brain Flashcards
medical geniculate body MGB
final processing stage before the signal reaches the cortex
located in the thalamus
no decussations occur here
limbic system
receives sensory information and sends signals to centers that control behavior, memory, hormone, and autonomic nervous system functions
inferior colliculus
plays a role in coding binaural info
receives stimulation from both SOCs
located in midbrain
Place Coding
mapping of stimulus frequencies to a place on the basilar membrane is reffered
place theory
theory explaining the process of hearing based on place coding
tonotopic organization
correspondence between stimulation frequency and place
place theory
nuerons fire on the basilar membrane determine the frequency
how much area is affected determines the intensity
Temporal/ frequency theory
process of hearing is based on the firing rate and patterns of nerve fibers
Central Auditory Nervous System
sound processing network of afferent and efferent auditory fiber tracts and nuclei
anterior
toward the front
posterior
toward the back
inferior
toward the bottom
superior
toward the top
medial
towards the middle
lateral
toward the side
sagittal
divides the body into right and left parts
frontal/coronal
divides the body into front and back
transverse
divides the body into top and bottom parts
horizontal
parallel with the horizon
what are the three primary regions of the brain
forebrain
midbrain
hindbrain
what does the forebrain consist of
cerebral hemisphere
what are the four lobes of the forebrain
frontal lobe
parietal lobe
occipital lobe
temporal lobe
2 systems of the forebrain
limbic system
insula system
where is the midbrain located
superior portion of the brainstem
what does the hindbrain include
medulla oblongata
pons
cerebellum
medulla oblongata
connected with the spinal cord by the foramen magnum
where is the cerebellum located
behind the pons and medulla
how is the cerebellum connected to the medulla, pons, and midbrain
fiber tracts
what is the cerebellum associated with
balance system
cerebellopontine angle (CPA)
where the cerebellum, medulla oblongata, and pons join
cochlear nucleus
located in the medulla of the hindbrain
only receives input ipsilaterally
ipsilaterally
located or affects the same side
contralaterally
located or affects the opposite side (ear)
what are the 2 divisions of the cochlear nuclei
ventral cochlear nucleus (VCN)
dorsal cochlear nucleus (DCN)
what happens when the cochlear nerve will split
part will descend to the VCN
other part descends to the DCN
tonotopicity
the spatial representation of the frequency layout of the cochlea in retrocochlear (past the cochlea) structures
cochlear nucleus
basal turn fibers go to one area
apical turn fibers go to another
trapezoid body
located in the pons
first decussation in the auditory pathway
decussation
crossover point that unites symmetrical portions of the brain’s two halves
superior olivary complex (SOC)
group of nuclei in the pons
first place to get binaural signals (ipsilateral and contralateral CN)
interaural timing difference (ITD)
time of sound arrival at the two ears
interaural intensity difference (IID)
the intensity difference at the two ears
what determines the location of low frequency sounds
ITD interaural timing difference
what determines the location of high frequency sounds
IID interaural intensity differences
lateral lemniscus
receives projections from the SOC
fiber tract from pons (hindbrain) to midbrain
what is the largest CANS fibers tract
lateral lemniscus
inferior colliculus
second site that plays role in coding binaural info
in midbrain
medical geniculate body (MGB)
final processing stage before the signal reaches the cortex
located in the thalamus (forebrain)
no decussations occur here
how do sounds cause specific emotions
connection between the MGB and the limbic system
limbic system
receives sensory info and sends signals to centers that control behavior, memory, hormone, and autonomic nervous system functions
heschl’s gyrus
receives and synthesizes auditory info coming from the MGB that has been processed at various stages within the brainstem, midbrain, and thalamus
located in the temporal lobe of the cerebral cortex (forebrain)
heschls gyrus
receives signals from both ears but primarily signals form the contralateral ear
temporal lobe
frequency characteristics of sound
insular area
temporal aspects of sound
parietal lobe
association of sound with past experiences
frontal lobe
memory of sound
right ear advantage
most people process speech better when it is directed toward the right ear
olivocochlear bundle (OCB)
efferent fibers from the superior olivary complex
controls the electromotility of the outer hair cells
reduces (inhibits) outer hair cell activity
decreases the amplification of the auditory signal at the level of the cochlea
inhibition of OHC motility
improves detection, localization, and perception of speech in background noise
After the signal leaves the cochlea through the nerve fibers where does it go first
internal auditory canal
if it is a high frequency sound, where will the nerve fiber be located in the cochlear nerve that is going through the IAC
on the outside of the nerve bundle
there are six major nuclei and 1 fiber tract the nerve signal will go in the afferent system what are they
cochlear nucleus trapezoid body superior olivary complex lateral lemniscus inferior colliculus medial geniculate body heschls gyrus
in the efferent system what is the nerve bundle that comes from the superior olivary complex called
olivocochlear bundle (OHC)
3 primary regions and their locations
forebrain>cerebral hemisphere, cerebral cortex
midbrain>superior portion of the brainstem
hindbrain> tail of brainstem (housing medulla oblongata, pons and cerebellum)
4 main lobes
frontal lobe
parietal
occipital
temporal
2 systems
limbic
insula
3 parts of the hindbrain and location
medulla oblongata> connected to the spinal cord through the foramen magnum
pons> superior to the medulla
cerebllum> connected posteriorly to medulla oblongataand pons by fiber tracts
purpose of cerebellum
balance; produces changes in skeletal muscle tone and maintain posture and coordinate movement
How many nerve fibers are in the vestibular and cochlear portions of the 8th nerve
30000 nerve fibers in cochlear portion, 20000 in vestibular portion
what is the cerebellopontine angle (CPA) and its location
where cerebellum,pons, and medulla oblongata meet
beyond the IAC attached to the brainstem
ipsilateral
located or affecting the same side of the ear
contralateral
located or affects opposite side of the ear
decussation
crossover point that unites symmetrical portions of the brains two halves
cochlear nucleus DCN and VCN
only ipsilateral
the cochlear nucleus will split and some nerves wll travel through the dorsal cochlear nucleus while others use the ventral cochlear nucleus
trapezoid body
first decussation
located in the pons; what nerve fibers from the cochlear nucleus travel through
superior olivary complex
first place to get info from both sides of brain
a group of nuclei in the pons; most nerve fibers from the trapezoid body will attach contralaterally to the SOC
lateral lemniscus
largest fiber tract
where the SOC sends projections; its fiber tract is from the pons to the midbrain
place where directional information is combined with other sound coding to create complex sound image
inferior colliculus
2nd site for binaural coding
located in the midbrain
medial geniculate body
no decussations, limbic system
final processing stage
located in the thalamus
Heschl’s gyrus
primary cortex
receives and synthesizes auditory info coming from the MGB
located in temporal lobe of the cerebral cortex
