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Frontiers in Neural Circuits 2014
Topics: Animals; Humans; Inferior Colliculi; Nerve Net; Neurons
PubMed: 25346661
DOI: 10.3389/fncir.2014.00113 -
Frontiers in Neural Circuits 2022
Topics: Auditory Perception; Inferior Colliculi
PubMed: 35664460
DOI: 10.3389/fncir.2022.898646 -
Hearing Research Nov 2022Sensory processing is frequently conceptualized as a linear flow of information from peripheral receptors through hierarchically organized brain regions, ultimately... (Review)
Review
Sensory processing is frequently conceptualized as a linear flow of information from peripheral receptors through hierarchically organized brain regions, ultimately reaching the cortex. In reality, this ascending stream is accompanied by massive descending connections that cascade from the cortex toward more peripheral subcortical structures. In the central auditory system, these feedback connections influence information processing at virtually every level of the pathway, including the thalamus, midbrain, and brainstem, and exert influence even at the level of the cochlea. The auditory cortico-collicular system, which connects the auditory cortex to the auditory midbrain, mediates manifold functions ranging from tuning shifts to defense behavior. In this review, we first summarize recent findings regarding the anatomical organization and physiological properties of the auditory cortico-collicular pathway. We then highlight several new studies that show that this projection system mediates high-level cognitive processes, acoustico-motor behaviors, and auditory plasticity, and discuss the circuit mechanisms through which they are mediated. Finally, we discuss remaining unanswered questions regarding cortico-collicular circuitry and function and potential avenues for future exploration.
Topics: Acoustic Stimulation; Auditory Cortex; Auditory Pathways; Inferior Colliculi
PubMed: 35351323
DOI: 10.1016/j.heares.2022.108488 -
The Journal of the Acoustical Society... Nov 2019Circadian rhythms control the timing of all bodily functions, and misalignment in the rhythms can cause various diseases. Moreover, circadian rhythms are highly... (Review)
Review
Circadian rhythms control the timing of all bodily functions, and misalignment in the rhythms can cause various diseases. Moreover, circadian rhythms are highly conserved and are regulated by a transcriptional-translational feedback loop of circadian genes that has a periodicity of approximately 24 h. The cochlea and the inferior colliculus (IC) have been shown to possess an autonomous and self-sustained circadian system as demonstrated by recording, in real time, the bioluminescence from PERIOD2::LUCIFERASE (PER2::LUC) mice. The cochlea and IC both express the core clock genes, Per1, Per2, Bmal1, and Rev-ErbĪ±, where RNA abundance is rhythmically distributed with a 24 h cycle. Noise exposure alters clock gene expression in the cochlea and the IC after noise stimulation, although in different ways. These findings highlight the importance of circadian responses in the cochlea and the IC and emphasize the importance of circadian mechanisms for understanding the differences in central and peripheral auditory function and the subsequent molecular changes that occur after daytime (inactive phase) or nighttime (active phase) noise trauma.
Topics: Activity Cycles; Animals; Circadian Clocks; Circadian Rhythm Signaling Peptides and Proteins; Cochlea; Inferior Colliculi; Noise
PubMed: 31795664
DOI: 10.1121/1.5132290 -
Hearing Research May 2019The inferior colliculus occupies a central position in ascending and descending auditory pathways. A substantial proportion of its neurons are GABAergic, and these... (Review)
Review
The inferior colliculus occupies a central position in ascending and descending auditory pathways. A substantial proportion of its neurons are GABAergic, and these neurons contribute to intracollicular circuits as well as to extrinsic projections to numerous targets. A variety of types of evidence - morphology, physiology, molecular markers - indicate that the GABAergic cells can be divided into at least four subtypes that serve different functions. However, there has yet to emerge a unified scheme for distinguishing these subtypes. The present review discusses these criteria and, where possible, relates the different properties. In contrast to GABAergic cells in cerebral cortex, where subtypes are much more thoroughly characterized, those in the inferior colliculus contribute substantially to numerous long range extrinsic projections. At present, the best characterized subtype is a GABAergic cell with a large soma, dense perisomatic synaptic inputs and a large axon that provides rapid auditory input to the thalamus. This large GABAergic subtype projects to additional targets, and other subtypes also project to the thalamus. The eventual characterization of these subtypes can be expected to reveal multiple functions of these inhibitory cells and the many circuits to which they contribute.
