Hippocampal area CA1 receives direct entorhinal layer III input via the temporoammonic path (TAP) and recent studies implicate TAP-CA1 synapses are important for some aspects of hippocampal memory function. Nonetheless, as few studies have examined TAP-CA1 synaptic plasticity in vivo, the induction and longevity of TAP-CA1 long-term potentiation (LTP) has not been fully characterized. We analyz...

Previous reports suggested that a low-frequency stimulus (LFS) of 1~2 Hz (600~900 pulses) induced a homosynaptic long-term depression (LTD) of synaptic efficacy in the hippocampal CA1 area of young rats (< 4-week old). However, these stimulation protocols often failed to induce LTD in the adult CA1 hippocampus. In the present study, we examined the effects of two novel tetanus patterns on LTD i...

The hippocampus is proposed to switch between memory encoding and retrieval by continually computing the overlap between what is expected and what is encountered. Central to this hypothesis is that area CA1 performs this calculation. However, empirical evidence for this is lacking. To test the theoretical role of area CA1 in match/mismatch detection, we had subjects study complex stimuli and th...

Vestibular compensation is a recovery process from vestibular symptoms over time after unilateral loss of peripheral vestibular end organs. The aim of the present study was to observe time-dependent changes in long-term potentiation (LTP) at Schaffer collateral-CA1 synapses in the CA1 area of the hippocampus during vestibular compensation. The input-output (I/O) relationships of fEPSP amplitude...

Objective(s) Nicotinic acetylcholine receptors (nAChRs) regulate epileptiform activity and produce a sustained pro-epileptogenic action within the hippocampal slices. In the present study, we investigated the effect of nAChRs on evoked glutamatergic synaptic transmission in area CA3 and CA1 of rat hippocampal slices to identify possible excitatory circuits through which activation of nAChRs pr...

Determining how the hippocampus supports the unique demands of memory encoding and retrieval is fundamental for understanding the biological basis of episodic memory. One possibility proposed by theoretical models is that the distinct computational demands of encoding and retrieval are accommodated by shifts in the functional interaction between the hippocampal CA1 subregion and its input struc...

Recent studies demonstrate that context-specific memory retrieval after extinction requires the hippocampus. However, the contribution of hippocampal subfields to the context-dependent expression of extinction is not known. In the present experiments, we examined the roles of areas CA1 and CA3 of the dorsal hippocampus in the context specificity of extinction. After pairing an auditory conditio...

Spatial distribution of theta activity was investigated in the dorsal hippocampal formation and overlying neocortex of the urethane-anesthetized rat. Laminar phase profiles from semi-microelectrode penetartions showed approximately 180 degrees phase shifts combined with small amplitude values in stratum radiatum of CA1, instratum moleculare of the dentate gyrus and in layer V/VI of the cingulat...