Cochlear™ Nucleus® Electrode Portfolio Reference Guide Electrodes for Typical Cochlea
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Pathophysiological Mechanisms and Functional Hearing Consequences of Auditory Neuropathy
doi:10.1093/brain/awv270 BRAIN 2015: 138; 3141–3158 | 3141 REVIEW ARTICLE Pathophysiological mechanisms and functional hearing consequences of auditory neuropathy Gary Rance1 and Arnold Starr2 The effects of inner ear abnormality on audibility have been explored since the early 20th century when sound detection measures were first used to define and quantify ‘hearing loss’. The development in the 1970s of objective measures of cochlear hair cell Downloaded from function (cochlear microphonics, otoacoustic emissions, summating potentials) and auditory nerve/brainstem activity (auditory brainstem responses) have made it possible to distinguish both synaptic and auditory nerve disorders from sensory receptor loss. This distinction is critically important when considering aetiology and management. In this review we address the clinical and pathophysiological features of auditory neuropathy that distinguish site(s) of dysfunction. We describe the diagnostic criteria for: (i) presynaptic disorders affecting inner hair cells and ribbon synapses; (ii) postsynaptic disorders affecting unmyelinated auditory http://brain.oxfordjournals.org/ nerve dendrites; (iii) postsynaptic disorders affecting auditory ganglion cells and their myelinated axons and dendrites; and (iv) central neural pathway disorders affecting the auditory brainstem. We review data and principles to identify treatment options for affected patients and explore their benefits as a function of site of lesion. 1 Department of Audiology and Speech Pathology, The University of Melbourne, -
Projections from the Trigeminal Nuclear Complex to the Cochlear Nuclei: a Retrograde and Anterograde Tracing Study in the Guinea Pig
Journal of Neuroscience Research 78:901–907 (2004) Projections From the Trigeminal Nuclear Complex to the Cochlear Nuclei: a Retrograde and Anterograde Tracing Study in the Guinea Pig Jianxun Zhou and Susan Shore* Department of Otolaryngology and Kresge Hearing Research Institute, University of Michigan, Ann Arbor, Michigan In addition to input from auditory centers, the cochlear cuneate nucleus innervation of cochlear nucleus has been nucleus (CN) receives inputs from nonauditory centers, hypothesized to convey information about head and pinna including the trigeminal sensory complex. The detailed position for the purpose of localizing a sound source in anatomy, however, and the functional implications of the space (Young et al., 1995). In addition, interactions be- nonauditory innervation of the auditory system are not tween somatosensory and auditory systems have been fully understood. We demonstrated previously that the linked increasingly to phantom sound perception, also trigeminal ganglion projects to CN, with terminal labeling known as tinnitus. This is demonstrated in the observa- most dense in the marginal cell area and secondarily in tions that injuries of the head and neck region can lead to the magnocellular area of the ventral cochlear nucleus the onset of tinnitus in patients with no hearing loss (VCN). We continue this line of study by investigating the (Lockwood et al., 1998). projection from the spinal trigeminal nucleus to CN in We demonstrated previously projections from the guinea pig. After injections of the retrograde tracers Flu- trigeminal ganglion to CN in guinea pigs (Shore et al., oroGold or biotinylated dextran amine (BDA) in VCN, 2000). Terminal labeling of trigeminal ganglion projec- labeled cells were found in the spinal trigeminal nuclei, tions to the CN was found to be most dense in the most densely in the pars interpolaris and pars caudalis marginal cell area and secondarily in the magnocellular with ipsilateral dominance. -
Direct Projections from Cochlear Nuclear Complex to Auditory Thalamus in the Rat
