We present real-time neuromorphic VLSI circuits

that implement the synaptic dynamics of Short Term Plasticity

(STP). STP supports useful signal processing computational

primitives such as change detection and gain control. Compact

circuits implementing these mechanisms play a key role in

providing neuromorphic VLSI systems with autonomous adaptation

capabilities. We propose two different, flexible, short-term

adaptation CMOS circuits for controlling the efficacy of synapses

in response to incoming spikes. These circuits can be configured

to either implement short-term depression or facilitation, with

independent control over the adaptation and recovery rates.

Our results demonstrate the dynamic properties of the