Sensory Neuroscience Flashcards
(267 cards)
1
Q
The auditory system can detect sound induced displacement up to what unit
A
picometer
2
Q
Auditory system can hear frequencies between…
A
20-20,000 Hz
3
Q
Sound in space is detected due to … between the 2 ears
A
microsecond differences in sound arrival
4
Q
The auditory system displays a …. fold acoustic power. From a pin drop to jet engine
A
trillion
5
Q
There are around …. people in the UK with hearing loss
A
11 million
6
Q
More than …% over the age of 50 have hearing loss. This rise to …% of people over 70
A
40% of 50yo.
71% over 70
7
Q
Sensory transduction converts sensory information into…because the brain only understands this.
A
electrical activity
8
Q
All sensory receptors are transducers of different..
A
modalities (of stimulus)
9
Q
A stimulus move the hair cell bundle which results in..
A
opening of channels and change in membrane permeability. K+ cause depolarisation.
10
Q
Sensory receptors transmit 4 types of information:
A
Modality
Location
Intensity
Duration
11
Q
Modality means the..
A
quality and nature of sound - what type of information
12
Q
Location of a sound is done by..
A
interaural timing and intensity differences. Most species use a combo.
13
Q
Large receptive fields allow sensory cells to detect stimuli over a ….area but with less…
A
Wider area, less precision
14
Q
Intensity of sound is processed by..
A
increased firing frequency.
increased recruitment of neurons
15
Q
Duration of sound is detected by..
A
Tonic receptors - slow adaptation, respond continuously, persistence.
Phasic receptors - burst, fast adaptation
16
Q
Sound works by compressing patches of air, increasing pressure. When an object moves away air is…
A
rarefacted, decreasing pressure
17
Q
Frequency is the number of…
A
compressions of air that pass our ears in 1 second (cycles per second)
18
Q
Intensity of sound is the difference in..
A
pressure between compressions and rarefactions.
19
Q
Human hearing range decreases significantly with…
A
age and exposure to noise
20
Q
sensory perception consists of…
A
stimulus, transducer, brain
21
Q
The cochlea is filled with … which causes …% of sound energy to be reflected
A
Fluid cause 97% of energy to be reflected. It takes up much more energy for sound to travel through air
22
Q
Sound travelling through air is reduced by fluid-filled cochlea and the … They transfer energy as … energy
A
ossicles of the middle ear allow sound energy to be transferred as mechanical energy
23
Q
The stapes attaches to the… which causes movement of fluid in the cochlea
A
oval window
24
Q
Vibrations of the ossicles vibrate the…
A
tympanic membrane
25
The tympanic membrane has an area ... fold greater than the oval window. This amplifies mechanical energy to the...
20 fold greater. Amplifies energy from the tympanic membrane to the oval window
26
The malleus and incus act to...
amplify sound waves
27
The outer ear is called the ... and its shape helps to collect sounds from..
The pinna collects sounds from a wide area
28
The auditory canal ends at..
the tympanic membrane/eardrum
29
The cochlea contains apparatus to transform .... into ....
physical motion of the oval window into neuronal response
30
Neuronal output from the cochlea is transferred and processed by...(4)
nuclei in the brainstem.
relay in thalamus.
mediate geniculate nucleus.
primary auditory cortex.
31
The size difference of tympanic membrane and oval window affects pressure, how?
Pressure exerted on the oval window is greater, sufficient to cause fluid movement in the cochlea
32
At the base of the cochlea, there are 2 membrane covered holes:
round window and oval window
33
The tube of the cochlea (inside) is divided into 3 fluid-filled chambers:
Scala vestibuli.
Scala media.
Scala tympani.
34
Reissner's membrane separates...
scala vestibuli and scala media
35
The basilar membrane separates..
scala tympani and scala media
36
On the basilar membrane is the ..... which contains auditory receptor neurons
Organ of Corti
37
On top of the organ of Corti is...
the tectorial membrane (collagen structure)
38
At the apex of the cochlea, the scala media .... and the scala vestibuli and tympani...