The Journal of Neuroscience, December 15, 2002, 22(24):10891–10897 Direct Projections from Cochlear Nuclear Complex to Auditory Thalamus in the Rat Manuel S. Malmierca,1 Miguel A. Mercha´n,1 Craig K. Henkel,2 and Douglas L. Oliver3 1Laboratory for the Neurobiology of Hearing, Institute for Neuroscience of Castilla y Leo´ n and Faculty of Medicine, University of Salamanca, 37007 Salamanca, Spain, 2Wake Forest University School of Medicine, Department of Neurobiology and Anatomy, Winston-Salem, North Carolina 27157-1010, and 3University of Connecticut Health Center, Department of Neuroscience, Farmington, Connecticut 06030-3401 It is known that the dorsal cochlear nucleus and medial genic- inferior colliculus and are widely distributed within the medial ulate body in the auditory system receive significant inputs from division of the medial geniculate, suggesting that the projection somatosensory and visual–motor sources, but the purpose of is not topographic. As a nonlemniscal auditory pathway that such inputs is not totally understood. Moreover, a direct con- parallels the conventional auditory lemniscal pathway, its func- nection of these structures has not been demonstrated, be- tions may be distinct from the perception of sound. Because cause it is generally accepted that the inferior colliculus is an this pathway links the parts of the auditory system with prom- obligatory relay for all ascending input. In the present study, we inent nonauditory, multimodal inputs, it may form a neural have used auditory neurophysiology, double labeling with an- network through which nonauditory sensory and visual–motor terograde tracers, and retrograde tracers to investigate the systems may modulate auditory information processing. -
Auditory and Vestibular Systems Objective • to Learn the Functional
Auditory and Vestibular Systems Objective • To learn the functional organization of the auditory and vestibular systems • To understand how one can use changes in auditory function following injury to localize the site of a lesion • To begin to learn the vestibular pathways, as a prelude to studying motor pathways controlling balance in a later lab. Ch 7 Key Figs: 7-1; 7-2; 7-4; 7-5 Clinical Case #2 Hearing loss and dizziness; CC4-1 Self evaluation • Be able to identify all structures listed in key terms and describe briefly their principal functions • Use neuroanatomy on the web to test your understanding ************************************************************************************** List of media F-5 Vestibular efferent connections The first order neurons of the vestibular system are bipolar cells whose cell bodies are located in the vestibular ganglion in the internal ear (NTA Fig. 7-3). The distal processes of these cells contact the receptor hair cells located within the ampulae of the semicircular canals and the utricle and saccule. The central processes of the bipolar cells constitute the vestibular portion of the vestibulocochlear (VIIIth cranial) nerve. Most of these primary vestibular afferents enter the ipsilateral brain stem inferior to the inferior cerebellar peduncle to terminate in the vestibular nuclear complex, which is located in the medulla and caudal pons. The vestibular nuclear complex (NTA Figs, 7-2, 7-3), which lies in the floor of the fourth ventricle, contains four nuclei: 1) the superior vestibular nucleus; 2) the inferior vestibular nucleus; 3) the lateral vestibular nucleus; and 4) the medial vestibular nucleus. Vestibular nuclei give rise to secondary fibers that project to the cerebellum, certain motor cranial nerve nuclei, the reticular formation, all spinal levels, and the thalamus. -
Use of Calcium-Binding Proteins to Map Inputs in Vestibular Nuclei of the Gerbil
THE JOURNAL OF COMPARATIVE NEUROLOGY 386:317–327 (1997) Use of Calcium-Binding Proteins to Map Inputs in Vestibular Nuclei of the Gerbil GOLDA ANNE KEVETTER* AND ROBERT B. LEONARD Departments of Otolaryngology, Anatomy and Neurosciences, and Physiology and Biophysics, University of Texas Medical Branch, Galveston, Texas 77555 ABSTRACT We wished to determine whether calbindin and/or calretinin are appropriate markers for vestibular afferents, a population of neurons in the vestibular nuclear complex, or cerebellar Purkinje inputs. To accomplish this goal, immunocytochemical staining was observed in gerbils after lesions of the vestibular nerve central to the ganglion, the cerebellum, or both. Eleven to fourteen days after recovery, the brain was processed for immunocytochemical identification of calretinin and calbindin. After lesion of the vestibular nerve, no calretinin staining was seen in any of the vestibular nuclei except for a population of intrinsic neurons, which showed no obvious change in number or staining pattern. Calbindin staining was