The Auditory Nervous System SPA 4302 Summer 2007

The Neuron Generally: Dendrites receive stim. Creates ______________ Transmitted along axon Causes ____________ ____________ Stimulates new neuron

The Ascending Auditory Pathway Primary Auditory Cortex Medial Geniculate Body Inferior Colliculus Lateral Lemniscus Superior Olivary Complex Cochlear Nucleus VIIIth Nerve

The Descending Auditory Pathways ________________ Neurons ______________ Neurons Innervation of Middle Ear _____________

Olivo-Cochlear Efferent Neurons Map of Auditory Efferents

Descending Pathways from Auditory Cortex Descending neurons from Auditory Cortex, MGB, and IC

Efferent Innervation of Tensor Tympani & Stapedius Muscles Innervation of middle ear musculature.

Development: VIIIth N. and Central Auditory Nervous System VIIIth nerve initially: days 25 to 45 Spiral Ganglion, Vestibular Ganglia identifiable by day 35 Little else known about dev. of CANS

Hearing Loss and the CANS VIIIth N: some SNHL, some normal ___________! ___________ SNHL, Initially high frequency Possibly poor Word Recognition ___________ Nerve Symptoms Disorders of the Auditory Nerve Vestibular Schwannoma _____________ Multiple Sclerosis Auditory Neuropathy: a new dx category Normal ________, Abnormal _______

Disorders of the Cochlear Nuclei Kernicterus: Result of Rh incompatibility Hyperbilirubinemia Cerebrovascular Accident: A brainstem stroke Congenital trauma, malformation Pressure (trauma, increased CSF pressure) Syphilis Aging

Disorders of the Higher Auditory Pathways Brainstem Tumors: Intra-axial: contralateral or __________ deficits Extra-axial: ____________ deficits Higher level lesions CVA/Stroke/Aneurysm produce _____________ deficits

Tests for Auditory Processing Disorder ______________ Filtered Speech Speech with Competition _____________ Competing Sentence Tests Dichotic Digits Test Staggered _________ Word Test Masking Level Difference Test

Therapeutic Management _____________ Modifications Improve Signal To Noise Ratios Pre-Teaching ______________ Activities Listening “Games” Computer Based Auditory Training ______________ Strategies Homework Buddy