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Neurophysiology Flashcards

1
Q

Why are sensory receptors known as transducers?

A

Convert physical/chemical stimulus into electrical impulse

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2
Q

How do sensory receptors allow the localisation of sensory stimuli?

A

Receptive field

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3
Q

What are receptor potentials?

A

Electrical impulse transduced by sensory receptors

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4
Q

How are (i) receptor potential (ii) firing frequency and (iii) sensory stimuli related?

A

Magnitude of sensory stimulus encodes for duration and intensity of APs
- ↑stimulus → ↑receptor potential → ↑freq. of AP (> exceed threshold)

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5
Q

In order to generate an action potential, the depolarisation of the membrane at the sensory receptor must reach a ______________.

A

Threshold potential

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6
Q

Odorants generate (fast/slow) receptor potential within cilia?

A

Slow

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7
Q

True or false. Odorants trigger a series of receptor potentials that propagate continuously along olfactory nerve axons.

A

False.
Odorants → slow RP in cilia
→ RP along dendrite
→ series of AP within soma
→ AP along axon

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8
Q

What are 4 sensory stimuli that are sensed by exteroceptors?

A

1) Pain
2) Temperature
3) Touch
4) Pressure

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9
Q

Where are proprioceptors located?

A

1) Muscles
2) Tendons
3) Joints

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10
Q

What are 5 modes of sensory detection?

A

1) Chemoreceptors
2) Photoreceptor
3) Thermoreceptors
4) Mechanoreceptors
5) Nociceptors

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11
Q

In the visual sensory system, what are the
i) modality
ii) stimulus
iii) receptor class
iv) receptor cell type

A

Visual:
i) Vision
ii) Light
iii) Photoreceptor
iv) Rods, cones

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12
Q

In the auditory sensory system, what are the
i) modality
ii) stimulus
iii) receptor class
iv) receptor cell type

A

Auditory:
i) hearing
ii) sound
iii) mechanoreceptors
iv) hair cells (cochlea)

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13
Q

In the vestibular sensory system, what are the
i) modality
ii) stimulus
iii) receptor class
iv) receptor cell type

A

Vestibular:
i) balance
ii) gravity
iii) mechanoreceptors
iv) hair cell (vestibular labyrinth)

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14
Q

In the gustatory sensory system, what are the
i) modality
ii) stimulus
iii) receptor class
iv) receptor cell type

A

Gustatory:
i) taste
ii) chemical
iii) chemoreceptor
iv) taste buds

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15
Q

In the olfactory sensory system, what are the
i) modality
ii) stimulus
iii) receptor class
iv) receptor cell type

A

Olfactory:
i) smell
ii) chemical
iii) chemoreceptor
iv) olfactory sensory receptors

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16
Q

For touch sensation in the somatosensory system, what are the
i) stimulus
ii) receptor class
iii) receptor cell type

A

i) Pressure
ii) Mechanoreceptor
iii) Cutaneous mechanoreceptors

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17
Q

For proprioceptive sensation in the somatosensory system, what are the
i) stimulus
ii) receptor class
iii) receptor cell type

A

i) Displacement
ii) Mechanoreceptor
iii) Muscle and joint receptors

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18
Q

For temperature sensation in the somatosensory system, what are the
i) stimulus
ii) receptor class
iii) receptor cell type

A

i) Thermal
ii) Thermoreceptor
iii) Cold and warm receptors

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19
Q

For pain sensation in the somatosensory system, what are the
i) stimulus
ii) receptor class
iii) receptor cell type

A

i) Chemical, thermal, mechanical
ii) Chemoreceptor, thermoreceptor, mechanoreceptor
iii) Polymodal, thermal, mechanical nocireceptor

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20
Q

For itch sensation in the somatosensory system, what are the
i) stimulus
ii) receptor class
iii) receptor cell type

A

i) chemical
ii) chemoreceptor
iii) chemical nociceptor

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21
Q

Are spinal and intracranial neurons sensitive to sensory stimuli eg. touch, sound, light, odor?