Scala media closes off.
| Scala vestibuli and scala tympani join - continuous with one another.
39
Fluid in scala vestibuli and scala tympani is called..
perilymph
40
perilymph has a silimar ionic content to..which is...
CSF - low K, high Na
41
Fluid in the scala media is called..
endolymph
42
endolymph has ionic content of:
high K, low Na. Like intracellular fluid
43
...lymph surrounds stereocilia bundles and ...lymph surround the rest of the hair cell
Endolymph surrounds sterocilia.
| Perilymph surrounds rest of hair cell.
44
Ionic content differences are generated by active transport at the..
stria vascularis (endothelium lining of scala media)
45
Endolymph has a potential ... more positive than perilymph
80mV
46
The basilar membrane is wider and stiffer at the... than at the base.
Wider and stiffer at the apex of the cochlea
47
High frequency sounds cause vibrations of the basilar membrane closer to the ... Low Hz sounds cause vibrations at the...
High Hz = base of cochlea
| Low Hz = apex of cochlea
48
Specific frequencies activate specific portions of the basilar membrane. Cochlea is a ...
frequency analyser
49
Sound displaces the basilar membrane during compression by..
| Stapes -> basilar membrane
Stapes moves inwards = inwards mov of oval window.
Increase of pressure of scala vestibuli causes fluid movement in opposite direction in scala tympani.
Causes outwards mov of round window = downwards mov of basilar membrane.
50
During rarefaction, sound displaces the basilar membrane by..
Stapes moves outwards = outwards mov of oval window.
Decrease in pressure in scala vestibuli. Mov of fluid in scala tympani causes inwards mov of round window. Basilar membrane moves upwards.
51
One hair cell has .... stereocilia extending from their top
1000
52
Sterocilia detect displacements of the....to what unit?
Basilar membrane. nanometers
53
Hair cells are sandwiched in between...
basilar membrane and reticular lamina
54
When the basilar membrane move up (rarefaction), stereocilia bend...
outwards - towards taller sterocilia
55
During compressions, the basilar membrane moves...and stereocilia move...
basilar membrane moves down and stereocilia move towards the shorter ones
56
Stereocilia move as a unit due to..
cross link filaments
57
On the tips of stereocilia, there are cation channels connected to..which are connected to...
elastic filaments called tip links which connect to the adjacent cilium.
58
When stereocilia are straight, tip link tension holds the channel...allows for..
partially open (10-20%). This allows for a small leak of K into the hair cell.
59
When stereocilia is moved by basilar membrane moving upwards, tip link tension...causing..
increases. This causes the channel to be opened further, increasing the inward K current into the hair cell.
60
Compressions causes tip link tension to..
be relieved. This closes the channel completely so no K+ moves into the hair cell.
61
Entry of K+ into the hair cell causes..
depolarisation. Activates Cav channels. Influx of Ca releases NT, activating SGN.
62
Reptiles have .... hair cells, with common afferent and efferent innervation.
a single class type of hair cell
63
Mammals have 2 types of hair cell. Inner hair cells contact ... fibres. Outer hair cells contact...fibres
IHCs contact the majority of afferent fibres.
| OHCs have strong efferent innervation
64
Inner hair cells are the primary..
sensory receptors
65
95% of afferent SGN innervates..by 1:1 ratio. This enhances..
IHCs.
| Frequency resolution
66
5% SGN innervate the... One SGN fibre innervates...
OHCs. One fibre innervates numerous cells.
67
Each hair cell is ... in diameter
10 micrometers
68
As sound intensity rises, ....decreases.
Sensitivity decreases
69
Cochlear output is from...
IHCs
70
The role of OHCs is to..
amplify mov of the basilar membrane during low intensity sounds to enhance sensitivity
71
Hair cells develop as many....with one...
microvilli (undifferentiated projections) with one kinocilium
72
In embryonic stages, the kinocilium...
migrates laterally to define polarity
73
After the kinocilium migrates, microvilli start to...
elongate and form stereocilia of graded heights
74
Short stereocilia grow up to .... post natally
5 days
75
Long stereocilia grow up to.... post-natally
12 days. This corresponds to the onset of hearing.
