RT Journal Article
SR Electronic
T1 Long-Term Depression in the Developing Hippocampus: Low Induction Threshold and Synapse Nonspecificity
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 1823
OP 1830
DO 10.1523/JNEUROSCI.22-05-01823.2002
VO 22
IS 5
A1 Pontus Wasling
A1 Eric Hanse
A1 Bengt Gustafsson
YR 2002
UL http://www.jneurosci.org/content/22/5/1823.abstract
AB It was observed that the use of paired-pulse afferent stimulation as test stimulation (0.1–0.02 Hz) in the hippocampal CA1 area in young (1–2 week) rats, but not in older ones, led to declining synaptic activity. We show that such very low-frequency stimulation leads to long-term depression (LTD) initiated by activation of NMDA receptor channels and/or T-type voltage-dependent calcium channels. The depression is initiated within three or four such stimuli, and <10 are sufficient to induce a notable long-term effect. When the paired-pulse stimulation exceeded threshold for postsynaptic spike activation, the depression was preceded by an NMDA receptor-dependent potentiation. Irrespective of whether homosynaptic potentiation or depression occurred, the paired pulse stimulation also induced depression in neighboring synapses alternately activated by single stimuli. These results point to a very high sensitivity for induction of synaptic depression during the neonatal period. They also support the notion that a brief rise in postsynaptic calcium can induce long-term potentiation (LTP) or LTD, a larger rise more likely to induce LTP, as well as that a prolonged modest increase produces selectively only LTD.