Jason Philip Lerch1, Adelaide P. Yiu2,
Alonso Martinez-Cabal2, Tanyar Pekar2, Veronique D.
Bohbot3, Paul Frankland2, R Mark Henkelman1,
Sheena A. Josselyn2, John G. Sled1
1Mouse Imaging Centre, Hospital for
Sick Children, Toronto, Ontario, Canada; 2Program in Neuroscience
and Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada; 3Douglas,
Department of Psychiatry, McGill University, Montreal, Quebec, Canada
We
correlated training induced volume changes seen by high-resolution mouse MRI
with four cellular markers to test whether (1) alterations in neuron
numbers/sizes; (2) alterations in astrocyte numbers/sizes; (3) increased neurogenesis/survival
of new neurons; or (4) remodelling of neuronal processes best explain the MRI
results. We detected a significant positive correlation between GAP-43 and
structure volume, but found no correlation between MR volume and any other
cellular measure. We can thus conclude that, among the hypotheses tested, the
largest explanatory factor for learning induced MRI detectable volume changes
is the remodelling of neuronal processes.