1
Q
Name the layers in the retina and what cells they contain
A
pigment epithelium
outer segments of photoreceptors
outer nuclear layer - nuclei of photoreceptors
outer plexiform - synapses btw PRs and bipolar cells + horizontal cells
inner nuclear layer - bipolar cells
inner plexiform - synapses btw bipolar and ganglion cells + amacrine cells
ganglion cell layer
nerve fiber
2
Q
What response does light (photons) cause in PRs?
A
hyperpolarization
3
Q
Describe rods in terms of:
time of reaction to light
convergence
sensitivity
location in retina
time of adaptation
signal amplification
A
slow reaction to light
large convergence
high sensitivity
in periphery
slow adaptation
large signal amplification
4
Q
Describe cones in terms of:
time of reaction to light
convergence
sensitivity
location in retina
time of adaptation
signal amplification
A
fast reaction to light
no convergence
low sensitivity
in fovea
fast adaptation
little signal amplification
5
Q
Which PRs are active in intense light?
A
Cones
6
Q
In low light, which PR adapts fast to higher light threshold?
A
Cones
7
Q
Which NT is released by bipolar cells?
A
Glutamate
8
Q
What is the response of ON bipolar cells to light?
A
Depolarization (thru mGluR6) -> sign inverting (PRs hyperpolarize)
9
Q
What is the response of OFF bipolar cells to light?
A
Hyperpolarization (thru AMPA) -> sign conserving (Prs also hyperpolarize
10
Q
Imagine an OFF-centre RF and light shines on surround. What is the response of:
PRs in centre
PRs in surround
bipolar in centre
RGC
A
PRs in centre - depolarize (no light)
PRs in surround - hyperpolarize (light)
bipolar in centre - depolarize
RGC - depolarize (increased firing)
11
Q
Imagine an OFF-centre RF and light shines on centre. What is the response of:
PRs in centre
PRs in surround
bipolar in centre
RGC
A
PRs in centre - hyperpolarize
PRs in surround - depolarize
bipolar in centre - hyperpolarize
RGC - hyperpolarize
12
Q
Imagine an ON-centre RF and light shines on centre. What is the response of:
PRs in centre
PRs in surround
bipolar in centre
RGC
A
PRs in centre - hyperpolarize
PRs in surround - depolarize
bipolar in centre - depolarize
RGC - depolarize
13
Q
Imagine an ON-centre RF and light shines on surround. What is the response of:
PRs in centre
PRs in surround
bipolar in centre
RGC
A
PRs in centre - depolarize
PRs in surround - hyperpolarize
bipolar in centre - hyperpolarize
RGC - hyperpolarize
14
Q
What are the 3 types or RGCs?
A
Magno (parasol)
Parvo (midget)
Konio
15
Q
What layers in LGN do Magno cells project to?
A
L 1 & 2
16
Q
What layers in LGN do Parvo cells project to?
A
L 3-6
17
Q
What input do Magno cells carry?
A
from rods -> luminance contrast, motion, position
18
Q
What input do Parvo cells carry?
A
from cones -> colour, shape
19
Q
What are the types of cones?
A
S -cones (blue)
M-cones (green)
L-cones (red)
20
Q
How do RGCs determine a color?
A
Compare activity btw 2 types of cones
21
Q
What happens with RGCs in color blindness?
A
RGCs still want to compare input from 2 cone types but since one is missing, they compare 2 of the same cone types. This leads to wrong perception
22
Q
What is protanopia?
A
Lack L-cones (less sensitivity to red)
23
Q
What is deuteranopia?
A
Lack M-cones (less sensitivity to green)
24
Q
Where do RGCs project to?
A
90% to LGN
10% to hypothalamus (circadian rhythms), pretectum (pupil reflex), superior colliculus (eye/head reflex)
25
What retinal info do top optic radiations carry?
superior retina / inferior visual field
26
What retinal info do bottom optic radiations carry?
inferior retinal / superior visual field
27
What vision defect will take place if there is a lesion between the eye and an optic chiasm?
fully blind in one eye
28
What vision defect will take place if there is a lesion at the optic chiasm?
