FIGURE 1.

Diagram of behavioral state-dependent activation of noradrenergic and cholinergic systems and their modulation of astroglia Ca²⁺ dynamics during sleep, rest, and vigilance. Astrocytes in primary visual cortex and somatosensory cortex, Hes5-positive astrocytes in spinal dorsal horn, and cerebellar Bergmann glia exhibit norepinephrine-dependent global Ca²⁺ rises during states of heightened vigilance. In Bergmann glia and Hes5-positive astrocytes of spinal dorsal horn, this arousal-associated Ca²⁺ signal is mediated by α_1A-adrenergic receptors. Cholinergic activation of hippocampal astrocytes through α7 nicotinic acetylcholine receptors has been found to modulate D-serine concentration depending on the sleep-wake state. LC, locus coeruleus; LDT, laterodorsal tegmental nucleus; PPN, pedunculopontine nucleus; MS, medial septal nucleus; DB, diagonal band of Broca; NBM, nucleus basalis of Meynert; SI, substantia innominata.