Bai Li, Huang Xiaoying, Yang Qian, Wu Jian-Young
Department of Physiology and Biophysics, Georgetown University Medical Center, Washington, DC 20057, USA.
J Neurophysiol. 2006 Nov;96(5):2528-38. doi: 10.1152/jn.00645.2006. Epub 2006 Jul 26.
We have discovered an evoked network oscillation in rat neocortical slices and have examined its spatiotemporal patterns with voltage-sensitive dye imaging. The slices (visual and auditory cortices) were prepared in a medium of low calcium, high magnesium and with sodium replaced by choline to reduce the excito-toxicity and sodium loading. After slicing, the choline was washed out while normal calcium, magnesium, and sodium concentrations were restored. The oscillation was evoked by a single electrical shock to slices bathed in normal artificial cerebral spinal fluid (ACSF). The oscillation was organized as an all-or-none epoch containing 4-13 cycles at a central frequency approximately 25 Hz. The activity can be reversibly blocked by 6-cyano-7-nitroquinoxalene-2,3-dione (CNQX). 2-amino-5-phosphonopentanoic acid (APV), and atropine but not by bicuculline, indicating polysynaptic excitatory mechanisms. Voltage-sensitive dye imaging showed high-amplitude oscillation signals in superficial and middle cortical layers. Spatiotemporally, the oscillations were organized as waves, propagating horizontally along cortical laminar. Each oscillation cycle was associated with one wave propagating in space. The waveforms were often different at different locations (e.g., extra cycles), suggesting the co-existence of multiple local oscillators. For different cycles, the waves often initiated at different locations, suggesting that local oscillators are competing to initiate each oscillation cycle. Overall our results suggest that this cortical network oscillation is organized at two levels: locally, oscillating neurons are tightly coupled to form local oscillators, and globally the coupling between local oscillators is weak, allowing abrupt spatial phase lags and propagating waves with multiple initiation sites.
我们在大鼠新皮质切片中发现了一种诱发的网络振荡，并使用电压敏感染料成像技术研究了其时空模式。切片（视觉和听觉皮质）在低钙、高镁且用胆碱替代钠的培养基中制备，以降低兴奋性毒性和钠负荷。切片后，洗去胆碱，同时恢复正常的钙、镁和钠浓度。振荡由对浸泡在正常人工脑脊液（ACSF）中的切片施加单次电击诱发。振荡组织为一个全或无的时段，在中心频率约25Hz下包含4 - 13个周期。该活动可被6 - 氰基 - 7 - 硝基喹喔啉 - 2,3 - 二酮（CNQX）、2 - 氨基 - 5 - 磷酸戊酸（APV）和阿托品可逆性阻断，但不能被荷包牡丹碱阻断，表明存在多突触兴奋性机制。电压敏感染料成像显示在皮质浅层和中层有高振幅振荡信号。在时空上，振荡组织为波，沿皮质层水平传播。每个振荡周期与一个在空间中传播的波相关联。波形在不同位置（例如额外的周期）通常不同，表明存在多个局部振荡器。对于不同的周期，波通常在不同位置起始，表明局部振荡器竞争启动每个振荡周期。总体而言，我们的结果表明这种皮质网络振荡在两个层面上组织：局部层面，振荡神经元紧密耦合形成局部振荡器；全局层面，局部振荡器之间的耦合较弱，允许突然的空间相位滞后以及具有多个起始位点的传播波。