A

No.
Each stimuli must be transduced by specialised sensory cells

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22
Q

True or false:
As a neuronal action potential is summative, the intensity of a stimulus can be directly calculated from a single sensory neuron action potential.

A

False.
Single neuron → “All or nothing” (threshold)

Intensity coded by (i) no. activated receptors (ii) freq. of AP from those receptors

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23
Q

What are the 2 modes of sensory receptor adaptation?

A

1) Tonic
- slowly adapting
- responsive during long stimuli
- for monitoring unchanging stimuli (eg. pressure)

2) Phasic
- rapidly adapting
- only detect onset of stimulus
- for detecting rapid changes in stimuli (eg. vibration)

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24
Q

What is receptor adaptation?

A

Sensory receptors become less responsive to a stimulus over time

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25
Q

How do neurons differentiate between new or changing stimuli rather than constant, unchanging ones?

A

Phasic receptors:
Once the stimulus reaches a steady state, phasic receptors adapt and “turn off,” effectively ignoring the continuous presence of the stimulus.
(only stimulated by “new” or different stimuli)

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26
Q

Sensory neurons that innervate sensitive areas have (larger/smaller) receptive fields.

A

Smaller

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27
Q

What is the physiology of two-point touch discrimination?

A

Less convergence of receptive fields by:
i) Smaller secondary receptive fields
ii) Less converges of primary neurons
→ 2 stimuli more likely to actively separate pathways
→ perceived as distinct stimuli
→ 2-point discrimination

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28
Q

How does lateral inhibition isolate/enhance contrast between stimuli?

A

Group of primary neurons stimulated
→ primary neuron with greatest stimulation → greatest response

Pathway of primary neuron with greatest response inhibits adjacent pathway → ↑SNR

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29
Q

What is labeled line coding?

A

1:1 association of a receptor with a sensation
(each receptor has a distinct pathway from receptor surface to brain)

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30
Q

True or false:
Labeled line coding is applicable for all sensory systems.

A

False:
Not applicable for auditory
- timing differences rather than labeled line coding to localise sound

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31
Q

True or false: Neurons in the ears have very small receptive fields to accurately localise auditory stimuli.

A

False:
- sensitive to different frequencies but no receptive fields
- geographical activation provides no information of location of sound → relies on delay of stimuli between left and right ear

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32
Q

Which sensory pathway does not synapse in the thalamus?

A

Olfactory

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33
Q

Most sensory pathways project to the ______ where they synapse and information is modified before being relayed to the relevant cortical centers.

A

Thalamus

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34
Q

Equilibrium pathways project primarily to the ____________.

A

Cerebellum

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35
Q

What are the 5 sensations that make up “taste”?

A

1) Sweet
2) Sour
3) Salty
4) Bitter
5) Umami

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36
Q

Each taste cell is a non-neural polarised ___________ cell that only has a tiny tip that protrudes into the oral cavity through a ______________.

A

Taste cell:
- non-neural polarised epithelial cell
- tiny tip protrudes through taste pore

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37
Q

What are 2 ways by with the apical membrane/ends of taste buds are adapted for its function?

A

1) Tight junctions link adjacent cells → limit movement of molecules between cells

2) Apical microvilli → ↑SA:Vol

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38
Q

How are taste particles transduced into action potentials in primary neurons?

A

1) Dissolve in saliva/mucus of mouth
2) Dissolved taste ligands interact with apical receptor/channel on taste cell
3) Signal transduction cascade initiated → AP in 1° neuron

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39
Q

How do the signal transduction mechanisms differ for salt, sour, bitter, sweet and “umami” tastants?

A

1) Stimuli (Na+/H+/tastant ligands)

2) Membrane receptors/ channels
- salt and sour: channel proteins
- bitter, sweet, umami: GPCR

3) Transmitter:
- salt and sour: serotonin via external Ca2+ influx
- bitter, sweet umami: ATP via internal Ca2+ → external Na+ influx

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40
Q

Describe the transduction mechanisms of salt and sour tastants.

