Abnormal functional brain connectivity is a candidate factor in developmental brain disorders associated with cognitive dysfunction. We analyzed a substantial (10 min per subject) record of dense array electroencephalography with spectral power and coherence methods in attention-deficit hyperactivity disorder (ADHD) (n = 42) and control (n = 21) 10- to 13-year-old children. We found topographically distinct narrow band coherence differences between subject groups: ADHD subjects showed elevated coherence in the lower alpha (8 Hz) band and reduced coherence in the upper alpha (10-11 Hz) band. The 8-Hz ADHD elevation and a 2- to 6-Hz control group coherence elevation were independent of stimulus presentation. In response to visual stimulation, the ADHD group exhibited reduced evoked potential power and elevated frontal coherence. Only the upper alpha band control group coherence elevation discriminated according to ADHD group medication status. The findings suggest a static state of deficient connectivity in ADHD and a stimulus-induced state of overconnectivity within and between frontal hemispheres.
We study collective behavior of Brodmann regions of human cerebral cortex
Using functional Magnetic Resonance Imaging (fMRI) and Random Matrix Theory
(RMT). The raw fMRI data is mapped onto the cortex regions corresponding to the
Brodmann areas with the aid of the Talairach coordinates. Principal Co...
We prove that the power spectrum of the Green's function is
Approximately constant. In addition we exploit a connection to Jacobi
Polynomials to derive formulas for computing reflection coefficients from
Partial amplitude data. Unlike most approaches to layered media, which
Variously involve scaling...
We study Chern-Simons theory on 3-manifolds M that are circle-bundles over
2-dimensional orbifolds S by the method of Abelianisation. This method, which
Completely sidesteps the issue of having to integrate over the moduli space of
Non-Abelian flat connections, reduces the complete partition functio...
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