Premium
Expression of long‐term potentiation in aged rats involves perforated synapses but dendritic spine branching results from high‐frequency stimulation alone
Author(s) -
Dhanrajan Tiruchinapalli M.,
Lynch Marina A.,
Kelly Aine,
Popov Victor I.,
Rusakov Dmitri A.,
Stewart Michael G.
Publication year - 2004
Publication title -
hippocampus
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.767
H-Index - 155
eISSN - 1098-1063
pISSN - 1050-9631
DOI - 10.1002/hipo.10172
Subject(s) - long term potentiation , perforant path , dendritic spine , neuroscience , excitatory postsynaptic potential , dentate gyrus , postsynaptic potential , stimulation , hippocampal formation , perforant pathway , ltp induction , hippocampus , chemistry , biology , inhibitory postsynaptic potential , receptor , biochemistry
Evidence for morphological substrates of long‐term changes in synaptic efficacy is controversial, partly because it is difficult to employ an unambiguous control. We have used a high‐frequency stimulation protocol in vivo to induce long‐term potentiation (LTP) in the hippocampal dentate gyrus of aged (22‐month‐old) rats and have found a clear distinction between animals that sustain LTP and those that fail to sustain it. The “failure group” was used as a specific/“like‐with‐like” control for morphological changes associated with the expression of LTP per se. Quantitative optical and electron microscopy was used to analyze large populations of dendritic spines and excitatory perforant path synapses; LTP was found to be associated with an increase in numbers of segmented (perforated) postsynaptic densities in spine synapses. In contrast, an increase in the number of branched spines appears to result from high‐frequency stimulation alone. These data shed light on the current controversy about the expression mechanism of LTP. © 2004 Wiley‐Liss, Inc.