76
Stereocilia within a hair bundle are organised..
in rows of decreasing height
77
In mammals, the kinocilium is present...
only in development - degenerates after birth
78
In development, mechanotransduction occurs before..
mature bundle formation and onset of hearing. Increased Ca influx cause by MET could be important for stereocilia development
79
Stereocilia are supported by bundles of...
polarised actin filaments - cross-bridged with fascin1 and plastin2
80
Tip links are composed of..
stereocilin, complex of homodimers: cadherin23 and protocadherin15
81
Stereocilia get ... as they insert into the hair cell membrane. This allows for...
Narrower. This allows for movement without bending. Actin filaments do not extend to this part to reduce stiffness
82
To maintain constant length of stereocilia, rates of ... and ... are coordinated
Actin polymerisation and depolymerisation
83
Actin binding proteins are involved in stereociliary growth and are:
Eps8
| Eps8L2
84
Which hair cells are attached to the tectorial membrane?
OHCs
85
Planar cell polarity of hair cell bundles ensures a...
coordinated response
86
Eps8 is found mainly on..
tips of taller stereocilia
87
KOs of Eps8 show..
dysregulation of height and no. of rows
88
Eps8L2 is found on..
shorter stereocilia
89
KOs of Eps8L2 show..
no change except for matured heights.
| Progressive hearing loss due to less coupling of stereocilia to the tectorial membrane
90
Cochlea and MET is studied in vitro by..(2)
electrophysiology.
2 photon imaging.
Sounds waves delivered to cochlear tissue on mesh by pipettes.
Use whole cell patch clamp recordings
91
Turtles have stereocilia which:
Have lots of rows, meaning greater adhesion and mroe MET channels.
Good for detecting low frequency stimuli
92
Bat IHCs have:
2 rows of stereocilia with lots of space in between.
This reduces resistance between hair cells, allowing them to move very fast.
Good for detecting high frequencies.
93
Hair cells show adaptation which is:
a decrease in response to a constant stimulus - can be slow (<100ms) or fast (<10ms)
94
Adaptation allows for:
Operating range to be reset in hair bundle.
Maintains sensitivity.
Prevents saturation.
95
The MET channel is non-selective for cations, it mainly transports..
K+
96
Ca interacts with the MET channel by..
binding to the channel pore and blocking it, causing fast adaptation
97
...hair cells have synaptic ribbons
IHCs
98
...hair cells have postsynaptic cisterns
Outer HCs
99
excitatory bundle deflection causes a maximum current...
depolarisation of -30mV in IHCs and -20mV in OHCs.
100
Cadherin23 of tip links is bound to...(3)
Myosin7a, Harmonin-b and Sans
101
Mutants of cadherin23 show..
loss of tip links
102
Mutations in tip link proteins are involved in..
Usher's syndrome - deafness and blindness
103
MET currents are difficult to measure in mammals because..
the kinetics are much faster than in non-mammalian hair cells
104
MET currents are measured in vitro by using different..
amplitudes and measuring peak transducer currents, generating a current displacement curve.
105
Slow adaptation is cause by calcium...
causing myosin motors to slip on actin filaments - reducing tip link tension, closing some MET channels
106
Normally, myosin interacts with actin filaments in order to... how?
myosin climbs up actin filament to maintain tension in the tip link
107
Proteins of the MET channel are recently being studied in..
KO mice - TMC1, TMIE and LHFPL5 - located on stereocilia tips, cause deafness
108
Loss of TMC1 in the MET channel causes..
Deafness in mice. Beethoven mice show progressive hearing loss.
Also reduced Ca permeability.
Affected adaptation.
Elimination of tonotopic gradient.
109
It is thought that MET channel complex (TMC, TMIE, LH) are bound to PCD15, and that the components are..
essential for proper function
110
Low Ca during depolarisation = larger open probability of MET channel = slower adaptation. Shifts I-X relation..
to the left compared to high Ca
111
....has shown the MET channels are at the lower end of tip links.
