Lund J S, Yoshioka T
Department of Psychiatry, University of Pittsburgh, Pennsylvania 15261.
J Comp Neurol. 1991 Sep 8;311(2):234-58. doi: 10.1002/cne.903110206.
We continue an investigation of the organization of local circuit neurons (largely inhibitory, GABAergic neurons, with smooth or sparsely spined dendrites) in the primary visual cortex of macaque monkey (Lund, '87: J. Comp. Neurol. 257:60-92; Lund et al., '88: J. Comp. Neurol. 276:1-29). This account covers local circuit neurons of layers 4B, 4A, and 3B; these three layers each receive different intrinsic second-order relays of principal thalamic inputs as well as receiving primary thalamic inputs in the case of two of the three laminae (4A and 3B). The study shows the existence of a number of different local circuit neurons making interlaminar projections between 4B, 4A, and 3B; each provides specific cross links between different combinations of the three laminae. It is known that the functional properties recorded physiologically from layers 4B, 4A, and 3B differ from one another and so these anatomical cross links may allow for correlation between different attributes of visual stimuli, e.g., color or motion, while still enabling separate processing of these different attributes to proceed in each of the three layers and be passed on to extrastriate areas. Whereas no spine-bearing neurons of layers 4B, 4A, or 3B provide "feedback" circuits to layer 4C (the source of their major intrinsic excitatory afferents), some of the local circuit neurons provide precisely structured axon feedback projections to divisions of 4C. The local circuit neurons also project to either lamina 5 or lamina 6, but not both and to superficial layers 3A, 2, and 1. Some local circuit neuron axon projections are of a dimension that would be confined to single functional clusters, e.g., cytochrome-rich "blobs," others reach out far enough to contact nearest neighbor "unlike" functional clusters, and yet others spread far enough to link repeating clusters of single function.
我们继续对猕猴初级视皮层中的局部回路神经元（主要是抑制性的、γ-氨基丁酸能神经元，具有光滑或稀疏棘状树突）的组织进行研究（伦德，1987年：《比较神经学杂志》257卷：60 - 92页；伦德等人，1988年：《比较神经学杂志》276卷：1 - 29页）。本报告涵盖4B、4A和3B层的局部回路神经元；这三层各自接收不同的主要丘脑输入的内在二级中继，并且在三层中的两层（4A和3B）还接收初级丘脑输入。该研究表明存在许多不同的局部回路神经元，它们在4B、4A和3B层之间进行层间投射；每个神经元在这三层的不同组合之间提供特定的交叉连接。已知从4B、4A和3B层生理记录的功能特性彼此不同，因此这些解剖学交叉连接可能允许视觉刺激的不同属性之间相互关联，例如颜色或运动，同时仍能使这三个层中的每一层对这些不同属性进行单独处理，并传递到纹外区域。虽然4B、4A或3B层中没有带棘神经元向4C层（其主要内在兴奋性传入纤维的来源）提供“反馈”回路，但一些局部回路神经元向4C的不同部分提供精确构建的轴突反馈投射。局部回路神经元也投射到5层或6层，但不会同时投射到这两层，并且还投射到浅层的3A、2和1层。一些局部回路神经元的轴突投射范围局限于单个功能簇，例如富含细胞色素的“斑片”，其他的投射范围足够远以接触最近的“不同”功能簇，还有一些则延伸得足够远以连接重复的单一功能簇。
