Stark Eran, Abeles Moshe
Department of Physiology, Hadassah Medical School, Hebrew University, Jerusalem 91120, Israel.
J Neurosci. 2007 Aug 1;27(31):8387-94. doi: 10.1523/JNEUROSCI.1321-07.2007.
Previous studies have shown that intracortical activity can be used to operate prosthetic devices such as an artificial limb. Previously used neuronal signals were either the activity of tens to hundreds of spiking neurons, which are difficult to record for long periods of time, or local field potentials, which are highly correlated with each other. Here, we show that by estimating multiunit activity (MUA), the superimposed activity of many neurons around a microelectrode, and using a small number of electrodes, an accurate prediction of the upcoming movement is obtained. Compared with single-unit spikes, single MUA recordings are obtained more easily and the recordings are more stable over time. Compared with local field potentials, pairs of MUA recordings are considerably less redundant. Compared with any other intracortical signal, single MUA recordings are more informative. MUA is informative even in the absence of spikes. By combining information from multielectrode recordings from the motor cortices of monkeys that performed either discrete prehension or continuous tracing movements, we demonstrate that predictions based on multichannel MUA are superior to those based on either spikes or local field potentials. These results demonstrate that considerable information is retained in the superimposed activity of multiple neurons, and therefore suggest that neurons within the same locality process similar information. They also illustrate that complex movements can be predicted using relatively simple signal processing without the detection of spikes and, thus, hold the potential to greatly expedite the development of motor-cortical prosthetic devices.
先前的研究表明，皮层内活动可用于操作诸如假肢之类的假体装置。先前使用的神经元信号要么是数十到数百个发放神经元的活动，这种活动难以长时间记录，要么是局部场电位，而局部场电位之间高度相关。在此，我们表明，通过估计多单元活动（MUA），即微电极周围许多神经元的叠加活动，并使用少量电极，能够准确预测即将发生的运动。与单个单元的尖峰信号相比，单个MUA记录更容易获得，并且随着时间的推移记录更稳定。与局部场电位相比，成对的MUA记录冗余度要低得多。与任何其他皮层内信号相比，单个MUA记录信息量更大。即使在没有尖峰信号的情况下，MUA也具有信息性。通过结合来自执行离散抓握或连续追踪运动的猴子运动皮层的多电极记录信息，我们证明基于多通道MUA的预测优于基于尖峰信号或局部场电位的预测。这些结果表明，大量信息保留在多个神经元的叠加活动中，因此表明同一局部区域内的神经元处理相似的信息。它们还表明，无需检测尖峰信号，使用相对简单的信号处理就能预测复杂运动，因此有望极大地加快运动皮层假体装置的开发。
