Darbin Olivier, Soares Jesus, Wichmann Thomas
Yerkes National Primate Research Center, School of Medicine, Emory University, Neuroscience Building, 3rd Floor, Atlanta, GA 30322, USA.
Brain Res. 2006 Nov 6;1118(1):84-93. doi: 10.1016/j.brainres.2006.08.027. Epub 2006 Sep 20.
Spontaneous discharge of basal ganglia neurons is often analyzed with time- or frequency-domain methods. However, it has been shown that sequences of inter-spike interval series are not fully described by such linear procedures. We therefore carried out a characterization of the nonlinear features of spontaneous discharge of neurons in the primate basal ganglia. We studied the spontaneous activity of neurons in the subthalamic nucleus (22 cells), as well as neurons in the external and internal pallidal segments (53 and 39 cells, respectively), recorded with standard extracellular recording methods in two awake Rhesus monkeys. As a measure of the statistical irregularity of neuronal discharge, we compared the approximate entropy of inter-spike interval sequences with that of shuffled representations of the same data. In all three basal ganglia structures, approximately 95% of the original data showed lower approximate entropy values than the shuffled data, suggesting a temporal organization in the original sequence. Fano factor analysis confirmed the presence of a temporal organization of inter-spike interval sequences, and indicated the presence of self-similarity in the great majority of them. In addition, Hurst exponent analysis showed that the inter-spike interval series are persistent. Hurst exponents often differ between short and long scaling ranges. Subsequent principal component analyses allowed us to identify three distinct patterns of the temporal evolution of inter-spike interval sequences in the phase space. These types were found in varying distributions in all three nuclei. Our analyses demonstrate that the discharge of most neurons in the basal ganglia of awake monkeys has nonlinear features that may be important for information coding in the basal ganglia.
基底神经节神经元的自发放电通常采用时域或频域方法进行分析。然而，研究表明，此类线性方法并不能完全描述峰峰间期序列。因此，我们对灵长类动物基底神经节神经元自发放电的非线性特征进行了表征。我们使用标准细胞外记录方法，在两只清醒的恒河猴中记录了丘脑底核（22个细胞）以及苍白球外部和内部节段（分别为53个和39个细胞）中神经元的自发放电活动。作为神经元放电统计不规则性的一种度量，我们将峰峰间期序列的近似熵与相同数据的重排表示的近似熵进行了比较。在所有三个基底神经节结构中，约95%的原始数据显示出比重排数据更低的近似熵值，这表明原始序列中存在时间组织。法诺因子分析证实了峰峰间期序列存在时间组织，并表明其中绝大多数存在自相似性。此外，赫斯特指数分析表明峰峰间期序列具有持续性。赫斯特指数在短和长标度范围内通常有所不同。随后的主成分分析使我们能够在相空间中识别出峰峰间期序列时间演化的三种不同模式。在所有三个核中均发现这些类型以不同的分布存在。我们的分析表明，清醒猴子基底神经节中大多数神经元的放电具有非线性特征，这可能对基底神经节中的信息编码很重要。