reduced in all nuclei except the dorsal part of the lateral vestibular nuclei. The density of staining of each marker, measured in the magnocellular medial vestibular nucleus, was signifi- cantly reduced. After the cerebellar lesion, no differences in calretinin staining were noted. However, calbindin staining was greatly reduced in all nuclei. The density of staining, measured in the caudal medial vestibular nucleus, was significantly lower. After a combined lesion of the cerebellum and vestibular nerve, the distribution and density of calretinin staining resembled that after vestibular nerve section alone, whereas calbindin staining was no longer seen. This study demonstrates that calretinin and calbindin are effective markers for the identification of vestibular afferents. -
Cranial Nerve VIII
Cranial Nerve VIII Color Code Important (The Vestibulo-Cochlear Nerve) Doctors Notes Notes/Extra explanation Please view our Editing File before studying this lecture to check for any changes. Objectives At the end of the lecture, the students should be able to: ✓ List the nuclei related to vestibular and cochlear nerves in the brain stem. ✓ Describe the type and site of each nucleus. ✓ Describe the vestibular pathways and its main connections. ✓ Describe the auditory pathway and its main connections. Due to the difference of arrangement of the lecture between the girls and boys slides we will stick to the girls slides then summarize the pathway according to the boys slides. Ponto-medullary Sulcus (cerebello- pontine angle) Recall: both cranial nerves 8 and 7 emerge from the ventral surface of the brainstem at the ponto- medullary sulcus (cerebello-pontine angle) Brain – Ventral Surface Vestibulo-Cochlear (VIII) 8th Cranial Nerve o Type: Special sensory (SSA) o Conveys impulses from inner ear to nervous system. o Components: • Vestibular part: conveys impulses associated with body posture ,balance and coordination of head & eye movements. • Cochlear part: conveys impulses associated with hearing. o Vestibular & cochlear parts leave the ventral surface* of brain stem through the pontomedullary sulcus ‘at cerebellopontine angle*’ (lateral to facial nerve), run laterally in posterior cranial fossa and enter the internal acoustic meatus along with 7th (facial) nerve. *see the previous slide Auditory Pathway Only on the girls’ slides 04:14 Characteristics: o It is a multisynaptic pathway o There are several locations between medulla and the thalamus where axons may synapse and not all the fibers behave in the same manner. -
Auditory Nerve.Pdf
1 Sound waves from the auditory environment all combine in the ear canal to form a complex waveform. This waveform is deconstructed by the cochlea with respect to time, loudness, and frequency and neural signals representing these features are carried into the brain by the auditory nerve. It is thought that features of the sounds are processed centrally along parallel and hierarchical pathways where eventually percepts of the sounds are organized. 2 In mammals, the neural representation of acoustic information enters the brain by way of the auditory nerve. The auditory nerve terminates in the cochlear nucleus, and the cochlear nucleus in turn gives rise to multiple output projections that form separate but parallel limbs of the ascending auditory pathways. How the brain normally processes acoustic information will be heavily dependent upon the organization of auditory nerve input to the cochlear nucleus and on the nature of the different neural circuits that are established at this early stage. 3 This histology slide of a cat cochlea (right) illustrates the sensory receptors, the auditory nerve, and its target the cochlear nucleus. The orientation of the cut is illustrated by the pink line in the drawing of the cat head (left). We learned about the relationship between these structures by inserting a dye-filled micropipette into the auditory nerve and making small injections of the dye. After histological processing, stained single fibers were reconstruct back to their origin, and traced centrally to determine how they terminated in the brain. We will review the components of the nerve with respect to composition, innervation of the receptors, cell body morphology, myelination, and central terminations. -
Anatomy of the Ear ANATOMY & Glossary of Terms
