Irle E, Markowitsch H J
Neuroscience. 1982;7(11):2637-47. doi: 10.1016/0306-4522(82)90088-4.
Efferent projections from the hippocampal formation to the cat's cortex were traced with the retrograde horseradish peroxidase technique. Different areas of the cortex of 31 cats were injected with small amounts of horseradish peroxidase. All subregions of the hippocampal formation were screened for labeled cells. It was found that, with the exception of the entorhinal injections, only subicular areas of the hippocampal formation contain labeled neurons. When HRP was injected into the entorhinal cortex, labeled cells are also found in the hippocampus proper. The most dense projection from the subicular cortex is directed to the medial part of the cortical hemisphere. Here, cingulate, retrosplenial and medial prefrontal fields receive a substantial number of subicular efferents. Furthermore, the entorhinal cortex is reached by a number of axons originating in the subicular area. Scarce projections from the subicular cortex terminate in the dorsal prefrontal, temporal, parietal and prepiriform cortex. It is suggested that the projection from the subicular cortex to the neocortical areas of the frontal pole (medial prefrontal cortex) is of special importance as it may constitute a link between the association areas of the neocortex and those regions of the limbic system thought to play a role in memory (subicular cortex, mamillary bodies, anterior thalamus, cingulate gyrus).
采用逆行辣根过氧化物酶技术追踪了猫海马结构向其大脑皮层的传出投射。向31只猫大脑皮层的不同区域注射少量辣根过氧化物酶。对海马结构的所有亚区进行标记细胞筛查。结果发现，除了内嗅区注射外，只有海马结构的下托区含有标记神经元。当将辣根过氧化物酶注入内嗅皮层时，在海马本部也发现了标记细胞。下托皮层最密集的投射指向大脑半球内侧部分。在此，扣带回、压后皮质和内侧前额叶区域接收大量下托传出纤维。此外，起源于下托区的一些轴突可抵达内嗅皮层。下托皮层的稀疏投射终止于背侧前额叶、颞叶、顶叶和梨前皮质。有人提出，下托皮层向额叶极新皮质区（内侧前额叶皮质）的投射具有特殊重要性，因为它可能构成新皮质联合区与边缘系统中那些被认为在记忆中起作用的区域（下托皮层、乳头体、丘脑前核、扣带回）之间的联系。