Confocal imaging of Ca induced fluorescence
112
MET channel information is still unknown because:
Small no. of cells.
| Cannot expand hair cells in vitro.
113
Usher's is a ... genetic disorder characterised by.. (3) There are ... types.
```
recessive.
Bilateral deafness.
Late onset visual impairment.
Vestibular dysfunction
3 types.
```
114
USH1 is characterised by:
Severe to profound deafness.
RP (retinitis pigmentosa) shows gradual narrowing of visual field apparent in childhood.
Vestibular abnormalities - sitting independently.
115
USH2 is characterised by:
Moderate to severe deafness.
Mainly affects high Hz sounds.
No vestibular dysfunction.
RP diagnosed between ages 10-40.
116
USH3 - hearing and visual loss begin during..
late childhood-adolescence
117
Genes mutated in Usher's 1:
```
Myo7a
Harmonin
Cadherin23
Protocadherin15
Sans
CIB2
```
118
All USH proteins have complex interactions with each other, meaning..
any mutation will affect auditory transduction
119
Cadherin23 and Protocadherin15 are ... dependent adhesion molecules
Ca
120
CADH23 and PCD15 were found on tip links by..
antibodies for gold staining found distribution on tip link;
CADH23 was found towards the top
PCD15 found mostly towards bottom
121
Analog of USH1B...
Shaker 1 gene in mice. Mutation arose spontaneously and these were the first mice used to model deafness
122
Shake 1 gene encodes.. In the absence of myo7a...
Myosin7a.
Mutants have completely disorganised hair cell bundles.
Rightwards shift in displacement curve - requires twice as much displacement to open the channel.
123
Mutated CIB2 shows..
Reduced organisation.
Over elongation.
Loss of function - gradual degeneration.
Complete loss of MET channel
124
....screens showed that CIB2 interacts with TMC1. Interaction is lost in mutants
Yeast 2 hybrid screens and FRET
125
type 1 SGN innervate..
IHCs
126
type 2 SGN innervate..
OHCs
127
a type 2 SGN fibre contacts how many cells?
one fibre innervates 3-10 outer hair cells
128
SGN fibres are...
afferent
129
Type 2 fibres are ... activated and need ... of stimulation
weakly activated - need a lot of stimulation. Not well understood
130
Ribbon synapses form between ... and...
IHC and SGN type 1 fibres
131
Conventional synapses form between ... and ...
OHC and type 2 SGN fibres
132
Ribbon synapses are present in: (3)
Auditory system -IHCs.
Visual system -retinal and pineal photoreceptors, bipolar cells.
Vestibular system.
133
Ribbon synapses are found when transmission requires...
graded modulation of ongoing vesicle exocytosis
134
Ribbon synapses allow sensory receptors to be tonically active but they vary... Allows for..
the degree of stimulation - firing rate, temporal info. This allows for precise coding across a wide range of stimulus intensities and locations.
135
Disrupting synaptic ribbons impairs .... processing and...
temporal processing which consequently causes issues with speech recognition and sound localisation
136
Ribbons are electron dense structures at presynaptic membranes. Its major component is .... which is anchored to the membrane by...
RIBEYE is anchored to the presynaptic membrane by Bassoon. This prevents structures from floating in the cytoplasm.
137
Ribbons contain proteins:
Rim1 - vesicle priming.
KIF2A - kinesin motor complex.
Piccolo - cytomatrix active zone.
GCAP2 - Ca binding protein.
138
Ribbons can have different shapes: ... and there can be 20-400 vesicles present
spherical, planar or oblong
139
In mammalian hair cells, ribbons are ... in width. Non-mammalian ribbons are ... in width.
Over 200nm in mammals.
| 200-400 nm in non-mammals.
140
Ribbons are closely linked to Cavs. There are .... channels per ribbon so that there is short diffusion distance.
100-200 channels per ribbon, although this varies - differential sensitivities, threshold and dynamic ranges.
