, 2011). In humans, the default mode network not only PD0325901 datasheet consists

of mPFC areas but also medial parietal areas (including midline anterior and posterior cingulate cortices; Raichle et al., 2001). Recent investigations in macaques have identified electrophysiological correlates of default mode processing in both mPFC and posterior cingulate cortices (Hayden et al., 2009; Kojima et al., 2009). The positron emission tomography imaging study of Kojima et al. (2009) in awake unanaesthetized monkeys clearly demonstrated a default mode of cortical activity with higher rest-related activity in mPFC areas compared with working memory tasks. The activity in macaque mPFC reported here before and during eye-closure may therefore represent in part alterations in the activity of mPFC areas associated with the default mode network in monkeys. It is of interest that Rudolph et al. (2007)

reported that a significant proportion (~45%) of presumed pyramidal (broad spike/regularly spiking) neurons in parietal association cortex also discharged during SWS and were silent during waking. In relation to these default mode network studies, the value of the present investigation is that it shows electrophysiologically that the firing rates of a significant NVP-BKM120 mouse number of mPFC neurons (those of cell Type 1 representing about 28% of sampled neurons) in the monkey were low in the awake state (mean 3.1 spikes/s) and increased significantly during sleep (mean 10.2 spikes/s). The firing rates of the neurons involved in default mode network activities, and exactly how they may change, is not directly measured in human neuroimaging studies. Given the increase in the human BOLD (blood oxygen level-dependent) response during operation of the default mode network, it is tempting to speculate that some of the neurons whose firing rates increased during periods of ‘eye-closure’ may have intracortical axonal arbors instrinsic to the mPFC that innervated nitric oxide (NO)-producing cells (Gabbott and Bacon, 1996). The activity of such cells would lead to local vasodilatation

(through NO-mediated mechanisms) and thus increased blood flow in specific mPFC regions with raised metabolic demands during periods of augmented information processing Methane monooxygenase (Duchemin et al., 2012). The data from the present study have implications for the generation of sleep activity in humans, both in health and in disease. Many neuropsychiatric and neurodevelopmental disorders, for example depression, schizophrenia and autism, which include functional modifications of the default mode network, have symptoms that include poor sleep architecture (Drevets et al., 1997; Wichniak et al., 2000; Vogt, 2009; Gregory et al., 2011; Vukadinovic, 2011; Price & Drevets, 2012). Patterns of abnormal sleep structure (narcolepsy, sleep inertia, parasomnias, non-REM and REM sleep behaviour disorders, etc.