It has been long believed that long-term potentiation (LTP) and long-term depression (LTD) are the primary mechanisms for encoding memory. However, causal evidence of this has thus far been elusive. Here we demonstrate a causal relationship between these mechanisms of plasticity and associative fear memory in rats. Using optogenetic targeting of auditory inputs to the lateral amygdala, an associative memory can be formed through light stimulation paired with foot-shock. Following this conditioning, fear memory can be activated through light stimulation as demonstrated by freezing and avoidance of a strongly rewarding task. LTD induction through low frequency stimulus leads to removal of this memory, demonstrated by continued reward task activity during light stimulation. Subsequent LTP induction through high frequency stimulation leads to restoration of the memory, as shown by restored freezing and award task avoidance during light stimulation. Using this simple series of experiments we have demonstrated the removal and reinstatement of a memory using LTD and LTP, thus demonstrating a causal relationship between these synaptic processes and memory