Auditory cortical activity elicited by infrared laser irradiation from the outer ear in Mongolian gerbils

• Published in: PloS one Vol. 15; no. 10; p. e0240227
• Main Authors: Tamai, Yuta, Ito, Yuki, Furuyama, Takafumi, Horinouchi, Kensuke, Murashima, Nagomi, Michimoto, Itsuki, Hishida, Ryuichi, Shibuki, Katsuei, Hiryu, Shizuko, Kobayasi, Kohta I
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 15-10-2020; Public Library of Science (PLoS)
• Subjects: Animals; Auditory cortex; Auditory Cortex - radiation effects; Biology and Life Sciences; Brain research; Care and treatment; Cochlea; Cochlear implants; Cortex (auditory); Cortex (temporal); Ear; Ear canal; Ear diseases; Ear, External - radiation effects; Electric Stimulation; Electrical stimuli; Electrodes; Engineering and Technology; Evoked Potentials, Auditory - radiation effects; Fluorescence; Gerbillinae; Health aspects; Hearing; Hearing loss; I.R. radiation; Infrared lasers; Infrared Rays; Irradiation; Laser therapy; Lasers; Medicine and Health Sciences; Methods; Microscopy, Fluorescence; Mitochondria; Neural stimulation; Neuroimaging; Neurophysiology; Noise; Physiological aspects; Research and Analysis Methods; Social Sciences; Stimulation; Temporal lobe; Japan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0240227

Infrared neural stimulation has been studied for its potential to replace an electrical stimulation of a cochlear implant. No studies, however, revealed how the technic reliably evoke auditory cortical activities. This research investigated the effects of cochlear laser stimulation from the outer ear on auditory cortex using brain imaging of activity-dependent changes in mitochondrial flavoprotein fluorescence signal. An optic fiber was inserted into the gerbil's ear canal to stimulate the lateral side of the cochlea with an infrared laser. Laser stimulation was found to activate the identified primary auditory cortex. In addition, the temporal profile of the laser-evoked responses was comparable to that of the auditory responses. Our results indicate that infrared laser irradiation from the outer ear has the capacity to evoke, and possibly manipulate, the neural activities of the auditory cortex and may substitute for the present cochlear implants in future.