No info can cross from nasal retina, so the visual field is narrow (no info from periphery)
29
What vision defect will take place if there is a lesion between optic chiasm and the LGN?
LGN processes information from the contralateral visual field, so a lesion will result in info only from ipsilateral visual field
30
What type of info is encoded in V1?
orientations
31
Which layer in V1 is strictly monocular?
L4 -> strict ocular dominance columns, in other layers visual info is not that separated with binocular cells also existing
32
What visual disorders are associated with lesions in the ventral pathway?
Hemi achromatopsia, paraidolia, prosopagnosia
33
What visual disorders are associated with lesions in the dorsal pathway?
akinetopsia
34
What is a binding problem?
how does the brain integrate different parts of perception?
35
What happens to V1 activation, if you pay attention to the stimulus?
it increases, while the orientation preference stays the same
36
Right LGN processes info from right/left visual field
left
37
are the cells in LGN monocular or binocular?
monocular
38
Which layers of LGN process info from the ipsilateral eye?
L 2,3,5
39
What is sound?
fast and small variations in air pressure
40
Describe the sound pathway from the ear to the auditory cortex
1. Auditory nerve
2. Cochlear nuclei
3. Superior olive
4. Lateral lemniscus
5. Inferior colliculus
6. Medial geniculate nucleus
7. Primary auditory cortex
41
What is auditory periphery?
ear + cochlea + audiroty nerve + medulla
42
What is it called when ears separate a mix of different sounds from one waveform?
spectral analysis
43
What organ performs spectral analysis?
cochlea (inner ear)
44
What does an amplitude of a waveform represent?
loudness
45
What does a frequency of a waveform represent?
pitch
46
What is a spectrum of audible frequencies?
20-20000Hz
47
What's a power spectrum?
how much does each frequency contribute to the sound; how loud is each frequency in the sound
48
What's a traveling wave?
Displacement of a basilar membrane by nms
49
Where on the basilar membrane do high frequency sounds locate?
at the base
50
Where on the basilar membrane do low frequency sounds locate?
at the apex
51
In which scala is organ of corti located?
scala media
52
What are the 2 types of hair cells?
IHCs - 1 row (afferent)
OHCs - 3 rows (efferent)
53
What is tonotopy?
Separation of frequencies by different nerve fibers
54
What are the types of auditory nerve?
Type I - innervate IHCs (afferent) -> project to cochlear nuclei
Type II - innervate OHCs (efferent) -> project from superior olive
55
What feature of auditory nerve recording gives info about sound frequency?
Which of the fibers is recorded from
56
What feature of auditory nerve recording gives info about sound amplitude?
firing rate
57
What feature of auditory nerve recording gives info about temporal patterns of a sound?
exact timing of firing
58
What feature of auditory nerve recording gives info about source location?
relative timing and amplitude btw ears
59
What are the 2 ways to analyze auditory nerve data?
count spikes or look at their timing
60
What curves can be produced from counting analysis of auditory nerve data?
Rate-frequency curve by varying frequencies with the same loudness -> looking at a frequency that produces the most spikes in that fiber
Threshold curve by varying loudness for one frequency (repeat for each frequency) -> looking at the minimal loudness necessary to produce spikes in a fiber -> shows a characteristic frequency for each fiber (lowest threshold)
61
What is phase locking?
When spikes match the waveform -> rate code (can see individual cycles). Can be seen up to 5kHz, after that the frequency is too high (individual fibers can't fire that fast). Phase locking is stochastic so individual spikes will be skipped
62
What is temporal jitter in the context of sound timing analysis?
slight variation in spike timing from trial to trial with the same stimulus -> increases with higher frequencies; disperses phase locking
63
What is cycle histogram?
