Figure 3.

Normal developmental trajectories of expression of inhibitory system components in the human prefrontal cortex. Normal development of GABA receptor components of the inhibitory system is dynamic until adolescence where the trajectories reach a steady or declining state. GABA_A (GABR_A) subunits display two distinct patterns, one of decreasing expression following birth (α2, α5, β1, γ1, γ3 subunits) and a M pattern (dynamic expression) with peaks at toddler and teenage time periods (α1, α4, β2, β3, γ2 subunits; Fillman et al., 2010). The peak in the ratio of GABA α1 to α2 subunits (GABRA1/GABRA2) coincides with increased gamma band power in the prefrontal cortex (refer Figure 1). Expression of inhibitory neuron markers display either decline over post-natal life (SST, somatostatin; CR, calretinin; NPY, neuropeptide Y), initial up-regulation and then decline or plateau around school age (CB, calbindin; VIP, vasoactive intestinal peptide), or increased expression over post-natal life (PV, parvalbumin; CCK, cholecystokinin; Fung et al., 2010).