Physiology of Hearing
James R. Tysome, Rahul G. Kanegaonkar in Hearing, 2015
The first site of binaural convergence of the cochlear nucleus output is the superior olive complex (SOC). There are three main SOC nuclei: the lateral superior olive (LSO), the medial superior olive (MSO) and the medial nucleus of the trapezoid body (MNTB). The MSO encodes interaural time differences while the LSO encodes interaural level differences. The MNTB is the site of giant synapses from cells in the cochlear nucleus and provides inhibitory input to other nuclei in the SOC. The output of the SOC joins projections from the cochlear nucleus that form the lateral lemniscal tract. This tract terminates in the inferior colliculus. The auditory midbrain consists of the inferior colliculus (IC) and the superior colliculus (SC). Cells in the IC have been found to be spatially selective but no map of auditory space has been found in this nucleus. In contrast, a map of auditory space does exist in the deep layers of the SC and is usually aligned with a visual map of space. It is fair to say that there is no clear idea of the functions of the mammalian auditory cortex when compared with the visual cortex. The primary auditory cortex is tonotopically organised and is bordered by one or more adjacent auditory areas.
Audiogenic Seizures in Mice and Rats
Steven L. Peterson, Timothy E. Albertson in Neuropharmacology Methods in Epilepsy Research, 2019
Seizure initiation appears to at least partially involve excitatory amino acid neurotransmission in the inferior colliculus. Faingold et al.50 demonstrated that bilateral microinjection of the excitatory amino acid antagonist 2-amino-7-phospho-heptanoate (AऩH) into the inferior colliculus completely abolished audiogenic seizures in GEPR-9s. Further, the inferior colliculus was much more sensitive to this effect than other auditory nuclei. This parallels a report in which focal microinjection of the excitatory amino acid NMDA into the inferior colliculus of nonsusceptible Sprague-Dawley rats induced audiogenic susceptibility.51 Finally, increased aspartate levels have been reported in the inferior colliculus of GEPRs following an audiogenic seizure.52
Auditory pathways
Stanley A. Gelfand in Hearing, 2017
Sensitivity to binaural information continues beyond the inferior colliculus to the auditory thalamus and cortex. Neurons in the medial geniculate body respond to ILDs or ITDs, both ILDs and ITDs, and to the locations (azimuths) of sound sources (e.g., Aitkin and Dunlop, 1968; Aitkin and Webster, 1972; Aitkin, 1973; Ivarsson et al., 1988; Stanford et al., 1992; Samson et al., 2000). It is interesting to note that the degree of tuning to ITDs appears to become increasingly selective (i.e., tuned to narrower ranges of ITDs) going from the SOC to the inferior colliculus and then to the auditory thalamus (Fitzpatrick et al., 1997). This is clearly seen in Figure 6.6, which shows that normalized responses are narrower as a function of ITD for cells in the auditory thalamus compared to those in the SOC.
Role of inferior colliculus in vestibular vertigo induced by water caloric irrigation
Published in Acta Oto-Laryngologica, 2020
Yu Song, Shan Xiong, Xin Fan, Ying Xin, Furong Ma
The inferior colliculus (IC), locating at the midbrain level, serves as a central hub for the integration of descending and ascending auditory information [4]. In addition to auditory pathway, the IC also receives anatomical input from non-auditory pathways, such as somatosensory pathways or motor pathways, for example, projections from ventral tegmental area [5] and transmits information to motor systems such as the cerebellum. These connections suggest that processing in the IC not only prepares auditory information but also modulates other non-auditory processing, such as in visual, oculomotor, eye position, and somatosensory information [6]. During medial vestibular nucleus (MVN) optogenetic stimulation using brain wide fMRI, BOLD responses were enhanced in the ipsilateral IC, which indicate that the auditory pathway is integrated with the central vestibular pathways [7].
Vision Beyond Vision: Lessons Learned from Amblyopia
Published in Journal of Binocular Vision and Ocular Motility, 2023
To explain the impairment of auditory localization in amblyopia, we reviewed the literature, which reveals two crucial pieces of information: the role of the superior colliculus in the developmental calibration of the auditory map and the anatomical arrangement of the retinocollicular pathway. First, in several classic experiments using barn owls, vision has been found to calibrate sound localization during early development.50–52 Two structures in the dorsal midbrain are involved – the superior colliculus that contains a retinotopically-organized visual map and the inferior colliculus that contains a spatially-organized auditory map. During development, vision guides sound localization so that the auditory map in the inferior colliculus is aligned with the visual map in the superior colliculus. However, after the barn owls have been raised wearing prisms, the auditory map in the inferior colliculus is realigned with the optically-displaced visual map in the superior colliculus.
Dry needling as a novel intervention for cervicogenic somatosensory tinnitus: a case study
Published in Physiotherapy Theory and Practice, 2022
Aaron Womack, Raymond Butts, James Dunning
The effect of DN on CST may be directly related to the effect of mechanotransduction via the dense concentration of muscle spindles located in the suboccipital muscles (Boyd-Clark, Briggs, and Galea, 2002; Kulkarni, Chandy, and Babu, 2001; Liu, Thornell, and Pedrosa-Domellöf, 2003), resulting in an alteration of afferent somatosensory signaling. This could affect the spontaneous neural activity to the cochlear nucleus and/or inferior colliculus from the trigeminocervical nucleus, the dorsal root ganglia and/or the dorsal column that has been theorized to be the basis for somatosensory tinnitus (Levine, 1999; Shore, Zhou, and Koehler, 2007). Kanold and Young (2001) reported that direct receptor stimulation via structures such as muscle spindles innervated by cervical spinal nerve branches resulted in an inhibition of somatosensory activity to the dorsal cochlear nucleus.
Related Knowledge Centers
- Auditory Cortex
- Auditory System
- Brainstem
- Corpora Quadrigemina
- Midbrain
- Somatosensory System
- Superior Cerebellar Peduncle
- Superior Colliculus
- Trochlear Nerve
- Multisensory Integration