Shows in what part of a cycle (waveform) are cells firing -> accurate with low frequencies (phase lock); becomes uniform with high frequencies (no phase lock)
64
What does vestibular system sense?
head movement and orientation in space
65
How many degrees of freedom does vestibular system have?
6
66
What is sensed by semicircular canals?
rotation in space
67
What is sensed by otoliths?
acceleration and tilt
68
What are the 2 otoliths?
Utricle and saccule
69
What lymph is in the bony labyrinth and in the membranous labyrinth?
Perilymph in bony
Endolymph in membranous
70
What is the longest hair cell called?
Kinocilium
71
What are the small hair cells called?
Stereocilia
72
In what lymph are hair cells located?
endolymph
73
When the hair cells bend away from the kinocilium, the cell (hyperpol/depol)?
hyperpolarizes
74
When the hair cells bend towards the kinocilium, the cell (hyperpol/depol)?
depolarizes
75
Why do vestibular system hair cells have a high baseline firing rate?
more info is transmitted during hyperpol/depolarization
76
Perilymph in low/high in Na+ and low/high in K+
High Na+
Low K+
77
Endolymph in low/high in Na+ and low/high in K+
Low Na+
High K+ (enters the hair cells during depolarization)
78
What are the types of vestibular hair cells?
Type I - calyx
Type II - bouton
Dimorphic - both
79
What type of spiking do type I vestibular hair cells show?
irregular spontaneous spiking
80
What type of spiking do type II vestibular hair cells show?
regular spontaneous spiking
81
How do type II vestibular hair cells transmit info?
via firing rate
82
How do type I vestibular hair cells transmit info?
via timing of firing
83
What are the advantages of type II vestibular hair cells?
lower detection threshold
84
What are the advantages of type I vestibular hair cells?
more sensitivity/gain
phase lead - earlier timing of response
-> optimized for natural stimuli
85
What is the purpose of dimorphic vestibular hair cells?
Dual coding
86
What is the purpose of mirrored semicircular canals?
1. +on one side, -on the other -> bilateral info
2. if one side damaged, the other still works
87
What is semicircular canal signal proportional to?
velocity
88
What is the orientation of the utricle?
horizontal + (vertical)
89
What is the orientation of the saccule?
vertical
90
What is otoconia?
Crystals in gelatinous layer in otoliths, they bend the hair cells during acceleration/tilt
91
How to differentiate tilt from linear acceleration?
During tilt, semicircular canals activate together with the otoliths, while during acceleration, only otoliths are active
92
What is the vestibular pathway of otoliths?
Otoliths -> CN VIII -> lateral vestibular nucleus -> cerebellum and limb motor neurons
93
What is the vestibular pathway of semicircular canals?
Canals -> CN VIII -> medial vestibular nucleus -> neck and extraocular motor neurons + VP thalamus
94
Describe vestibulospinal projections (what signal, to what parts of SC)
Lateral VS tract - otolith signal for maintaining posture, ipsilateral, to cervical, thoracic and lumbar spine
Medial VS tract - canal signal for keeping the head still in place, mostly ipsilateral, to cervical spine via medial longitudinal lemniscus
95
To what type of neurons in the vestibular nuclei do regular spiking hair cells project and what function is associated with that?
to position-vestibular-pause (PVP) neurons for gaze stabilization (VOR)
and to flocculate target neurons (FTN) for modulation of VOR
96
To what type of neurons in the vestibular nuclei do irregular spiking hair cells project and what function is associated with that?
to vestibular only (VO) neurons for posture, balance (VSR) and estimation of self-motion
97
What is the VOR pathway?
Medial vestibular nucleus -> abducens nucleus -> (via medial longitudinal fasciculus) -> oculomotor nucleus -> eye muscles
98
What ocular muscles are controlled in pair by horizontal semicircular canals during VOR?
R lateral + L medial rectus muscles
or
L lateral + R medial rectus muscles
99
What ocular muscles are controlled in pair by LARP semicircular canals during VOR?
