Abstract
In addition to ascending, descending, and lateral auditory projections, inputs extrinsic to the auditory system also influence neural processing in the inferior colliculus (IC). These types of inputs often have an important role in signaling salient factors such as behavioral context or internal state. One route for such extrinsic information is through centralized neuromodulatory networks like the serotonergic system. Serotonergic inputs to the IC originate from centralized raphe nuclei, release serotonin in the IC, and activate serotonin receptors expressed by auditory neurons. Different types of serotonin receptors act as parallel pathways regulating specific features of circuitry within the IC. This results from variation in subcellular localizations and effector pathways of different receptors, which consequently influence auditory responses in distinct ways. Serotonin receptors may regulate GABAergic inhibition, influence response gain, alter spike timing, or have effects that are dependent on the level of activity. Serotonin receptor types additionally interact in nonadditive ways to produce distinct combinatorial effects. This array of effects of serotonin is likely to depend on behavioral context, since the levels of serotonin in the IC transiently increase during behavioral events including stressful situations and social interaction. These studies support a broad model of serotonin receptors as a link between behavioral context and reconfiguration of circuitry in the IC, and the resulting possibility that plasticity at the level of specific receptor types could alter the relationship between context and circuit function.
Highlights
INTERACTIONS OF RECEPTORS CREATE NOVEL COMBINATIONS OF EFFECTS. As instructive as it is to understand the effects of individual serotonin receptor types, a realistic model of the effects of serotonin in the inferior colliculus (IC) must involve some degree of receptor interaction, because multiple receptor types would likely be co-activated by the release of serotonin
Each receptor influences the timing of evoked responses for some neurons, with the 5-HT1A receptor usually increasing first-spike latency and ISI, and the 5-HT1B receptor often decreasing first-spike latency and ISI
The experiments described above support the model of different serotonin receptor types as gates to separate but interacting effector pathways
Summary
From behavioral context to receptors: serotonergic modulatory pathways in the IC. Department of Biology, Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN, USA. In addition to ascending, descending, and lateral auditory projections, inputs extrinsic to the auditory system influence neural processing in the inferior colliculus (IC) These types of inputs often have an important role in signaling salient factors such as behavioral context or internal state. Serotonin receptor types interact in nonadditive ways to produce distinct combinatorial effects This array of effects of serotonin is likely to depend on behavioral context, since the levels of serotonin in the IC transiently increase during behavioral events including stressful situations and social interaction. These studies support a broad model of serotonin receptors as a link between behavioral context and reconfiguration of circuitry in the IC, and the resulting possibility that plasticity at the level of specific receptor types could alter the relationship between context and circuit function
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
