Modelling the magnetic signature of neuronal tissue
Section snippets
Neuron simulations
Our simulations are based on compartmentalized models of neurons. Our computer code, BioSENSE (biologically-based sensory-enhanced neural simulation engine), solves the balance of currents in each compartment through successive time steps. It is one of the original neural simulators (Travis, 1986, Travis, 1988) and has undergone a number of revisions since its introduction. It can simulate the dynamics of individual neurons or collections of neurons, including structured systems such as sensory
Results and discussions
The modelled neuron and its electric current distribution and magnetic field produced at a fixed moment of time are shown in Fig. 1. The chosen reference frame is such that the z-axis is parallel to the magnetic field of the MR scanner, and the dendritic arbour of the neuron is predominantly in the x–y plane. This frame of reference is chosen arbitrarily with respect to the apical dendrite since, in an MRI experiment, the neuronal orientation will vary throughout the cortex.
In Fig. 2A, the time
Conclusions
This study is a step in the chain of efforts to determine the detectability of neuronal activity via MRI (Bandettini et al., 2005). Details of the dynamics of the magnetic fields of individual neurons may be important for resolving this issue and should be examined before, or at least in conjunction with, studies of populations of realistic neurons. There are relatively few reported studies on neuronal magnetic fields in brain tissue. Xue et al. (2006) considered synchronized activity of
Acknowledgments
K.B. Blagoev would like to thank Vince Clark, Anders Dale, Anna Devor, Paul Mullins, Bruce Rosen, Kamil Ugurbil and Van J. Wedeen for valuable discussions.
Supported by LANL-LDRD and NS44623.
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