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Biomedical subjects

J J Brickley

Publications and source records attributed to J J Brickley.

7 recordsLinked to original sources
PubMed1984

Reversible visual evoked potential abnormalities in vitamin E deficiency.

A patient with cystic fibrosis and cirrhosis developed a progressive neurological syndrome associated with ataxia, proximal weakness, and ophthalmoplegia. Profound deficiencies of vitamins A, D, and E were present. Visual acuity and results of retinal funduscopy were normal. The pattern reversal visual evoked potential was initially abnormal (P100 latency, 136 and 130 ms from left and right eyes, respectively) but became normal (less than 3 standard deviations from mean control P100 latency) over a two-month period when vitamin E was administered. This case documents a potentially reversible visual evoked potential abnormality in a visually asymptomatic patient with vitamin E deficiency.

Adult↗
PubMed1982

Evaluation of digital image enhancement techniques for liver scintigrams.

Digital image enhancement techniques were employed in an effort to improve the resolution of Anger camera liver images. The premise employed was that methods which improve lesion detectability in liver phantoms should also do so in actual liver scintigrams. The types of image processing evaluated were: contrast enhancement, finite and infinite impulse response, modulation transfer function correction, homomorphic and median filtering. Observers were used to evaluate each method for its ability to improve lesion detectability using a five category rating system. The Localization Receiver Operating Characteristic (LROC) curve was used as the primary rank ordering method. A point system and analysis of variance were used as corroborative methods, incorporating measures of accuracy and consistency of the observers' answers.

Humans↗
PubMed1980

Visual evoked potentials to stimulus trains: normative data and application to photosensitive seizures.

Visual evoked potentials (VEPs) to intermittent flash trains of various stimulus frequencies (VEP-T) were studied in 10 normal subjects and in 10 patients with photosensitive generalized seizures, 5 on medication and another 5 subjects without medication. In the normal group, early negative peaks were consistently demonstrated at 71 +/- 8 msec for monocular stimuli and 67 +/- 9 msec for binocular stimuli, regardless of different frequencies of stimuli. An oscillatory potential, poststimulus continuation of the oscillatory activity and damping out within 100 msec followed the initial peaks. The RMS values of the response epochs were stable and demonstrated consistent temporal changes at each stimulation frequency. In photoconvulsive seizures, the responses were facilitated with most marked changes over the second and third 125 msec epoch of the VEP-Ts with late slow negative deflections in some cases. These changes were pronounced in patients who were not taking anticonvulsant medication, but were not significantly different than controls in patients whose seizures were controlled with medication. It is suggested that the VEP-T is a more effective technique than single flash stimuli in consistently identifying early significant peaks and demonstrating neuronal excitability changes within the visual system.

Adolescent↗
PubMed1980

A multivariable evoked potential measure applied to human epilepsy.

Based upon a three-dimensional plot (response plane) representing a condensation of human sensory evoked potential data obtained from a paired stimulus protocol, a study was undertaken to investigate electrophysiological changes following sodium valproate administration in subjects with photosensitive epilepsy. Initial results in two patients and two normal subjects suggest that the measure is reproducible and sensitive to electrophysiological changes accompanying anticonvulsant administration.

Adult↗
PubMed1979

Cerebellar stimulation: regional effects on a thalamocortical system.

Regional effects of electrical stimulation of the cerebellar surface were quantitatively analyzed. Computer controlled stimulus sequences were delivered to ventrolateral thalamus and evoked responses recorded from ipsilateral sensorimotor cortex in the cat. Threshold and excitability profiles were produced with an on-line computer, and their modification by cerebellar stimulation was determined. The results of electrical stimulation of the cerebellar surface were: (1) depressed excitability from paramedian lobule and lobulus simplex; (2) uniquely elevated thresholds from paramedian lobule; and (3) a profound and long-lasting depression of excitability following termination of lobulus simplex stimulation. In comparison with our anticonvulsant drug studies, these data suggest that cerebellar surface stimulation has a far greater capacity to control excitability and threshold responsiveness of thalamocortical systems. Cerebellar electrode placement and temporal pattern of stimulation appear to be important factors in the production of antiepileptic effects.

Animals↗
PubMed1977

Effects of antiepileptic drugs on thalamocortical excitability.

Comparative effects of anticonvulsant drugs on the thalamocortical system were analyzed quantitatively. Paired stimuli were delivered to the ventrolateral thalamus with evoked responses recorded from the ipsilateral sensorimotor cortex in the cat. Threshold and excitability profiles were developed with an on-line computer. Effects of phenytoin and diazepam were generally similar, with depression of excitability and slight elevation of thresholds. Ethosuximide produced a pronounced pair-interval dependent effect of unchanged or increased excitability and lowered threshold at shorter intervals, with depressed excitability and raised threshold at longer intervals. These data demonstrate a marked difference in effect of the petit mal and grand mal agents tested and suggest a basis for the effectiveness of ethosuximide in controlling 3-per-second repetitive activity.

Animals↗