Craig Sarah, Commins Sean
Department of Psychology, National University of Ireland, Maynooth, Co. Kildare, Ireland.
Neurosci Res. 2005 Oct;53(2):140-6. doi: 10.1016/j.neures.2005.06.009.
The hippocampus communicates with the neocortex via the entorhinal cortex and is thought to be critically involved in the consolidation of memories. This paper contains in vivo evidence of a projection from the hippocampal area CA1 to the entorhinal cortex. Current theories of memory formation suggest that the backprojections from the hippocampus to the neocortex should undergo some form of plastic change in order that memories become consolidated. Paired-pulse facilitation (PPF) and long-term potentiation (LTP) are forms of short- and long-term plasticity, respectively. We show that the CA1 to entorhinal cortex projection is capable of sustaining PPF over a wide range of stimulus intervals. In addition we demonstrate that following high frequency stimulation of this pathway the evoked response in the entorhinal cortex remains potentiated for at least 30 min. Finally, we demonstrate that PPF changes following LTP depending on the initial ratio of PPF, suggesting that LTP expression on this pathway may contain a presynaptic component. These findings should provide insight into the hippocampal function in memory formation.
海马体通过内嗅皮质与新皮质进行交流，并且被认为在记忆巩固过程中起着关键作用。本文包含了从海马体CA1区到内嗅皮质投射的体内证据。当前的记忆形成理论表明，从海马体到新皮质的反向投射应该经历某种形式的可塑性变化，以便记忆得以巩固。配对脉冲易化（PPF）和长时程增强（LTP）分别是短期和长期可塑性的形式。我们表明，从CA1区到内嗅皮质的投射能够在广泛的刺激间隔范围内维持PPF。此外，我们证明，在对该通路进行高频刺激后，内嗅皮质中的诱发反应至少在30分钟内保持增强。最后，我们证明，PPF在LTP后发生变化，这取决于PPF的初始比率，表明该通路上的LTP表达可能包含一个突触前成分。这些发现应该能为海马体在记忆形成中的功能提供见解。