141
There are 3 types of vesicle at a ribbon synapse:
Readily releasable - closest to membrane.
Secondary pool - resupply.
Cytoplasmic pool - resupply.
Rapid and continuous/sustained depolarisation.
142
Ribbons studied by confocal microscopy, using antibodies against... What was seen?
RIBEYE and GluR2. There is tonotopic distribution from apex to base, with high levels of synapses at a particular Hz range. This gives high sensitivity at these Hz
143
Synaptic vesicles are prepared for use. First:
Vesicles are primed so they are Ca responsive.
Ca mediates vesicle fusion involving SNAREs (not ribbons).
In ribbons, Ca is sensed by Otoferlin.
144
Otoferlin mutations cause..
reduced exocytosis in IHCs, despite vesicles accumulating at the active site. Causes deafness.
145
Ca sensors of synaptic vesicles also include:
Synaptotagmins
| Syt1, Syt2
146
Development of synaptic machinery has been studied in ... since systems are very well conserved
mice and rat studies
147
...weeks are needed before the cochlea can detect sound in mice
3 weeks
148
In babies, even though IHCs cannot hear sounds, they show...important for..
spontaneous APs driven by Ca important for refining the tonotopic projections of the pathway.
149
In development, Ca spikes are....and become...at P6
small and broad. They become faster
150
Developmental, spontaneous Ca APs arise due to...
resting potential of IHCs is close to threshold of Cav activation.
151
Ribbons appear later in development; appearing as ...at P6, and changing to ... at ....
Appear as spherical at P6, change to elongated at P12
152
In ribbons, there is an increase of Ca current through development which then..
steadies out. Also seen downreg of Cav channels
153
immature IHCs need Ca entry through...compared to mature IHCs
multiple channels - exponential relationship.
| Mature IHCs have closer Cav, Ca entry through one channel is sufficient. Linear relationship
154
Swtich from expontential to linear relationship of Ca entry and exocytosis increases...
release efficiency. Allows for maintenance of sensitivity for different intensities.
155
immature IHCs show .... immunostaining
much more RIBEYE, Cav and GluRA2/3
156
NT release is measured by..
capacitance - cell surface area due to vesicle fusion
157
Vestibular system allows for..
Proprioception - body positions and movements to be relayed to the brain.
Rapid reflex
158
Vestibular system works from .. to .. frequencies.
very low (30Hz) to high (a few kHz)
159
Vestibular system works with ... and ... to maintain posture and balance.
Somatosensory and proprioceptive systems
160
Visual inputs are stabilised by the..
vestibular ocular reflex - occurs in response to head movement
161
Vestibular ocular reflex detects head movement which relays signals to the eye muscles. This allows for..
eye movements in the opposite direction to head movement to keep the image in the centre of the visual field.
162
vestibular ocular reflexes are the..
fastest in the body and are highly accurate
163
Vestibular hair cells are contained in..
interconnected sets of chambers called labyrinths
164
Vestibular labyrinths have 2 structures with different functions:
Otolith organs - orientated at right angles, detect linear acceleration of head.
Semicircular canals - ant, post, and horizontal, sensitive to angular acceleration (x, y, z axes)
165
Semicircular canals are sensitive to..
changes in velocity - not just velocity
166
Otolith organs are:
saccule and utricle
167
Vestibular hair cells make excitatory synapses with..
a sensory fibre of the vestibular nerve
168
Sensory organs of the saccule and utricle are... It differs in the organs by..
sensory epithelia called macula. In the saccule it is vertical, in the utricle it is horizontal.
169
Macula are orientated differently so that..
linear acceleration in all directions can be detected.
170
Macula supporting cells have cilia (which bend) projecting into a ..
gelatinous cap - this adds weight to the membrane so that otolith organs respond to gravity.
171
The utricle and saccule are mirrored on each side of the head so that when hair cells on one side are excited...
hair cells on the other side tend to be inhibited.
172
Semicircular canals detect angular acceleration which is..
generated by sudden rotational movement
173
Hair cells of semicircular canals are clustered within a sheet of cells called ... located in a buldge along the canal called..
