Events
BII Seminar: Learning in the fast lane: diffusion MRI of neuroplasticity in the hippocampus and related pathways
Speaker: Prof Yaniv Assaf, Ph.D, Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
Date: Thursday 2nd February 2012 from 1.30pm (lunch from 1pm in the cafe area on the mezzanine floor)
Venue: Room 1.006, A.V. Hill building
Neuro-plasticity is one of the key processes in our brain's physiology. This process allows our brain to change itself, functionally and structurally, following the acquisition of a new skill or experience (1-8). While functional aspects of neuro-plasticity can be studied using non-invasive techniques such as fMRI, EEF and MEG, investigation of the structural tissue characteristics of neuro-plasticity requires invasive histological or invasive approaches.
Structural MRI studies of long-term brain plasticity reveal significant volumetric/regional changes (9-12). Yet, the micro-structure correlates of these changes are not well understood. An open question is what happens at shorter term learning and memory processes?
In a short term spatial navigation study performed both in humans and rodents (13), we found that diffusion MRI can detect structural changes in cell morphology induced by plasticity within few hours. Both in humans and rodents, the micro-structural changes, as observed by MRI, were localized to the anticipated brain regions: hippocampus, para-hippocampus, visual cortex, cingulate cortex and insular cortex.
Our results indicate that significant structural occur in the tissue within mere hours - an interesting result by itself from the neurophysiological point of view. However, by investigating the induced structural changes both by histology and MRI it is possible to elucidate the relations between tissue micro-structure and the diffusion MRI signal. Preliminary results of such comparison indicate that one of most significant cellular component that is in correlation with the diffusion MRI indices is the density and shape of astrocytes (13-15).
The ability of MRI to follow such subtle and rapid cellular changes is striking and opens a new window into brain physiology and plasticity localization. In addition, investigation of underlying tissue changes may lead to better understanding of the diffusion MRI signal.
If you would like to attend this seminar, please complete the on-line registration form.
References:
1. Holtmaat A, Svoboda K. Experience-dependent structural synaptic plasticity in the mammalian brain. Nat Rev Neurosci 2009;10(9):647-658.
2. Bruel-Jungerman E, Davis S, Laroche S. Brain plasticity mechanisms and memory: a party of four. Neuroscientist 2007;13(5):492-505.
3. Bruel-Jungerman E, Rampon C, Laroche S. Adult hippocampal neurogenesis, synaptic plasticity and memory: facts and hypotheses. Rev Neurosci 2007;18(2):93-114.
4. Johansen-Berg H. Structural plasticity: rewiring the brain. Curr Biol 2007;17(4):R141-144.
5. Markham JA, Greenough WT. Experience-driven brain plasticity: beyond the synapse. Neuron Glia Biol 2004;1(4):351-363.
6. Lamprecht R, LeDoux J. Structural plasticity and memory. Nat Rev Neurosci 2004;5(1):45-54.
7. Muller D, Nikonenko I, Jourdain P, Alberi S. LTP, memory and structural plasticity. Curr Mol Med 2002;2(7):605-611.
8. Gross CG. Neurogenesis in the adult brain: death of a dogma. Nat Rev Neurosci 2000;1(1):67-73.
9. Lerch JP, Yiu AP, Martinez-Canabal A, Pekar T, Bohbot VD, Frankland PW, Henkelman RM, Josselyn SA, Sled JG. Maze training in mice induces MRI-detectable brain shape changes specific to the type of learning. Neuroimage 2011;54(3):2086-2095.
10. Voss HU, Schiff ND. MRI of neuronal network structure, function, and plasticity. Prog Brain Res 2009;175:483-496.
11. Draganski B, May A. Training-induced structural changes in the adult human brain. Behav Brain Res 2008;192(1):137-142.
12. Scholz J, Klein MC, Behrens TE, Johansen-Berg H. Training induces changes in white-matter architecture. Nat Neurosci 2009;12(11):1370-1371.
13. Blumenfeld-Katzir T, Pasternak O, Dagan M, Assaf Y. Diffusion MRI of structural brain plasticity induced by a learning and memory task. PLoS One 2011;6(6):e20678.
14. Theodosis DT, Poulain DA, Oliet SH. Activity-dependent structural and functional plasticity of astrocyte-neuron interactions. Physiol Rev 2008;88(3):983-1008.
15. Shao Y, McCarthy KD. Plasticity of astrocytes. Glia 1994;11(2):147-155.
Biography
Yaniv joined TAU in 2004. After completing his BSc, MSc and PhD degrees at TAU, he pursued a joint post-doctorate fellowship at the Tel Aviv-Sourasky Medical Center and the National Institutes of Health (NIH). During this time, Yaniv specialized in MRI research, developing new analysis tools that enhance MRI use and implementing new techniques for assessing tissue damage in a range of diseases.
