Brain connectivity biomarkers predict specific memory consolidation deficits across dementia subtypes
Mr Tu's research investigates different aspects of memory in dementia sufferers and how changes to a series of brain structures that comprise the ‘limbic memory circuit’ can affect their performance in the early stages of the disease. Moving away from the traditional approach of looking solely at the hippocampus, he looks at multiple interconnected brain structures that are all involved in memory processes. Over the past year he has successfully reconstructed a critical white matter pathway using neuroimaging techniques to allow investigation of the memory circuit, and whether he can detect changes that will aid diagnosis in the earliest stages of dementia.
Another aspect of my project is developing novel clinical tests that can improve classification of dementia into its subtypes, in particular Alzheimer’s disease and behavioural variant frontotemporal dementia. Two mental processes that show distinct changes in these conditions are long-term memory and orientation. He has now developed an online test of long-term memory as well as a realistic virtual assessment of orientation that are currently being piloted in patients.
The project aims to develop better diagnostic tools to classify different subtypes of dementia in their earliest stages, using a combination of magnetic resonance imaging and novel cognitive tasks. Mr Tu's research focuses on changes in the limbic memory circuit, in particular those that occur beyond the hippocampus. To date, he has developed an online long-term memory task that has been shown in healthy participants to functionally involve the limbic memory circuit and is ready for assessment in patients. He has established a protocol to reconstruct the mammillothalamic tract using diffusion tensor imaging tractography, for the first time in patients, allowing us to assess the integrity and connectivity of the limbic memory circuit extending from the hippocampus to the thalamus. This method has since been validated in a group of thalamic stroke patients to demonstrate accelerated long-term forgetting after a 24-hour delay resulting solely from lesions in the anterior thalamus. In addition, a novel clinical assessment of spatial orientation has been created and piloted in Alzheimer’s disease and frontotemporal dementia patients with positive results. The results obtained from the past year have resulted in the submission of two manuscripts to international peer-review journals and are currently under review.
Dalton, M.A., Tu, S., Hornberger, M., Hodges, J.R., Piguet, O. (2013). Medial temporal lobe contributions to intra-item associative recognition memory in the ageing brain. Frontiers in Behavioural Neuroscience.
Flanagan, E. C., Tu, S., Ahmed, S., Hodges, J. R., Hornberger, M. (2013). Memory and orientation in the logopenic and nonfluent subtypes of primary progressive aphasia. Journal of Alzheimer’s Disease.
Tu, S., Miller, L., Piguet, O., & Hornberger, M. (2013). Impact of thalamic lesions on long-term memory consolidation. 41st Annual Coast Association Tow Research Awards, 22 November, 2013, Sydney, Australia.
Tu, S., Miller, L., & Hornberger, M. (2013). Anterior thalamus contributions to long-term consolidation of contextual memory. 43rd Annual Meeting of the Society for Neuroscience, 9-13 November, 2013, San Diego, USA.
Tu, S. (2013). Functional involvement of the Papez circuit in long-term contextual memory. Australian Research Council Centre of Excellence in Cognition and its Disorders: Memory Symposium, 31 October, 2013, Neuroscience Research Australia, Sydney, Australia.
Tu, S., Piguet, O., & Hornberger, M. (2013). Functional interaction along the Papez circuit for long-term contextual memory. Brain Sciences UNSW Symposium, 18 October, 2013, University of New South Wales, Sydney, Australia.
Tu, S., Miller, L., Piguet, O., & Hornberger, M. (2013). Long-term anterograde memory in thalamic stroke patients. Prince of Wales Clinical School Research Symposium, 11 October, 2013, Prince of Wales Hospital, Sydney, Australia.
Mr Tu has also published a short article on the Neuroscience Research Australia blog regarding findings of orientation performance in dementia conducted by our research group. This article can be found at - http://blog.neura.edu.au/2013/08/20/lost-and-forgotten-improving-our-diagnosis-of-dementia
Mr Tu is a PhD Candidate based at Neuroscience Research Australia (Neura). He began his PhD in early 2013.