Kocsis B, Vertes R P
Center for Complex Systems, Florida Atlantic University, Boca Raton 33431.
J Neurosci. 1994 Nov;14(11 Pt 2):7040-52. doi: 10.1523/JNEUROSCI.14-11-07040.1994.
We examined the activity of single cells of the supramammillary nucleus (SUM), the mammillary body (MB), and adjacent regions of the diencephalon with respect to the hippocampal electroencephalogram (EEG) in urethane-anesthetized rats. Twenty-nine of 170 cells were found to discharge synchronously with the theta rhythm of the hippocampus (theta-related neurons). All of the 29 theta-related cells were localized to the SUM or MB. A subset of theta-related cells of SUM and MB discharged in short-duration bursts comparable to the pyramidal complex spike cells of the hippocampus. In contrast to hippocampal complex spikes, however, which predominantly exhibit this mode of firing during non-theta states, the burst firing of SUM/MB cells was strongly correlated with the theta rhythm. The proportion of bursting neurons was higher in MB than in SUM. Using partial coherence analysis, we examined the relationship between SUM/MB theta-related cells and the two generators of theta of the dorsal hippocampus. The theta-related cells of MB showed a stronger correlation with "CA1" than with "dentate" theta, whereas no such asymmetry was found in the relationship between neuronal firing of SUM cells and the two generators of theta in the hippocampus. The foregoing suggests that the theta-related cells of MB are driven by descending projections from the hippocampal formation (CA1), whereas those of the SUM are not. The SUM and MB are intimately connected with the hippocampal formation--the SUM mainly via ascending projections to the dentate gyrus, and the MB via direct descending projections from the subiculum. Theta-related SUM/MB cells may be directly involved in the generation of theta and/or the transfer of theta rhythmicity to various parts of the limbic system and forebrain.
我们在氨基甲酸乙酯麻醉的大鼠中，研究了乳头体上核（SUM）、乳头体（MB）以及间脑相邻区域的单个细胞相对于海马脑电图（EEG）的活动。在170个细胞中，有29个被发现与海马的θ节律同步放电（θ相关神经元）。所有这29个θ相关细胞均定位于SUM或MB。SUM和MB中一部分θ相关细胞以短阵发放的形式放电，类似于海马的锥体细胞簇放电。然而，与海马复合锋电位不同，海马复合锋电位在非θ状态下主要呈现这种放电模式，而SUM/MB细胞的阵发放电与θ节律密切相关。MB中爆发性放电神经元的比例高于SUM。使用偏相干分析，我们研究了SUM/MB的θ相关细胞与背侧海马θ节律的两个产生源之间的关系。MB的θ相关细胞与“CA1”θ节律的相关性强于与“齿状回”θ节律的相关性，而在SUM细胞的神经元放电与海马θ节律的两个产生源之间的关系中未发现这种不对称性。上述结果表明，MB的θ相关细胞由海马结构（CA1）的下行投射驱动，而SUM的θ相关细胞则不然。SUM和MB与海马结构紧密相连——SUM主要通过向齿状回的上行投射，而MB则通过来自下托的直接下行投射。与θ相关的SUM/MB细胞可能直接参与θ节律的产生和/或将θ节律传递到边缘系统和前脑的各个部位。