Since joining TAU, at the department of Neurobiology, Yaniv has focused on developing MRI techniques and analysis frameworks that will enable indirect measurement of micron and nano scales structures thorough low resolution MRI. The main hypothesis behind his group's research is that brain morphology and brain function are linked. The morphological finger print of the tissue should resemble its functional one, thus if one can develop tools for in-vivo detection of microscopic tissue features, it might be a good tool for studying morphological changes induced by brain plasticity and other functional aspects of the brain.
Under this topic Yaniv's group focuses on extracting micron scale structures of both white and grey matter in animals as well as in the human brain. This is done with the aim of enhancing the information extracted from MRI beyond the resolution limitation of the millimeter scale. In particular current research in the group includes the characterization of the assembly of neuronal networks to produce micron and sub-micron fiber bundles that transmit electrical conductance throughout the brain and the local arrangement of cellular structures in the cortical grey matter layers and their relation to the functional anatomy of the human brain. To that end Yaniv and his group combine these methods with electrophysiological and functional measures.
In addition, the group use their novel methods as well as conventional routines to study brain structural plasticity in health and disease. Recent works have focused on understanding the long and short term structural plasticity following spatial memory tasks (water maze in rat and car racing game in humans). In addition they study the abnormal structural correlates in mice and humans that carry the ApoE4 allele (risk factor of Alzheimer's disease).
Their current budget includes grant support from the Israel Science Foundation on the subject of: "Diffusion MRI of Brain Plasticity" and the EU FP7 under the CONNECT project (www.brain-connect.eu)
BII Seminar: Simultaneous EEG-fMRI - from acquisition methods to application
Speaker: Dr Karen Mullinger
Date: Wednesday 8th February 2012 at 1pm (lunch from 12.30 in the cafe area on the mezzanine floor)
Venue: Room 1.006, A.V. Hill building
Combining electroencephalography (EEG) with functional Magnetic Resonance Imaging (fMRI) in simultaneous recordings offers a unique capability to monitor brain function with high spatial and temporal resolution. The successful exploitation of EEG-fMRI is remarkable given the very large artefacts that are generated in the EEG data recorded during concurrent fMRI. Here I will outline the methods we have developed to reduce these artefacts during data acquisition and also to improve correction techniques. These methods improve the quality of the EEG data that can be obtained in the MR environment, increasing the applications of this multi-modal technique. I will demonstrate one powerful application of high quality simultaneous EEG-fMRI data in understanding neurovascular coupling in positive and negative BOLD regions.
Biography
Since completing a BSc in Physics with Medical Physics 7 years ago Karen has gained unique and wide-ranging experience in the development and application of simultaneous EEG-fMRI working with the first MR-compatible EEG system at the Sir Peter Mansfield Magnetic Resonance Centre, Nottingham. This has involved collaboration with academic and industrial research leaders.
Karen's PhD addressed many aspects of simultaneous EEG-fMRI recordings including: improving EEG artefact correction, reducing artefacts at ultra-high field to make simultaneous recordings feasible, and identifying the major sources of MR image distortion due to EEG hardware. Subsequently, as a Sir Peter Mansfield Research Fellow, she has played a leading role in research aimed at understanding the origins of the gradient and pulse artefacts in EEG data, as well as in the development of beamformer techniques for localising EEG sources in EEG-fMRI experiments. Most recently, Karen has exploited the techniques we have developed to investigate neurovascular coupling via correlation of fMRI and EEG signals, in collaboration with Birmingham University’s School of Psychology.
If you would like to attend this seminar please complete the on-line registration form.
BII Symposium: Language Imaging
Speakers:Anna Woollams, Paul Hoffman, Patti Adank, Shirley-Ann Rueschemeyer
Date: 14th March 2012, 1-5pm
Venue: Room 5.206 University Place
More details about this symposium to follow shortly.
If you would like to attend this symposium, please complete the on-line registration form.
BII Symposium: Quantitative Imaging in Dementia
Speakers: Karl Herholz (University of Manchester) Steve Williams (University of Manchester), Peter Nestor (University of Cambridge)
Date: Weds 23rd May 2012, 1pm (with lunch from 12.30-1pm)
Venue: Rooms 306a and 306b, Ground floor, Jean MacFarlane Building
This symposium will include the following talks:
"The relation between atrophy, synaptic function, and amyloid deposition in Alzheimer's Disease" (Karl Herholz)
"Metabolomic Biomarkers of Alzheimer’s Disease: Investigation by Magnetic Resonance Spectroscopy of a Transgenic Mouse Model" (Steve Williams)
If you would like to attend this symposium, please complete the on-line registration form.