Background: Although a large body of knowledge about both brain structure and function has been gathered over the last decades, we still have a poor understanding of their exact relationship. Graph theory provides a method to study the relation between network structure and function, and its application to neuroscientific data is an emerging research field. We investigated topological changes in large-scale functional brain networks in patients with Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD) by means of graph theoretical analysis of resting-state EEG recordings. EEGs of 20 patients with mild to moderate AD, 15 FTLD patients, and 23 nondemented individuals were recorded in an eyes-closed resting-state. The synchronization likelihood (SL), a measure of functional connectivity, was calculated for each sensor pair in 0.5-4 Hz, 4-8 Hz, 8-10 Hz, 10-13 Hz, 13-30 Hz and 30-45 Hz frequency bands. The resulting connectivity matrices were converted to unweighted graphs, whose structure was characterized with several measures: mean clustering coefficient (local connectivity), characteristic path length (global connectivity) and degree correlation (network 'assortativity'). All results were normalized for network size and compared with random control networks.

Anal incontinence prevails in 40 per cent of women 5 years after primary repair of a third-degree perineal rupture. The presence of a combined sphincter defect or subsequent vaginal delivery increase the risk of anal incontinence.

SUMMAR Y Although complaints of impaired daytime functioning are essential to the diagnosis of primary insomnia, objective evidence for cognitive dysfunction has been hard to establish. A prerequisite for understanding the neurocognitive consequences of primary insomnia is to establish task paradigms that robustly differentiate insomniacs from well-sleeping subjects. We hypothesized that the decline in performance that typically occurs with an increasing cognitive demand would provide a more sensitive measure than performance on a single task version. The hypothesis was tested, first, by assessing the performance on two vigilance tasks with different cognitive demands in 25 elderly patients with primary insomnia and 13 healthy well-sleeping age-matched subjects. Secondly, we investigated the performance response to sleep therapy using a waiting-list controlled design. Sleep therapy consisted of a multi-component intervention including sleep restriction, cognitive behavioral therapy, bright-light therapy, structured physical activity and body temperature manipulations. The results show that insomniacs differed markedly from controls in their reaction times across tasks with different cognitive demands: patients responded faster on the ÔsimpleÕ vigilance task, yet slower on the ÔcomplexÕ vigilance task. Sleep therapy effectively restored normal performance: patients became significantly slower on the ÔsimpleÕ task and faster on the ÔcomplexÕ task, returning to the performance levels of control subjects. These findings indicate that the performance decline associated with increasing cognitive demands is possibly the first sensitive and robust measure of the neurocognitive sequelae of insomnia. We suggest that future studies on cognition in primary insomnia should apply a design that varies task demands.k e y w o r d s arousal, attention, insomnia, sleep disorders, task complexity, vigilance

Although insomnia is common and disabling, its neural correlates remain enigmatic. Stoffers et al. use structural and functional MRI to demonstrate that hyperarousal, its clearest characteristic, involves reduced recruitment and connectivity of the left caudate that may predispose to insomnia and perpetuate it.

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