電気生理学的手法 Electrophysiology
P2-2-234 運動野のマルチニューロン活動に対する経頭蓋直流電気刺激の影響 Effects of the transcranial direct current stimulation on multi-unit neural activities in the rat motor cortex ○田中智子1, 礒村宜和2, 花川隆1,3, 田中悟志4, 本田学1,3 ○Tomoko Tanaka1, Yoshikazu Isomura2, Takashi Hanakawa1,3, Satoshi Tanaka4, Manabu Honda1,3 国立精神神経医療研究センター・神経研究所・疾病研究第七部1, 玉川大学脳科学研究所2, 国立精神神経医療研究センター脳病態統合イメージングセンター3, 名古屋工業大学4 Department of Functional Brain Research, National Institute of Neuroscience, NCNP, Tokyo, Japan1, Tamagawa University, Tokyo, Japan2, Integrative Brain Imaging Center, NCNP, Tokyo, Japan3, Nagoya Institute of Technology, Aichi, Japan4 Transcranial direct current stimulation (tDCS) is a non-invasive procedure that induces polarity-dependent modulation of neuronal membrane potentials. Previously, we reported that the cathodal tDCS to the rat cortex increased extracellular dopamine levels in the striatum. This result seems to be associated with neuronal activity changes of cortex. Therefore, in the present study, we measured changes of multi-unit activity (MUA) in the rat motor cortex in vivo induced by tDCS. The experiment was carried out under urethane anesthesia. We inserted the recording electrodes into the motor cortex just beneath the tDCS stimulus electrode. The multi-neuron recording was performed to observe changes in neuronal activity before and after the application of tDCS. After multi-neuron recording for more than 2 hours, cathodal tDCS was applied over the cortex for 10 minutes with a current intensity of 800 μA (cathodal tDCS group, n = 8) or for 10 second with a current intensity of 10μA (sham group, n = 5). In the cathodal tDCS group, the MUA increased up to 150 percent of the baseline in the motor cortex. The increase of MUA lasted for at least 2 hours after the cessation of tDCS. This result seems contradictory to the classical view on the effect of tDCS. However, previous studies were performed in vitro or involved applying direct current to a dendrite of the recording cell. To our knowledge, this is the first study investigating alterations of firing rate of cortical neurons beneath the stimulus electrode induced by transcranially-delivered direct current stimulation in vivo. The alteration of neuronal excitability induced by transcranial stimulation might differ from that induced by direct current stimulation of recording cell dendrites. The mechanisms of this effect of tDCS will be further clarified by studies at single-neuron activity and local field potential levels.	P2-2-235 光遺伝学的に誘発されたラット視覚領皮質脳波の周波数特性 Frequency responses of optogentically evoked micro-electrocorticogram in the rat visual cortices ○戸田春男1, 佐藤翔1中原潔2, 澤畑博人1, 堀江正男3, 竹林浩秀3, 長谷川功1,2 ○Haruo Toda1, Sho Sato1, Asim Bepari3, Kiyoshi Nakahara2, Hirohito Sawahata1, Masao Horie3, Hirohide Takebayashi3, Isao Hasegawa1,2 新潟大・医・生理11, 新潟大・超域2, 新潟大・医・解剖23 Department of Physiology, Graduate School of Medical and Dental Sciences, Niigata University1, Center for Transdisciplinary Research, Niigata University2, Department of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University3 Channelrhodopsin-2 (ChR2) is widely used to stimulate neurons with a high spatiotemporal resolution. However, the effect of stimulation frequency on the cerebral cortex is not clearly known. To address this issue, we newly combined two methods: optogenetic activation and electrocorticogram (ECoG) with a flexible electrode array (ECoG mesh). Recombinant adeno-associated virus vector expressing hChR2 (E123T/T159C)-EYFP under control of the CaMKIIα promoter was injected in the 4 primary visual cortices of 2 adult Long-Evans rats. After 3-4 weeks, a 32ch ECoG mesh was subdurally attached over the EYFP fluorescent positive site, where strong ChR2-EYFP expression were detected post hoc in the pyramidal cells by in situ hybridization. Then, an optrode was inserted into the site for photostimulation and intracortical recording of local field potentials (icLFP) and spike activities. Photostimulations were 5, 11, 19, 41, 79, 156 or 238-Hz laser pulses (473 nm, pulse width: 0.5 ms). Virus injection and electrophysiological recording were conducted under general anaesthesia (injection: Nembutal, recording: urethane). Even in 156 or 238-Hz stimulation trials, the ECoG and icLFP signals responding to every laser pulses and high frequency harmonics up to 500 Hz were found. These high-frequency components were mainly recorded from the ECoG electrodes adjacent to the optrode, but also recorded from a few electrodes with distances larger than 3 mm to the optrode. Simultaneously, we recorded two types of spike activities: plausible regular spiking neurons responding to 238 Hz stimulations (n=7) and plausible fast spiking neurons responding to 41 Hz or lower frequency stimulations (n=2). The former may play a role in generation of the high-frequency components in the optogenetically evoked ECoGs and icLFPs. These results indicate that our optogentics-ECoG mesh combined method is a hopeful tool to investigate the spatiotemporal dynamics of the cortical activities.
P2-2-236 Moved to Oral Session O1-8-4-4	P2-2-237 モーター駆動マイクロドライブによる神経活動の無線記録システム A wireless system with a motorized microdrive for neural recording in freely behaving animals ○長谷川拓1, 田代紘一郎1, 野々村万有1, 藤本久貴2,3, 土谷亮4, 渡邊大1,2 ○Taku Hasegawa1, Kouichiro Tashiro1, Mayu Nonomura1, Hisataka Fujimoto2,3, Akira Tsuchiya4, Dai Watanabe1,2 京大院・生命・高次脳機能1, 京大院・医・生体情報2, 阪大院・医・眼科3, 京大院・情報・大規模集積回路4 Grad Sch of Biostudies, Kyoto Univ, Kyoto, Japan1, Grad Sch of Medicine, Kyoto Univ, Kyoto2, Grad Sch of Medicine, Osaka Univ, Osaka, Japan3, Grad Sch of Informatics, Kyoto Univ, Kyoto, Japan4 Methods for isolating neural signals from single neuron in awake, behaving animals have been reported. However, the previous techniques require animals to be tethered; this imposes problems when animals explore in a large space or socially interact with others. Here we describe a wireless system that can precisely control the movement of electrodes and enable single-unit recording of neurons from freely-behaving animals. This recording system consists of three components: 1) a motorized microdrive housing three pairs of motors and electrodes (11 × 5 × 17 mm and 1.1 grams), 2) a wireless interface board (WIB) for transmitting recorded neuronal signals and receiving microdrive control commands (20 × 16 × 7 mm and 3.1 grams), and 3) a lithium polymer battery (4.0 to 17.2 grams depending on the duration of a recording session). Because recorded neuronal signals are immediately amplified and digitized within the WIB implanted on the skull of animals, a shielded Farady cage is not required during the recording. Electrodes can remotely be controlled with 2 to 40 μm stepping distances through the WIB, and this enables efficient recording of neuronal activity at a single-cell level without affecting animal behavior. Furthermore, this wireless recording system can be controlled at least from the distance of 5 meters. Thus, this wireless recording system can become a potential tool for the study of brain mechanisms underlying natural behaviors both in a large space and during the social interaction.

上部に戻る

前に戻る