Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
J Neural Eng. 2013 Aug;10(4):046005. doi: 10.1088/1741-2560/10/4/046005. Epub 2013 Jun 7.
Local field potentials (LFPs) that carry information about the subject's motor intention have the potential to serve as a complement or alternative to spike signals for brain-machine interfaces (BMIs). The goal of this study is to assess the utility of LFPs for BMIs by characterizing the largely unknown information coding properties of multichannel LFPs.
Two monkeys were implanted, each with a 16-channel electrode array, in the parietal reach region where both LFPs and spikes are known to encode the subject's intended reach target. We examined how multichannel LFPs recorded during a reach task jointly carry reach target information, and compared the LFP performance to simultaneously recorded multichannel spikes.
LFPs yielded a higher number of channels that were informative about reach targets than spikes. Single channel LFPs provided more accurate target information than single channel spikes. However, LFPs showed significantly larger signal and noise correlations across channels than spikes. Reach target decoders performed worse when using multichannel LFPs than multichannel spikes. The underperformance of multichannel LFPs was mostly due to their larger noise correlation because noise de-correlated multichannel LFPs produced a decoding accuracy comparable to multichannel spikes. Despite the high noise correlation, decoders using LFPs in addition to spikes outperformed decoders using only spikes.
These results demonstrate that multichannel LFPs could effectively complement spikes for BMI applications by yielding more informative channels. The utility of multichannel LFPs may be further augmented if their high noise correlation can be taken into account by decoders.
携带关于主体运动意图信息的局部场电位（LFPs）有可能作为脑机接口（BMIs）的尖峰信号的补充或替代。本研究的目的是通过描述多通道 LFPs 中大部分未知的信息编码特性，来评估 LFPs 用于 BMI 的效用。
两只猴子被植入了 16 通道电极阵列，分别位于顶叶伸展区，在这个区域中，LFP 和尖峰都被认为可以编码主体的预期伸展目标。我们研究了多通道 LFPs 在伸展任务期间如何共同携带伸展目标信息，并将 LFP 性能与同时记录的多通道尖峰进行了比较。
LFP 比尖峰产生了更多的关于伸展目标的信息通道。单通道 LFP 比单通道尖峰提供了更准确的目标信息。然而，LFP 显示出比尖峰更大的信号和噪声跨通道相关性。当使用多通道 LFPs 而不是多通道尖峰时，伸展目标解码器的性能更差。多通道 LFPs 的性能下降主要是由于其噪声相关性较大，因为去相关多通道 LFPs 的噪声产生了与多通道尖峰相当的解码精度。尽管噪声相关性较高，但与仅使用尖峰的解码器相比，同时使用 LFPs 和尖峰的解码器表现更好。
这些结果表明，多通道 LFPs 通过产生更多信息通道，可以有效地补充尖峰用于 BMI 应用。如果解码器可以考虑多通道 LFPs 的高噪声相关性，则可以进一步提高多通道 LFPs 的效用。
