Cover legend: Spatial relationship between an orientation preference map and the two-dimensional distribution of parvalbumin (PV)-containing GABAergic neurons in superficial layers of visual cortex (area 18). All PV neurons (open and closed circles) residing in layer 2/3 are superimposed on the orientation map. The somata are distributed in a complete random fashion and give rise to long horizontal dendrites extending across different orientation columns (bottom right). When one considers dendritic fields arising from numerous cells in the map, the high degree of overlap will be expected there. Importantly, dendrites of PV neurons in this area form a dense network linked by gap junctions. These topological features suggest relatively homogeneous coupling in the gap junctional network. For more information, see the article by Fukuda et al. from the March 29, 2006 issue (pages 3434–3443).