Brain

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Brain structure and tissue characterisation

Standard anatomical imaging provides in-plane resolution of the order of 100μm, whilst diffusion-weighted imaging provides image contrast based on the microstructure of white matter fibres. Quantitative analysis of diffusivity, anisotropy and tract characteristics is proving useful in the investigation of neurodegenerative diseases such as dementia.

(from left to right) T2-weighted fast spin echo image, mean diffusivity, fractional anisotropy and fibre direction maps. 300μm resolution. Stack of 20 slices acquired in 40 minutes (Horsburgh lab).

Brain function

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Small changes in local blood flow and oxygenation accompany neuronal activity and lead to intensity changes on suitable MRI images. By comparing images acquired at ‘baseline’ with those acquired during a specific ‘condition’ (e.g. visual stimulation), maps of brain activity can be generated.

References:

• Mahmoud AD, et al. AMP-activated Protein Kinase Deficiency Blocks the Hypoxic Ventilatory Response and Thus Precipitates Hypoventilation and Apnea. Am J Respir Crit Care Med. 2016 May 1;193(9):1032-43.
• Harris AP, et al. The role of brain-derived neurotrophic factor in learned fear processing: an awake rat fMRI study. Genes Brain Behav. 2016 Feb;15(2):221-30.
• Harris AP, et al. Imaging learned fear circuitry in awake mice using fMRI. Eur J Neurosci. 2015 Sep;42(5):2125-34.
• Holland PR, et al. Hypertension fails to disrupt white matter integrity in young or aged Fisher (F44) Cyp1a1Ren2 transgenic rats. J Cereb Blood Flow Metab. 2015 Feb;35(2):188-92.
• Pedroni SM, et al. Complement inhibition and statins prevent fetal brain cortical abnormalities in a mouse model of preterm birth. Biochim Biophys Acta. 2014 Jan;1842(1):107-15.
• Brydges NM, et al. Imaging conditioned fear circuitry using awake rodent fMRI. PLoS One. 2013;8(1):e54197.
• Holland PR, et al. MRI is a sensitive marker of subtle white matter pathology in hypoperfused mice. Neurobiol Aging. 2011 Dec;32(12):2325.e1-6.
• Jackson SJ, et al. Manganese-enhanced magnetic resonance imaging (MEMRI) of rat brain after systemic administration of MnCl₂: hippocampal signal enhancement without disruption of hippocampus-dependent behavior. Behav Brain Res. 2011 Jan 1;216(1):293-300.

For more information on how we created a study-specific rat brain template for use in SPM analysis of fMRI data, click on the document link below.