Multiple methods have been developed in an attempt to quantify stimulus-induced neural coordination and to understand internal coordination of neuronal responses by examining the synchronization phenomena in neural discharge patterns. In this work we propose a novel approach to estimate the degree of concomitant firing between two neural units, based on a modified form of mutual information (MI) applied to a two-state representation of the firing activity. The binary profile of each single unit unfolds its discharge activity in time by decomposition into the state of neural quiescence/low activity and state of moderate firing/bursting. Then, the MI computed between the two binary streams is normalized by their minimum entropy and is taken as positive or negative depending on the prevalence of identical or opposite concomitant states. The resulting measure, denoted as Concurrent Firing Index based on MI (CFI_MI), relies on a single input parameter and is otherwise assumption-free and symmetric. Exhaustive validation was carried out through controlled experiments in three simulation scenarios, showing that CFI_MI is independent on firing rate and recording duration, and is sensitive to correlated and anti-correlated firing patterns. Its ability to detect non-correlated activity was assessed using ad-hoc surrogate data. Moreover, the evaluation of CFI_MI on experimental recordings of spiking activity in retinal ganglion cells brought insights into the changes of neural synchrony over time. The proposed measure offers a novel perspective on the estimation of neural synchrony, providing information on the co-occurrence of firing states in the two analyzed trains over longer temporal scales compared to existing measures.

已经开发了多种方法，试图通过检查神经放电模式中的同步现象来量化刺激引起的神经协调并了解神经元反应的内部协调。在这项工作中，我们提出了一种新方法来估计两个神经单元之间的伴随放电程度，该方法基于应用于放电活动的双态表示的互信息 (MI) 的修改形式。每个单个单元的二元分布通过分解为神经静止/低活动状态和中度放电/爆裂状态，及时展开其放电活动。然后，两个二进制流之间计算的 MI 被它们的最小熵归一化，并根据相同或相反伴随状态的普遍性被视为正或负。_MI )，依赖于单个输入参数，否则是无假设和对称的。通过在三个模拟场景中的受控实验进行了详尽的验证，表明 CFI _MI独立于发射率和记录持续时间，并且对相关和反相关的发射模式敏感。使用临时替代数据评估其检测非相关活动的能力。此外，CFI _MI的评估对视网膜神经节细胞中尖峰活动的实验记录带来了对神经同步性随时间变化的见解。所提出的措施为估计神经同步性提供了一个新的视角，与现有措施相比，在更长的时间尺度上提供了关于两个分析的列车中点火状态同时发生的信息。