They provide the main

They provide the main IWR-1 purchase innervation from the mesopontine junction to the thalamic relay nuclei but also innervate the intralaminar and reticular thalamic nuclei, as well as the lateral hypothalamus, basal forebrain, and prefrontal cortex ( Hallanger et al., 1987 and Satoh and Fibiger, 1986). Many neurons in the PPT and LDT fire most rapidly during wakefulness and REM sleep, and most slowly during NREM sleep, suggesting that they help drive cortical activation ( el Mansari et al., 1989 and Steriade

et al., 1993). These nuclei are heterogeneous, but extracellular recordings combined with juxtacellular labeling confirm that cholinergic neurons in the LDT fire during cortical activation, usually increasing their firing rates just

before the transition from cortical slow waves to faster frequencies ( Boucetta and Jones, 2009). The monoaminergic cell groups at the mesopontine level that project to the forebrain include the noradrenergic locus coeruleus (LC) and the serotoninergic dorsal and median raphe nuclei ( Aston-Jones and Bloom, 1981, Dahlström and Fuxe, 1964 and Kocsis et al., 2006), as well as dopaminergic neurons adjacent XAV-939 chemical structure to the dorsal raphe nucleus ( Lu et al., 2006a). Histaminergic neurons in the tuberomammillary nucleus (TMN) have similar projection targets and firing patterns ( Panula et al., 1989 and Steininger et al., 1999). Axons from these cell groups predominantly target the lateral hypothalamus, basal forebrain, Parvulin and cerebral cortex, where they

terminate extensively, particularly in the prefrontal cortex. Each of these monoaminergic systems also sends smaller but important populations of axons to the thalamus where they largely target the intralaminar and reticular nuclei. Generally, neurons in these cell groups fire most actively during wakefulness, decrease activity during non-REM sleep, and fall silent during REM sleep ( Aston-Jones and Bloom, 1981, Kocsis et al., 2006, Steininger et al., 1999, Takahashi et al., 2006 and Takahashi et al., 2010). Another source of arousal influence from the rostral pons may be glutamatergic neurons in the parabrachial nucleus and the adjacent precoeruleus area (PC, the lateral corner of the rostral pontine periventricular gray matter, just rostral to the main body of the LC), which have been found to send major projections to the lateral hypothalamus, basal forebrain, and cerebral cortex ( Hur and Zaborszky, 2005, Lu et al., 2006b, Saper, 1987 and Saper and Loewy, 1980). The activity patterns of these glutamatergic neurons have not yet been studied, but recordings in this area in cats and Fos studies in rats have shown predominantly wake- and REM-sleep-active neurons ( Chu and Bloom, 1973, Lu et al., 2006b and Saito et al., 1977). Tests of the role of these neurons in wakefulness would be of great interest. Several forebrain neuronal systems also support wakefulness.

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