Nucleus detection is performed by applying an automatic intensity threshold58 on DAPI stained images after background subtraction and Gaussian blurring, followed by a watershed-based separation of touching nuclei. To determine the cellular subtype, the mean intensity for each particle was measured in the TBR1, CTIP2, SATB2 and HuC/HuD images. For every neuronal marker an empirical cut-off value was determined, above which cells were considered to belong to a specific neuronal subtype.
