Ventriglia F
Istituto di Cibernetica, CNR, Arco Felice, NA, Italy.
Bull Math Biol. 1998 Mar;60(2):373-407. doi: 10.1006/bulm.1997.0032.
The comprehension of activities and functions of complex brain structures requires, among other things, information on simultaneous activities in several regions. Results reported in the literature using multi(micro/macro)electrode recordings or imaging techniques provide incomplete information due either to the small size and/or small number of investigated regions or to the poor spatiotemporal resolution, respectively. This is particularly true for the hippocampus and its subfields, and mathematical modeling and computer simulation have been used with the aim of obtaining information when this is lacking. Global activities in the CA3 field of the hippocampus, and in particular the genesis of theta rhythm and sharp waves, have been investigated here by a mathematical model formulated within the frame of a kinetic theory of neural systems. The model has taken into account data of experimental results both on different PSPs recorded in hippocampal neurons and on recurrent pyramidal collateral geometries. The computational 'experiments' to which the model was subjected suggest that the sharp waves arise through a selective and short block of the fast inhibitory neurons of CA3, produced by a medial septum inhibitory input, whereas the theta activity is produced by a durable, continuous inhibition of the slow inhibitory neurons. Information obtained also suggests that the recurrent pyramidal collaterals subserve a competitive, rather than a cooperative, organization. Based on these results a hypothesis on the possible functional organization of the CA3 field and of the entire hippocampus has been formulated. According to this hypothesis, the CA3 imposes a serial order on the flow of activity arriving at the hippocampus from the entorhinal cortex and from its connected polymodal cortical regions. This ordering permits cortical activities, arriving at CA3 on appropriate time intervals, to produce effects in regions of brain to which the CA3 projects. The competing cortical activities are lost.
要理解复杂脑结构的活动和功能，除其他因素外，还需要有关多个区域同步活动的信息。文献中使用多（微/宏）电极记录或成像技术报告的结果，分别由于所研究区域的尺寸小和/或数量少，或者时空分辨率差，而提供了不完整的信息。对于海马体及其子区域尤其如此，当缺乏此类信息时，数学建模和计算机模拟已被用于获取信息。本文通过在神经系统动力学理论框架内构建的数学模型，研究了海马体CA3区的整体活动，特别是theta节律和尖波的产生。该模型考虑了海马神经元中记录的不同兴奋性突触后电位（PSP）以及回返锥体侧支几何结构的实验结果数据。对该模型进行的计算“实验”表明，尖波是由内侧隔核抑制性输入产生的CA3区快速抑制性神经元的选择性短暂阻断引起的，而theta活动是由慢速抑制性神经元的持久、持续抑制产生的。获得的数据还表明，回返锥体侧支发挥的是竞争性而非协作性组织作用。基于这些结果，已提出关于CA3区以及整个海马体可能的功能组织的假说。根据这一假说，CA3区对从内嗅皮质及其相连的多模态皮质区域到达海马体的活动流施加序列顺序。这种排序允许以适当时间间隔到达CA3区的皮质活动，在CA3区投射的脑区产生效应。相互竞争的皮质活动则被消除。