Topics: Animals; Auditory Pathways; Calcium-Binding Proteins; Cell Surface Extensions; GABAergic Neurons; Inferior Colliculi; Models, Neurological; Receptors, Neurotransmitter; Vesicular Glutamate Transport Protein 2
PubMed: 30314930
DOI: 10.1016/j.heares.2018.10.001 -
The Journal of Physiological Sciences :... Nov 2015The inferior colliculus (IC) is a critical nexus between the auditory brainstem and the forebrain. Parallel auditory pathways that emerge from the brainstem are... (Review)
Review
The inferior colliculus (IC) is a critical nexus between the auditory brainstem and the forebrain. Parallel auditory pathways that emerge from the brainstem are integrated in the IC. In this integration, de-novo auditory information processed as local and ascending inputs converge via the complex neural circuit of the IC. However, it is still unclear how information is processed within the neural circuit. The purpose of this review is to give an anatomical and physiological overview of the IC neural circuit. We address the functional organization of the IC where the excitatory and inhibitory synaptic inputs interact to shape the responses of IC neurons to sound.
Topics: Animals; Inferior Colliculi; Mammals; Neurons
PubMed: 26362672
DOI: 10.1007/s12576-015-0394-3 -
Frontiers in Neural Circuits 2022The lateral superior olive (LSO) is a key structure in the central auditory system of mammals that exerts efferent control on cochlear sensitivity and is involved in the...
The lateral superior olive (LSO) is a key structure in the central auditory system of mammals that exerts efferent control on cochlear sensitivity and is involved in the processing of binaural level differences for sound localization. Understanding how the LSO contributes to these processes requires knowledge about the resident cells and their connections with other auditory structures. We used standard histological stains and retrograde tracer injections into the inferior colliculus (IC) and cochlea in order to characterize two basic groups of neurons: (1) Principal and periolivary (PO) neurons have projections to the IC as part of the ascending auditory pathway; and (2) lateral olivocochlear (LOC) intrinsic and shell efferents have descending projections to the cochlea. Principal and intrinsic neurons are intermixed within the LSO, exhibit fusiform somata, and have disk-shaped dendritic arborizations. The principal neurons have bilateral, symmetric, and tonotopic projections to the IC. The intrinsic efferents have strictly ipsilateral projections, known to be tonotopic from previous publications. PO and shell neurons represent much smaller populations (<10% of principal and intrinsic neurons, respectively), have multipolar somata, reside outside the LSO, and have non-topographic, bilateral projections. PO and shell neurons appear to have widespread projections to their targets that imply a more diffuse modulatory function. The somata and dendrites of principal and intrinsic neurons form a laminar matrix within the LSO and share quantifiably similar alignment to the tonotopic axis. Their restricted projections emphasize the importance of frequency in binaural processing and efferent control for auditory perception. This study addressed and expanded on previous findings of cell types, circuit laterality, and projection tonotopy in the LSO of the mouse.
Topics: Animals; Mice; Superior Olivary Complex; Olivary Nucleus; Auditory Pathways; Inferior Colliculi; Neurons; Mammals
PubMed: 36338332
DOI: 10.3389/fncir.2022.1038500 -
BioMed Research International 2017To assess the incidence of testicular appendices (Tas), epididymal anomalies (EAs), and processus vaginalis (PV) patency in patients with undescended testis (UT)...
OBJECTIVES
To assess the incidence of testicular appendices (Tas), epididymal anomalies (EAs), and processus vaginalis (PV) patency in patients with undescended testis (UT) according to testicular position and to compare them with human fetuses.
METHODS
We studied 85 patients (108 testes) with cryptorchidism and compared the features with those of 15 fetuses (30 testes) with scrotal testes. We analyzed the relationships among the testis and epididymis, patency of PV, and the presence of TAs. We used the Chi-square test for statistical analysis ( < 0.05).
