The sensory contribution of the cortex containing cortical barrel C1 vibrissa was studied in rats using ablation-behavior method. Three independent experiments were performed, each requiring stimulus transduction by but varying their perceptual demands. first required detection sinusoidal oscillations generated an oscillating airstream directed vertically onto tip. second a change rate oscillation. third blinded rat to jump gap elevated runway after palpating far side with its vibrissa....

Abstract The afferent projections to the lateral superior olive (LSO) were examined with horseradish peroxidase, peroxidase‐wheat germ agglutinin conjugate, 125 I‐wheat and tritiated leucine autoradiography, anterograde axonal degeneration, 14 C‐2‐deoxyglucose methods. pathway ipsilateral LSO orginates in spherical cells anteroventral cochlear nucleus. Although some of fibers pass above nucleus trapezoid body, most below it turn at right angles enter either directly through its ventral,...

Abstract When this series of experiments was begun in 1984, the activity each lateral superior olive (LSO) mammalian hindbrain known to encode hemifield acoustic space containing a sound source. However, almost random bilaterality its ascending projections seemed jumble that identification before reaching midbrain. At same time, electrophysiological studies LSO and efferent target inferior colliculus, along with strictly contralateral deficits localization resulting from unilateral lesions...

Objectives: Electrocochleography (ECochG) obtained through a cochlear implant (CI) is increasingly being tested as an intraoperative monitor during implantation with the goal of reducing surgical trauma. Reducing trauma should aid in preserving residual hearing and improve speech perception overall. The purpose this study was to characterize intracochlear ECochG responses throughout insertion range array types and, when applicable, relate these measures preservation. signal subjects complex,...

The cochlear summating potential (SP) to a tone is baseline shift that persists for the duration of burst. It often considered most enigmatic potentials because its magnitude and polarity vary across frequency level origins are uncertain. In this study, we used pharmacology isolate sources SP originating from gerbil cochlea. Animals either had full complement outer inner hair cells (OHCs IHCs) an intact auditory nerve or systemic treatment with furosemide kanamycin (FK) remove cells....

Introduction: One major obstacle in validating drugs for the treatment or prevention of hearing loss is limited data available on distribution and concentration human inner ear. Although small animal models offer some insights into ear pharmacokinetics, their smaller organ size different barrier (round window membrane) permeabilities compared to humans can complicate study interpretation. Therefore, developing a reliable large model drug delivery crucial. The middle anatomy domestic pigs...

Abstract Conventional retrograde and orthograde axonal transport tract‐tracing techniques were used in cats to explore the auditory decussations commissures upper pons midbrain. In all, 8 differing either origin or contralateral termination found. Three of (from dorsal nucleus lateral lemniscus lemniscus, from inferior colliculus, sagulum sagulum) reach their targets via commissure Probst. The remaining 5 colliculus medial geniculate, intermediate geniculate) colliculus. results also suggest...

Abstract A detailed cytoarchitectonic atlas of the chinchilla cochlear nucleus complex was prepared in transverse plane with Nissl method. Subdivisions were defined on basis cell size, packing density, and, some cases, cytological features types. In general, has an organizational plan similar to that described for other mammalian species. As rodents, a large and well‐developed dorsal consisting three distinct layers. The ventral consists two nuclear masses, posterior group anterior group,...

Abstract Retrograde transport of HRP by the abducens nerve results in labelling its principal nucleus and, addition, a second about 2.5 mm ventrolateral to nucleus. The presence this or accessory mammal confirms observations several Nineteenth Century anatomists and rebuts conclusions more recent investigators who argued that was allied instead facial trigeminal nerves. same technique applied nerves shows is parasagittal plane as most caudal cells motor nuclei fall ventrocaudal dorsorostral...

Light sheet fluorescence microscopy (LSFM) provides a rapid and complete three-dimensional image of the cochlea. The method retains anatomical relationships-on micrometer scale-between internal structures such as hair cells, basilar membrane (BM), modiolus with external surface round oval windows. Immunolabeled cells were used to visualize spiraling BM in intact cochlea without time intensive dissections or additional histological processing; yet material prepared for LSFM could be...

