Poster Presentation

Poster F in Poster Session F: Thursday, August 6, 1:45 – 3:30 pm, Kimmel Center, Shorin & Rosenthal Rooms

Impaired decision-making from intrinsic epileptiform disruption of human brain activity

Niloufar Shahdoust¹, Rhiannon L Cowan¹, T. Alexander Price¹, Bornali Kundu², Tyler S Davis¹, John D Rolston³, Shervin Rahimpour¹, Ben Shofty¹, Elliot H Smith¹; ¹University of Utah, ²University of Missouri, ³Harvard University

Presenter: Niloufar Shahdoust

Interictal epileptiform discharges (IEDs) are brief pathological events that may impair cognition, yet their moment-to-moment impact during different stages of decision-making is not well characterized. In this study, intracranial EEG from 55 epilepsy patients performing the Balloon Analogue Risk Task (BART) was analyzed, relative to four task time periods of interest: 500-ms windows of post-stimulus onset, pre-response, post-response, and pre-outcome. IED occurrences were detected across time and iEEG contacts, and behavioral measures in IED versus non-IED trials across participants were compared. IED occurrences were associated with worse behavioral performance, including reduced accuracy and increased reaction time (RT) and inflation time (IT), compared to non-IED trials. To test whether behavioral disruption changed with the number of detected IEDs, RT, IT, and accuracy on trials with 1 versus 2+ IEDs were compared. Trials with 2+ IEDs across iEEG contacts had lower accuracy trials with 1 IED (permutation test, p<0.001). In contrast, RT and IT were not associated with the number of detected IEDs (IT: permutation test, p=0.26; RT: permutation test, p=0.982). Finally, mean band-limited (1-150 Hz) power (averaged within each time-frequency range) across IED-significant (i.e., in brain areas where IEDs occurred and significantly affected behavior), IED-nonsignificant (i.e., in brain areas where IEDs occurred and did not significantly affect behavior) and non-IED trials was quantified. We found the strongest power differences in hippocampus, followed by the middle temporal gyrus and superior frontal gyrus in some windows. These results are consistent with region-specific neural disruption during the same task time periods where behavior is affected. Overall, our results show that IEDs cause brief, time-locked disruptions of neural activity that translate into measurable, time-specific behavioral impairment on the BART.

Topic Area: Decision-Making, Cognitive Control & Event Cognition