Reduced Right Hemisphere ‘Functional Connectivity' and Neuropsychological Integration in Non-Verbal Learning Disorder

Transfer Function between EEG and BOLD Signals of Epileptic Activity

“…Although more detailed models of EEG-fMRI integration have been presented in the literature (Riera et al, 2006, 2007), the heuristic benefits from its simplicity in application and interpretability. The dependency of the BOLD signal on the EEG spectral profile has often been experimentally reported in studies of spontaneous or evoked fluctuations of brain rhythms, and the results are most frequently found to be in concordance with Kilner’s heuristic predictions (Goldman et al, 2002; Gonçalves et al, 2006; Laufs et al, 2006; de Munck et al, 2009; Michels et al, 2010; Zumer et al, 2010; Khursheed et al, 2011). Rosa et al (2010b) have explicitly employed the heuristic to analyze EEG-fMRI data collected during a visual flicker stimulation task in healthy subjects, and showed that BOLD signal decreases were indeed associated with changes in the EEG spectral profile, namely its RMSF, which did not arise from power changes in one specific frequency band.…”

“…The most consensual evidence comes from the recording of electrical activity using micro-electrodes implanted in the cortex of (non-human) animals, simultaneously with fMRI, indicating that the BOLD signal reflects mostly slow, post-synaptic input activity measured by local field potentials (LFPs), rather than fast, spiking output activity measured by single/multi-unit activity (S/MUA; Logothetis et al, 2001). In humans, a growing number of simultaneous EEG-fMRI studies on healthy subjects as well as epilepsy patients have now been reported (Goldman et al, 2002; Laufs et al, 2003, 2006; Moosmann et al, 2003; de Munck et al, 2009), and biophysical models of the neurovascular coupling have been proposed (Riera et al, 2006, 2007). Overall, reports in the literature do not provide a clear picture of the link between EEG and BOLD signals.…”

“…In particular, contradictory results have been presented regarding the dependency of BOLD changes on the EEG power and spectral profiles. These include, for example, positive and negative BOLD correlations with specific frequency band power changes in the human EEG (de Munck et al, 2009), BOLD decoupling from LFP power in mice (Ekstrom, 2010), and negative BOLD associated with large increases in LFP and MUA during seizures also in mice (Schridde et al, 2008). Rosa et al (2010b) addressed this topic by comparing different models of the transfer function between EEG and BOLD signals, in the prediction of fMRI data, in a visual stimulation experiment with human healthy subjects.…”