Roy S, Alloway K D
Department of Neuroscience and Anatomy, Milton S. Hershey Medical Center, Penn State University College of Medicine, Hershey, Pennsylvania 17033-2255, USA.
J Neurophysiol. 1999 Mar;81(3):999-1013. doi: 10.1152/jn.1999.81.3.999.
Spontaneous and stimulus-induced responses were recorded from neighboring groups of neurons by an array of electrodes in the primary (SI) somatosensory cortex of intact, halothane-anesthetized cats. Cross-correlation analysis was used to characterize the coordination of spontaneous activity and the responses to peripheral stimulation with moving or stationary air jets. Although synchronization was detected in only 10% (88 of 880) of the pairs of single neurons that were recorded, cross-correlation analysis of multiunit responses revealed significant levels of synchronization in 64% of the 123 recorded electrode pairs. Compared with spontaneous activity, both stationary and moving air jets caused substantial increases in the rate, proportion, and temporal precision of synchronized activity in local regions of SI cortex. Among populations of neurons that were synchronized by both types of air-jet stimulation, the mean rate of synchronized activity was significantly higher during moving air-jet stimulation than during stationary air-jet stimulation. Moving air jets also produced significantly higher correlation coefficients than stationary air jets in the raw cross-correlograms (CCGs) but not in the shift-corrected CCGs. The incidence and rate of stimulus-induced synchronization varied with the distance separating the recording sites. For sites separated by </=300 microm, 80% of the multiunit responses displayed significant levels of synchronization during both types of air-jet stimulation. For sites separated by >/=500 microm, only 37% of the multiunit responses were synchronized by discrete stimulation with a single air jet. Measurements of the multiunit CCG peak half-widths showed that the correlated activity produced by moving air jets had slightly less temporal variability than that produced by stationary air jets. These results indicate that moving stimuli produce greater levels of synchronization than stationary stimuli among local groups of SI neurons and suggest that neuronal synchronization may supplement the changes in firing rate which code intensity and other attributes of a cutaneous stimulus.
在完整的、氟烷麻醉的猫的初级体感皮层（SI）中，通过电极阵列记录相邻神经元群的自发反应和刺激诱发反应。采用互相关分析来表征自发活动的协调性以及对移动或静止气流外周刺激的反应。尽管在记录的单个神经元对中只有10%（880对中的88对）检测到同步，但对多单位反应的互相关分析显示，在记录的123对电极中，有64%存在显著水平的同步。与自发活动相比，静止和移动气流均导致SI皮层局部区域同步活动的速率、比例和时间精度大幅增加。在通过两种气流刺激实现同步的神经元群体中，移动气流刺激期间同步活动的平均速率显著高于静止气流刺激期间。在原始互相关图（CCG）中，移动气流产生的相关系数也显著高于静止气流，但在移位校正的CCG中并非如此。刺激诱发同步的发生率和速率随记录位点之间的距离而变化。对于间距≤300微米的位点，在两种气流刺激期间，80%的多单位反应显示出显著水平的同步。对于间距≥500微米的位点，只有37%的多单位反应通过单个气流的离散刺激实现同步。多单位CCG峰半高宽的测量表明，移动气流产生的相关活动在时间变异性上略小于静止气流产生的相关活动。这些结果表明，在SI神经元的局部群体中，移动刺激比静止刺激产生更高水平的同步，并且提示神经元同步可能补充了编码皮肤刺激强度和其他属性的放电率变化。