RESULTS
In 108 UT, 72 (66.66%) had PV patent, 67 (62.03%) had TAs, and 39 (36.12%) had EAs. Of the 108 UT, 14 were abdominal (12.96%; 14 had PV patency, 9 TAs, and 7 EAs); 81 were inguinal (75%; 52 had PV patency, 45 TAs, and 31 EAs), and 13 were suprascrotal (12.03%; 6 had PV patency, 13 TAs, and 1 EAs). The patency of PV was more frequently associated with EAs ( = 0.00364). The EAs had a higher prevalence in UT compared with fetuses ( = 0.0005).
CONCLUSIONS
Undescended testis has a higher risk of anatomical anomalies and the testes situated in abdomen and inguinal canal have a higher risk of presenting patency of PV and EAs.
Topics: Child; Child, Preschool; Cryptorchidism; Epididymis; Fetus; Humans; Infant; Inferior Colliculi; Inguinal Canal; Male; Peritoneum; Risk Factors; Testicular Hydrocele; Testis
PubMed: 29445742
DOI: 10.1155/2017/5926370 -
Journal of Comparative Physiology. A,... Jan 2023The mammalian inferior colliculus (IC) is massively innervated by multiple descending projection systems. In addition to a large projection from the auditory cortex (AC)... (Review)
Review
The mammalian inferior colliculus (IC) is massively innervated by multiple descending projection systems. In addition to a large projection from the auditory cortex (AC) primarily targeting the non-lemniscal portions of the IC, there are less well-characterized projections from non-auditory regions of the cortex, amygdala, posterior thalamus and the brachium of the IC. By comparison, the frog auditory midbrain, known as the torus semicircularis, is a large auditory integration center that also receives descending input, but primarily from the posterior thalamus and without a projection from a putative cortical homolog: the dorsal pallium. Although descending projections have been implicated in many types of behaviors, a unified understanding of their function has not yet emerged. Here, we take a comparative approach to understanding the various top-down modulators of the IC to gain insights into their functions. One key question that we identify is whether thalamotectal projections in mammals and amphibians are homologous and whether they interact with evolutionarily more newly derived projections from the cerebral cortex. We also consider the behavioral significance of these descending pathways, given anurans' ability to navigate complex acoustic landscapes without the benefit of a corticocollicular projection. Finally, we suggest experimental approaches to answer these questions.
Topics: Animals; Auditory Pathways; Inferior Colliculi; Auditory Cortex; Mesencephalon; Amygdala; Mammals
PubMed: 36323876
DOI: 10.1007/s00359-022-01588-5 -
Hearing Research Aug 2014We live in a world imbued with a rich mixture of complex sounds. Successful acoustic communication requires the ability to extract meaning from those sounds, even when... (Review)
Review
We live in a world imbued with a rich mixture of complex sounds. Successful acoustic communication requires the ability to extract meaning from those sounds, even when degraded. One strategy used by the auditory system is to harness high-level contextual cues to modulate the perception of incoming sounds. An ideal substrate for this process is the massive set of top-down projections emanating from virtually every level of the auditory system. In this review, we provide a molecular and circuit-level description of one of the largest of these pathways: the auditory corticocollicular pathway. While its functional role remains to be fully elucidated, activation of this projection system can rapidly and profoundly change the tuning of neurons in the inferior colliculus. Several specific issues are reviewed. First, we describe the complex heterogeneous anatomical organization of the corticocollicular pathway, with particular emphasis on the topography of the pathway. We also review the laminar origin of the corticocollicular projection and discuss known physiological and morphological differences between subsets of corticocollicular cells. Finally, we discuss recent findings about the molecular micro-organization of the inferior colliculus and how it interfaces with corticocollicular termination patterns. Given the assortment of molecular tools now available to the investigator, it is hoped that his review will help guide future research on the role of this pathway in normal hearing.
Topics: Acoustic Stimulation; Animals; Auditory Cortex; Auditory Pathways; Cues; Humans; Inferior Colliculi; Neural Pathways; Neuronal Plasticity; Neurons; Perception; Sound
PubMed: 24911237
DOI: 10.1016/j.heares.2014.05.004