Objective Examination of Verbal Discrimination and Comprehension in Aphasia Using the Contingent Negative Variation: A Pilot Study

Abstract

A negative ‘direct current’ (‘DC’) shift of the resting potential of the brain (expectancy wave, contingent negative variation [CNV]) is observed if two stimuli, first a ‘warning’ and then an ‘imperative’ stimulus, are presented to a subject at a given interval. By using two different word groups as ‘warning’ and ‘non-warning’ stimuli (e.g., group I: animals; group II: plants) and following only one group with a flash, the appearence of the CNV following only one group gives positive objective proof that the subject ‘understands’ the tested words. In aphasia this method gives objective evidence of verbal comprehension disorders. The author describe two cases. In one post-operative verbal comprehension recovered and so did the language-evoked response. In the other a perseveration phenomenon was demonstrated by language-evoked response audiometry (LERA).

Key Words:

• Electric Response Audiometry (ERA)
• Contingent Negative Variation (CNV)
• Aphasia
• Language evoked potentials