Traub Roger D, Contreras Diego, Cunningham Mark O, Murray Hilary, LeBeau Fiona E N, Roopun Anita, Bibbig Andrea, Wilent W Bryan, Higley Michael J, Whittington Miles A
Department of Physiology, State University of New York, Downstate Medical Center, 450 Clarkson Ave., Box 31, Brooklyn, NY 11203, USA.
J Neurophysiol. 2005 Apr;93(4):2194-232. doi: 10.1152/jn.00983.2004. Epub 2004 Nov 3.
To better understand population phenomena in thalamocortical neuronal ensembles, we have constructed a preliminary network model with 3,560 multicompartment neurons (containing soma, branching dendrites, and a portion of axon). Types of neurons included superficial pyramids (with regular spiking [RS] and fast rhythmic bursting [FRB] firing behaviors); RS spiny stellates; fast spiking (FS) interneurons, with basket-type and axoaxonic types of connectivity, and located in superficial and deep cortical layers; low threshold spiking (LTS) interneurons, which contacted principal cell dendrites; deep pyramids, which could have RS or intrinsic bursting (IB) firing behaviors, and endowed either with nontufted apical dendrites or with long tufted apical dendrites; thalamocortical relay (TCR) cells; and nucleus reticularis (nRT) cells. To the extent possible, both electrophysiology and synaptic connectivity were based on published data, although many arbitrary choices were necessary. In addition to synaptic connectivity (by AMPA/kainate, NMDA, and GABA(A) receptors), we also included electrical coupling between dendrites of interneurons, nRT cells, and TCR cells, and--in various combinations--electrical coupling between the proximal axons of certain cortical principal neurons. Our network model replicates several observed population phenomena, including 1) persistent gamma oscillations; 2) thalamocortical sleep spindles; 3) series of synchronized population bursts, resembling electrographic seizures; 4) isolated double population bursts with superimposed very fast oscillations (>100 Hz, "VFO"); 5) spike-wave, polyspike-wave, and fast runs (about 10 Hz). We show that epileptiform bursts, including double and multiple bursts, containing VFO occur in rat auditory cortex in vitro, in the presence of kainate, when both GABA(A) and GABA(B) receptors are blocked. Electrical coupling between axons appears necessary (as reported previously) for persistent gamma and additionally plays a role in the detailed shaping of epileptogenic events. The degree of recurrent synaptic excitation between spiny stellate cells, and their tendency to fire throughout multiple bursts, also appears critical in shaping epileptogenic events.
为了更好地理解丘脑皮质神经元集群中的群体现象，我们构建了一个包含3560个多室神经元（包含胞体、分支树突和部分轴突）的初步网络模型。神经元类型包括浅层锥体神经元（具有规则发放[RS]和快速节律性爆发[FRB]发放行为）；RS棘状星形神经元；快速发放（FS）中间神经元，具有篮状和轴突-轴突连接类型，位于皮质浅层和深层；低阈值发放（LTS）中间神经元，与主细胞树突形成联系；深层锥体神经元，可能具有RS或内在爆发（IB）发放行为，具有无簇状顶树突或长簇状顶树突；丘脑皮质中继（TCR）细胞；以及网状核（nRT）细胞。在可能的情况下，电生理学和突触连接均基于已发表的数据，尽管存在许多必要的任意选择。除了突触连接（通过AMPA/海人藻酸、NMDA和GABAA受体）外，我们还纳入了中间神经元、nRT细胞和TCR细胞树突之间的电耦合，以及某些皮质主神经元近端轴突之间的电耦合（以各种组合形式）。我们的网络模型复制了几种观察到的群体现象，包括：1）持续的γ振荡；2）丘脑皮质睡眠纺锤波；3）一系列同步的群体爆发，类似于脑电图癫痫发作；4）孤立的双群体爆发并叠加非常快速的振荡（>100Hz，“VFO”）；5）棘波-慢波、多棘波-慢波和快速发放（约10Hz）。我们发现，当GABAA和GABAB受体均被阻断时，在体外培养的大鼠听觉皮质中，在存在海人藻酸的情况下，会出现包含VFO的癫痫样爆发，包括双爆发和多爆发。轴突之间的电耦合似乎对于持续的γ振荡是必要的（如先前报道），并且在癫痫发生事件的详细形成过程中也起作用。棘状星形细胞之间反复的突触兴奋程度及其在多个爆发中持续发放的倾向，在癫痫发生事件的形成中似乎也很关键。
