Interneurons in the brain that use GABA (γ-aminobutyric acid) as a neurotransmitter are essential for functional circuits. During development, these interneurons migrate tangentially from their birthplace in embryonic ganglionic eminences to their functional homes in the neocortex. In mice lacking the distal-less homeobox genes (Dlx1 and -2), this migration is disrupted. Studying mouse brain development, Le et al. now show that Dlx1 and -2 regulate not only interneuron migration but also production of GABA. These genes bind to and regulate promotors of genes encoding GAD (glutamic acid decarboxylase), which converts the excitatory neurotransmitter glutamate into the inhibitory neurotransmitter GABA.