A

Tastant ions either (i) pass directly through respective membrane channels or (ii) block them
→ membrane depolarisation
→ opening of voltage gated Na+ and Ca2+ channels → influx
→ exocytosis of serotonin from synaptic vesicles
→ gustatory afferent axon

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41
Q

Describe the transduction mechanisms for bitter, sweet and umami tastants.

A

Tastants bind to GPCR
→ activate Phospholipase C → ↑IP3
→ triggers intracellular release of Ca2+
→ open taste-specific ion channel → ↑Na+ influx
→ depolarisation → ATP release
→ ATP diffuse through ATP-permeable channels → gustatory afferent axon

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42
Q

What is the typical life span of an olfactory neuron?

A

2 months
- replaced by new cells whose axons must find their way to the olfactory bulb

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43
Q

The olfactory epithelium is located _______________________ and comprises of ____________ cells which project into the olfactory bulb.

A

Olfactory epithelium
- high within nasal cavity
- olfactory cells (1° sensory neurons) → project into olfactory bulb

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44
Q

How are olfactory receptors replaced?

A

By basal cell layer beneath lamina propria of olfactory epithelium

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45
Q

Describe the mechanism of olfactory transduction.

A

Odorant dissolves in apical mucus layer
→ binds to odorant receptor protein of Golf-protein (GCPR)
→ activate adenylyl cyclase → ↑cAMP
→ open Ca2+ and Na+ channels → influx
→ ↑Ca2+ → Cl- efflux
→ membrane depolarisation

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46
Q

What are the constituents of the external ear?

A

1) Outer ear
2) Pinna
3) Ear canal

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47
Q

What is the function of the pinna?

A

Directs sounds waves into the ear

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48
Q

The ear canal is sealed at its internal end by ______________________.

A

Tympanic membrane (eardrum)
- thin membranous sheet of tissue

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49
Q

What structure separates the external ear from the middle ear?

A

Tympanic membrane

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50
Q

What is the middle ear?

A

Air-filled cavity that connects with the pharynx through the eustachian tube

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51
Q

Describe the regulation of middle ear pressure.

A

Eustachian tube
- normally collapsed → seal off middle ear
- opens transiently to allow middle ear pressure to equilibrate with atmospheric pressure during eg. chewing, swallowing, yawning

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52
Q

What is otitis media?

A

Infection of the middle ear

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53
Q

What structure separates the fluid-filled inner ear from the air-filled middle ear?

A

Oval and round window
- membranous discs

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54
Q

What are the 3 bones of the middle ear?

A

1) Malleus (hammer)
2) Incus (anvil)
3) Stapes (stirrup)

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55
Q

How are the 3 bones of the middle ear related?

A

Connected by biological “hinges”

  • 1 end of malleus attached to tympanic membrane
  • stirrup end of stapes attached to thin membrane separating middle ear from inner ear
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56
Q

What are the 2 major sensory structures of the inner ear?

A

1) Vestibular apparatus
- sensory transducer
- semicircular canals

2) Cochlea
- contains sensory receptors
- membranous tube coiled like snail shell within bony cavity

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57
Q

Which nerve leads from the inner ear to the brain to transmit sensory stimuli to the vestibular and cochlear nuclei of the pons and medulla oblongata.

A

Vestibulocochlear nerve
- branches of CNVIII

58
Q

Sound waves are distinguished by their ______________.

A

1) Amplitude (dB)
2) Frequency (Hz)

59
Q

Intensity is measured on a ________ scaled in (units) and is a function of wave _____________.

A

Intensity
- measured logarithmic scale in dB
- function of wave amplitude

60
Q

What is the typical audible ranges of frequency and noise level?

A

Frequency:
- 20-20000Hz

Noise level:
~60dB (depends on sensitivity of individual ear)

61
Q

Describe the process of sound transmission through the ear?

