Neurons regulate the strength of their synapses in response to a perturbation in order to stabilize neuronal signaling through a form of homeostatic plasticity known as synaptic scaling. The process of scaling has the potential to alter all of a cell’s miniature postsynaptic current (mPSC) amplitudes by a single multiplicative factor (uniform scaling), and in doing so could change action potential-dependent or evoked synaptic strength by that factor. However, recent studies suggest that individual synapses scale with different scaling factors (non-uniform). This could complicate the simple multiplicative transform from mPSC scaling to the evoked response. We have previously identified a slow AMPAergic and GABAergic synaptic scaling in chick embryo motoneurons following 2-day in vivo perturbations inhibiting neuronal activity or GABAAR function, and now show a rapid form of scaling following NMDA receptor blockade in vitro . Slow GABAergic scaling appeared to be of a classical uniform pattern. Alternatively...