Serotonin Differentially Modulates Responses to Tones and Frequency-Modulated Sweeps in the Inferior Colliculus

Although almost all auditory brainstem nuclei receive serotonergic innervation, little is known about its effects on auditory neurons. We address this question by evaluating the effects of serotonin on sound-evoked activity of neurons in the inferior colliculus (IC) of Mexican free-tailed bats. Two...

Full description

Saved in:
Bibliographic Details
Published in:The Journal of neuroscience 1999-09, Vol.19 (18), p.8071-8082
Main Authors: Hurley, Laura M, Pollak, George D
Format: Article
Language:English
Subjects:
Acoustic Stimulation
Analysis of Variance
Animals
Auditory Perception - drug effects
Auditory Perception - physiology
Chiroptera
Discrimination (Psychology)
Electrophysiology - methods
Evoked Potentials, Auditory - drug effects
Evoked Potentials, Auditory - physiology
Functional Laterality
Inferior Colliculi - drug effects
Inferior Colliculi - physiology
Iontophoresis
neuromodulation
Neurons - drug effects
Neurons - physiology
Reaction Time
Serotonin - pharmacology
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Although almost all auditory brainstem nuclei receive serotonergic innervation, little is known about its effects on auditory neurons. We address this question by evaluating the effects of serotonin on sound-evoked activity of neurons in the inferior colliculus (IC) of Mexican free-tailed bats. Two types of auditory stimuli were used: tone bursts at the neuron's best frequency and frequency-modulated (FM) sweeps with a variety of spectral and temporal structures. There were two main findings. First, serotonin changed tone-evoked responses in 66% of the IC neurons sampled. Second, the influence of serotonin often depended on the type of signal presented. Although serotonin depressed tone-evoked responses in most neurons, its effects on responses to FM sweeps were evenly mixed between depression and facilitation. Thus in most cells serotonin had a different effect on tone-evoked responses than it did on FM-evoked responses. In some neurons serotonin depressed responses evoked by tone bursts but left the responses to FM sweeps unchanged, whereas in others serotonin had little or no effect on responses to tone bursts but substantially facilitated responses to FM sweeps. In addition, serotonin could differentially affect responses to various FM sweeps that differed in temporal or spectral structure. Previous studies have revealed that the efficacy of the serotonergic innervation is partially modulated by sensory stimuli and by behavioral states. Thus our results suggest that the population activity evoked by a particular sound is not simply a consequence of the hard wiring that connects the IC to lower and higher regions but rather is highly dynamic because of the functional reconfigurations induced by serotonin and almost certainly other neuromodulators as well.
ISSN:0270-6474
1529-2401
DOI:10.1523/jneurosci.19-18-08071.1999