The electroencephalogram and mental activation.

Abstract

The mental activation (MA) is a simple test consisting of two questions and two commands given during the waking record. The responses are documented by + or - sign notations made by the technologist. In this manner, data were rapidly obtained from 1280 patients; there were 598 patients with EEG records within normal limits and 682 with various degrees of EEG abnormality. The MA serves the following purposes: a. to study the repercussions of the test on the EEG activity, b. to ascertain the optimal level of vigilance, c. to attempt a correlation of MA responses and the degree of EEG abnormality and d. to obtain brief information on the patient's mental state. The test is administered during conventional EEG recordings. It was found that alpha blocking or attenuation was the exception rather than the rule during the test. Diffuse and focal slowing also remained unchanged in the vast majority of the cases, whereas focal intermittent rhythmical delta activity (FIRDA) was blocked or reduced in most patients exhibiting this pattern. Epileptic conditions were also studied and it was found that, in a single observation, even the most difficult part of the test (item D: mental arithmetic) could be carried out during ictal-subclinical regional EEG activity.