L superior + L inferior recti + R obliques
100
What ocular muscles are controlled in pair by RALP semicircular canals during VOR?
R superior + R inferior recti + L obliques
101
Which neurons in the vestibular nuclei are inhibited during gaze redirections?
PVP (normally controlling VOR, but now its counterproductive)
102
What region controls motor learning of VOR?
cerebellum
103
What is net acceleration?
tilt + translation -> firing rate that tells what movement is happening
104
What is somatogravic illusion?
confusing acceleration for tilt in the dark (planes taking off at night)
sustained acceleration interpreted as gravity
105
What movement is encoded by vestibular nuclei (active/passive)?
Passive
106
What input is transmitted by net vestibular afferents?
Active + passive
107
What happens to the vestibular signal during voluntary movement?
If the signal for the canals/otoliths matches the efference copy of the predicted movement, vestibular signal is suppressed and no VSR takes place (VSR is counterproductive during voluntary movement)
108
What is the closed-loop system of vestibular control of balance?
Balance orientation -> Neural integration + control -> motor command -> biomechanics -> body motion -> sensory dynamics -> sensory signals -> neural integration of balance orientation
109
What happens to a person standing when only vestibular signals (out of all senses) are available? Why?
Sway increases bc vestibular signal has a high threshold for sway detection
110
When the vestibular control is taken over from a person, which muscles shut down and which remain in control?
Body muscles shut down bc they are not needed anymore for maintaining balance
Neck muscles do not shut down since they are responsible for head orientation, they are part of computation (head-in-space vs. head-on-body) not just effectors like body muscles -> vestibular drive is irrespective of postural task
111
Body muscles respond to vestibular information:
1) only when its relevant for postural control
2) irrespective of relevance for postural control
1) only when its relevant for postural control
112
What are the differences between chemo sensation and vision/hearing?
its matter-based vs energy-based, its slower, its G-protein-receptor-based
113
Describe the olfactory pathway from nasal cavity to the cortex
Nasal cavity -> olfactory epithelium (olfactory receptors) -> cribriform plate (olfactory nerve) -> olfactory bulb (synapse btw ORNs and mitral cells) -> (lateral) olfactory tract -> pyriform cortex, olfactory tubercule, amygdala, entorhinal cortex -> orbitofrontal cortex, thalamus, hypothalamus
114
What is different about olfaction compared to other sensory systems?
Olfactory input doesn't go directly to thalamus
115
What's anosmia?
inability to smell
116
What gland produces mucus in the nose?
Bowman's gland
117
What channels are activated by Golf protein-coupled receptors?
Na+/Ca2+ cAMP-gated channels
118
Are the olfactory receptors one-size-fits-all?
No, each odor has a specific receptor
119
What are glomeruli?
regions in olfactory bulb that receive input only from one type of receptor from ORNs (symmetrical on both sides) -> create odor maps
Different levels of activation btw glomeruli provide info about the exact smell -> feature extraction
120
What cells receive input from glomeruli?
Mitral neurons
121
Via which tract do mitral cells project to the cortex?
Lateral olfactory tract
122
One odorant causes small/broad activation in the cortex
broad -> memory representation
123
ORNs to mitral cells: divergence or convergence?
convergence -> 25 000 ORNs to 25 mitral cells
124
What is vomeronasal system?
similar to olfactory
PPP -- predator, prey, potential mate
125
What chemicals are sensed from predators/prey by vomeronasal system?
kairomones
126
What chemicals are sensed from potential mates by vomeronasal system?
pheromones
127
What receptors are sensitive to kairomones?
V2
128
What receptors are sensitive to pheromones?
V1
129
What organs are involved in vomeronasal system?
vomeronasal organ (less receptors that in ORNs) -> accessory olfactory bulb
130
What are the 5 gustatory inputs and how are they spatially organized on a tongue?
sweet -> tip of the tongue
sour -> sides of the tongue
bitter -> back of the tongue
umami -> whole anterior tongue
salty -> tip and sides of the tongue
131
How is taste info converted into a nerve impulse?
papilla on the tongue contain taste buds (in the trench of papilla) that contain receptors
132
What type of receptors are responsible for taste info?
