Hong Nari, Joo Sunghoon, Nam Yoonkey
IEEE Trans Biomed Eng. 2017 Feb;64(2):492-498. doi: 10.1109/TBME.2016.2567424. Epub 2016 May 12.
Axonal propagation has a pivotal role in information processing in the brain. However, there has been little experimental study due to the difficulty of isolation of axons and recording their signals. Here, we developed dual chamber neuronal network interconnected with axons by integrating microchannel devices with microelectrode arrays (MEAs) to investigate axonal signals in developmental stage.
The device was composed of two chambers and microchannels between them, and hippocampal neurons were cultured in both chambers. Neuronal activity was recorded for four weeks.
Large axonal signal was detected in microchannels, which were 137.0 ± 8.5 μV at 14 days in vitro (DIV). It was significantly larger than those in chambers with a similar range of signal-to-noise ratio. Detection efficiency of axonal spikes was analyzed by calculating the number of active electrodes over time. We found that active electrodes were detected earlier and their number increased faster in microchannels than those in chambers. Finally, we estimated the axonal conduction velocity and 73% of axons had the velocity in range of 0.2-0.5 m/s at 14 DIV. By estimating the velocity over the cultivation period, we observed that axonal conduction velocity increased linearly over time.
Using MEAs and microchannel devices, we successfully detected large axonal signals and analyzed their detection efficiency and conduction velocity. We first showed the gradual increase in conduction velocity depending on cultivation days.
The developed microchannel device integrated MEA may be applicable for the studies of axonal conduction in cultured neuronal networks.
轴突传播在大脑信息处理中起关键作用。然而，由于轴突分离和信号记录困难，相关实验研究较少。在此，我们通过将微通道装置与微电极阵列（MEA）集成，开发了与轴突相连的双室神经元网络，以研究发育阶段的轴突信号。
该装置由两个腔室及它们之间的微通道组成，两个腔室均培养海马神经元。记录神经元活动四周。
在微通道中检测到较大的轴突信号，体外培养14天（DIV）时为137.0±8.5μV。该信号明显大于在具有相似信噪比范围内腔室中的信号。通过计算随时间的有源电极数量来分析轴突尖峰的检测效率。我们发现，与腔室相比，微通道中更早检测到有源电极，且其数量增加更快。最后，我们估计了轴突传导速度，在14 DIV时，73%的轴突速度在0.2 - 0.5 m/s范围内。通过估计整个培养期的速度，我们观察到轴突传导速度随时间呈线性增加。
利用MEA和微通道装置，我们成功检测到较大的轴突信号，并分析了其检测效率和传导速度。我们首次展示了传导速度随培养天数逐渐增加。
所开发的集成MEA的微通道装置可能适用于培养的神经元网络中轴突传导的研究。
