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Multiple mechanisms govern the dynamics of depression at neocortical synapses of young rats
Author(s) -
Fuhrmann Galit,
Cowan Anna,
Segev Idan,
Tsodyks Misha,
Stricker Christian
Publication year - 2004
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2003.058107
Subject(s) - excitatory postsynaptic potential , neurotransmission , neuroscience , depression (economics) , somatosensory system , postsynaptic potential , chemistry , biophysics , biology , psychology , inhibitory postsynaptic potential , receptor , biochemistry , macroeconomics , economics
Synaptic transmission between pairs of excitatory neurones in layers V ( N = 38) or IV ( N = 6) of somatosensory cortex was examined in a parasagittal slice preparation obtained from young Wistar rats (14–18 days old). A combined experimental and theoretical approach reveals two characteristics of short‐term synaptic depression. Firstly, as well as a release‐dependent depression, there is a release‐independent component that is evident in smaller postsynaptic responses even following failure to release transmitter. Secondly, recovery from depression is activity dependent and is faster at higher input frequencies. Frequency‐dependent recovery is a Ca 2+ ‐dependent process and does not reflect an underlying augmentation. Frequency‐dependent recovery and release‐independent depression are correlated, such that at those connections with a large amount of release‐independent depression, recovery from depression is faster. In addition, both are more pronounced in experiments performed at physiological temperatures. Simulations demonstrate that these homeostatic properties allow the transfer of rate information at all frequencies, essentially linearizing synaptic responses at high input frequencies.