Neuropeptide Y expression defines a novel class of GABAergic projection neuron in the inferior colliculus.
Located in the midbrain, the inferior colliculus (IC) integrates information from numerous auditory nuclei and is an important hub for sound processing. Despite its importance, little is known about the molecular identity and functional roles of defined neuron types in the IC. Using a multifaceted approach in mice of both sexes, we found that neuropeptide Y (NPY) expression identifies a major class of inhibitory neurons, accounting for approximately one-third of GABAergic neurons in the IC. Retrograde tracing showed that NPY neurons are principal neurons that can project to the medial geniculate nucleus. In brain slice recordings, many NPY neurons fired spontaneously, suggesting that NPY neurons may drive tonic inhibition onto postsynaptic targets. Morphological reconstructions showed that NPY neurons are stellate cells, and the dendrites of NPY neurons in the tonotopically-organized central nucleus of the IC cross isofrequency laminae. Immunostaining confirmed that NPY neurons express NPY, and we therefore hypothesized that NPY signaling regulates activity in the IC. In crosses between Npy1r(cre) and Ai14 Cre-reporter mice, we found that NPY Y1 receptor (Y1R)-expressing neurons are glutamatergic and were broadly distributed throughout the rostro-caudal extent of the IC. In whole-cell recordings, application of a high affinity Y1R agonist led to hyperpolarization in most
Silveira Marina A; Anair Justin D; Beebe Nichole L; Mirjalili Pooyan; Schofield Brett R; Roberts Michael T
The Journal of neuroscience : the official journal of the Society for Neuroscience
2020
2020-05-06
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
journalArticle
<a href="http://doi.org/10.1523/JNEUROSCI.0420-20.2020" target="_blank" rel="noreferrer noopener">10.1523/JNEUROSCI.0420-20.2020</a>
A novel class of inferior colliculus principal neurons labeled in vasoactive intestinal peptide-Cre mice
auditory; Inferior colliculus; mouse; neural circuits; neuron types; neuroscience; optogenetics; VIP
Located in the midbrain, the inferior colliculus (IC) is the hub of the central auditory system. Although the IC plays important roles in speech processing, sound localization, and other auditory computations, the organization of the IC microcircuitry remains largely unknown. Using a multifaceted approach in mice, we have identified vasoactive intestinal peptide (VIP) neurons as a novel class of IC principal neurons. VIP neurons are glutamatergic stellate cells with sustained firing patterns. Their extensive axons project to long-range targets including the auditory thalamus, auditory brainstem, superior colliculus, and periaqueductal gray. Using optogenetic circuit mapping, we found that VIP neurons integrate input from the contralateral IC and the dorsal cochlear nucleus. The dorsal cochlear nucleus also drove feedforward inhibition to VIP neurons, indicating that inhibitory circuits within the IC shape the temporal integration of ascending inputs. Thus, VIP neurons are well-positioned to influence auditory computations in a number of brain regions.
Goyer David; Silveira Marina A; George Alexander P; Beebe Nichole L; Edelbrock Ryan M; Malinski Peter T; Schofield Brett R; Roberts Michael T
eLife
2019
2019-04
<a href="http://doi.org/10.7554/eLife.43770" target="_blank" rel="noreferrer noopener">10.7554/eLife.43770</a>