Showing papers on "Aging brain published in 1976"

Average Evoked Response (AER) in the Electroencephalographic Diagnosis of the Normally Aging Brain: A Practical Application

Abstract: There are two major methods of assessment of the electrical activity of the brain. The first method consists of evaluation of the frequency composition, amplitude, symmetry and morphological features of the spontaneous electroencephalogram (EEG). The second method consists of evaluation of the waveshape and symmetry of the characteristic transient electrical oscillations, or evoked potentials, produced by various brain regions in response to the presentation of specific stimuli in different sensory modalities. These two kinds of phenomena, the EEG and the evoked potential, provide unique insights into the structural and functional integrity of the brain, into the dynamic interactions between different brain regions, and into the physiological processes which are involved in the encoding, transmission and analysis of information by the brain. A steadily growing body of literature documents the sensitivity and utility of these electrophysiological measures for the diagnosis of brain damage or dysfunction. A portion of this accumulated knowledge describes the changes which have been found in these measures with aging. Naturally, as it was realized that the EEG and the evoked potential changed with maturation and aging, it became of interest to search for features of brain electrical activity which might distinguish between normal old persons and patients with senile dementia or chronic brain syndrome. Evaluations of the electrical activity of the brain performed by visual-manual examination of the complex diversity of electrical phenomena produce an unmanagably voluminous quantity even in brief recording sess·ions. Many studies, for example those of Berqer l , Surwillo \". Obrist and Busse I , Muller, Grad, and Kra1 4 , Muller and Grad 5 and a host of others too numerous to review, led to the generally accepted conclusion that aged subjects tended to show slowing of the alpha rhythm and a diffuse increase of delta waves in various head regions. Shertdon s and his co-workers have presented evidence showing that such slowing of the EEG in the aged is usually correlated with arteriosclerotic changes. Deisenhammer, Hofer and Jellinqer? found that many aged patients with EEG slowing displayed cerebral atrophy. In general, persistence of fast activity in the EEG was correlated with good performance in the more difficult psychological and cognitive tasks. A relatively small subset of the EEG literature on changes accompanying aging has been concerned with features specifically related to cognitive impairment and the senile psychoses. Mundy-Castle and his colleoquesf reported a diffuse increase in delta activity in the senile psychoses, but failed to demonstrate any distinctive difference between this increase in slow waves and the increase usually found to accompanyaging.