GPCRs for sweet, bitter and umami
Ion channels (always open) for salty and sour (acid) -> cation influx -> depolarization
133
What NTs are released by taste buds?
GABA, serotonin, ATP
134
Will very low concentrations of taste stimuli cause taste perception?
No, there is a threshold of concentration
135
Are taste receptors only present on the tongue?
No, also in the GI tract -> for metabolism, vomiting, etc.
136
How is taste info conveyed to the brain? (the pathway)
taste buds:
- palate + anterior 2/3 of the tongue -> CN VII (facial)
- posterior 1/3 of the tongue -> CN IX (glossopharyngeal)
- pharynx, upper esophagus -> CN X (vagus)
-> CN ganglia -> nucleus of solitary tract -> VPM thalamus, hypothalamus, amygdala
from VPM thalamus -> insular and frontal gustatory cortices -> amygdala
137
What are the 2 theories about how taste info if conveyed to the brain?
1. Labelled lines - each flavor (eg sweet) receptor on the taste bud has a separate fiber in the CN that brings the (sweet) info to the brain. Only one (sweet neuron is firing
2. Across neuron pattern - info from multiple flavor inputs (eg sweet and salty receptors) is conveyed within one CN fiber to the brain. Many neurons are firing with different relative frequency.
In reality, its probably a mix of both
138
With what other sensory system does gustatory system strongly interact with?
Olfactory
139
What is conditional taste aversion?
Induced sickness after sweet water will lead to avoiding the water
Happens bc of amygdala
140
What is a whisker?
Hair growing out of a follicle sinus complex
141
What is a follicle-sinus complex?
mechanoreceptive organ that consists of follicle (epidermis) + blood sinuses (dermis)
Ring sinus -> can have more/less blood -> more blood = more rigid = more sensitive (more in rodents)
Cavernous sinus -> more rigid (bigger in aquatic animals)
142
Which mammals do not have whiskers?
monotremes (echidna and platypus), anteaters, adult dolphins and rhinos, humans
143
Which sensory brain regions expanded first during evolution?
olfactory and tactile
144
Where are whiskers located?
throughout the whole body but more around the mouth and cheeks -> depends on usual behavior of the species
145
How are whisker inputs organized in the cortex?
in rows and columns -> barrel cortex in layer 4 -> 1 whisker = 1 barrel
Some animals also have in-between regions where input from multiple whiskers is processed
146
Which species tend to have bigger whiskers?
arboreal, aerial, nocturnal, marine, semi-aquatic, with poor (near-) sight
147
What functions other than tactile info do whiskers have?
proprioception (cats), partner recognition (sea lions)
148
What nerve innervates the follicle-sinus complex?
trigeminal
149
Describe the pathway of whisker info to the cortex?
Whisker -> trigeminal ganglion -> trigeminal nuclei -> VPM thalamus -> barrel cortex
150
How many pairs of spinal nerves do we have?
31
151
What is sensory transduction?
converting external stimuli into nerve impulses
152
What is sensibility?
ability to feel, perceive and sense
153
What is reception?
sensory receptors responding to specific type of stimuli
154
What are the 3 types of sensibility?
exteroception - skin
proprioception - musculoskeletal system
interception - internal organs
155
What are the 2 types of somatosensation?
Gnostic - fine touch, proprioception
Vital - pain, temperature, itch
156
What is the main organ responsible for touch perception?
Cutaneous/glabrous skin (skin with little hair)
157
Mechanoreceptors with small receptive fields are close to/deeper from the skin surface
close to the surface
158
Mechanoreceptors with large receptive fields are close to/deeper from the skin surface
deeper
159
What are the 4 types of gnostic mechanoreceptors? In which skin layer are they located?
