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.