Direct neuronal current detection by low field MR: a feasibility study in a phantom
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1
Technical University Ilmenau, Germany
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2
Physikalisch-Technische Bundesanstalt, Germany
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3
PTB, Germany
The direct detection of neuronal currents (NC) by high field magnetic resonance (MR) techniques remains controversial. The approach of low field MR (LFMR) promises to be an alternative and the utilization of a resonant and a direct current (DC) mechanism has been proposed. In this work the emphasis is put on the DC effect. Long lasting neuronal currents manifest themselves as additional local magnetic fields in the near DC range thereby altering the MR line shape and/or position. This necessitates a sustained brain activity which can be elicited e.g. by electric stimulation of the median nerve. DC-MEG measurements show that such an activity can be modelled by an equivalent current dipole with a typical strength of around 15 nAm. In order to alleviate the demonstration of the DC effect we emulate the sustained neuronal activity by means of a single dipolar source in a physical phantom. The phantom setup consists of a hollow sphere made of plastics, which is filled with saline solution. Inside the sphere an electric current dipole is mounted, which is made from two insulated twisted copper wires with non-insulated platinum endings. The dipole is driven by a battery powered current generator and allows for flexible signal forms due to a built-in programmable microcontroller unit. Measurements are to be carried out inside the heavily shielded room BMSR-2 at PTB and include the characterization of the field distribution of the phantom using a multichannel SQUID magnetometer system. Subsequently, the principal feasibility of NC detection by LFMR will be assessed by investigating the influence of the parameter changes such as the dipole moment in the phantom on the MR signal. The evoked current dipole moments in the phantom will be at least one order larger than the measured ones in the DC-MEG.
Conference:
Biomag 2010 - 17th International Conference on Biomagnetism , Dubrovnik, Croatia, 28 Mar - 1 Apr, 2010.
Presentation Type:
Poster Presentation
Topic:
Instrumentation and Multi-modal Integrations: MEG, Low-field MRI,EEG, fMRI,TMS,NIRS
Citation:
Haueisen
J,
Körber
R,
Höfner
N,
Martens
S and
Burghoff
M
(2010). Direct neuronal current detection by low field MR: a feasibility study in a phantom.
Front. Neurosci.
Conference Abstract:
Biomag 2010 - 17th International Conference on Biomagnetism .
doi: 10.3389/conf.fnins.2010.06.00432
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Received:
12 Apr 2010;
Published Online:
12 Apr 2010.
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Correspondence:
Jens Haueisen, Technical University Ilmenau, Ilmenau, Germany, jens.haueisen@tu-ilmenau.de