Cortical Imaging
It is of importance to develop a high resolution spatio-temporal functional imaging modality to image spatially distributed brain activity. Cortical imaging is one of electrophysiological neuoimaging modalities which aims at substantially increasing the spatial resolution of electroencephalogram (EEG) modality while maintains the high temporal resolution the EEG enjoys. A novel cortical imaging technique has been developed in our laboratory to estimate cortical potential distributions, which reflect well the cortical source distributions, directly from scalp–recorded EEG signals in a realistic geometry inhomogeneous head model by means of the boundary element method (He et al. 1999, pdf). This technique provides a unique inverse solution to the EEG inverse problem and offers an important capability of estimating noninvasively cortical potentials which are currently recorded by means of invasive sub-dural electrodes in a clinical setting. The validity of this technique has been rigorously validated in a group of patients (He et al. 2002, pdf). Furthermore, our cortical imaging results demonstrate its capability of imaging cortical regions displaying epileptiform activity as confirmed by neurosurgical treatment in the same patients(Zhang et al. 2003, pdf).
Fig. 1 Schematic diagram of electrophysiological cortical imaging.
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Fig. 2 Top row: Scalp-recorded EEG. Middle row: Invasively recorded
cortical potentials. Bottom row: Noninvasive cortical imaging results in
the same patient. Note the substantially enhanced spatial resolution of the
cortical potentials as compared with scalp potentials, and the
correspondence between the recorded and imaged cortical potentials in the
same patient. |
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