Meissner corpuscle (epidermis)
Merkel cell-neurite complex (epidermis)
Ruffini corpuscle (dermis)
Pacinian corpuscle (subcutaneous layer0
160
What are the properties of Meissner corpuscles (adaptation, RF, stimulus)?
small RF, fast adapting, skin motion detection, grip control
161
What are the properties of Merkel cells (adaptation, RF, stimulus)?
small RF, slow adapting, shape, texture, edges, curvature
162
What are the properties of Ruffini corpuscles (adaptation, RF, stimulus)?
large RF, slow adapting, skin stretch, tangential force
163
What are the properties of Pacinian corpuscles (adaptation, RF, stimulus)?
large RF, fast adapting, vibration
164
What is the name of gnostic mechanoreceptors? What type of stimuli so they respond to?
Piezo 1 and 2
Flow (extracellular C-terminal)
Interaction with gating springs (extra- and intracellular)
Pull/pressure on skin leading to membrane thinning/curvature (extra- and intracellular)
These receptors are also located in blood vessels, intestines, CNS (CSF accumulation)
165
How is tactile acuity measured?
With calipers
If 2 points are too close together, they likely fall within one RF of a mechanoreceptor -> only one cell is firing -> perceived as one point
If 2 points are further apart, they fall within 2 RF -> 2 cells fire -> perceived as 2 points
166
Is 2-point discrimination threshold directly or inversely proportional to tactile acuity?
Inversely
167
Why is tactile acuity higher in finger tips compared to back?
Finger tips have a higher density of receptors + the receptors have smaller RFs
Discrimination threshold is approximately the same between the two
168
Which receptor cells contribute most to 2-point discrimination?
Meissner and Merkel cells
169
Is different size of RFs of tactile receptors related to accuracy of perception or sensitivity or both?
Only accuracy of perception
Sensitivity is the ease of stimulation and has nothing to do with the size of a receptive field
170
Why are RFs different sizes in different body parts?
Depends on branching of afferents and density of receptors
171
How is tactile sensitivity measured?
with von Frey hairs - they have different rigidity and when touch skin with the same force, the threshold of sensitivity can be measured (at what point start feeling smth on skin)
172
What is proprioception?
info about the mechanical forces arising within the body that inform about the position of body in space
173
What are the 2 main proprioceptive organs?
muscle spindles and Golgi tendon organ
174
What is the role of muscle spindles? Where do they get their info?
Detect changes in muscle length
Located deeper within the muscle where sensory afferents coil around the intrafusal muscle fibers
175
What are the 2 types of afferents that carry info from the muscle spindles?
Ia - rapid adaptation to changes in muscle length (muscle dynamics)
II - sustained response to constant muscle length (muscle position)
176
What is the role of Golgi tendon organ? Where does it get its info?
Detect changes in muscle tension, protect muscle by detecting overstretching of GTO, trigger inverse myotonic reflex (muscle relaxation)
Located in the tendon (attach muscle to the bone) where sensory afferent are positioned between collagen fibrils (intrafusal fasciculi)
177
What is the type of afferent that carries info from Golgi tendon organ?
Ib
178
What are the types of gnostic afferent fibers? What are their properties?
Ia/b -> highly myelinated, large axon diameter, fast conduction, carry proprioceptive info
Abeta -> myelinated, quite large diameter, quite fast, carry touch info from skin
179
What are the types of vital afferent fibers? What are their properties?
Agama -> little myelin, small axon diameter, slow conduction, carry info about first sharp pain that triggers action
C -> no-myelin, small atom diameter, very slow conduction, carry info about sustained nagging second pain
180
What sensory afferents have a large diameter?
Ia/b, II and Abeta
181
What sensory afferents have slow conduction velocity?
Agamma and C
182
What sensory fibers carry touch info?
Abeta
183
How does touch info from the body get to the brain? Describe the pathway
Abeta fibers enter the dorsal horn and ascend ipsilaterally in dorsal column (no synapse). Lower body info ascends in gracile tract and upper body info ascends in cuneate tract.
