Schedule of Events | Search Abstracts | Invited Symposia | Symposia | Rising Stars | Poster Sessions | Data Blitz

How Causal Are Language-Related fMRI Activations? Evidence from Awake Direct Electrocortical Stimulation (DES)

Poster Session A - Saturday, March 7, 3:00 – 5:00 pm, Fairview/Kitsilano Ballrooms

Berfin Gürcan^1,2 (berfingurcan27@gmail.com), Tamer Gezici^1,2, Özge Şengil, Burak Karaaslan⁴, Emrah Çeltikçi⁴, Murat Zinnuroğlu⁴, Güzide Atalık⁴, Ausaf Ahmed Farooqui^1,2,3; ¹Bilkent University, Ankara, Türkiye, ²Aysel Sabuncu Brain Research Center, Ankara, Türkiye, ³National Magnetic Resonance Research Center, Ankara, Türkiye, ⁴Gazi University, Ankara, Türkiye

Activation of a common set of frontotemporal regions during any kind of language processing is a well-replicated finding and has led to the characterization of the language network. However, the extent to which these regions are causally necessary is not fully understood. For patients with tumors near language regions, intraoperative direct electrocortical stimulation (DES) during awake surgery is the key to identifying brain regions causally needed for language ability. For eight right-handed brain-tumor patients (2 females; 19–48 years) undergoing awake surgery, we located fMRI activation blobs in the language network using a variety of language localizer tasks, then did DES on these and surrounding regions to quantify causal necessity. Across 98 cortical points stimulated with DES, 50 produced language deficits (51%). Of 38 DES stimulations delivered within fMRI activation clusters, including but not limited to those within the language network, 20 caused language impairment, indicating a positive predictive value of 52.6%. Of the 50 DES-positive points, 17 lay within fMRI activation blobs, yielding 34% sensitivity. We then limited our analysis to language network regions. Thirty-five stimulation sites lay within these regions, and 13 led to deficits (37.1% positive predictive value), and 13 of 41 DES-positive points fell within language-network clusters (31.7% sensitivity). Because this analysis was restricted to the language network regions, one patient had no DES-positive sites within these regions, so the analysis included 41 rather than 50 DES-positive points. We thus found that most fMRI activation blobs are not causally necessary, including blobs within the supposed language network.

Topic Area: LANGUAGE: Other