Anatomy of the Ear ANATOMY & Glossary of Terms By Vestibular Disorders Association HEARING & ANATOMY BALANCE The human inner ear contains two divisions: the hearing (auditory) The human ear contains component—the cochlea, and a balance (vestibular) component—the two components: auditory peripheral vestibular system. Peripheral in this context refers to (cochlea) & balance a system that is outside of the central nervous system (brain and (vestibular). brainstem). The peripheral vestibular system sends information to the brain and brainstem. The vestibular system in each ear consists of a complex series of passageways and chambers within the bony skull. Within these ARTICLE passageways are tubes (semicircular canals), and sacs (a utricle and saccule), filled with a fluid called endolymph. Around the outside of the tubes and sacs is a different fluid called perilymph. Both of these fluids are of precise chemical compositions, and they are different. The mechanism that regulates the amount and composition of these fluids is 04 important to the proper functioning of the inner ear. Each of the semicircular canals is located in a different spatial plane. They are located at right angles to each other and to those in the ear on the opposite side of the head. At the base of each canal is a swelling DID THIS ARTICLE (ampulla) and within each ampulla is a sensory receptor (cupula). HELP YOU? MOVEMENT AND BALANCE SUPPORT VEDA @ VESTIBULAR.ORG With head movement in the plane or angle in which a canal is positioned, the endo-lymphatic fluid within that canal, because of inertia, lags behind. When this fluid lags behind, the sensory receptor within the canal is bent. -
Acoustically Responsive Fibers in the Vestibular Nerve of the Cat
The Journal of Neuroscience, October 1994, 74(10): 6056-6070 Acoustically Responsive Fibers in the Vestibular Nerve of the Cat Michael P. McCue1v2*a and John J. Guinan, Jr.r.2.3-4 ‘Eaton-Peabody Laboratory of Auditory Physiology, Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114, 2Harvard-MIT Division of Health Science and Technology and Research Laboratory of Electronics, and 3Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and 4Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts 02115 Recordings were made from single afferent fibers in the and levels within the normal range of human hearing. We inferior vestibular nerve, which innervates the saccule and suggest a number of auditory roles that these fibers may posterior semicircular canal. A substantial portion of the fi- play in the everyday life of mammals. bers with irregular background activity increased their firing [Key words: saccule, otoliths, auditory system, mamma- in response to moderately intense clicks and tones. lian sound reception, middle-ear muscles, cochlear nucleus] In responsive fibers, acoustic clicks evoked action poten- tials with minimum latencies of I 1 .O msec. Fibers fell into The vertebrate inner ear contains several senseorgans involved two classes, with the shortest latency either to condensation in the maintenance of equilibrium and the detection of vibra- clicks (PUSH fibers) or to rarefaction clicks (PULL fibers). tion. The precise sensory role assumedby homologous organs Low-frequency (800 Hz) tone bursts at moderately high sound varies among species.For example, the sacculeis thought to act levels (>80 dB SPL) caused synchronization of spikes to asa linear accelerometerin mammals(Fernindez and Goldberg, preferred phases of the tone cycle. -
Anatomic Moment
Anatomic Moment Hearing, I: The Cochlea David L. Daniels, Joel D. Swartz, H. Ric Harnsberger, John L. Ulmer, Katherine A. Shaffer, and Leighton Mark The purpose of the ear is to transform me- cochlear recess, which lies on the medial wall of chanical energy (sound) into electric energy. the vestibule (Fig 3). As these sound waves The external ear collects and directs the sound. enter the perilymph of the scala vestibuli, they The middle ear converts the sound to fluid mo- are transmitted through the vestibular mem- tion. The inner ear, specifically the cochlea, brane into the endolymph of the cochlear duct, transforms fluid motion into electric energy. causing displacement of the basilar membrane, The cochlea is a coiled structure consisting of which stimulates the hair cell receptors of the two and three quarter turns (Figs 1 and 2). If it organ of Corti (Figs 4–7) (4, 5). It is the move- were elongated, the