van Groen T, Wyss J M
Department of Cell Biology and Anatomy, University of Alabama, Birmingham 35294.
Brain Res. 1990 Jun 4;518(1-2):227-43. doi: 10.1016/0006-8993(90)90976-i.
The present study describes the differences and similarities between the connections of the presubiculum and parasubiculum based on retrograde and anterograde tracing experiments. The results demonstrate that both areas have several similar afferent connections, particularly those from subcortical areas such as the claustrum, diagonal band of Broca, anterior thalamus, nucleus reuniens, locus coeruleus, and raphe nuclei. Both subicular areas also are innervated by axons originating in the ipsilateral and contralateral entorhinal cortex, presubiculum, and parasubiculum. In contrast to these similarities, most axons innervating the presubiculum originate in the lateral dorsal thalamic nucleus, the claustrum, and the contralateral presubiculum. Conversely, the parasubiculum is innervated primarily by axons that originate in area CA1 of the hippocampus, the basolateral nucleus of the amygdala, and the contralateral presubiculum and parasubiculum. The major efferent projection from the presubiculum and parasubiculum courses bilaterally to the medial entorhinal cortex; however, the results of the present study confirm previous suggestions that presubicular axons terminate almost exclusively in layers I and III, whereas parasubicular axons innervate layer II. The presubiculum also projects to the anteroventral and laterodorsal nuclei of the thalamus, and the lateral ventral portion of the medial mammillary nucleus, whereas the parasubiculum projects prominently to the anterodorsal nucleus of the thalamus, the contralateral presubiculum and parasubiculum, and the lateral dorsal segment of the medial mammillary nucleus. Thus despite some similarities, the major connections of presubiculum and parasubiculum are distinct from one another and distinct from the projections of the adjacent subiculum and postsubiculum. These results suggest that the subicular cortex is considerably more complex than previously envisioned and indicate that each segment may subserve a distinct role in the processing of information by the hippocampal formation.
本研究基于逆行和顺行示踪实验，描述了前扣带回和旁扣带回连接之间的差异和相似之处。结果表明，这两个区域有几个相似的传入连接，特别是来自皮质下区域的连接，如屏状核、布罗卡斜带、丘脑前核、 reuniens核、蓝斑和中缝核。两个扣带回区域也由起源于同侧和对侧内嗅皮质、前扣带回和旁扣带回的轴突支配。与这些相似之处形成对比的是，支配前扣带回的大多数轴突起源于背外侧丘脑核、屏状核和对侧前扣带回。相反，旁扣带回主要由起源于海马体CA1区、杏仁核基底外侧核以及对侧前扣带回和旁扣带回的轴突支配。前扣带回和旁扣带回的主要传出投射双向地到达内侧内嗅皮质；然而，本研究结果证实了先前的观点，即前扣带回轴突几乎只终止于I层和III层，而旁扣带回轴突支配II层。前扣带回还投射到丘脑的前腹侧和背外侧核，以及内侧乳头体核的外侧腹侧部分，而旁扣带回则突出地投射到丘脑的前背侧核、对侧前扣带回和旁扣带回，以及内侧乳头体核的外侧背侧段。因此，尽管有一些相似之处，前扣带回和旁扣带回的主要连接彼此不同，也不同于相邻的扣带回和后扣带回的投射。这些结果表明，扣带回皮质比以前设想的要复杂得多，并表明每个节段在海马结构的信息处理中可能发挥不同的作用。