A

1) Sound waves strikes tympanic membrane → vibrations

2) Sound wave energy transferred to 3 bones of middle ear → vibrate

3) Stapes transmit vibration to fluid within cochlea through membrane of oval window

4) Fluid waves push on flexible membranes of the cochlear duct → hair cells bend → open ion channels

5) Depolarisation → NT release → sensory neurons → AP through cochlear nerve to brain

6) Wave energy transfers across cochlear duct into tympanic duct and dissipated back into middle ear at round window

62
Q

What are the 3 ducts of the inner ear?

A

1) Vestibular duct (perilymph)
2) Cochlear duct (endolymph)
3) Tympanic duct (perilymph)

63
Q

Hair cells are (neural/non-neural) receptor cells.

A

Non-neural

64
Q

Describe the process of signal transductions in the hair cells.

A

At rest:
- ~10% ion channels open → tonic signals

Excitation:
- hair cells bend → depolarisation → ↑AP freq. in associated sensory neuron

Inhibition:
- hair cells bend in opposite direction → ion channels close → hyperpolarisation → ↓AP

65
Q

Describe the process of sensory coding for pitch.

A

Primarily by basilar membrane:
- tiff & narrow near round/oval window attachments, distal & flexible near distal end

  • frequency determines displacement of basilar membrane
    → location of maximal displacement/active hair cells
    → differential response to frequency
    → transform temporal aspect (pitch and frequency) into spatial (along basilar membrane) coding for pitch
66
Q

Where are the sensory cell bodies in the PNS located?

A

Spinal ganglion of each spinal nerve

67
Q

Where is the spinal cord are lower motor neurons found?

A

Anterior horn

68
Q

Where are the the cell bodies and exit paths of primary efferent autonomic fibers?

A

Cell bodies → lateral horn

Leave through anterior root

69
Q

Where in the spinal cord do afferent autonomic and somatic fibres travel?

A

Posterior root

70
Q

Describe the general pathway for somatic perception.

A

1) Spinothalamic tract:
- Pain, temperature, coarse touch decussate in spinal cord

2) DCML pathway:
- Fine touch, vibration, proprioception decussate in medulla

3) Sensory pathways synapse in thalamus

4) Sensations perceived in primary somatic sensory cortex

71
Q

The amount of space/size of the somatosensory cortex devoted to each body part is proportional to _____________________.

A

Sensitivity of that part

72
Q

The receptive fields of Meissner’s corpuscles are relatively (bigger/smaller) than that of Pacinian corpuscle

A

Meissner’s (fine touch) < Pacinian (vibration)

73
Q

What are 3 modalities by which mechanosensitive ion channels transduce sensory stimuli into electrochemical gradients?

A

1) Sensitive to stretch of lipid membrane

2) Linked to extracellular peptides (sensitive to force)

3) Linked to intracellular proteins (eg. cytoskeleton)

74
Q

What are 2 types of temperature receptors?

A

1) Cold receptors
- sensitive to <body temp

2) Warm receptors
- sensitive to >body temp

75
Q

How does temperature above a certain level create a pain sensation?

A

Beyond ~45° → warm + nociceptor activation

76
Q

Which thermosensitive TRP channel is responsive to menthol?

A

TRPM8

77
Q

Which thermosensitive TRP channel is responsive to capsaicin?

A

TRPV1

78
Q

Which type of receptor is more prevalent, cold or warm receptors?

A

Cold > warm

79
Q

How does the brain differentiate between changing and ambient temperature?

A

Temperature receptors slowly adapt between 20°C and 40°C
- initial response → temp is changing
- sustained response → ambient temperature

80
Q

Do thermoreceptors adapt beyond ~40°C?

A

No, likelihood of tissue damage is greater

81
Q

Cold receptors are coupled to ___________ fibers while warm receptors are coupled to _________________ fibers.

A

Cold: A-δ, C fibres

Warm: C fibres

82
Q

Are thermoreceptors more responsive to sudden or slow changes in temperature?

