THALAMIC CONTROL OF CORTICAL VISUAL PROCESSING

这个项目的长期目标是了解如何传入 并行通道有助于视觉信息的处理 大脑皮层。视网膜的输出被组织成至少 三个通道(W、X和Y细胞)，通过侧向传递 膝状核(LGN)至视皮层。LGN是一种叠层 结构，层叠的模式在物种之间有很大的差异。在……里面 猫，三个视网膜通道分布在视网膜的九层 LGN复合体，在形态层面上创造了几个组织 额外的传入通道。大脑皮层中的许多单个细胞接收 来自多个渠道的前馈和汇聚输入 反馈途径。皮质和其他中央结构严重突出到 因此，LGN能够强烈地调节LGN传输 到大脑皮层。皮质内传入通道的复杂相互作用 电路和对LGN的中央反馈可能是动态的 根据知觉需求和行为状态进行调节 这只动物的。检查清醒的动物的这些回路，行为是 对于深入了解他们的职能作用至关重要。这三个方面 在经过视觉运动任务训练的清醒猫身上，将研究它们之间的相互作用。 LGN中的细胞将被记录以研究眼跳的影响， 凝视角度，以及对它们活动的空间选择性关注，以及 确定这些效果如何因层和单元格类型而异。活动 初级视皮层中皮质膝状体细胞的数量将在 相同的行为环境来识别动态变化， 与LGN细胞中观察到的相同或不同。为了 了解各个LGN层对动态变化的贡献 在皮质中，层将被选择性地灭活，通过微量注射 阻滞剂，而视觉运动行为和皮质活动 观察到的。为了深入了解物种间差异的起源 LGN的层状结构，将猴LGN的形态发生模型化 LED采用模拟退火法。其目的是测试 假设在恒河猴中，与偏心率相关的变异 视网膜的区域差异促进了层数的增加 神经节细胞密度，盲点决定了 它的图案通过充当“种子晶体”而改变，从而导致 前后部自由能梯度的突然变化 确定最稳定的状态。

The long-term objective of this project is to understand how afferent parallel channels contribute to the processing of visual information in cerebral cortex. The output of the retina is organized into at least three channels (W, X and Y cells), which are relayed through the lateral geniculate nucleus (LGN) to the visual cortex. The LGN is a laminated structure, and the pattern of lamination varies greatly among species. In the cat, three retinal channels are distributed among nine layers of the LGN complex, creating at the morphological level of organization several additional afferent channels. Many individual cells in cortex receive convergent inputs from multiple channels through both feedforward and feedback pathways. Cortex and other central structures project heavily to the LGN, and therefore are capable of strongly regulating LGN transmission to cortex. The complex interactions of afferent channels, intracortical circuits, and central feedback to the LGN are probably dynamically regulated in accordance with the perceptual demands and behavioral state of the animal. Examining these circuits in the awake, behaving animal is critical for insights into their functional roles. Three aspects of these interactions will be examined in awake cats trained in visuomotor tasks. Cells in the LGN will be recorded to investigate the effects of saccades, gaze angle, and spatially-selective attention on their activity, and to determine how these effects vary by layer and by cell type. The activity of corticogeniculate cells in primary visual cortex will be examined under the same behavioral circumstances to identify dynamic changes that are common to or different from those observed in LGN cells. In order to understand the contributions of individual LGN layers to dynamic changes in cortex, layers will be selectively inactivated with microinjections of blocking agents while visuomotor behavior and cortical activity are observed. To gain insights into the origins of interspecies variations in LGN laminar structure, the morphogenesis of the monkey LGN will be model led with simulated annealing techniques. The aim is to test the hypotheses that in the rhesus monkey, eccentricity-related variations in the number of layers are promoted by regional variations in retinal ganglion cell density, and that the blind spot determines the point at which the pattern changes by serving as a "seed crystal", causing an abrupt change in the anterior-posterior free-energy gradient that determines the most stable state.