Reach the brainstem and synapse on gracile and cuneate nuclei, then decussate and ascend contralaterally thru medial lemniscus to thalamus (dorsal - upper body; ventral - lower body)
At pons medial lemniscus rotates 90deg. (medial - upper body; lateral lower body)
Synapse on VPL thalamus
Synapse on somatosensory cortex
Some sensory info goes directly to motor output for spinal reflexes
184
How does proprioceptive info from the body get to the brain? Describe the pathway
Ia/b and II fibers enter the dorsal horn and ascend ipsilaterally. Lower body info ascends in gracile tract and synapses on Clarke's nucleus, mid body info synapses directly on Clarke's nucleus and upper body info ascends thru cuneate tract and synapses on cuneate nucleus
From Clarke's nucleus info ascends ipsilaterally to cerebellum
185
How does vital info from the body get to the brain? Describe the pathway
Agama and C fibers synapse on dorsal horn and decussate immediately. Ascend contralaterally thru anterolateral fascicle
Synapses on VPL thalamus -> S1 -> S2
186
What is Brown-séquard syndrome?
Following a unilateral lesion, no pain/temp. sensation on the contralateral side and no touch sensation on the ipsilateral side from the lesion
187
How does touch info from the face get to the brain? Describe the pathway
Trigeminal nerve enters the brainstem and synapses on principal trigeminal nucleus
Decussates at pons and ascends contralaterally thru trigeminothalamic tract to VPM thalamus -> S1
188
How does proprioception info from the face get to the brain? Describe the pathway
Trigeminal nerve enters the brainstem and synapses on mesencephalic trigeminal nucleus
Decussates at pons and ascends contralaterally thru trigeminothalamic tract to VPM thalamus -> S1
189
How does vital info from the face get to the brain? Describe the pathway
Trigeminal nerve enters the brainstem and synapses on spinal trigeminal nucleus
Decussates at pons and ascends contralaterally thru trigeminothalamic tract to VPM thalamus -> S1
190
What type of somatosensory info reaches VPL thalamus?
Gnostic and vital info from the body
191
What type of somatosensory info reaches VPM thalamus?
Gnostic and vital info from the face
192
What info is received by BA1 in somatosensory cortex?
cutaneous info
193
What info is received by BA3b in somatosensory cortex?
Cutaneous info
194
What info is received by BA3a in somatosensory cortex?
proprioceptive info
195
What info is received by BA2 in somatosensory cortex?
cutaneous and proprioceptive info
196
Which BA receives info from VP complex of thalamus?
Layer 4 of BA3b
197
Where does BA3b project to?
BA1 and BA2
and S2
198
Where does BA3a project to?
S2 and BA2
199
Where does BA1 project to?
S2
200
Where does BA2 project to?
S2 and Parietal areas
201
Where does S2 project to?
amygdala and hippocampus
202
Where do somatosensory parietal areas project to?
motor and premotor cortical areas
203
What happens to slow and fast adapting somatosensory cells in cortex?
remain partially segregated, while their RFs overlap on skin
204
What is pain?
unpleasant sensory input + emotional experience from tissue damage
205
What fibers receive nociceptive info?
free nerve endings of Agamma and C fibers
206
What are the 2 types of Agamma fibers?
I - mechanical and chemical pain
II - heat
207
Is non-noxious heat carried in gnostic or vital pathway?
vital
208
What receptor is responsible for noxious thermosensation? What activates it?
Vanilloid/TRPV-1
Activated by heat, acid, and ligands (Capsaicin)
209
What fibers are activated by Capsaicin?
C-fibers (can be desensitized with prolonged activation)
210
Why labubu happened?
it is magic
211
Primary nociceptive fibers are both receptors and terminals. Explain what does that mean
Free nerve ending transmit pain information to the spinal cord but they are also responsible for symptoms associated with tissue damage. They release substance P and CGRP that interact with neutrophil and blood vessels and cause inflammation and redness/swelling
212
What is hyperalgesia?
increased sensation of pain of an already painful stimulus
213
What is allodynia?
sensation of pain to a non-painful stimulus
214
Hyperalgesia and allodynia are an example of ...
