Original Article

Exp Neurobiol 2011; 20(4): 189-196

Published online December 30, 2011

© The Korean Society for Brain and Neural Sciences

Odor-Dependent Hemodynamic Responses Measured with NIRS in the Main Olfactory Bulb of Anesthetized Rats

Hyun Joo Lee1,5#, Yunjun Nam2#, Chin Su Koh1, Changkyun Im1, In Seok Seo1, Seungjin Choi2,3,4 and Hyung-Cheul Shin1*

1Department of Physiology, College of Medicine, Hallym University, Chuncheon 200-702, 2School of Interdisciplinary Bioscience and Bioengineering, 3Division of IT Convergence Engineering and 4Department of Computer Science, POSTECH, Pohang 790-784, 5Department of Electrical Engineering, University of California, Los Angeles, CA, 90095, USA

Correspondence to: #These authors equally contributed to this work.
*To whom correspondence should be addressed.
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In this study, we characterize the hemodynamic changes in the main olfactory bulb of anesthetized Sprague-Dawley (SD) rats with near-infrared spectroscopy (NIRS, ISS Imagent) during presentation of two different odorants. Odorants were presented for 10 seconds with clean air via an automatic odor stimulator. Odorants are: (i) plain air as a reference (Blank), (ii) 2-Heptanone (HEP), (iii) Isopropylbenzene (IB). Our results indicated that a plain air did not cause any change in the concentrations of oxygenated (Δ[HbO2]) and deoxygenated hemoglobin (Δ[Hbr]), but HEP and IB induced strong changes. Furthermore, these odor-specific changes had regional differences within the MOB. Our results suggest that NIRS technology might be a useful tool to identify of various odorants in a non-invasive manner using animals which has a superb olfactory system.

Keywords: near-infrared spectroscopy (NIRS), hemodynamic response, main olfactory bulb (MOB), non-invasive, odorant, brain-machine interface (BMI)