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Evidence is presented that a neurophysiologically-inspired mathematical model, originally developed for the generation of spontaneous EEG (electroencephalogram) activity, can produce VEP (visual evoked potential)-like waveforms when pulse-like signals serve as input. It was found that the simulated VEP activity was mainly due to intracortical excitatory(More)
The relationship between the latencies and amplitudes of the N1 and P2 components of the visual evoked potential (VEP) and the psychophysiological state of the brain immediately preceding the time of the stimulus has been investigated in 7 male subjects. Power spectral measures in the delta, theta, alpha and beta bands of the 1 sec pre-stimulus EEG were(More)
The pathogenic spirochete Borrelia burgdorferi contains a set of integral membrane proteins which were selectively extracted into the detergent phase upon solubilization of intact B. burgdorferi with the nonionic detergent Triton X-114. Virtually all of these hydrophobic proteins were recognized by antibodies in pooled sera from patients with chronic Lyme(More)
Root-mean-square (RMS) amplitude derived from power spectral measures in the alpha band of the 1 s prestimulus EEG were related to the peak-to-peak amplitude of the N1 and P2 components (N1P2PP) of the visual evoked potential (VEP) in 7 male subjects. Stimuli were low intensity flashes delivered randomly between 2 and 6 whole seconds. Trials were rank(More)
An algorithm and set of procedures for measuring volumes of cerebrospinal fluid (CSF), white matter, and gray matter from transaxial magnetic resonance images (MRI) of the brain are described. The algorithm is a variant of the fuzzy c-means clustering method for texture identification. This technique is used mainly to solve the problem of volume averaging(More)
There is an increasing need for in vitro testing of compounds for topical application. Reconstructed epidermal models may provide a suitable and relevant model for screening compounds that may affect the activities of phase I and II enzymes involved in epidermal detoxification. In this study, we measured the activity of a phase I enzyme, cytochrome P450(More)
  • M E Brandt
  • 1997
An increasing number of studies over the last decade or so have suggested that evoked potential (EP) morphology is partially due to a reorganization of the phase of the ongoing EEG. Phase resetting is common to non-linear oscillatory systems in response to a perturbation and has been observed in a number of biological systems such as circadian rhythms and(More)
OBJECTIVE To determine whether children with shunted hydrocephalus show variations in regional brain tissue composition that relate to cognitive functions. DESIGN Nonequivalent control group. PATIENTS AND METHODS Magnetic resonance imaging (MRI) and cognitive skills assessments were obtained on 28 children, 6 to 9 years of age, with shunted(More)
Although children with hydrocephalus frequently show poor development of nonverbal cognitive skills relative to verbal skills, little is known about the neuropathologic correlates of these discrepancies. In this study, cerebral white-matter structures and lateral ventricles were measured from the magnetic resonance images of age-matched children with(More)
We used a diffusion tensor imaging-based whole-brain tissue segmentation to characterize age-related changes in (a) whole-brain grey matter, white matter, and cerebrospinal fluid relative to intracranial volume and (b) the corresponding brain tissue microstructure using measures of diffusion tensor anisotropy and mean diffusivity. The sample, a healthy(More)