Cerebral Hemispheric Control of Speech during the Intracarotid Sodium Amytal Procedure: An Acoustic Exploration

In this study we investigated lateralized control of speech during the intracarotid amobarbital procedure. Vowel segments were extracted from recordings made during two separate amobarbital procedures and involving two patients. Subjects were right-handed, presented with focal left mesial temporal epileptogenic foci. Age of onset of seizure disorders was 1.5 years for one subject and 16 years for the other. Recorded pre- and postinjection speech samples were digitized. Analyses were conducted on formants 1 and 2 (F1, F2) measures to determine the extent of formant fluctuation in the time course of the IAP. Preliminary results showed, for these two cases, that the left hemisphere is involved in the control of both F1and F2and the right in the control of F2only. The data reveal the potential of coupling the IAP procedure and the acoustical analysis of speech in the study of cerebral control of speech.