Transcranial near infrared laser irradiation to primary auditory cortex alters auditory neural activities

Abstract

Event Abstract Back to Event Transcranial near infrared laser irradiation to primary auditory cortex alters auditory neural activities Naoya Akiyama1, Kohta I. Kobayasi2 and Hiroshi Riquimaroux1, 2* 1 Doshisha University, Department of Biomedical Engineerling and Biomedical Infomation, Graduate School of Life and Medical Science, Japan 2 Doshisha University, Biomedical Information, Japan The laser irradiation with a near-infrared wavelength (830nm) has been recently developed to reversibly inactivate neural activities. Irradiation of near-infrared laser (NIRL) has advantages over other methods for neural suppression (i.e., physical ablation or pharmacological method). The advantages of NIRL are as follows: 1) it may irradiate a small focal area, 2) its inactivation is reversible and 3) inactivation and recovery occurs immediately. Previous studies irradiated NIRL directly to the brain with craniotomy. The NIRL irradiation through the skull without craniotomy is much less invasive and well suited for behavioral studies. The purpose of this study was to evaluate the method of reversible inhibition of neural activity by transcranial irradiation. Five male gerbils (Meriones unguiculatus) were used as subjects. Animal was anesthetized by ketamine and xylazine. We made a hole near the parietal region and silver electorode, tip of which was loop-shaped, was placed on epidula over the primary auditory cortex. We recorded auditory evoked potential (AEP) to clicks and compared the difference in potential before, during and after NIRL irradiation. In addition, we presented light flash to record visual evoked potential (VEP) from the identical location for comparison with AEP. We alternately presented clicks and light flashes to record AEP and VEP. Delay between visual and auditory stimuli was 1 s. All stimulus duration was set at 100 µs. The recordings were made in a soundproof box. Light-emitting diode (LED), loud speaker and optical fiber for laser irradiation were installed in the soundproof box. The first 10 minutes was used for recordings without irradiation. The next 10 minutes was dedicated for recordings during laser irradiation. Then, we continued recordings for 50 minutes after stopping irradiation for examining the recovery process. With irradiation level of 70 mW/mm2 or lower, AEPs did not change during laser irradiation. However, with of irradiation level of 100 mW/mm2 or more, AEP (middle latency responses) was altered. The AEP recovered within 2 minutes after laser irradiation was terminated. On the other hand, the VEP was not altered, regardless of the laser irradiation on auditory cortex. Results indicate that the middle latency AEP (10-50 ms after the sound stimulus) originated in the primary auditory cortex, was possibly suppressed by transcranial NIRL irradiation to the primary auditory cortex. Successful alteration of the AEP by tranxcranial laser irradiation suggests possible application of this methods to free moving or awake behaving animals. Keywords: auditory evoked potential (AEP), visual evoked potential (VEP) Conference: Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012. Presentation Type: Poster (but consider for participant symposium and student poster award) Topic: Novel Tools and Methods Citation: Akiyama N, Kobayasi KI and Riquimaroux H (2012). Transcranial near infrared laser irradiation to primary auditory cortex alters auditory neural activities. Conference Abstract: Tenth International Congress of Neuroethology. doi: 10.3389/conf.fnbeh.2012.27.00374 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. 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Received: 01 May 2012; Published Online: 07 Jul 2012. * Correspondence: Prof. Hiroshi Riquimaroux, Doshisha University, Department of Biomedical Engineerling and Biomedical Infomation, Graduate School of Life and Medical Science, Kyotanabe, Kyoto, 610-0321, Japan, hrikimar@mail.doshisha.ac.jp Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Naoya Akiyama Kohta I Kobayasi Hiroshi Riquimaroux Google Naoya Akiyama Kohta I Kobayasi Hiroshi Riquimaroux Google Scholar Naoya Akiyama Kohta I Kobayasi Hiroshi Riquimaroux PubMed Naoya Akiyama Kohta I Kobayasi Hiroshi Riquimaroux Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.