Four-Dimensional Map of the Effective Connectivity from the Olfactory Tract
Abstract number :
1.172
Submission category :
3. Neurophysiology / 3E. Brain Stimulation
Year :
2019
Submission ID :
2421167
Source :
www.aesnet.org
Presentation date :
12/7/2019 6:00:00 PM
Published date :
Nov 25, 2019, 12:14 PM
Authors :
Aki Mizuno, Yokohama City University; Ayaka Sugiura, Wayne State University; Kyosuke Dozono, Kagoshima University; Kento Koyahara, Yokohama City University; Takaaki Maruiwa, Kagoshima University; Yoshiyuki Matsuki, Kagoshima University; Katsuhiro Saito, K
Rationale: The olfactory pathway includes the olfactory nerve, bulb, tract, and cortex. Olfactory hallucination can be elicited by high-frequency electrical stimulation at either olfactory tract in the subfrontal space or olfactory cortex in the anterior-medial temporal lobe. The present study delineated the dynamics of neural flows from the olfactory tract to the olfactory cortex using cortico-cortical evoked potentials (CCEPs) measured as part of our presurgical evaluation of patients with drug-resistant focal epilepsy. Methods: The present study included ten patients who underwent cortical resection following extra-operative electrocorticography recording. High-frequency (50-Hz) electrical stimulation via adjacent pairs of subdural electrodes was performed to localize the olfactory tract. Subsequently, single-pulse stimulation was delivered to the olfactory tract sites (stimulus intensity: 5 mA; stimulus frequency: 1 Hz) to evaluate the CCEP-based connectivity to remote sites. We then animated the time course of CCEP voltages on the 3D standard brain surface image. Our Institutional Review Board has approved the study, and we obtained the informed consent (and assent as needed) from the patients or the guardian of pediatric patients. Results: High-frequency stimulation at an intensity ranging from 3 to 6 mA elicited a percept of odor consistently and localized the olfactory tract in each patient. Single-pulse stimulation for CCEP measurement did not induce such a percept. Approximately 10-30 ms following single-pulse stimulation of the olfactory tract sites, the uncus of each hemisphere generated early CCEPs with anterior negative and posterior positive potential distributions. Both medial and lateral temporal lobe cortices of each hemisphere showed delayed CCEPs of negative potentials at 150-250 ms. Conclusions: Our 4D map successfully clarified the spatiotemporal dynamics of rapid neural propagation from the olfactory tract to the olfactory cortex within each hemisphere. Funding: NIH grant NS064033 (to E. Asano).
Neurophysiology