jmarkow's Arnsten:AF [2 articles]

Abstract

Norepinephrine (NE) has widespread projections throughout the brain, and thus, is ideally positioned to orchestrate neural functions based on arousal state. For example, NE can increase ” signal/noise” ratio in the processing of sensory stimuli, and can enhance long-term memory consolidation in the amygdala and hippocampus through actions at α-1 and β adrenoceptors. Over the last 20 years, NE has also been shown to play a powerful role in regulating the working memory and attention functions of the prefrontal cortex (PFC). Moderate ...

Note (first note only)

This review provides a surprising confluence of evidence from rat and young and mature monkey, and even human, suggesting that the mechanisms detailed in the article serve "essential" functions, e.g. the components of survival. More precisely, they hone in on the complementary functions of the LC and alpha2, alpha1, and beta receptors, which have a high-affinity for NE. Akin to earlier studies of IT in delayed-match-to-sample paradigms, the maintenance of delay-period activity of direction-selective cells in PFC supposedly underpins working memory.

Abstract

Spatial working memory (WM; i.e., "scratchpad" memory) is constantly updated to guide behavior based on representational knowledge of spatial position. It is maintained by spatially tuned, recurrent excitation within networks of prefrontal cortical (PFC) neurons, evident during delay periods in WM tasks. Stimulation of postsynaptic alpha2A adrenoceptors (alpha2A-ARs) is critical for WM. We report that alpha2A-AR stimulation strengthens WM through inhibition of cAMP, closing Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels and strengthening the functional connectivity of PFC networks. Ultrastructurally, HCN channels and ...

Note (first note only)

This study focuses on the effects of hyperpolarization-activated nucleotide-gated (HCN) channels primarily through the infusion of an HCN antagonist, ZD7288. The use of the term "memory field", inter alia, evokes the terminology used to describe the microcircuit, which simply employs clusters of pyramidal neurons with similar spatial tuning with inhibitory interconnections from (presumably) basket cells. Bearing this in mind, the interactions between alpha2a-receptors, cAMP signaling, and HCN channels provides some fine-grained insight into the machinations of this putative circuit. Where yohimbe