Ishikawa Takahiro, Sato Takaaki, Shimizu Akira, Tsutsui Ken-Ichiro, de Curtis Marco, Iijima Toshio
Division of Systems Neuroscience, Tohoku University Graduate School of Life Sciences, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
J Neurophysiol. 2007 Jan;97(1):670-9. doi: 10.1152/jn.01366.2005. Epub 2006 Jul 26.
We developed a new technique to isolate a whole guinea pig brain with an intact olfactory epithelium (OE) that enables us to access the ventral surface of the brain including olfactory areas with ease during natural odor stimulation. We applied odorants to OE and confirmed that odor-induced local field potentials (LFPs) could be induced in olfactory areas. In the olfactory bulb (OB) and the piriform cortex (PC), odor-induced LFPs consisted of a phasic initial component followed by a fast activity oscillation in the beta range (20 Hz). To understand the neural mechanisms of odor-induced responses especially in the anterior PC, we analyzed odor-induced LFPs, together with unit activity data. We confirmed that the initial component of odor-induced response has a characteristic temporal pattern, generated by a relatively weak direct afferent input, followed by an intra-cortical associative response, which was associated with a phasic inhibition. The beta oscillation might be formed by the repetition of these network activities. These electrophysiological data were consistent with the results of previous studies that used slice or in vivo preparations, suggesting that the olfactory neural network and activities of the brain are preserved in our new in vitro preparation. This study provides the basis for clarifying the sequence of neural activities underlying odor information processing in the brain in vitro following natural olfactory stimulation.
我们开发了一种新技术，用于分离带有完整嗅上皮（OE）的整个豚鼠大脑，这使我们能够在自然气味刺激期间轻松接触到大脑的腹侧表面，包括嗅觉区域。我们将气味剂应用于OE，并证实气味诱导的局部场电位（LFP）可在嗅觉区域诱发。在嗅球（OB）和梨状皮质（PC）中，气味诱导的LFP由一个相位初始成分组成，随后是β范围（20Hz）内的快速活动振荡。为了理解气味诱导反应的神经机制，特别是在前PC中的机制，我们分析了气味诱导的LFP以及单位活动数据。我们证实，气味诱导反应的初始成分具有特征性的时间模式，由相对较弱的直接传入输入产生，随后是皮质内联想反应，这与相位抑制有关。β振荡可能由这些网络活动的重复形成。这些电生理数据与先前使用切片或体内制备的研究结果一致，表明嗅觉神经网络和大脑活动在我们新的体外制备中得以保留。本研究为阐明体外自然嗅觉刺激后大脑中气味信息处理背后的神经活动序列提供了基础。