Crista are located in the ampulla
174
Cilia of crista project into gelatinous cupula which span the lumen of the canals within... What does this do?
the ampulla. This synchronises movement of hair cells
175
Hair cells in a given ampulla are in the...
same direction - all get excited or inhibited together
176
There are 2 types of vestibular hair cells:
Type 1 - tear drop shape, calyx nerve endings which surround 1-3 VHCs.
Type 2 - columnar, afferent boutons, provide slower graded responses
177
Some VHCs are contact by..
both calices and afferent boutons
178
VHCs differ to IHCs and OHCs because:
Longer bundles.
More rows.
Stereocilia vary greatly in length (steep staircase).
Kinocilium present but not functional
179
Slow adaptation in VHCs is dependent on..
Myosin 1c - mutations show complete loss of slow adaptation
180
There is a large proportion of slow adaptation in VHCs due to..
greater no. of rows of stereocilia
181
VHCs have .... ribbons per cell
6-20
182
Alcohol causes vertigo and oscillopsia by..
altering the density of the gelatinous membranes
183
The lateral line is seen in ... It is located...
All aquatic vertebrates. It is located on the surface of the entire body, seen as series of dots.
184
Units of the lateral line are called..
neuromasts.
185
Neuromasts contain ... and ... cells which are innervated by..
Hair cells and supporting cells are innervated by both afferent and efferent fibres
186
Aquatic vertebrates detect auditory and vestibular stimuli such as:
Sound waves in water.
Pressure gradients in water.
Movement.
Allows for schooling, escape, sexual courtship and predation
187
In Zebrafish, the lateral line has 2 major branches:
Anterior - around the head.
| Posterior - length of trunk and tail.
188
Zebrafish has ... semicircular canals, with anterior and posterior maculae
3 semicircular canals - angular acceleration.
| Maculae - linear acceleration and gravity.
189
Weberian ossicles connect to the ... and ...
Saccule and swimbladder
190
The swimbladder compresses gas which cause oscillation. This...
amplifies sound delivered to the saccule
191
The lateral line is functional ... post fertilisation since it is critical for survival
48 hours post fertilisation.
| Starts at 20 hours pf
192
Zebrafish are an attractive model organism for studying hair cells because..
Less time to wait for development.
| Zebrafish are good transgenic tools.
193
The lateral line emerges from a ... called prim1. This deposits ... and ... along the body of the fish at..
Primordium. This deposits 5 clusters of hair cell groups and growth cones of axons, and a continuous stripe of interneuromast cells during P1-5.
194
Lateral line hair cells are stimulated..
directly
195
The cochlea is highly sensitive and specialised but this come at a cost:
Loss of regenerative ability.
| Need stimuli amplified.
196
Lateral line hair cells on the surface allow for..
a much quicker response and detection of stimuli from any direction.
197
How is the auditory system scaled in aquatic vertebrates?
The lateral line is larger depending on the size of the fish, but the size of hair cells is the same - there are just more
198
Neuromasts differ from mammalian hair cells as...
They have a kinocilium.
Neuromast stereocilia look more like VHCs.
Neuromasts are embedded in a cupula
199
Neuromasts can respond to stimuli from all directions because their neuromast hair cells...
show direction polarity - respond in all directions
200
Afferent fibres of neuromasts innervate many hair cells of/from...
one polarity. This means only one set of fibres will be excited by a stimulus coming from a particular direction.
201
1 neuromast is innervated by ... afferent neurons
8 neurons
202
Long stereocilia would cause..
reduced stiffness - too floppy. Bending at the top instead of base to a stimulus. Would reduce sensitivity.
203
Mutation of CADH23 in Zebrafish specifically impacts..
mechanotransduction
204
Zebrafish have a duplication of TMC2, a ... would be required to study TMCs
triple KO
205
LHFPL5 Zebrafish mutants show..
deafness and deficits in balance. Also seems to be important for localisation of PCD15
206
At higher Hz, IHCs are unable to encode info and show a sustained response. OHC help by...
feedback on IHCs to stimulate them more
207
Type 1 SGN neurons are ... and travels to the...
