Margrie T W, Rostas J A, Sah P
The Neuroscience Group, Faculty of Medicine and Health Sciences, University of Newcastle, Callaghan NSW, 2308, Australia.
J Neurosci. 1998 Feb 15;18(4):1207-16. doi: 10.1523/JNEUROSCI.18-04-01207.1998.
The avian hippocampus plays a pivotal role in memory required for spatial navigation and food storing. Here we have examined synaptic transmission and plasticity within the hippocampal formation of the domestic chicken using an in vitro slice preparation. With the use of sharp microelectrodes we have shown that excitatory synaptic inputs in this structure are glutamatergic and activate both NMDA- and AMPA-type receptors on the postsynaptic membrane. In response to tetanic stimulation, the EPSP displayed a robust long-term potentiation (LTP) lasting >1 hr. This LTP was unaffected by blockade of NMDA receptors or chelation of postsynaptic calcium. Application of forskolin increased the EPSP and reduced paired-pulse facilitation (PPF), indicating an increase in release probability. In contrast, LTP was not associated with a change in the PPF ratio. Induction of LTP did not occlude the effects of forskolin. Thus, in contrast to NMDA receptor-independent LTP in the mammalian brain, LTP in the chicken hippocampus is not attributable to a change in the probability of transmitter release and does not require activation of adenylyl cyclase. These findings indicate that a novel form of synaptic plasticity might underlie learning in the avian hippocampus.
鸟类海马体在空间导航和食物储存所需的记忆中起着关键作用。在此，我们使用体外脑片制备技术研究了家鸡海马结构内的突触传递和可塑性。通过使用尖锐微电极，我们发现该结构中的兴奋性突触输入是谷氨酸能的，并激活突触后膜上的NMDA型和AMPA型受体。对强直刺激的反应中，兴奋性突触后电位（EPSP）表现出持续超过1小时的强大的长时程增强（LTP）。这种LTP不受NMDA受体阻断或突触后钙螯合的影响。应用福斯可林可增加EPSP并减少双脉冲易化（PPF），表明释放概率增加。相反，LTP与PPF比率的变化无关。LTP的诱导并未阻断福斯可林的作用。因此，与哺乳动物脑中不依赖NMDA受体的LTP不同，鸡海马体中的LTP并非归因于递质释放概率的变化，也不需要腺苷酸环化酶的激活。这些发现表明，一种新的突触可塑性形式可能是鸟类海马体学习的基础。
