Acetylcholine

A major neuromodulator in the CNS and neurotransmitter at neuromuscular junctions. It is an ester of acetic acid and choline.

Location

 * neuromuscular junctions
 * nAChR vs. mAChRs
 * autonomic nervous system
 * CNS
 * brainstem
 * mesopontine tegmentum area
 * pedunculopontine nucleus
 * laterodrosal tegmental nucleus
 * basal forebrain
 * nucleus basalis --> mainly M1Rs in neocortex
 * medial septal nucleus --> M1Rs in hippocampus and cortex

Function

 * "Cholinergic activity consistently increases the efficacy of feedforward processing relative to that of local recurrent connections" (paraphrased a little).
 * Stimulating nucleus basalis paired with auditory stimuli can cause massive reorganization of primary auditory cortex in adult rat.
 * Can gate the induction of LTD in visual cortical slices along with Norepinephrine and mGluR5 receptors.
 * M1R agonist can enable LTD in L2/3 visual cortical rat slices. Together with β-Adrenergic receptor agonists can enable standard STDP (with pre before post leading to LTP).
 * Musc. Rs have been shown to increase activation of immediate early genes and expression of plasticity-related genes.
 * It's proposed that acetylcholine projections play the role of desynchronizing cortical activity to improve signal to noise ratio for salient information.
 * De-innervation of cholinergic afferents leads to attention deficits.
 * stimulation of these afferents can lead to reinforced behavior associated with rewarding or aversive stimuli.
 * It's also been found to be important for switching neuron networks into high-arousal states.
 * A paper found that acetylcholine went up in Hippocampus and Frontal Cortex during REM sleep only when it was followed by wakefulness.
 * Acetylcholine binding to receptors on astrocytes can lead to an increase in intracellular Calcium.
 * Acetylcholine excites Somatostatin-expressing Neurons, increasing their firing rate in V1. This seems to disinhibit pyramidal neuron leading to a desynchronized state in the cortex.