Magnetic field tomography of coherent thalamocortical 40-Hz oscillations in humans.
This paper introduces the use of magnetic field tomography (MFT), a noninvasive technique based on distributed source analysis of magnetoencephalography data, which makes possible the three-dimensional reconstruction of dynamic brain activity in humans. MFT has a temporal resolution better than 1 msec and a spatial accuracy of 2-5 mm at the cortical level, which deteriorates to 1-3 cm at depths of 6 cm or more. MFT is used here to visualize the origin of a spatiotemporally organized pattern of coherent 40-Hz electrical activity. This coherence, initially observed during auditory input, was proposed to be generated by recurrent corticothalamic oscillation. In support of this hypothesis, we illustrate well-defined 40-Hz coherence between cortical-subcortical sites with a time shift that is consistent with thalamocortical conduction times. Studies on Alzheimer patients indicate that, while a similar activity pattern is present, the cortical component is reduced in these subjects.
Ribary
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Department of Physiology and Biophysics, New York University Medical Center, NY 10016.
Ioannides
A A
AA
Singh
K D
KD
Hasson
R
R
Bolton
J P
JP
Lado
F
F
Mogilner
A
A
Llinás
R
R
D000328:Adult; D000368:Aged; D001307:Auditory Perception; D002540:Cerebral Cortex / Q000033:anatomy & histology* / Q000502:physiology; D006309:Hearing; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008959:Models, Neurological; D011336:Probability; D012016:Reference Values; D013788:Thalamus / Q000033:anatomy & histology* / Q000502:physiology