Steele G E, Weller R E
Department of Psychology, University of Alabama at Birmingham 35294-1170, USA.
Vis Neurosci. 1995 Jul-Aug;12(4):701-22. doi: 10.1017/s0952523800008981.
On the basis of cortical and subcortical connections and architectonics, inferior temporal (IT) cortex of squirrel monkeys consists of a caudal region, ITC, with dorsal (ITCd) and ventral (ITCv) subdivisions; a rostral region, ITR; and possibly a third region intermediate to ITC and ITR, ITI (Weller & Steele, 1992; Steele & Weller, 1993). The present study qualitatively and quantitatively examined the terminal arborizations of 26 axons in ITR and ITI labeled by injections of biocytin or, in one case, horseradish peroxidase, in ITCv. The majority of axons gave rise to a single terminal arbor, with a small number branching into two overlapping or nearby arbors. Presumptive terminal specializations consisted of rounded, bead-like swellings, most often located en passant. All axons terminated in layer 4 of cortex, and most had additional terminations in layers 3 and 5. The total extent of each axon's terminal arbor was 125-750 microns dorsoventrally (mean = 360.6 microns) and 150-725 microns anteroposteriorly (mean = 328.1 microns; all values uncorrected for shrinkage). In most axons, especially those with larger terminal fields, boutons were not uniformly distributed, but formed 2-4 clumps (mean = 2.2), with a mean width of 149 microns, separated by narrower regions of fewer boutons. Based on a cluster analysis of characteristics of the 26 axons, axons projecting from caudal (ITCv) to rostral (ITR or ITI) IT cortex of squirrel monkeys comprised three groups that we called Type I, Type II, and Type III. Type I axons, the smallest in area extent of terminal arbor, terminated predominantly in dorsal ITR. Type III axons, largest in areal extent, and Type II axons, intermediate in areal extent, terminated in ventral ITR and throughout ITI. The three classes of axons may correspond to different types of visual information entering rostral IT cortex. The clumping of boutons suggests that individual axons terminate in limited patches within their terminal fields.
基于皮质和皮质下连接以及结构学，松鼠猴的颞下（IT）皮质由一个尾侧区域ITC组成，ITC又分为背侧（ITCd）和腹侧（ITCv）亚区；一个吻侧区域ITR；以及可能位于ITC和ITR之间的第三个区域ITI（韦勒和斯蒂尔，1992年；斯蒂尔和韦勒，1993年）。本研究定性和定量地检查了26条轴突在ITR和ITI中的终末分支，这些轴突是通过在ITCv中注射生物素或在一个案例中注射辣根过氧化物酶标记的。大多数轴突产生单个终末分支，少数分支成两个重叠或相邻的分支。推测的终末特化由圆形、珠状膨大组成，最常见于轴突走行过程中。所有轴突都终止于皮质第4层，大多数在第3层和第5层也有额外的终末。每个轴突终末分支的总范围在背腹方向为125 - 750微米（平均 = 360.6微米），前后方向为150 - 725微米（平均 = 328.1微米；所有值未校正收缩）。在大多数轴突中，尤其是那些终末野较大的轴突，终扣分布不均匀，而是形成2 - 4个团块（平均 = 2.2），平均宽度为149微米，由终扣较少的较窄区域分隔开。基于对这26条轴突特征的聚类分析，从松鼠猴尾侧（ITCv）投射到吻侧（ITR或ITI）IT皮质的轴突分为三组我们称为I型、II型和III型。I型轴突终末分支面积最小，主要终止于背侧ITR。III型轴突面积最大，II型轴突面积居中，终止于腹侧ITR和整个ITI。这三类轴突可能对应于进入吻侧IT皮质的不同类型视觉信息。终扣的团块化表明单个轴突在其终末野内的有限斑块中终止。
