Cover legend: Serotonergic fibers (labeled for serotonin transporter; red) and cell nuclei (labeled with diamidino-2-phenylindole; blue) in the hippocampus of mice lacking cytoplasmic regions of protocadherin-α. The serotonergic fibers abnormally innervate the hippocampus. For more information, see the article by Katori et al. in this issue (pages 9137–9147).