Some neurons release a neurotransmitter to activate Gi/o-coupled receptors and in turn GIRK channels on their own dendrites (autaptic transmission), causing self-inhibition (Figure 3A). For example, a train of action potentials fired by low threshold spiking (LTS) interneurons of the cortex results in long-lasting hyperpolarization. This change in excitability occurs in a cell-autonomous way through endocannabinoids released from dendrites and the activation of CB1 receptors coupled to GIRK channels on the very same dendrites113. This modulation of LTS neurons may lead to long-lasting changes in cortical networks owing to altered glutamate transmission in pyramidal neurons. Dopamine neurons also exhibit a form of autaptic inhibition. Here, dendodendritic release of dopamine activates dopamine D2 receptors coupled to GIRK channels, leading to suppression of firing114.
