THALAMIC CONTROL OF CORTICAL VISUAL PROCESSING

这个项目的长期目标是了解传入 平行通道有助于处理视觉信息， 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），通过横向中继 膝状体核（LGN）的视觉皮层。 LGN是一种层压 结构，层压模式在物种之间变化很大。在 在猫的视网膜中，三个视网膜通道分布在九层中。 LGN复合体，在组织的形态水平上创造了几个 额外的传入通道。大脑皮层中的许多细胞 来自多个通道的收敛输入， 反馈路径 皮层和其他中央结构大量投射到 LGN，因此能够强烈地调节LGN传输 到皮层。 皮质内传入通道的复杂相互作用 电路，和中央反馈到LGN可能是动态的 根据感知需求和行为状态进行调节 的动物。 在清醒的动物中检查这些回路， 这对于深入了解他们的职能作用至关重要。 其中三个方面 将在接受视觉任务训练的清醒猫中检查相互作用。 将记录LGN中的细胞以研究扫视的影响， 注视角度，以及对他们活动的空间选择性注意， 确定这些效应如何随层和细胞类型而变化。 活动 初级视皮层中皮质膝状体细胞的数量将在 同样的行为环境，以确定动态变化， 与在LGN细胞中观察到的那些相同或不同。 为了 了解各个LGN层对动态变化的贡献 在皮层，通过显微注射， 阻断剂，而视觉行为和皮层活动是 观察 为了深入了解物种间变异的起源， LGN层状结构，猴LGN的形态发生将是模型 模拟退火技术。 目的是测试 假设在恒河猴中， 视网膜的区域变化促进了层的数量 神经节细胞密度，盲点决定了 其图案通过充当“籽晶”而改变， 前后自由能梯度的突然变化， 决定了最稳定的状态。

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.