Intracranial recordings reveal high-frequency activity in the human temporal-parietal cortex supporting non-literal language processing

Poster Session F - Tuesday, April 16, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Shweta Soni¹ (shwetanbrc@gmail.com), Jacqueline Overton², Julia W.Y. Kam^3,4, Penny Pexman³, Akshay Prabhu⁵, Nicholas Garza⁵, Ignacio Saez⁶, Fady Girgis^1,5; ¹Dept. of Clinical Neurosciences, University of Calgary, ²Depts. of Neuroscience and Psychiatry, Icahn School of Medicine, Mount Sinai, NY, ³Dept. of Psychology, University of Calgary, ⁴Hotchkiss Brain Institute, University of Calgary, ⁵Dept. of Neurological Surgery, University of California, ⁶Depts. of Neuroscience, Neurosurgery and Neurology, Icahn School of Medicine, Mount Sinai, NY

Non-literal expressions such as sarcasm, metaphor, and simile refer to words and sentences that convey meanings or intentions that are different and more abstract than literal expressions. Neuroimaging studies have shown activations in a variety of frontal, parietal, and temporal brain regions implicated in non-literal language processing. However, neurophysiological correlates of these brain areas underlying non-literal processing remain underexplored. To address this, we investigated patterns of intracranial EEG activity during non-literal processing by leveraging a unique patient population. Seven neurosurgical patients with invasive electrophysiological monitoring of superficial brain activity were recruited. Intracranial responses were recorded over the temporal-parietal junction (TPJ) and its surrounding areas while patients performed a language task. Participants listened to vignettes that ended with non-literal or literal statements and then responded verbally to some related questions. We found differential neurophysiological activity during the processing of non-literal statements than to literal statements, especially in low-Gamma (30-70 Hz) and delta (1-4 Hz) bands. In addition, we found that neural responses related to non-literal processing in the high-gamma band (>70 Hz) were significantly more prominent at TPJ electrodes as compared to non-TPJ (i.e., control) electrodes in most subjects. Moreover, in half of the patients, high-gamma activity related to non-literal processing was accompanied by delta-band modulation. These results suggest that both low- and high-frequency activities in the human temporal-parietal junction play a crucial role during non-literal language processing. This investigation provides an opportunity to gain insights into the localized brain dynamics of the TPJ during the processing of non-literal language expressions.

Topic Area: OTHER