Johnson M J, Alloway K D
Department of Neuroscience and Anatomy, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.
Exp Brain Res. 1994;102(2):181-97. doi: 10.1007/BF00227508.
Neuronal responses to hairy skin stimulation were simultaneously recorded in the ventral posterolateral nucleus (VPL) of the thalamus and primary somatosensory cortex (SI) of halothane-anesthetized cats. Among 233 thalamocortical neuron pairs, cross-correlation analysis revealed significant interactions in 120 pairs. Excitatory interactions were most prevalent and included influences occurring exclusively in the thalamocortical (41 pairs) or corticothalamic (23 pairs) directions as well as multiphasic interactions (40 pairs) in both directions. Only 16 pairs exhibited inhibitory interactions and 7 of these involved multiphasic combinations of excitation and inhibition. In 14 of these neuron pairs, inhibition was exerted in the corticothalamic direction. Receptive field (RF) overlap between thalamic and cortical neurons varied considerably, and neuronal interactions were more likely for neuron pairs sharing large portions of their combined RFs. Computer-controlled stimulation was delivered to multiple RF sites but only 46% of the neuron pairs displayed interactions at more than one stimulation site and only four neuron pairs showed interactions at all stimulus positions. When interactions occurred at multiple stimulus sites, 40% of these interactions were characterized by timing shifts where the time interval between VPL and SI discharges varied as much as 20 ms because of stimulus relocation. In nine neuron pairs, systematic shifts in stimulus position produced reversals in the temporal sequence of thalamic and cortical neuronal discharges. Functional interactions between thalamic and cortical neurons were detected during both spontaneous and stimulus-induced activity. Matched-sample comparisons of connection strength and half-widths of thalamocortical peaks during spontaneous and stimulus-induced activity indicated that functional interactions produced by cutaneous stimulation were significantly stronger and had less temporal variability than those occurring spontaneously.
在氟烷麻醉的猫的丘脑腹后外侧核（VPL）和初级体感皮层（SI）中，同时记录了对毛发皮肤刺激的神经元反应。在233对丘脑皮质神经元对中，互相关分析显示120对存在显著的相互作用。兴奋性相互作用最为普遍，包括仅在丘脑皮质（41对）或皮质丘脑（23对）方向发生的影响，以及双向的多相相互作用（40对）。只有16对表现出抑制性相互作用，其中7对涉及兴奋和抑制的多相组合。在这些神经元对中的14对中，抑制作用是在皮质丘脑方向发挥的。丘脑和皮质神经元之间的感受野（RF）重叠差异很大，并且对于共享大部分组合RF的神经元对，神经元相互作用更有可能发生。计算机控制的刺激被施加到多个RF位点，但只有46%的神经元对在多个刺激位点显示出相互作用，只有4对神经元对在所有刺激位置都显示出相互作用。当在多个刺激位点发生相互作用时，其中40%的相互作用的特征是时间偏移，即由于刺激位置的重新定位，VPL和SI放电之间的时间间隔变化高达20毫秒。在9对神经元对中，刺激位置的系统性变化导致丘脑和皮质神经元放电的时间顺序发生反转。在自发活动和刺激诱发活动期间都检测到了丘脑和皮质神经元之间的功能相互作用。对自发活动和刺激诱发活动期间丘脑皮质峰的连接强度和半高宽进行匹配样本比较表明，皮肤刺激产生的功能相互作用比自发发生的功能相互作用显著更强，并且时间变异性更小。
