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. 2007 Aug 6;104(33):13490–13495. doi: 10.1073/pnas.0705708104

Fig. 2.

Fig. 2.

O-LM cells coordinate multiple cell assemblies. (A) Network scheme. Within each module, O-LM (O) cell population inhibits the distal apical dendrites of pyramidal (E) cell population, basket (I) cell population inhibits E cell at the soma and also inhibits itself and O cell population, and E cell excites both O and I cells. Connections among modules are made through O–E synapses on distal apical dendrites. (B) Representative spike rastergram of a network consisting of four modules (labeled 1 to 4 on the y axis). Each module consisted of 40 E (black), 10 O (blue), and 10 I cells (red). For clarity, however, just half the number of cells is shown. During the first 500 ms, all E cells received drive currents uniformly distributed from 217–236 pA. Note that E cells spike sparsely and randomly (6.72 ± 2.76 Hz) in this regime and that O–E synapses are able to induce synchrony among modules. For the second 500 ms of simulation, 12 E cells inside each module were activated with higher drive currents. E cells of modules 1 and 2 received random drive from 330–349 pA, whereas activated E cells in modules 3 and 4 received drive from 820–849 pA. Note the suppression of the less active E cells inside each module as well as the formation of two distinct gamma assemblies induced by O–E synapses. (C) Normalized phase difference histograms obtained for the parameter regime shown in the first 500 ms of B, showing synchrony among all modules. (D) Same as in C, but for the regime shown in the second 500 ms of B. Note the loss of synchrony between modules with distinct levels of excitation. (E) Power spectra of the model LFPs of modules 1 and 4 after the activation of subsets of E cells showing theta and (distinct) gamma peaks. (F) Coherence analysis between modules of similar and distinct activated E cell drives. Note the loss of gamma coherence between modules of distinct drive along with no change in theta coherence. C–F were obtained by analyzing 10 s of simulation. E cell drive was applied at the distal apical dendritic compartment. Other parameters are presented in SI Table 1. The same color convention for the cells will be used in the other rastergrams.