTS: The pattern of brain activity identified in a semantic processing task in the preterm children closely resembled the pattern of brain activity identified in a phonologic processing task in term controls. The greater this resemblance in the preterm children, the lower their verbal comprehension IQ scores and the poorer their language comprehension during the scanning task. CONCLUSIONS: Preterm children with the poorest language comprehension seemed not to fully engage normal semantic processing pathways in a language comprehension task. These children instead engaged pathways that normal term children used to process meaningless phonologic sounds. Aberrant processing of semantic content in these preterm children may account in part for their lower verbal IQ scores.

Benzophenones↗

PubMedDate not supplied

Modified oscillating gradient pulses for direct sampling of the diffusion spectrum suitable for imaging sequences.

A variation of the oscillating gradient spin echo method had been developed, which isolates temporal frequencies of the dephasing spectrum. This allows sampling of the diffusion spectrum, the Fourier transform of the velocity correlation function (VCF). It has been shown that restriction and flow alter this function in ways that can be mathematically characterized, yielding quantitative information on restriction geometry and flow parameters. It is demonstrated that in many systems of interest, dispersion of velocity will produce a peak in the VCF spectrum near omega=0, while restricted diffusion will manifest itself in the spectrum at higher frequencies. The method, therefore, may be useful for decoupling their effects on the apparent diffusion coefficient (ADC), as well as in revealing the physics of both phenomena. This method has been implemented in model systems of packed beads, yielding data consistent with theoretical models of restricted diffusion spectra and data from one previous study. The method may have significant application to biology and medicine, as well as the study of transport phenomena in porous media and complex flow.

Diffusion↗