Myelinated, bipolar and unbranched. They travel to the cochlea nucleus in brainstem
208
More than 1 type 1 SGN fibre to each IHC means that..
the signal is split into different streams - they remain segregated along the pathway to allow IHCs to encode more info. Also, if 1 fibre is damaged, IHC doesnt lose all function.
209
Apically, SGNs have:
Prologened latency.
Slow onset time
Longer AP duration.
Greater density of presynaptic proteins
210
Basally, SGNs have:
```
Short latency (by Kv channels).
Increased expression of postsynaptic receptors AMPA, GluR2/3
```
211
Type 2 SGNs are branched and... They contact up to...
unmyelinated. 30 OHCs
212
Function of type 2 SGNs is not known. They seem to response only when..
All contacted OHCs are activated - perhaps for damage/overstimulation feedback - nociception
213
LOC efferents are from the..and synapse with..
lateral superior olive. They synapse with Type 1 SGNs
214
LOC efferent fibres may function as inhibitory. This could cause..
inhibition of type 1 SGNs to reduce excitotoxicity
215
MOC efferents are from the...and form ....synapses with OHCs
medial superior olive. They form large inhibitory synapses with OHCs. This reduces cochlea amplification to prevent damage.
216
Afferent fibres leaving the cochlea form 2 pathways:
Dorsal - sound localisation, bypasses superior olive
| Ventral - encoding sound
217
The superior olive receives input from both cochlea in order to...
encode interaural time and level differences for sound localisation
218
What does the inferior colliculus do?
Combines cochlear input with somatosensory and visual centres for multimodal processing
219
The mediate geniculate nucleus is involved in...
memory and learning
220
Primary auditory cortex has roles in...
decisions, cognition and memory
221
Staggered firing of multiple neurons on successive cycles along with....allows for complete encoding of a sound
When staggered firing is summated, there is complete encoding called phase locking.
222
The ability to phase lock is lost above...
2kHz - IHCs cannot encode very high frequencies
223
Intensity is encoded by:
No. of neurons - more fibres firing = louder sounds.
| Spike rate increasing until it saturates
224
3 forms of hearing loss occur by:
Auditory processing disorder - brain
Conductive - outer and middle ear
Sensorineural - cochlea and auditory nerves
225
ABR is response to repetitive acoustic stimulation recorded from...
scalp EEG. Has 5 peaks. Wave 1 is called the compound action potential
226
DPOAE are distortion product otoacoustic emission. They are used to test...
function of OHCs by the vibrations of the basilar membrane
227
Neuropathies can occur due to problems in:
IHC NT release.
Spike generation in SGNs.
Propagation of spikes along SGNs.
Transmission from SGN to cochlea nucleus
228
Synaptopathies of hair cells are caused by:
Genetics - genes related to ribbon function, NT release, Ca current
Acquired - noise-induced hearing loss, age, chemicals (antibiotics, cancer drugs)
229
Inherited mutation in OTOF gene causes...
```
Otoferlin inactivation and non-syndromic hearing loss.
Absent exocytosis (Ca triggered)
```
230
VGluT3 mediates vesicular glutamate uptake at IHC synapses. Mutations cause...
dominant hearing loss.
| mental and motor retardation in some individuals.
231
Cav1.3 makes up 90% of Ca current in hair cells. Important for...
triggering vesicle exocytosis - reduced ribbons and postsynaptic receptor clusters
232
Mutations in CACNA1D cause..
syndromic deafness and sinoatrial node dysfunction
233
Permanently damaging levels of sound are over... They cause damage to:
140 dB. Damages stereocilia, nerve fibres, and causes thresholds to shift.
234
Temporary damaging levels of sound are about ...dB. They cause..
