Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213, USA.
Lab Chip. 2011 Mar 21;11(6):1081-8. doi: 10.1039/c0lc00450b. Epub 2011 Feb 4.
Persistent activity in the brain is involved in working memory and motor planning. The ability of the brain to hold information 'online' long after an initiating stimulus is a hallmark of brain areas such as the prefrontal cortex. Recurrent network loops such as the thalamocortical loop and reciprocal loops in the cortex are potential substrates that can support such activity. However, native brain circuitry makes it difficult to study mechanisms underlying such persistent activity. Here we propose a platform to study synaptic mechanisms of such persistent activity by constraining neuronal networks to a recurrent loop like geometry. Using a polymer stamping technique, adhesive proteins are transferred onto glass substrates in a precise ring shape. Primary rat hippocampal cultures were capable of forming ring-shaped networks containing 40-60 neurons. Calcium imaging of these networks show evoked persistent activity in an all-or-none manner. Blocking inhibition with bicuculline methaiodide (BMI) leads to an increase in the duration of persistent activity. These persistent phases were abolished by blockade of asynchronous neurotransmitter release by ethylene glycol tetraacetic acid (EGTA-AM).
大脑中的持续活动与工作记忆和运动规划有关。大脑在起始刺激后很长一段时间内保持信息“在线”的能力是前额叶皮层等脑区的标志。丘脑皮质回路和皮质中的往返回路等反复网络回路是可以支持这种活动的潜在基质。然而，内源性脑回路使得研究这种持续活动背后的机制变得困难。在这里，我们提出了一个平台，通过将神经元网络约束在类似于循环的几何形状上来研究这种持续活动的突触机制。使用聚合物冲压技术，将粘性蛋白精确地转移到玻璃基底上的环形中。原代大鼠海马培养物能够形成包含 40-60 个神经元的环形网络。对这些网络的钙成像显示，以全或无的方式诱发持续活动。用肌内碘化物（BMI）阻断抑制作用会导致持续活动的持续时间增加。通过阻断乙二胺四乙酸（EGTA-AM）对异步神经递质释放的阻断，这些持续相位被消除。