What does it involve?
sensitization of C-fibers to pain following a long-lasting stimulation
Its a form of plasticity that involves NMDA receptors normally blocked by Mg2+
KCC2 channels are also involved (normally make Cl- go out of the cell -> important for inhibition)
215
What is neuropathic pain?
spontaneous pain resulting from activation of a damaged nerve ending or neuroma
Neuroma/endbulb in full of Na+ channels that get activated spontaneously, by mechanical or chemical stimuli or by another fiber)
216
What is a neuroma?
Endbulb of a damaged nerve
217
On what dorsal horn laminae do Agamma fibers synapse?
Lamina I and V
218
On what dorsal horn laminae do C fibers synapse?
Lamina I and II
219
On what dorsal horn laminae do Abeta collateral fibers synapse?
Lamina III-V
220
On what dorsal horn laminae in wide-dynamic-range neuron located?
Laminae V
221
What is a wide-dynamic-range neuron?
Second-order neuron in the spinal cord that responds to a broad range of somatosensory intensities (from light touch to pain)
222
Anterolateral tract splits into 2 pathways in the brain. What are they?
Sensory-discriminative pathway -> location and intensity of pain -> processed in S1/S2
Emotional/affective pathway -> emotional feeling of pain -> processed in ACC and insula (thru hypothalamus and amygdala)
223
What is referred pain?
pain from internal organs that is felt in other body areas (eg heart pain -> left arm etc)
224
What changes in brain activity are observed during a placebo effect?
reduction of activity in ACC and insula
project back to dorsal horn to inhibit pain
225
How does pain inhibition in PNS work?
pain -> + -> C-fibers (-> - -> inhibitory interneuron) -> + -> projection neuron
Rubbing the skin where it hurts: Abeta -> + -> inhibitory interneuron -> - -> projection neuron (reduced pain sensation
226
How does pain inhibition in CNS work?
descending inhibitory systems (from locus coeruleus and raphe nucleus)
227
What are the 2 goals of itch?
1. Remove irritant from skin
2. Induce tissue damage to improve healing
228
What are the similarities between itch and pain?
1. anatomical routes from stimulus to perception are comparable
2. patients that do not feel pain, also do not feel itch
3. many dorsal horn neurons respond to both pain and itch
4. brain areas activated by pain and itch are similar and largely overlapping
229
What are the differences between itch and pain?
1. ultimate function is different
2. opioids inhibit pain but may induce or increase itch
3. painful stimuli diminish itch
4. itch can only be felt on epithelium (skin)
230
What is encoded in Medial Superior Olive?
Interaural Time Differences (ITDs)
231
What is encoded in Lateral Superior Olive?
Interaural Level (Intensity) Differences (ILDs)
232
Gaze redirections and active head movements similarly suppress vestibular signals of head motion in vestibular nuclei neurons. Which of these two motor tasks involves a complete suppression of all incoming vestibular signals? Explain why this would not be ideal for the other motor task?
Gaze redirections -> complete suppression. Because during a saccade, the brain needs the eyes to move precisely to the target without vestibular interference. Suppressing all vestibular signals prevents “double correction” by VOR
Active head movements only partially suppress vestibular signals. This allows the brain to still detect unexpected head motion (e.g., if the head is bumped or perturbed) and generate corrective reflexes like the VSR to maintain balance.
233
The dorsal cochlear nucleus is involved in sound processing. During self-generated licking, what information enters the DCN, what processes occurs in the DCN and what information comes out of the DCN?
1. Corollary discharge of the motor command and the auditory information (currently heard sound) enter
2. Self-generated signal is subtracted from the perceived sound, and three is plasticity in case of persistent mismatch
3. Outgoing signal is the perceived sound without the self-generated part of it
sensorimotor systems
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