Interareal phase coherence as a mechanism for attention-dependent neuronal signal routing: A model-guided causal analysis using new, multi-contact floating silicon probes for intracortical chronic stimulation and recording in primates

大脑由大量紧密相连的神经网络组成。根据上下文和任务，选择子网络，以便执行特定的计算，最终导致适当的行为输出。因此，感觉信号被选择性地通过大脑传导。后者在选择性注意期间的视觉系统中尤为明显：在视觉皮层的高级区域，如V4，神经元在其接受野中对几种刺激的反应被证明是相似的，就好像只有被注意的刺激会出现一样。在之前的实验中，我们发现视觉区V4的神经元和那些为参与刺激提供信号的输入神经元之间的神经元活动是特异性同步的。最重要的是，我们可以在最近的实验中证明，注意依赖同步是注意依赖信号路由的因果关系。这些发现提出了注意如何控制区域间同步机制的问题。目前还没有一个模型能够将相关实验结果纳入统一的框架；在灵长类动物大脑中，从大量神经元中并行获取数据并以高时间和空间分辨率影响它们的方法仍处于起步阶段。在这个项目中，我们作为神经生物学家、理论家和工程师一起来解决这些问题。为了改善实验访问和控制正在研究的网络，我们已经共同开发了完全可植入的，几乎无力的浮动多接触电极，用于灵长类动物皮质内的慢性记录和刺激。使用这种电极将使我们能够使用高分辨率电刺激作为一种因果工具，直接操纵选择性信号和信息路由的潜在注意控制机制。我们将改进我们的新工具，以允许植入整个多接触电极阵列，增加寿命和刺激能力，直接影响皮层网络动力学的不同方面。此外，研究结果将有助于表征网络动态特性的基本特性，并将用于建立注意力依赖信号路由控制机制的现实模型。

The brain consists of large neuronal networks that are densely inter-connected. Depending on context and task, sub-networks become selected such that specific computations are performed, which ultimately lead to the appropriate behavioural output. Thereby sensory signals become selectively channelled through the brain. The latter is particularly evident in the visual system during selective attention: In higher areas of visual cortex such as V4, the responses of neurons with several stimuli in their receptive fields were shown to be similar as if only the attended stimulus would be present. In previous experiments, we showed that neuronal activity synchronizes specifically between neurons in visual area V4 and those input neurons which provide the signals for the attended stimulus. Most importantly, we could show in recent experiments that attention-dependent synchronization is causally responsible for attention-dependent signal routing.These findings raise the question how attention controls interareal synchronization mechanisms. Still there is no model available that captures and integrates the relevant experimental results in unifying framework; and methods to acquire data from high numbers of neurons in parallel and to influence them with high temporal and spatial resolution in the primate brain are still in their infancy. In this project we join as neurobiologists, theorists and engineers to attack these questions. To improve experimental access to, and control of the networks under investigation we already developed together fully implantable, virtually force-free floating multi-contact electrodes for chronic intracortical recording and stimulation in the primate cortex. Using such electrodes will allow us to use high resolution electric stimulation as a causal instruments to directly manipulate the mechanisms putatively underlying attentional control of selective signal and information routing. We will improve our new tools to allow implantation of entire arrays of multi-contact electrodes with increased longevity and stimulation capabilities to directly influence different aspects of the dynamics of the cortical networks. Furthermore, the results will serve to characterize the fundamental properties of the network's dynamic properties and will be used to build realistic models for control mechanisms of attention-dependent signal routing.