Finnerty G T, Jefferys J G
Department of Physiology and Biophysics, St Mary's Hospital Medical School, Imperial College of Science, Technology and Medicine, London, U.K.
Neuroscience. 1993 Sep;56(1):101-8. doi: 10.1016/0306-4522(93)90566-x.
Anatomical advances have led to a reappraisal of the organization of hippocampal circuitry. However, it is not clear whether the functional connectivity is fully determined by the anatomical connectivity or whether it is significantly modified by feed-forward inhibition and modulatory inputs. Therefore, we have mapped CA1 responses evoked by stimulation of ipsilateral and contralateral CA3 in vivo. Population spike amplitude and threshold were plotted to produce response maps. All CA3 subregions projected diffusely to ipsilateral CA1. However, a pattern of maximal response emerged. Caudal CA3 stimulation evoked the maximal responses septally, while rostral CA3 responses were maximal temporally. The ipsilateral CA3 response maps were compared with those produced by stimulation at the homotopic point in the contralateral CA3. The CA1 areas of maximal functional connectivity were the same implying that there is convergence of the input to CA1 from homotopic CA3 sites in the two hippocampi. Although a response in CA1 was evoked widely, our results suggest that the functional connectivity is ordered, within and between the dorsal hippocampi, and that it is consistent with the recent anatomical data. The present findings allow more precise study of the propagation of normal and abnormal neuronal activity, within and between the dorsal hippocampi. Information on the site and speed of propagation of neuronal activity would be necessary for the development of a physiologically realistic model of hippocampal computation.
解剖学的进展促使人们重新审视海马回路的组织方式。然而，尚不清楚功能连接是否完全由解剖连接决定，或者它是否会受到前馈抑制和调制输入的显著影响。因此，我们绘制了在体情况下同侧和对侧CA3刺激诱发的CA1反应。绘制群体峰电位幅度和阈值以生成反应图谱。所有CA3亚区域均广泛投射至同侧CA1。然而，出现了一种最大反应模式。尾侧CA3刺激在隔区诱发最大反应，而头侧CA3反应在颞区最大。将同侧CA3反应图谱与对侧CA3同位点刺激产生的图谱进行比较。最大功能连接的CA1区域相同，这意味着来自两个海马体同位CA3位点的输入汇聚到CA1。尽管CA1广泛诱发反应，但我们的结果表明，背侧海马体内和之间的功能连接是有序的，并且与最近的解剖学数据一致。目前的研究结果有助于更精确地研究背侧海马体内和之间正常和异常神经元活动的传播。神经元活动传播的部位和速度信息对于构建生理现实的海马计算模型是必要的。
