Abstracts

Rationale: Is electrical brain activity at certain frequencies in children with idiopathic epilepsy associated with better performance on quantitative measures of intelligence and attention? Here we report correlations of EEG spectra with WASI full scale IQ and CPT-2 measures of attention in children with idiopathic epilepsy. If certain EEG frequencies are consistently associated with better brain function, future goals may be (1) to target neural networks with these frequencies for further study, and (2) to devise interventions that intentionally increase brain activity at these frequencies.   Methods: 48 children ages 8-18 with idiopathic epilepsy who underwent comprehensive neuropsychological evaluation and EEG were retrospectively identified. EEG’s were all obtained within 6 months of neuropsychological evaluation. For each child, 36 10-second windows of artifact-free EEG in bipolar montage sampled at 256 Hz were extracted and subjected to frequency analysis using the damped-oscillator pseudo-wavelet. Wechsler Abbreviated Scale of Intelligence full scale IQ (FSIQ) and Continuous Performance Test-II measures of attention (errors of omission) and impulsivity (errors of commission) were correlated with EEG spectra using the correlation function c(f,n) =Here f is the frequency, n is the EEG channel, S(f,n,i) is the frequency spectral density for subject i, x(i) is a neuropsychological measure of interest for subject i, and the angular brackets denote an average over the 48 subjects. The correlation values are normalized by dividing c(f,n) by its standard deviation as calculated over the frequency range from 0.25 to 120 Hz in steps of 0.25 Hz. Results: Figure 1 shows normalized correlations of the EEG spectral density S(f,n) with FSIQ as a function of frequency. There is a positive peak at 22 Hz in the frontal electrodes (3.6 standard deviations above zero), and a positive peak at 9 Hz in the posterior electrodes (6.4 standard deviations above zero). When S(f,n) is correlated with errors of omission (not shown), there are positive peaks at 9 Hz (indicating fewer errors of omission with more EEG activity at this frequency) in all locations, but most prominently in the posterior electrodes. When S(f,n) is correlated with errors of commission (not shown), there are still positive peaks at 9 Hz in the posterior electrodes, but in the frontal electrodes, it is especially the 22 Hz peak that dominates. Conclusions: Our results show that, in children with idiopathic epilepsy, frontal 22 Hz EEG activity and posterior 9 Hz EEG activity are correlated with improved performance on quantitative tests of IQ, attention and impulsivity. In future, spatiotemporal distributed neural circuits with these frequencies may be targeted for study, and possibly for direct intervention, for example, using electrical stimulation. Funding: NIH R01-NS044351-08A1 and the Mathias Koch Memorial Fund.