Complex sentence: In particular, recent research focuses on glutamate for its responsibility in hippocampal LTP and long-term depression (LTD)--the long-lasting decrease of synaptic excitability.
Split into simpler sentences: In particular, recent research focuses on glutamate for its responsibility in hippocampal LTP and long-term depression (LTD). LTD is the long-lasting decrease of synaptic excitability.