Expression of two-pore-domain channels in the thalamus and striatum. Shown are low-power dark-field images of emulsion-dipped sections through the telencephalon, corresponding to the film autoradiograms in Figure 1J. The line drawing (D) indicates the relevant fiber tracts and brain nuclei (for abbreviations, see Table 2). In the caudate putamen, there was uniformly high signal for TREK-1 in cells densely distributed throughout the nucleus (C); these are likely GABAergic output neurons. In contrast, TASK-3 labeled a set of large, sparsely located cells, likely cholinergic interneurons, one of which is marked with an arrow in the dark-field image (B) and in the corresponding high-power bright-field micrograph in H. Also note the intense signal for TWIK-1 in the thalamic reticular nucleus and in the choroid plexus (G). Scale bar: A–G, 500 μm; H, 25 μm.