Strathclyde Institute of Pharmacy and Biomedical Sciences, University of StrathclydeGlasgow, United Kingdom.
Front Neural Circuits. 2017 Sep 14;11:64. doi: 10.3389/fncir.2017.00064. eCollection 2017.
The basal forebrain (BF) has long been implicated in attention, learning and memory, and recent studies have established a causal relationship between artificial BF activation and arousal. However, neural ensemble dynamics in the BF still remains unclear. Here, recording neural population activity in the BF and comparing it with simultaneously recorded cortical population under both anesthetized and unanesthetized conditions, we investigate the difference in the structure of spontaneous population activity between the BF and the auditory cortex (AC) in mice. The AC neuronal population show a skewed spike rate distribution, a higher proportion of short (≤80 ms) inter-spike intervals (ISIs) and a rich repertoire of rhythmic firing across frequencies. Although the distribution of spontaneous firing rate in the BF is also skewed, a proportion of short ISIs can be explained by a Poisson model at short time scales (≤20 ms) and spike count correlations are lower compared to AC cells, with optogenetically identified cholinergic cell pairs showing exceptionally higher correlations. Furthermore, a smaller fraction of BF neurons shows spike-field entrainment across frequencies: a subset of BF neurons fire rhythmically at slow (≤6 Hz) frequencies, with varied phase preferences to ongoing field potentials, in contrast to a consistent phase preference of AC populations. Firing of these slow rhythmic BF cells is correlated to a greater degree than other rhythmic BF cell pairs. Overall, the fundamental difference in the structure of population activity between the AC and BF is their temporal coordination, in particular their operational timescales. These results suggest that BF neurons slowly modulate downstream populations whereas cortical circuits transmit signals on multiple timescales. Thus, the characterization of the neural ensemble dynamics in the BF provides further insight into the neural mechanisms, by which brain states are regulated.
基底前脑（BF）长期以来一直与注意力、学习和记忆有关，最近的研究已经确立了人工 BF 激活与觉醒之间的因果关系。然而，BF 中的神经集合动力学仍然不清楚。在这里，我们在麻醉和非麻醉条件下同时记录 BF 和皮质中的神经群体活动，研究了在小鼠中 BF 和听觉皮层（AC）之间自发群体活动结构的差异。AC 神经元群体表现出偏向的尖峰率分布、更高比例的短（≤80ms）尖峰间隔（ISI）和丰富的跨频率节律放电模式。尽管 BF 中的自发放电率分布也是偏向的，但短 ISI 可以在短时间尺度（≤20ms）内用泊松模型来解释，并且与 AC 细胞相比，尖峰计数相关性较低，用光遗传学鉴定的胆碱能细胞对表现出异常高的相关性。此外，较少比例的 BF 神经元在跨频率上表现出尖峰-场同步：一部分 BF 神经元以较慢的（≤6Hz）频率有节奏地放电，与持续的场电位有不同的相位偏好，而 AC 群体则有一致的相位偏好。这些慢节律 BF 细胞的放电比其他节律性 BF 细胞对的相关性更高。总的来说，AC 和 BF 之间群体活动结构的根本区别在于它们的时间协调，特别是它们的操作时间尺度。这些结果表明，BF 神经元以较慢的速度调节下游群体，而皮质回路在多个时间尺度上传递信号。因此，BF 中的神经集合动力学的特征提供了对大脑状态调节的神经机制的进一步深入了解。
