Division of Physiology, Department of Human Development and Fostering, Meikai University School of Dentistry, 1-1 Keyaki-dai, Sakado, Saitama, 350-0283, Japan.
Department of Pharmacology, Nihon University School of Dentistry, 1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo, 101-8310, Japan.
Pflugers Arch. 2020 Jun;472(6):721-732. doi: 10.1007/s00424-020-02399-w. Epub 2020 May 27.
Gustation and olfaction are integrated into flavor, which contribute to detection and identification of foods. We focused on the insular cortex (IC), as a possible center of flavor integration, because the IC has been reported to receive olfactory in addition to gustatory inputs. In the present report, we tested the hypothesis that these two chemosensory signals are integrated in the IC. We examined the spatiotemporal dynamics of cortical responses induced by stimulating the chorda tympani nerve (CT) and the main olfactory bulb (mOB) in male Sprague-Dawley rats by in vivo optical imaging with a voltage-sensitive dye (VSD). CT stimulation elicited responses in the rostral part of the dysgranular IC (DI), while responses to mOB stimulation were observed in the agranular IC (AI) as well as in the piriform cortex (PC). To characterize the temporal specificity of these responses, we performed combined mOB and CT stimulation with three different timings: simultaneous stimulation and the stimulation of the mOB 150 ms before or after CT stimulation. Simultaneous stimulation increased the signal amplitude in AI additively. These results indicate that the AI and DI contribute to the convergence of gustatory and olfactory information. Of them the DI predominantly processes the taste information, whereas the AI is more sensitive to the olfactory signal.
味觉和嗅觉整合为风味，有助于食物的检测和识别。我们专注于脑岛（IC），因为它被报道接收除味觉输入外的嗅觉输入，可能是风味整合的中心。在本报告中，我们检验了以下假设，即这两种化学感觉信号在 IC 中整合。我们通过使用电压敏感染料（VSD）的活体光学成像，检查了刺激鼓索神经（CT）和主嗅球（mOB）在雄性 Sprague-Dawley 大鼠中诱导的皮质反应的时空动力学。CT 刺激在颗粒状 IC（DI）的前部诱发反应，而 mOB 刺激在颗粒状 IC（AI）和梨状皮层（PC）中观察到反应。为了表征这些反应的时间特异性，我们进行了 mOB 和 CT 联合刺激，具有三种不同的定时：同时刺激和 CT 刺激前或后 150 毫秒的 mOB 刺激。同时刺激在 AI 中附加地增加了信号幅度。这些结果表明，AI 和 DI 有助于味觉和嗅觉信息的汇聚。其中，DI 主要处理味觉信息，而 AI 对嗅觉信号更敏感。
