This study demonstrates that long-term potentiation (LTP) and long-term depression (LTD) can be used to activate and deactivate associative memories. Using optogenetics, the researchers conditioned rats to associate a foot shock with auditory stimuli. They found that LTD inactivates the memory, while LTP reactivates it. This was confirmed by testing the rats' responses to the auditory stimuli after conditioning with either LTD or LTP. The results suggest that LTP and LTD are directly involved in the formation and modification of memories. The study also shows that LTP can restore a memory that had been inactivated by LTD, indicating a causal relationship between synaptic plasticity and memory. The findings support the idea that memories are encoded by synaptic modifications, and that LTP and LTD are essential for memory formation and retrieval. The study also highlights the importance of specific synaptic inputs in memory formation and the role of synaptic plasticity in memory processes. The results provide strong evidence for the causal link between synaptic plasticity and memory, and demonstrate that memories can be manipulated using bidirectional synaptic plasticity.This study demonstrates that long-term potentiation (LTP) and long-term depression (LTD) can be used to activate and deactivate associative memories. Using optogenetics, the researchers conditioned rats to associate a foot shock with auditory stimuli. They found that LTD inactivates the memory, while LTP reactivates it. This was confirmed by testing the rats' responses to the auditory stimuli after conditioning with either LTD or LTP. The results suggest that LTP and LTD are directly involved in the formation and modification of memories. The study also shows that LTP can restore a memory that had been inactivated by LTD, indicating a causal relationship between synaptic plasticity and memory. The findings support the idea that memories are encoded by synaptic modifications, and that LTP and LTD are essential for memory formation and retrieval. The study also highlights the importance of specific synaptic inputs in memory formation and the role of synaptic plasticity in memory processes. The results provide strong evidence for the causal link between synaptic plasticity and memory, and demonstrate that memories can be manipulated using bidirectional synaptic plasticity.