Correlation of visuospatial memory ability with right parietal EEG spindling during sleep

Individual differences in human sleep EEG spindling were shown to be associated with psychometric measures of cognitive ability. Previous results revealed a frequency- and region specificity of this effect, suggesting that only fast, but not slow spindle-related oscillatory activity over the frontal region correlated with cognitive performance. Our aim is to test the hypothesis that region-specific spindle-type oscillatory activity is related to specific cognitive abilities reflecting the cortical localization of the corresponding cognitive function. The visuospatial abilities are the focus of the present report. Nineteen healthy volunteers were tested with the Rey-Osterrieth Complex Figure (ROCF) test and memory performances correlated with the spindle analysis of the second night's polysomnographic recordings. Correlations were age-corrected and subjected to descriptive data analysis. ROCF recall performances at 3 and 30 minutes delay, correlated positively and significantly with fast sleep spindle density measured over the right parietal area. No significant relationship between recognition performance and sleep EEG variables emerged. Slow spindle density did not correlate with test performances. Our findings converge with other data suggesting the involvement of right parietal functioning in visuospatial abilities. Moreover, these results support the hypothesis that region-specific differences in fast sleep spindling could be markers of specific neuropsychological performances.