Fig. 1.

Excitatory/Inhibitory Imbalance in ASD. (A) Normal/optimum condition (balanced excitation, inhibition and synaptic regulation). (B) Hyper-excitatory condition due to increased excitation from a variety of genetic and/or environmental factors (B-1, i.e. FMR1, MeCP2, NLGN3, PTEN, SAHNK2 and PTEN genetic knockout/mutations; LPS and VPA prenatal exposures) or decreased-inhibitory regulators (B-2, i.e. CNTNAP2, GABRB3, MeCP2, RELN genetic knockout/mutations; prenatal VPA exposure) affecting synaptic strength; synaptic regulators could be normal. (C) Hyper-inhibitory condition due to increased inhibition from genetic or environmental factors (C-1, for example, NLGN3 mutation) and decreased excitation inducers (C-2, i.e. SHANK2 & UBE3A genetic knockout/mutations).