Abstracts

Rationale: The rationale of our ECoG-based language mapping is to localize cortical sites showing augmentation of high-gamma activity70-110 Hz during a task in which patients listen to and overtly respond to sets of auditory questions. Based on the timing of high-gamma augmentation relative to stimulus presentation and response onset, ECoG-based mapping can localize cortical areas sequentially involved in auditory, cognitive, and motor functions. To our best knowledge, few standardized auditory stimuli have been available in the epilepsy surgery community. Here, we provide standardized stimuli, in an open-access manner, to investigators who are considering implementation of ECoG-based language mapping. Methods: We have created 100 auditory stimuli for each of English-, Arabic-, Hindi-, and Japanese-speaking patients. Specifications of stimuli are described below.  Results: Each stimulus consists of a 1.8-second sentence question articulated by female speakers; for example, ‘What flies in the sky?’ in each of the four languages. The patient is expected to answer each of the questions with an appropriate noun such as ‘Bird’ or ‘Plane’. Questions in English begin with either ‘What’, ‘When’, ‘Where’ or ‘Who’, and are also translated to Arabic, Hindi, and Japanese. We made our best effort to make the questions as universal and simple as possible so that patients can understand and answer them regardless of gender, age, culture, or religion. We designed all stimulus sets to work through Microsoft PowerPoint software; thus, most investigators can deliver auditory stimuli using a regular laptop computer. Patients are instructed to say: ‘I don’t know’, in case they fail to generate an answer in mind at any trial. For young children with limited vocabulary, we generally ask the family member to customize a set of personal questions likely to be answered by a given child; for example, ‘What is the name of your dog?’. We have been successful in conducting ECoG-based language mapping using our auditory naming task for children as young as 4 years old.  Conclusions: We hope that our auditory stimuli will be utilized for ECoG-based language mapping by several investigators across multiple countries and will further clarify the utility of event-related high-gamma activity in presurgical evaluation for children and adults with drug-resistant focal epilepsy.  Funding: NIH grant NS64033 (E. Asano)