Focused arousal and the cognitive 40-Hz event-related potentials: differential diagnosis of Alzheimer's disease

Focused arousal is a first-order energetic functional component of information processing, operative between sensory inputs and motor outputs. At the neural level of analysis, it represents a first-order interactive system of neural connectivity, providing a mechanism for the organization of unit specificities--coherent resonance at an optional periodicity in finite cell assemblies. Cognitive 40-Hz event-related potentials (CERP), loosely coupled with antecedent and concurrent stimuli, index the operation of focused arousal in circuitry convergent at parietal-temporal-occipital cortex. Methods are described for recording and computer-analyzing CERP, integrated with an automated behavioral testing procedure. The present report summarizes the results from a series of three studies where CERP was used to differentiate early Alzheimer patients from normal geriatrics, multi-infarct, and retarded depression patients. The three normal geriatric groups showed consistent task-dependent hemispheric lateralization. CERP was significantly higher in the left hemisphere with a verbal task, and in the right hemisphere, with a visual-spatial task. The Alzheimer patients showed no hemispheric lateralization and were markedly lower on CERP under all behavioral conditions, as compared with the normal geriatric, multi-infarct, and depression groups. Predictive efficiency of individual cases, differentiating Alzheimer patients from normal geriatrics, multi-infarct, and retarded depression patients, was 80 to 90 percent.