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. 2005 Oct 19;25(42):9567–9580. doi: 10.1523/JNEUROSCI.2992-05.2005

Figure 7.

Figure 7.

Presynaptic GABAB inhibition mediates propagation of temporoammonic EPSPs. A, Temporoammonic (TA) pathway stimulation. The activation profile image, generated from the raster scan of the path of interest, shows the spatiotemporal response to the TA burst stimulus. Note that the voltage-sensitive dye (VSD) signal revealed an inhibitory response in SR, whereas the excitatory response is compartmentalized to the apical tuft in SLM. SC, Schaffer collateral stimulation; TA, TA stimulation. The voltage-sensitive dye signals were averaged over 12 trials. B, Schaffer (SC) pathway stimulation. The activation profile image shows the spatiotemporal response to the Schaffer collateral stimulus that returns to baseline and does not exhibit prolonged depolarization in stratum radiatum during the time window in which the TA pathway is activated. C, Schaffer-temporoammonic (SC&TA) pathway stimulation. The Schaffer and temporoammonic stimulus are paired so that a single Schaffer stimulus precedes the temporoammonic burst stimulus by 60 ms. The propagation of temporoammonic EPSPs are gated to stratum radiatum and stratum oriens (asterisk). Temporoammonic (TA) pathway (D) and Schaffer (SC) (E) stimulation in the presence of the GABAB antagonist CGP 55845A (2 μm). Note the appearance of a late depolarizing component. F, Schaffer-temporoammonic (SC&TA) pathway stimulation in the presence of GABAB antagonist CGP 55845A (2 μm). CGP 55845A significantly blocks the gating of temporoammonic EPSPs to stratum radiatum and stratum oriens (**p = 0.05; ANOVA; n = 4).