The Journal of Neuroscience, February 15, 1998, 18(4):1207-1216
Long-Term Potentiation of Synaptic Transmission in the Avian
Hippocampus
Troy W.
Margrie1,
John
A. P.
Rostas1 and
Pankaj
Sah2
The Neuroscience Group and the 1 Disciplines of Medical
Biochemistry and 2 Human Physiology, Faculty of Medicine
and Health Sciences, University of Newcastle, Callaghan NSW, 2308, Australia
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.
Key words:
calcium; plasticity; NMDA; memory; forskolin; PPF; cAMP
Copyright © 1998 Society for Neuroscience 0270-6474/98/1841207-10$05.00/0