Proceedings of The Physiological Society

University College Dublin (2009) Proc Physiol Soc 15, PC208

Poster Communications

Optimized voxel-based morphometry of the rat brain reveals cortical and hippocampal volume decline with age

R. J. Kelly1, C. Blau1, E. O' Hanlon1, C. G. Connolly1, C. Kerskens1, M. Lynch1

1. Physiology, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin, Ireland.

  • Coronal image of the rat brain highlighting areas of significant tissue decline in the aged rat brain compared to young.

Voxel-based morphometry (VBM) is commonly used for analysing differences in human brain volumes [1], but similar methodology has not been developed for use in the rat brain. In this study, an optimized VBM protocol has been developed for the rat brain and using this, we have undertaken an analysis of age-related changes in brain volume in rats. High resolution structural MRI images were obtained from groups of young (N = 5) and aged (N = 7) rats using a Bruker 7 Tesla animal scanner (Bruker BioSpin, Ettlingen, Germany) and compared using FSL (FMRIB Software Library, 4.0) tools [2]. The animals were anaesthetised before entering the magnet with isoflurane (4% induction), delivered in oxygen. The isoflurane was then reduced to the minimum level to keep the animal asleep, with the depth of anaesthesia controlled by altering the percentage of isoflurane in response to changes in respiratory rate. Images were skull-stripped using the brain extraction tool (within MIPAV 4.0.2 software, [3]) and the grey matter partitions were registered to the same stereotaxic space using an in-house generic grey matter template image. The resulting images were averaged to create a study-specific template, to which the individual images were compared. Permutation-based non-parametric statistical analysis was undertaken. The data indicate that there was a significant reduction in volume in the hippocampus and cortex of aged, compared with young, rats. Specifically, volume reduction was observed in area CA1 of the hippocampus, as well as in the motor areas M1 and M2 of the cortex. These findings indicate that this optimized VBM methodology can be used to analyse volumetric changes in the rodent brain.

Where applicable, experiments conform with Society ethical requirements