Search Abstracts | Symposia | Slide Sessions | Poster Sessions
How Causal Are Language-Related fMRI Activations?
Poster Session B, Wednesday, September 30, 4:30 - 6:30 pm, Wangari Maathai
Ausaf Farooqui1, Berfin Gurcan1, Tamer Gezici1, Guzide Atalık2, Burak Karaaslan2, Murat Zinnuroğlu2; 1Bilkent University, Turkiye, 2Gazi University, Turkiye
Activation of a common set of frontotemporal regions during language processing is a very reliable finding, and on this basis, neuroimaging studies have characterized a well-defined language network. However, the extent to which these regions are causally necessary remains unclear. For patients with tumors near language regions, intraoperative direct electrocortical stimulation (DES) during awake surgery is key to identifying brain regions causally required for language function. This stimulation temporarily disrupts the region around the stimulation site. If this region was causally needed for language ability, then patients would show immediate impairment in the ongoing language task. We identified fMRI activation peaks using a variety of language localizer tasks in 8 right-handed brain-tumor patients (2 females; 19–48 years) undergoing awake surgery, then performed DES on these and surrounding regions to assess their causal necessity. We stimulated a total of 98 cortical points, regardless of their location with respect to the language network and activation during language tasks. 50 (51%) of these produced language deficits. 38 stimulations were delivered to points that had shown significant language-related activation; 20 (52.6%) of these caused language impairments. We then limited our analysis to cortical sites that lay within the well-characterized frontotemporal language network. Of the 35 stimulation sites that lay within this network, 13 (31.7%) led to deficits. We thus found that regions that show significant activations during language processing are not always causally necessary for language. Notably, this was the case even when the stimulated regions lay within the frontotemporal language network identified in previous neuroimaging studies.
Topic Areas: Disorders: Acquired, Methods