Event Calendar:

September 2014

Mo Tu We Th Fr Sa Su
36 01 02 03 04 05 06 07
37 08 09 10 11 12 13 14
38 15 16 17 18 19 20 21
39 22 23 24 25 26 27 28
40 29 30 01 02 03 04 05

» All Events

Contact

Hannes M. Wiesner

Address: Spemannstr. 41
72076 Tübingen
Room number: 3.B.03
Phone: +49 7071 601 927
Fax: +49 7071 601 702
E-Mail: Hannes.Wiesner

 

Picture of Wiesner, Hannes M.

Hannes M. Wiesner

Position: Guest Scientist  Unit: Scheffler

Increased oxygenation of blood is the base for signal increases in the BOLD signal in functional Brain Imaging (fMRI). I am interested in the question to what extent energy consumption measured by oxygen consumption is related to an increase in the neural activity in the brain during the processing of information (stimulation). Aerobic metabolism (i.e. oxidative phosphorylation from oxygen gas to water and carbon-dioxide) being the most efficient biochemical pathway of tissue respiration, could be used as a key indicator of the bioenergetics of neural networks.

In my project in the group 'physiological basis of fMRI signals' of Dr. Uludag the oxygen metabolism of brain tissue in rats is investigated at 16.4 Tesla by the use of 17-O MRI, fMRI and ASL. Using the strongest available field-strength of an MRI-magnet this size, the challenges in the imaging of the low abundant, fast relaxing nucleus of oxygen-17 are adressed by: physiological stability, custom MRI sequences, novel heteronuclear 17O/1H RF-coils and further development in the quantification of the cerebral metabolic rate of oxygen (CMRO2).

Further literature can be found here.



Increases of neural activity result in changes of blood flow (CBF) in brain tissue, involving increases in glucose consumption as well as changes in the cerebral metabolic rate of oxygen consumption (CMRO2) and most prominently in a change of blood oxygenation (BOLD) which is the base of fMRI brain-imaging. The dynamics of CMRO2 are investigated by the use of 17-O in this project.

It is widely assumed that neural activity is accompanied by an increase of oxygen consumption, but measurements from positron emission tomography (PET) lack consistent confirmation of this effect due to limits of spatial resolution and reproducibility of the method. Therefore, the detailed coupling between oxygen metabolism, hemodynamics and neural activity is still debated, especially during prolonged activity and different types of stimuli. Using the stable isotope of oxygen 17-O, which is rare in natural abundance, it is possible to image oxygen metabolism with nuclear magnetic resonance. The approach is similar as in PET but more specifically focused in terms of resolution and specifically limited on the product of oxygen metabolism in mitochondria: metabolized water.

Measuring MR signals of 17-O at ultra high field strengths like 9.4 up to 16.4 Tesla, in animals and humans is especially advantageous as 17-O is hardly detectable at lower field strengths. With specific MR equipment and kinetic models developed in this project the imaging of oxygen metabolism is potentially expected to excel in spatial resolution, have higher functional specificity and presumably show higher reproducibility than alternative oxygen imaging methods. This opens up the possibility to correlate the coupling of CMRO2 with BOLD contrast and CBF, resulting in a better understanding of the underlying physiology of the BOLD signal.

For further literature related to this project visit: http://www.zotero.org/groups/neurometabolic_mri

Curriculum Vitae

Education

2000-2003 Dipl.Ing.(BA) in Information Technology & B.Sc.(hons) in Engineering at Baden-Wuerttemberg Cooperative State University - Stuttgart (DHBW)

2004-2005 M.Sc. in Cognitive Science and Natural Language at University of Edinburgh, Thesis on Neural Computation under supervision of Dr. Mark van Rossum.

2006-present PhD student in the IMPRS for Neural Sciences and Behaviour at the High-Field Magnetic Resonance Center, MPI for Biological Cybernetics in the research group on fMRI & brain physiology of Dr. Kamil Uludag

2007-present Visiting research fellow at CMRR, University of Minnesota investigating cerebral oxygen metabolism for Prof. Wei Chen and Prof. Kamil Ugurbil.

Professional Experience

2003-2004 Software-Developer at plenum Systems
2006 Internship at MPI for Human Cognitive and Brain Sciences in the group of Prof. John-Dylan Haynes.
2007 Independent Lecturer in 'Database Systems' at BA Stuttgart.

Preferences: 
References per page: Year: Medium:

  
Show abstracts

Articles (2):

Balla DZ Person, Schwarz S Person, Wiesner HM Person, Hennige AM and Pohmann R Person (July-2014) Monitoring the stress-level of rats with different types of anesthesia: A tail-artery cannulation protocol Journal of Pharmacological and Toxicological Methods 70(1) 35-39.
Zhu X-H , Zhang Y , Wiesner HM Person, Ugurbil K and Chen W (August-2013) In vivo measurement of CBF using 17O NMR signal of metabolically produced H217O as a perfusion tracer Magnetic Resonance in Medicine 70(2) 309–314.

Posters (8):

Hagberg GE Person, Balla D Person, Wiesner HM Person and Logothetis NK Person (May-9-2011): Small-scale Phase and Magnitude fluctuations in fMRI time series, 19th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2011), Montréal, Canada.
Wiesner HM Person, Pohmann R Person, Balla DZ Person, Chen W , Ugurbil K and Uludag K Person (May-2011): Measurement of CMRO2 changes by somatosensory stimulation in rat using oxygen-17 at 16.4 T, 19th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2011), Montréal, Canada.
pdf
Zhu X-H , Zhang Y , Wiesner HM Person, Ugurbil K and Chen W (May-2010): Estimation of CBF Based on the Metabolic H217O Decay Rate in CMRO2 Measurement Using In Vivo 17O MR Approach, ISMRM-ESMRMB Joint Annual Meeting 2010, Stockholm, Sweden.
pdf
Balla DZ Person, Wiesner HM Person, Shajan G Person and Pohmann R Person (May-2010): Functional MRI in the rat at 9.4 T and 16.4 T, ISMRM-ESMRMB Joint Annual Meeting 2010, Stockholm, Sweden.
pdf
Wiesner HM Person, Balla DZ Person, Pohmann R Person, Chen W , Ugurbil K and Uludag K Person (April-2009): 17 O T1/T2* tissue-relaxation rates with anatomical contrast in the rat brain at 16.4 T, 17th Annual Meeting of the International Society for Magnetic Resonance in Medicine (ISMRM 2009), Honolulu, HI, USA.
pdf
Balla DZ Person, Wiesner HM Person, Shajan G Person and Pohmann R Person (April-2009): Functional MRI in the rat brain with single-shot gradient echo EPI at 16.4 T, 17th Annual Meeting of the International Society for Magnetic Resonance in Medicine (ISMRM 2009), Honolulu, HI, USA.
pdf
Balla DZ Person, Wiesner HM Person, Shajan G Person, Faber C and Pohmann R Person (April-2009): TurboCRAZED BOLD imaging detects specific activation in the rat brain after somatosensory stimulation at 16.4 Tesla, 17th Annual Meeting of the International Society for Magnetic Resonance in Medicine (ISMRM 2009), Honolulu, HI, USA.
pdf
Wiesner HM Person, Balla DZ Person, Pohmann R Person, Chen W , Ugurbil K and Uludag K Person (October-15-2008): In-vivo T1 and T2* tissue-relaxation rates of H2O17 at 16.4 Tesla, ISMRM Workshop on High-Field Systems and Applications 2008: "Whats special about 7T+?", Toronto, Canada.
pdf

Export as:
BibTeX, XML, Pubman, Edoc, RTF
Last updated: Friday, 17.01.2014