Auditory 2 Flashcards
Auditory nerve fibers synapse in the
cochlear nucleus
Two distinct pathways with different functions originate in the cochlear nucleus
Recognition of sound patterns
Localizing sounds
For recognition of sound patterns–>
Dorsal and Ventral cochlear nuclei project directly to contralateral inferior colliculus via the lateral lemniscus
Dorsal and ventral cochlear nuclei (pattern of sound) project to contralateral inferior colliculus via
lateral lemniscus
Localizing sounds:
Ventral cochlear nucleus also projects to the
superior olivary complex (SOC) in the pons
The SOC is the first place for
binaural convergence
Subsequently the SOC projects to
inferior colliculus
Inferior colliculus relays both (pattern and localization) pathways to
medial geniculate nucleus of the thalamus
Medial geniculate fibers terminate in
primary auditory cortex (A-I, area 41)
Located in superior temporal lobe, Heschel’s gyrus
For sound localization and pattern recognition, there are multiple crossover so all levels are biaural except
cochlear nucleus
for auditory when you try to diagnose lesions, laterlization insn’t very helpful because
they paths from both ears converge so soon
Heschels gyrus is area ____ and located in
41
superior temporal lobe
We have an expansion on the left cortex d/t
wernikes area
Primary auditory cortex projects to multiple higher order cortical areas surrounding
A-I
o In the left hemisphere of humans, this includes _______ – important for speech interpretation. Note expansion of cortex on the left.
Wernicke’s area
unless the lesion occurs peripherally or in the cochlear nucleus…..
This duplication of pathways makes it difficult to selectively cut afferents from one ear or from one part of the frequency spectrum
The topography of the receptor array is______in the nervous system
preserved
For an auditory nerve cell , the region of the basilar membrane to which it is responsive describes
The “receptive field”
A cell’s best frequency is called the
characteristic frequency
how well a cell responds to higher and lower frequencies.
Frequency tuning curve
Increasing sound intensity makes the tuning curve
broaden.
Cortex surrounding the primary auditory area, A1, is responsible for
higher order processing of sound
o Wiernicke’s area is important for
o Broca’s area is important for
speech analysis
speech production.
Lesions of auditory cortex do not affect sensation of simple sounds but disrupt
perception of complex sounds such as speech
Higher order cortical areas can contain cells that are selectively responsive to combinations of
tones, such as those found in speech sounds.
cortex where cells can be selectively responsive to featurse of sound
audiorty cortex
example:
This slide shows the responses of a neuron in auditory cortex that responds little to a single tone but strongly to a combination of two tones.
o Adding a third tone, suppresses the response
______ and______ differences in the two ears can be used to locate a sound
Binaural time
intensity
complex contains cellular structures uniquely designed to detect auditory time and intensity differences
The superior olivary
This type of circuitry in the superior olive can create a neural code for location in space
“Temporal coincidence”
