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. 2004 May 14;558(Pt 2):465–478. doi: 10.1113/jphysiol.2004.064519

Figure 4. Global propagation of LTS evoked by local synaptic stimulation.

Figure 4

A, z-projection of an LTS interneurone from layer 5 of primary somatosensory cortex. S marks the location of the stimulation electrode, which was always placed adjacent to terminal dendritic branches. Coloured boxes indicate the dendritic domains selected for line scan imaging at an additional 10× zoom (not shown). Scale bar = 20 μm. We systematically tested dendritic calcium responses throughout the dendritic tree. Ba and Ca, voltage response (top) to 5 ms somatic current injection (bottom) to a cell held at −78 mV (B), and −55 mV (C). Bb and Cb, calcium transients at the soma, and at three dendritic locations, as colour-coded in A. Da and Ea, synaptic response to a train of 3 stimulations (40 Hz) delivered at −78 mV (D) and −55 mV (E). Note how the LTS was triggered by the third stimulation when the cell was hyperpolarized. Db and Eb, calcium transients plotted as in Bb and Cb during synaptic stimulations. Dot markers indicate the timing of the synaptic stimulations. Note that the calcium influx was time-locked to the LTS in D, and to the AP in E. Also note that the magnitude of the synaptically evoked LTS was comparable to the somatically evoked LTS throughout the dendritic tree.