Polyanskii V B, Evtikhin D V, Sokolov E N, Alymkulov D E
Department of Higher Nervous Activity, M. V. Lomonosov Moscow State University.
Neurosci Behav Physiol. 2007 Mar;37(3):237-47. doi: 10.1007/s11055-007-0007-6.
The responses of 51 neurons in the lateral geniculate nucleus of the rabbit to substitution of colored stimuli different brightness and stimuli differing only in intensity were studied. Neurons in the geniculate nucleus, like neurons in the visual cortex, were found to respond with initial phasic discharges at 50-90 msec after stimulus substitution, the magnitudes of these responses correlating with the interstimulus differences; neurons also showed prolonged tonic responses in which the spike frequency depended on the intensity of the stimulus presented. Analysis of phasic responses allowed two groups of neurons to be identified: some were specialized to discriminate stimulus intensity only, while others were specialized to discriminate both the intensity and the color tone of the stimulus. Use of the magnitude of the early phasic discharge as a measure of the difference between stimuli yielded a sensory space for lateral geniculate nucleus neurons. The responses of neurons in the first group (44 cells, 86%) produced a two-dimensional achromatic space with two axes--brightness and darkness; this structure appeared independently of whether stimuli were of the same or different color tones. The phasic responses of neurons in the second group (seven of 51, 14%) generated a four-dimensional space with two color and two achromatic axes. The color and achromatic spaces of lateral geniculate nucleus neurons were analogous to the spaces previously identified for neurons in the rabbit visual cortex using the same stimulation conditions. The sensory spaces reconstructed on the basis of neuron phasic discharges essentially coincided with the spaces obtained from analysis of the N85 component of visual evoked potentials in rabbits, which provides support for the vector information coding principle in the visual analyzer. The tonic discharges of most lateral geniculate nucleus neurons correlated linearly with changes in stimulus intensity and can be regarded as reflecting a pre-detector function for the visual cortex detector neurons.
研究了兔外侧膝状核中51个神经元对不同亮度的彩色刺激以及仅强度不同的刺激进行替换时的反应。结果发现，外侧膝状核中的神经元与视觉皮层中的神经元一样，在刺激替换后50 - 90毫秒会出现初始相位放电，这些反应的幅度与刺激间差异相关；神经元还表现出持续的紧张性反应，其中放电频率取决于所呈现刺激的强度。对相位反应的分析使我们能够识别出两组神经元：一些神经元专门用于仅区分刺激强度，而另一些则专门用于区分刺激的强度和色调。将早期相位放电的幅度用作刺激间差异的度量，得出了外侧膝状核神经元的感觉空间。第一组神经元（44个细胞，占86%）的反应产生了一个二维消色差空间，有两个轴——亮度和暗度；这种结构的出现与刺激的色调是否相同无关。第二组神经元（51个中的7个，占14%）的相位反应产生了一个四维空间，有两个颜色轴和两个消色差轴。外侧膝状核神经元的颜色和消色差空间类似于先前在相同刺激条件下为兔视觉皮层神经元所识别的空间。基于神经元相位放电重建的感觉空间与通过对兔视觉诱发电位的N85成分分析获得的空间基本一致，这为视觉分析器中的矢量信息编码原理提供了支持。大多数外侧膝状核神经元的紧张性放电与刺激强度的变化呈线性相关，可被视为反映了视觉皮层检测神经元的预检测功能。
