Theta frequency stimulation induces a local form of late phase LTP in the CA1 region of the hippocampus.

The late phase of LTP (L-LTP) is typically induced by repeated high-frequency stimulation. This form of LTP requires activation of transcription and translation and results in the cell-wide distribution of gene products that can be captured by other marked synapses. Here we report that theta frequency stimulation (5 Hz, 30 sec) applied to the Schaeffer-collateral pathway can induce a form of late phase of LTP that is restricted locally to the dendritic compartment. The late phase of theta frequency LTP is maintained even in isolated CA1 dendrites and is dependent on dendritic translation and actin cytoskeletal regulation, but is independent of transcription. This local form of L-LTP is not accessible to synaptic capture by other synapses, indicating that this form of LTP is restricted to the synaptic compartment. These results indicate that different patterns of synaptic stimulation can induce distinct forms of LTP that may have different roles in memory storage.