IMPEDANCE MEASUREMENTS IN BRAIN TISSUE OF ANIMALS USING MICROVOLT SIGNALS
IMPEDANCE MEASUREMENTS IN BRAIN TISSUE OF ANIMALS USING MICROVOLT SIGNALS
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DOI：
10.1016/0014-4886(62)90069-9
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发表时间：
1962-01-01
影响因子：
5.3
通讯作者：
DIDIO, J
中科院分区：
文献类型：
--
作者：
ADEY, WR;KADO, RT;DIDIO, J
描述了一种用于测量脑阻抗的技术，其中组织中的信号具有1至20jiV幅度，并且具有每平方微米电极表面10-13安培量级的电流密度，速度为1000循环/秒。该系统将解决电阻阻抗 1% 的变化，并且灵敏度仅受差分放大器的输入噪声的限制。使用长期植入猫体内的同轴电极进行脑电图和阻抗测量，观察到阻抗的某些清晰且一致的变化，特别是在海马锥体细胞的树突层和隔膜中，响应躯体、嗅觉、视觉和听觉刺激，意识生理状态的变化，以及巴比妥麻醉期间药物引起的变化和致幻剂的作用。海马癫痫发作期间也观察到某些可重复的变化。生理性外周刺激都会导致海马树突层阻抗短暂降低。从正常睡眠中唤醒后，基线也会向较低阻抗转变。意识的减弱伴随着返回到更高的水平。正常睡眠伴随着间隔中非常规则的正弦波序列，频率约为 3 个周期/分钟。在戊巴比妥麻醉期间，海马树突层的阻抗显着增加，并且随着意识的恢复而恢复到用药前的水平。一种拟精神病环己胺药物产生了一系列相反的变化。间隔刺激在海马体中引起的癫痫发作伴随着阻抗的快速小扰动，然后以大约 1 周期/秒的节奏发生阻抗变化，发生在阻抗基线上升的情况下。首次癫痫发作时的阻抗变化与 10 天后相同刺激所发生的阻抗变化之间存在差异。讨论了这些阻抗变化与神经元元件（或两者）和神经胶质组织以及细胞外空间之间的离子位移和体积变化的可能关系，并参考神经胶质组织对树突电子现象的可能调节影响。
A technique is described for measurement of cerebral impedance with signals in the tissues of 1 to 20jiV amplitude, and having a current density of the order of 10-13 amperes per square micron of electrode surface at 1000 cycles/sec. The system will resolve a 1 per cent shift in resistive impedance, and is limited in sensitivity only by the input noise of the differential amplifier. Using chronically implanted coaxial electrodes in the cat for both EEG and impedance measurements, certain clear and consistent changes in impedance were observed, particularly in the dendritic layer of hippocampal pyramidal cells and in the septum, in response to somatic, olfactory, visual, and auditory stimuli, and to changing physiological states of consciousness, as well as drug-induced changes during barbiturate anesthesia and the effects of hallucinogenic agents. Certain repeatable changes were also observed during hippocampal seizures. Physiological peripheral stimuli all produced a transient decrease in impedance in the hippocampal dendritic layer. Arousal from normal sleep was also followed by a baseline shift towards a lower impedance. Waning of consciousness was accompanied by a return to a higher level. Normal sleep was accompanied by trains of very regular sinusoidal waves in the septum at about 3 cycles/min. During Nembutal anesthesia, there was a marked increase in impedance in hippocampal dendritic layers, and a return to pre-drug levels with recovery of consciousness. A psychotomimetic cyclo-hexamine drug produced a converse series of changes. Seizures induced in the hippocampus by septal stimulation were accompanied by small rapid perturbations in impedance, and followed by rhythmic impedance changes at about 1 cycle/sec, occurring on a rising impedance baseline. Differences were noted between impedance changes in the initial seizure episodes and those occurring from identical stimulation 10 days later. The possible relationship of these impedance changes to ionic shifts and volume changes between neuronal elements (or both) and glial tissue, and the extracellular space is discussed, with reference to a possible modulating influence by glial tissue on electronic phenomena in dendrites.