cochlea would be approxi- ment of hair cells that generates the electric mately 30 mm in length. The fluid-filled spaces potentials that are converted into action poten- of the cochlea are comprised of three parallel tials in the auditory nerve fibers. The basilar canals: an outer scala vestibuli (ascending spi- membrane varies in width and tension from ral), an inner scala tympani (descending spi- base to apex. As a result, different portions of ral), and the central cochlear duct (scala media) the membrane respond to different auditory fre- (1–7). The scala vestibuli and scala tympani quencies (2, 5). These perilymphatic waves are contain perilymph, a substance similar in com- transmitted via the apex of the cochlea (helico- position to cerebrospinal fluid. -
Processing in the Cochlear Nucleus
Processing in The Cochlear Nucleus Alan R. Palmer Medical Research Council Institute of Hearing Research University Park Nottingham NG7 2RD, UK The Auditory Nervous System Cortex Cortex MGB Medial Geniculate Body Excitatory GABAergic IC Inferior Colliculus Glycinergic DNLL Nuclei of the Lateral Lemniscus Lateral Lemniscus Cochlear Nucleus DCN PVCN MSO Lateral Superior Olive AVCN Medial Superior Olive Cochlea MNTB Medial Nucleus of the Trapezoid Body Superior Olive The cochlear nucleus is the site of termination of fibres of the auditory nerve Cochlear Nucleus Auditory Nerve Cochlea 1 Frequency Tonotopicity Basilar membrane Inner hair cell Auditory nerve Fibre To the brain Each auditory-nerve fibre responds only to a narrow range of frequencies Tuning curve Action potential Evans 1975 2 Palmer and Evans 1975 There are many overlapping single-fibre tuning curves in the auditory nerve Audiogram Palmer and Evans 1975 Tonotopic Organisation Lorente - 1933 3 Tonotopic Organisation Base Anterior Cochlea Characteristic Basilar Membrane Frequency Hair Cells Auditory Nerve Apex Cochlear Nucleus Spiral Ganglion Posterior Tonotopic projection of auditory-nerve fibers into the cochlear nucleus Ryugo and Parks, 2003 The cochlear nucleus: the first auditory nucleus in the CNS Best frequency Position along electrode track (mm) Evans 1975 4 stellate (DCN) Inhibitory Synapse Excitatory Synapse DAS to inferior colliculus cartwheel fusiform SUPERIOR OLIVARY giant COMPLEX INFERIOR COLLICULUS granule vertical vertical OCB AANN to CN & IC via TB golgi DORSAL -
The Vestibulo-Cochlear Nerve (Cranial Nerve 8) (Vestibular & Auditory Pathways)
The Vestibulo-cochlear Nerve (Cranial Nerve 8) (Vestibular & Auditory Pathways) By : Prof. Ahmed Fathalla & Dr. Sanaa AlShaarawy OBJECTIVES At the end of the lecture, the students should be able to: qList the nuclei related to vestibular and cochlear nerves in the brain stem. qDescribe the type and site of each nucleus. qDescribe the vestibular pathways and its main connections. qDescribe the auditory pathway and its main connections. BRAIN – VENTRAL SURFACE Ponto-medullary Sulcus (cerebello- pontine angle) Vestibulo-Cochlear Nerve • Type: Special sensory (SSA) • Conveys impulses from inner ear to nervous system. • Components: § Vestibular part: conveys impulses associated with body posture ,balance and coordination of head & eye movements. § Cochlear part: conveys impulses associated with hearing. • Vestibular & cochlear parts leave the ventral surface of brain stem through the pontomedullary sulcus ‘at crebellopontine angle’ (lateral to facial nerve), run laterally in posterior cranial fossa and enter the internal acoustic meatus along with 7th nerve. Vestibular Nerve • The cell bodies (1st order neurons) are Vestibular nuclei belong to located in the vestibular ganglion special somatic afferent within the internal auditory meatus. column in brain stem. • The Peripheral processes (vestibular nerve fibers) make dendritic contact with hair cells of the membranous labyrinth (inner ear). 2 • The central processes (form the vestibular nerve) ‘’Efferent Fibres’’ : 1. Mostly end up in the lateral, medial, inferior and superior 1 vestibular nuclei (2nd order neurons) of the rostral medulla, located beneath the lateral part of the floor of 4th ventricle 2. Some fibers go to the cerebellum through the inferior cerebellar peduncle • Other Efferents from the vestibular nuclei project to other regions for the maintenance of balance, conscious awareness of vestibular stimulation , co-ordination of head & eye movements and control the posture.