LOW-FREQUENCY STIMULATION DOES NOT READILY CAUSE LONG-TERM DEPRESSIONOR DEPOTENTIATION IN THE DENTATE GYRUS OF AWAKE RATS

The ability of low-frequency stimulation (LFS) to induce either long-t erm depression (LTD) or depotentiation was assessed for perforant path synapses in the dentate gyrus of awake, adult rats. Neither LFS at 1 Hs (100 or 900 pulses) nor LFS at 3 Hz (900 pulses) was sufficient to produce either LTD or depotentiation. LFS at 3 Hz did produce a transi ent response depression of previously potentiated synapses, but this l asted less than 24 h and was secondary to seizure-like afterdischarges . We conclude that the LFS protocols so effective at eliciting LTD and depotentiation in area CA1 are ineffective for perforant path synapse s in the dentate gyms.