Driving activity. A quantitative study

A comparative study of driving activity between normal subjects and neurological patients was performed. Driving activity was considered as the energy of the visual evoked potentials filtered at the same frequency of stimulation (1, 2, 4, 7, 10, 12 and 15 cps) using a CAT 400 C computer as a digital filter. The hemispheric symmetry of the responses was measured by the Pearson product moment correlation coefficient and the signal energy ratio. Each symmetry measure for every patient was compared with the normal values and considered abnormal when differences were greater than 3 SD from the normal mean. Of 25 patients 14 of them with a normal EEG, 23 presented severe alterations in the symmetry of the filtered visual evoked responses. Each patient showed a peculiar pattern of abnormality. It is concluded that the procedure described is a very powerful method in the discrimination of brain lesions.