Ippocampal Ca1 Synaptic Plasticity as a Gamma Ransfer Function

bstract—The capacity of activity-dependent synaptic modifiation is essential in processing and storing information, yet ittle is known about how synaptic plasticity alters the input– utput conversion efficiency at the synapses. In the adult ouse hippocampus in vivo, we carefully compared the input– utput relationship, in terms of presynaptic activity levels ersus postsynaptic potentials, before and after the inducion of synaptic plasticity and found that synaptic plasticity ed synapses to respond more robustly to inputs, that is, ynaptic gain was increased as a function of synaptic activity ith an expansive, power-law nonlinearity, i.e. conforming to he so-called gamma curve. In extreme cases, long-term poentiation and depression coexist in the same synaptic pathay with long-term potentiation dominating over long-term epression at higher levels of presynaptic activity. These ndings predict a novel function of synaptic plasticity, i.e. a ontrast-enhancing filtering of neural information through a amma correction-like process. © 2006 Published by Elsevier td on behalf of IBRO.