Delivery of pharmaceutical therapeutics to the inner ear treat and prevent hearing loss is challenging. Systemic delivery not effective as only a small fraction therapeutic agent reaches ear. Invasive surgeries inject through round window membrane (RWM) or cochleostomy may cause damage An alternative approach administer drugs into middle using an intratympanic injection, with primarily passing RWM However, barrier, permeable number molecules. To study enhance permeability, we developed ex...

Labeling cochlear nerve fibers in the inner ear of chinchillas with biotinylated dextran polyamine was used to trace thin (Type II), which likely innervate outer hair cells. These axons, 0.1–0.5 μm diameter, were distinguished from thicker Type I, innervating cells, and traced small-cell clusters nucleus. This study provided two major new insights into cell connections nucleus potential significance very axons synaptic nests, are widespread CNS. 1) EM serial reconstructions labeled unlabeled...

The inferior colliculus (IC) is the common target of separate pathways that transmit different types auditory information. Beyond tonotopy, little known about organization response properties within 3-dimensional layout midbrain in most species. Through study interaural time difference (ITD) processing, functional neurons can be readily characterized and related to specific pathways. To characterize representation ITDs relative frequency hodological IC, were recorded sites recovered...

Cochlear synaptopathy is the loss of synapses between inner hair cells and auditory nerve despite survival sensory cells. The findings extensive cochlear in animals after moderate noise exposures challenged long-held view that are elements most sensitive to insults lead hearing loss. However, has been difficult identify humans. We applied novel algorithms determine cell neural contributions electrocochleographic (ECochG) recordings from round window animal human subjects. Gerbils with normal...

The small cell shell of the cochlear nucleus contains a complex integrative machinery which can be used to study roles interneurons in sensory processing. clusters nerve root chinchilla provide simplest example this structure. Reported here are neuronal architecture and synaptic organization three principal types distinctive neuropil structures that could characterized with Nissl Golgi methods electron microscopy. Granule cells were by several dendrites claw-like terminals received contacts...

The effect of a reversible, unilateral hearing loss on 2-deoxyglucose (2-DG) uptake in the central auditory system was studied using young gerbils. All animals had conductive (CHL), induced by atresia, postnatal day 21 (P21). One week later, P28, their atresia repaired (CHL/R), or not (CHL/NR), and CHL/NR entered 2-DG experiments. CHL/R were allowed 1-week period restored binaural experience prior to entering experiments P35. Animals each group injected with exposed ambient sounds for 45 min...

In contrast to the ease of finding tonotopicity in other nuclei, both anatomical and electrophysiological methods have failed demonstrate a clear simple tonotopic map within ventral nucleus lateral lemniscus (VLL). The present study was undertaken cat with hope that not used previously studies VLL might succeed demonstrating an orderliness its exiting fibers (i.e., efferents) or incoming afferents). Since same organization ascending frequencies cochlea is maintained these as well all main...

Electrocauterization and subsequent transection of the cochlear nerve induce greater injury to nucleus than sharp alone.Some studies show that neurofibromatosis Type 2 (NF2) patients fit with auditory brainstem implants (ABIs) fail achieve speech perception abilities similar ABI recipients without NF2. Reasons for these differences remain speculative. One hypothesis posits poorer performance surgically induced trauma from electrocautery. Sustained electrosurgical depolarization may cause...

Abstract To explore the potential for structural variation and new growth at synapse, we studied morphological patterns of end‐bulbs cochlear nerve axons in adult cats by using rapid Golgi, reduced silver, electron microscopic methods. Horseradish peroxidase labeling these endings anterior division antroventral nucleus was produced anterograde transport following injection into cochlea. Three types were distinguished, regardless method: reticular, coalescent, ringed forms, all synapsing on...

Labeling cochlear nerve fibers in the inner ear of chinchillas with biotinylated dextran polyamine was used to trace thin (Type II), which likely innervate outer hair cells. These axons, 0.1–0.5 μm diameter, were distinguished from thicker Type I, innervating cells, and traced small-cell clusters nucleus. This study provided two major new insights into cell connections nucleus potential significance very axons synaptic nests, are widespread CNS. 1) EM serial reconstructions labeled unlabeled...