Multiphysics Neuron Model for Cellular Volume Dynamics
ABSTRACT Even though cellular volume dynamics has been linked to cell apoptosis and intrinsic optical signals, there is no quantitative model for describing neuronal volume dynamics on the millisecond time scale. This study introduces a multiphysics neuron model, where the cell volume is a time-varying variable and multiple physical principles are combined to build governing equations. Using this model, we analyzed neuronal volume responses during excitation, which elucidated the variety of optical signals observed experimentally across the literature. Several physiological conditions were examined to investigate their effect on the pattern of volume response. In addition, we analyzed volume responses on a longer time scale with repetitive stimulation to study the characteristics of slow cell swelling. This multiscale analysis of the multiphysics model will provide not only a novel quantitative elucidation of physiologically important issues related with cellular volume dynamics but also a chance for further studies, such as the interesting possibility of inferring the balance of ion flux from plateau volume changes.
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ABSTRACT: We report preliminary results on high-resolution in vivo imaging of fast intrinsic optical signals of neuronal activity in the frequency domain. An optical coherence tomography (OCT) system was used for dynamic imaging of the cross section of rodent somatosensory cortex at 250 frame/s. Neurons in the cortex were excited by contralateral forepaw stimulation, and the ipsilateral forepaw was stimulated as a control. Hemodynamic responses at the cortical surface, which were simultaneously measured using a CCD, confirmed that forepaw stimulation properly evoked neuronal activation. Analysis of the OCT signal in the frequency domain resulted in that the spectrum significantly increased at the stimulation frequency during activation. This spectrum change was only observed during contralateral stimulation and highly localized at the stimulation frequency in the frequency space. Therefore, the spectrum change we observed is likely associated with neuronal activation.Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 08/2012; 2012:2643-6. DOI:10.1109/EMBC.2012.6346507