Sukov W, Barth D S
Department of Psychology, University of Colorado, Boulder, Colorado 80309-0345, USA.
J Neurophysiol. 2001 Mar;85(3):1235-45. doi: 10.1152/jn.2001.85.3.1235.
The purpose of this study was to clarify the neurogenesis of thalamically evoked gamma frequency (approximately 40 Hz) oscillations in auditory cortex by comparing simultaneously recorded extracellular and intracellular responses elicited with electrical stimulation of the posterior intralaminar nucleus of the thalamus (PIL). The focus of evoked gamma activity was located between primary and secondary auditory cortex using a 64-channel epipial electrode array, and all subsequent intracellular recordings and single-electrode field potential recordings were made at this location. These data indicate that PIL stimulation evokes gamma oscillations in auditory cortex by tonically depolarizing pyramidal cells in the supra- and infragranular layers. No cells revealed endogenous membrane properties capable of producing activity in the gamma frequency band when depolarized individually with injected current, but all displayed both sub- and supra-threshold responses time-locked to extracellular fast oscillations when the population was depolarized by PIL stimulation. We propose that cortical gamma oscillations may be produced and propagated intracortically by network interactions among large groups of neurons when mutually excited by modulatory input from the intralaminar thalamus and that these oscillations do not require specialized pacemaker cells for their neurogenesis.
本研究的目的是通过比较丘脑后内侧核（PIL）电刺激同时记录的细胞外和细胞内反应，阐明听觉皮层中丘脑诱发的γ频率（约40Hz）振荡的神经发生机制。使用64通道软脑膜电极阵列，诱发γ活动的焦点位于初级和次级听觉皮层之间，所有后续的细胞内记录和单电极场电位记录均在此位置进行。这些数据表明，PIL刺激通过使颗粒上层和颗粒下层的锥体细胞持续去极化，在听觉皮层诱发γ振荡。当单独用注入电流使其去极化时，没有细胞显示出能够在γ频段产生活动的内源性膜特性，但当群体被PIL刺激去极化时，所有细胞都表现出与细胞外快速振荡锁时的阈下和阈上反应。我们提出，当被丘脑板内核的调制输入相互兴奋时，皮层γ振荡可能由大量神经元之间的网络相互作用在皮层内产生和传播，并且这些振荡在其神经发生过程中不需要专门的起搏器细胞。
