Analysis of immunohistochemistry

As previously described (67), all immunohistochemistry images (except Fig. 3A) were captured using a confocal microscope (Zeiss LSM 510 Meta) at ×10 magnification, converted to gray scale, and normalized to background staining. Sections chosen for analysis were anatomically matched between comparing groups and included samples from rostral, medial, and caudal regions. For the analysis of interneuron distribution across the cortex, a selected curved region (300-μm-wide) from the dorsal cortex to ventral preoptic area was outlined, straightened, and divided into seven equal regions of interest (ROIs) to capture the tangential migratory paths of newborn interneurons (ImageJ). Fluorescently labeled cells within each ROI were counted using the Image-based Tool for Counting Nuclei (ITCN) plugin for ImageJ (ITCN parameters: width, 20 to 25 pixels; minimum distance, 10 to 13 pixels; threshold, 0.3 pixels). For the analysis of interneuron distribution across the neocortex in adult offspring, five ROIs immunolabeled with either PV or CB antibodies were outlined across the neocortex along the medial-lateral axis. The number of PV- and CB-positive cells was counted and presented as a percentage of total cells in the five ROIs.