06d: Central Auditory System Flashcards
Sensory ganglion cells of auditory system are formally called:
Spiral ganglion cells
Several spiral ganglion cells contact one (inner/outer) HC. This results in (high/low) resolution.
Inner;
Higher
One spiral ganglion cell contracts several (inner/outer) HCs. This results in (high/low) resolution.
Outer;
Lower
Most, (X)%, of spiral ganglia are in contact with (inner/outer) HCs.
X = 90
Inner
Only (X)% of spiral ganglia are in contact with (inner/outer) HCs.
X = 10
Outer
Spiral ganglia project primarily to (ipsi/contra)-lateral (X).
Ipsilateral;
X = cochlear nucleus
Cochlear nuclei neurons project primarily to (ipsi/contra)-lateral (X).
Contralateral (mainly) and ipsilateral;
X = superior olive
“Trapezoid body” refers to:
Bundles of crossing axons, projecting from cochlear nuclei to contralateral superior olives
Although most input to (X) comes from the (ipsilateral/contralateral) (Y), there are a few axons from cochlear nuclei that project directly to (X). These all travel via (Z).
X = inferior colliculus;
Ipsilateral;
Y = superior olive
Z = lateral lemniscus
Bilateral lesion of inferior colliculus will result in:
complete deafness
Unilateral lesion of inferior colliculus will prevent (ipsi/contra)-lateral ascending auditory input from reaching cerebral cortex
Neither! Inputs cross midline several times before reaching IC
List locations in auditory pathway, before inferior colliculus, where ascending auditory inputs cross midline.
- trapezoid body
2. nucleus of LL
In ascending auditory pathway, neurons of IC project (ipsilaterally/contralaterally/bilaterally) to (X) via (Y).
Ipsilaterally;
X = MGN of thalamus
Y = brachium of IC
Bilateral lesion of MGN will result in:
Complete deafness
In ascending auditory pathway, neurons of MGN project to (X) via (Y).
X = cerebral cortex Y = internal capsule
L auditory cortex receives input from (R/L) ear.
Both R and L cortices receive input from both R and L ears
(Doral/ventral) cochlear nuclei contain(s) tonotopic maps.
Both
Projections to (ipsi/contra/bi)-lateral IC comes from (ventral/dorsal) cochlear nuclei.
Ipsi and contralateral;
Dorsal
Projections to (ipsi/contra/bi)-lateral superior olivary complex comes from (ventral/dorsal) cochlear nuclei.
Bilateral;
Ventral
(Dorsal/ventral) cochlear nucleus receives giant synapses called (X) from (Y).
Ventral;
X = endbulbs of Held
Y = primary sensory afferents
(Dorsal/ventral) cochlear nucleus projects to (X) via giant synapses called (Y).
Ventral;
X = SOC
Y = calyceal endings
Giant synapses (end bulbs of Held and calcyeal endings) to/from (X) nucleus is important for which reasons?
X = ventral cochlear nucleus
- Reliability
- Speed
Key function of Superior olivary complex is (X). It does this by which mechanism(s)?
X = detection of localization of sound
- Interaural time difference (below 3 KHz)
- Interaural level difference (above 3 KHz)
The (X) can localize high frequency (above 3 Hz) sound based on (Y) mechanism. This is a result of sound reaching the two ears with difference in (Z).
X = SOC Y = ILD (inter aural level difference) Z = intensity
The (X) can localize low frequency (below 3 Hz) sound based on (Y) mechanism. This is a result of sound reaching the two ears with difference in (Z).
X = SOC Y = ITD (interaural time difference) Z = time
Interaural level difference involves excitation of (ipsi/contra/bi)-lateral (X) and inhibition of (ipsi/contra/bi)-lateral (Y).
Ipislateral;
X = lateral superior olive AND
Contralateral medial nucleus of trapezoid body;
Contralateral;
Y = lateral superior olive (via MNTB)
Medial nucleus of trapezoid body, when receiving (stimulatory/inhibitory) input from (ipsilateral/contralateral) cochlear nuclei, projects (stimulatory/inhibitory) output to (ipsilateral/contralateral) (X).
Stimulatory; Contralateral; Inhibitory; Ipsilateral; X = LSO
The localization of sound that’s 10 Hz is encoded by (absolute/relative) level of (excitation/inhibition) of (X).
Relative;
Excitation and inhibition
X = ipsi and contralateral LSOs
Interaural time difference involves (X) SO nucleus, which has neurons arranged in (Y) fashion.
X = medial; Y = medial to lateral
Interaural time difference: L cochlear nuclei sends output to (R/L) medial superior olive via (X).
Both R and L;
Contralateral output via:
X = trapezoid body
In localization of sound based on ITD, the (MSO/LSO) neuron is maximally activated when:
MSO;
Coincident synaptic input reaches neuron from both ipsilateral and contralateral cochlear nuclei
(X) is an obligatory relay of ascending auditory inputs.
X = IC and MGN
Ascending auditory pathway: Some (X) neurons send axons across midline to contralateral (X) via commissure of (X).
X = IC
Ascending auditory pathway: IC projects to (ipsilateral/contralateral) (X) via (Y).
Ipsilateral;
X = MGN;
Y = brachium of IC
At (X), there is convergence of binaural inputs, producing topographic map of auditory space.
X = IC
In ascending auditory pathway, the (X) plays role in encoding complex sounds of speech.
X = MGN
Descending input to MGN from (X) cortex functions to:
X = auditory;
select/control ascending input
Primary auditory cortex is also called:
A1 or Brodmann’s area 41
Primary auditory cortex (above/below) secondary auditory cortex. Both found at which gyrus?
Transverse gyrus (of Heschl)
(Primary/secondary) auditory cortex organized so rostral end receives sound that are (X). Caudal end receives sounds that are (Y).
Primary;
X = low in frequency
Y = high in frequency
Sounds that vibrate the very base of the basilar membrane will eventually project to (rostral/caudal/middle) of primary auditory cortex.
Caudal
The “belt areas”, aka (X), receive more (localized/diffuse) input than primary auditory cortex.
X = secondary auditory cortex (or Brodmann’s area 42)
Diffuse
Wernicke’s area is located in (primary/secondary) auditory cortex.
Secondary
(X) is the lowest level of ascending auditory system at which binaural input to the same neuron occurs.
X = superior olive