100. They cause a temporary shift in thresholds by glutamatergic excitotoxicity in IHCs.
Can lead to hidden hearing loss (struggling to hear in noisy environments) - not detected in standard hearing tests
235
In hidden hearing loss ... dendrites are affected
afferent terminal dendrites of low spontaneous rate
236
With age, synapses between ... and ... are lost before hair cells are affected
SGN and IHCs
237
Potential therapies of hearing loss is injection of ... into the round window, 24h after noise exposure. What would this do?
NT3 - neurotrophic factor. This restores synapse number and hearing function.
238
Transfection of VGlut3 by AAV into the round window can do what..
restore expression of VGlut3. Shows restored ABR thresholds for 7 weeks. However, does not improve SGN
239
AAV transfection of otoferlin (in 2 parts) in DFNB9 mice was injected into the round window. What happened
After 4 weeks, mice showed complete restoration of ABR threshold
240
Hair cells are derived from prosensory cells in the...
cochlea duct - ventral side of the otocyst
241
Cells of the early otocyst express....to remain undifferentiated
Jag1, Sox2, Notch, Wnt and FGF
242
At E..... p27 is upregulated and causes...
E12-14. P27 inhibits cell cycle and stops division so cells can divide
243
At E14, cells become sensory hair cells by expression of...
ATOH1, Wnt and FGF
244
At E14, cells become non-sensory cells through expression of..
Hes1, Hes5 and FGF
245
At E9-10, otocyst cells migrate to form...
Neurons - through expression og Ngn1 and NeuroD
246
At E17, the inner ear....
is fully formed
247
p27 is expressed in a .... gradient. This means that cells exit cycle at different times and cells which are last to exit....
Longitudinal gradient. Cells which exit cell cycle last differentiate first
248
ATOH1 KO mice fail to...
produce hair cells
249
Inner and outer HCs are only differentiated.. Which matures first?
after birth. OHCs mature before IHCs
250
MET channel and mechanotransduction occurs..
post natally - 4 days before onset of hearing
251
miRNA96 is important for determining..
cell fate and development in the inner ear
252
miRNA96 is expressed until p5 in ... and p14 in ...
p5 in cochlear hair cells and p14 in SGNs
253
A singular base change in miRNA96 in mice and humans causes
non-syndromic progressive deafness
254
Mutant miRNA96 mice show:
Thinner stereocilia.
Reduced surface area.
OHCs are shorter but normal arrangement of HCs. - development up until birth is normal
255
After birth of mutant miRNA96 mice, what is shown?
```
Early onset hearing deficits.
IHCs show retention of Ca APs.
IHCs fail to acquire K channels.
Altered synaptic development.
Immature IHCs
```
256
miRNA96 is crucial for...
functional differentiation and maturation after birth
257
Electromotility is the ability of OHCs to change their length in response to stimulus. This requires...
motor protein - prestin.
258
Mutated prestin causes .... fold decrease in sound sensitivity
100
259
Prestin reduces its area when the cell depolarises, amplifying ...
movement of the basilar membrane
260
Ikzf2 is expressed only in OHCs from p4 through to maturation. Ikzf2 encodes..
Helios, a Zn finger protein
261
Mutations in Helios (encoded by Ikzf2) cause..
hearing impairment, loss of hair cell bundles, functional deficit in OHCs, early onset sensorineural hearing loss
262
Cello mice are models of hearing loss, they have mutations in Ikzf2. They show highly reduced expression of prestin in OHCs meaning..
highly reduced electromotility in OHCs
263
Immature OHCs fire .... APs very quickly. These are completely lost at P4 which corresponds to the expression of...
Ca driven APs. Lost when prestin in expressed.
264
Immature Ca APs are important for development since..
they may act to trigger functional maturation of the OHCs - upreg or downreg of channels (?)
265
In ARHL there is..
```
stiffening of the eardrum.
Loss of HCs
Degen of stria vascularis
Decrease of neurons.
Decreased temporal lobe activity.
```
266
3 techniques used to study auditory cells:
Fluorescence imaging.
Patch clamp electrophysiology
Optogenetics
267
To see when and where events occur, studying techniques need to show..(5)
```
high temporal resolution.
high spatial resolution.
scalability.
high sensitivity.
minimal invasiveness.
```
