Dynamic Statistical Parametric Neurotechnique Mapping: Combining fMRI and MEG for High-Resolution Imaging of Cortical Activity

of focal sources (Sherg and VonCramon, 1985; Schmidt Functional magnetic resonance imaging (fMRI) can et al., 1999). An additional constraint can be derived provide maps of brain activation with millimeter spatial from the assumption that the sources are temporally resolution but is limited in its temporal resolution to uncorrelated (Mosher et al., 1992). These assumptions the order of seconds. Here, we describe a technique are particularly appropriate when analyzing early senthat combines structural and functional MRI with magsory responses, where the activity might reasonably be netoencephalography (MEG) to obtain spatiotemporal expected to be relatively focal and constrained to a maps of human brain activity with millisecond tempofew primary sensory areas. On the other hand, such ral resolution. This new technique was used to obtain assumptions are less justified in higher-level cognitive dynamic statistical parametric maps of cortical activexperiments, which have been found by intracranial reity during semantic processing of visually presented cordings in humans to involve extensive networks of words. An initial wave of activity was found to spread more or less synchronously activated brain areas (Halrapidly from occipital visual cortex to temporal, parigren et al., 1994a, 1994b, 1995a, 1995b; Baudena et al., etal, and frontal areas within 185 ms, with a high de1995). Similarly, the interictal spikes characteristic of gree of temporal overlap between different areas. Reppartial epilepsy typically spread very rapidly to involve etition effects were observed in many of the same a network extended across multiple cortical and limbic areas following this initial wave of activation, providing regions (Chauvel et al., 1987). evidence for the involvement of feedback mechanisms An alternative approach to analyzing EEG/MEG sigin repetition priming. nals is to impose constraints based on anatomical and

[1]  Eric Halgren,et al.  Localized brain metabolic response correlated with potentials evoked by words , 1991, Behavioural Brain Research.

[2]  E. Halgren,et al.  Human medial temporal lobe potentials evoked in memory and language tasks. , 1986, Electroencephalography and clinical neurophysiology.

[3]  T. Allison,et al.  Word recognition in the human inferior temporal lobe , 1994, Nature.

[4]  A. Grinvald,et al.  Imaging Cortical Dynamics at High Spatial and Temporal Resolution with Novel Blue Voltage-Sensitive Dyes , 1999, Neuron.

[5]  T. Wiesel,et al.  Functional architecture of cortex revealed by optical imaging of intrinsic signals , 1986, Nature.

[6]  W. Menke.  Geophysical data analysis : discrete inverse theory , 1984 .

[7]  R. Hari,et al.  Activation of the human occipital and parietal cortex by pattern and luminance stimuli: neuromagnetic measurements. , 1998, Cerebral cortex.

[8]  A. van Oosterom,et al.  The use of the spatial covariance in computing pericardial potentials , 1999, IEEE Transactions on Biomedical Engineering.

[9]  Arthur K. Liu,et al.  Spatiotemporal brain imaging , 2000 .

[10]  V S Caviness,et al.  Functional MRI Localization of Language in a 9-Year-Old Child , 1996, Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques.

[11]  Leslie G. Ungerleider.  Two cortical visual systems , 1982 .

[12]  P. Strick,et al.  Motor areas of the medial wall: a review of their location and functional activation. , 1996, Cerebral cortex.

[13]  T. L. Davis,et al.  Automated shimming at 1.5 t using echo‐planar image frequency maps , 1995, Journal of magnetic resonance imaging : JMRI.

[14]  A. Grinvald,et al.  Linking spontaneous activity of single cortical neurons and the underlying functional architecture. , 1999, Science.

[15]  S. Hillyard,et al.  Involvement of striate and extrastriate visual cortical areas in spatial attention , 1999, Nature Neuroscience.

[16]  R. Turner,et al.  Dynamic magnetic resonance imaging of human brain activity during primary sensory stimulation. , 1992, Proceedings of the National Academy of Sciences of the United States of America.

[17]  J W Belliveau,et al.  Borders of multiple visual areas in humans revealed by functional magnetic resonance imaging. , 1995, Science.

[18]  T. Allison,et al.  Comparison of cortical activation evoked by faces measured by intracranial field potentials and functional MRI: Two case studies , 1997, Human brain mapping.

[19]  S. Petersen,et al.  Practice-related changes in human brain functional anatomy during nonmotor learning. , 1994, Cerebral cortex.

[20]  M. Posner,et al.  Scalp electrical potentials reflect regional cerebral blood flow responses during processing of written words. , 1995, Proceedings of the National Academy of Sciences of the United States of America.

[21]  A. Oosterom.  The use of the spatial covariance in computing pericardial potentials , 1999 .

[22]  William H. Press,et al.  Numerical recipes in C , 2002 .

[23]  M. Scherg,et al.  Two bilateral sources of the late AEP as identified by a spatio-temporal dipole model. , 1985, Electroencephalography and clinical neurophysiology.

[24]  R. Shulman,et al.  Lactate rise detected by 1H NMR in human visual cortex during physiologic stimulation. , 1991, Proceedings of the National Academy of Sciences of the United States of America.

[25]  Edgar M. Housepian.  Atlas d'anatomie stereotaxique du telencephale. , 1968 .

[26]  D. M. Schmidt,et al.  Bayesian inference applied to the electromagnetic inverse problem , 1998, Human brain mapping.

[27]  G. Mangun,et al.  ERP and fMRI measures of visual spatial selective attention , 1998, Human brain mapping.

[28]  D. Regan,et al.  Human brain electrophysiology , 1989 .

[29]  D. Barth,et al.  Three-dimensional analysis of spontaneous and thalamically evoked gamma oscillations in auditory cortex. , 1998, Journal of neurophysiology.

[30]  K Lehnertz,et al.  Real-time tracking of memory formation in the human rhinal cortex and hippocampus. , 1999, Science.

[31]  M Steinschneider,et al.  Localization of ERP generators and identification of underlying neural processes. , 1995, Electroencephalography and clinical neurophysiology. Supplement.