A

Sudden
- adapt over several seconds

83
Q

The diameter of an axon is correlated with its ____________________________.

A

1) Conduction velocity
2) type of sensory receptor to which it is connected

84
Q

What are the different nerve fibre groups and which are myelinated?

A

Myelinated:
1) A-α
2) A-ß
3) A-δ

Unmyelinated:
4) C

85
Q

Thicker nerve fibers transmit information (more/less) quickly?

A

Thicker → faster

86
Q

What is the somatosensory cortex?

A

part of the brain that recognizes where ascending sensory tracts originate/processes sensory information

87
Q

What is the homunculus and how is it related to the organisation of sensory pathways in the somatosensory cortex?

A

Mapping of the geographical sensory tributaries onto the cortex
- columnar arrangement → maintain association with receptors and sensory modality

88
Q

What is the physiological mechanism behind phantom limb pain?

A

Somatotropic map plasticity
- portion of the somatosensory cortex devoted to the missing structure begins to be taken over by sensory fields of adjacent structures.

89
Q

What are the 2 sensations perceived upon nociceptor activation?

A

Pain and itch

90
Q

How is sharp pain differentiated from dull pain?

A

Primary vs secondary pain

Primary
- A-δ fibres → well localised sharp pain

Secondary
- C fibres → poorly localised dull pain

91
Q

How does tissue injury cause pain?

A

Tissue injury
→ release of bradykinin, 5-HT, prostaglandins, K+
→ stimulate C-fibres

92
Q

How do active C-fibers aid in tissue inflammation?

A

Release CGRP and substance P →
i) Stimulate mast cells → histamine
ii) Vasodilation

93
Q

What are the 2 types of synaptic targets of A-δ and C fibres?

A

1) Nociceptive-specific (NS) cells
- only synapse with A-δ and C fibers

2) Wide dynamic range (WDR) neurons
- synapse with all types of sensory fibers

94
Q

What are the neurotransmitters and their respective receptors in a posterior horn nociceptive synapse?

A

1) Glutamate → AMPA, NMDA , mGLu

2) Substance P → NK1

3) CGRP → CGRP

95
Q

Nociceptive synapses in the posterior horn are (excitatory/inhibitory).

A

Excitatory

96
Q

How is the intensity of dull pain transmitted to the brain?

A

C-fibers → WDR neurons
- WDR can fire APs in graded fashion: “wind-up” → progressive amplification of repetitive C-fibre stimulated APs

∴ ↑pain/stimulation → ↑freq. of C-fibre discharge → ↑WDR neuron response

97
Q

What is “wind-up” in the spinal cord and how does it happen?

A

Amplification in response to repetitive excitatory stimulation of WDR neurons from nociceptive input from C-fibers

1) ↑repetitive C-fiber input → ↑AP freq. + sustained membrane depolarisation

2) Usual blockade of NMDA receptor by Mg2+ released by sustained depolarisation

3) NMDA activated by glutamate → Ca2+ influx

4) Insertion of Na+ channels + block K+ → ↑Na and K+ in cell → ↑depolarisation and ↓hyperpolarisation/refraction
→ ↑ neuronal excitability / response to C-fibre input

98
Q

What is the difference between hyperalgesia and allodynia?

A

Hyperalgesia
- heightened response to normally painful stimulus

Allodynia
- normally non-painful stimulus perceived as painful

99
Q

What are the 2 ascending pain pathways and how do they differ?

A

1) Lateral sensory-discriminative
- organised somatotropically → pain localisation in 1° somatosensory cortex

2) Medial affective-motivational pathways
- dull, poorly localised pain
- influences:(i) emotional (ii) visceral (iii) descending pain modulation

100
Q

Using gate-control theory, explain why rubbing a bumped elbow lessens the perceived pain.

A

Rubbing → non-painful stimulus → activate A-ß fibres → synapse on inhibitory interneurons
→ enhance tonic inhibition of ascending pain pathway

∴ Partial inhibition of summative ascending pathway stimulation even with C-fibre stimulation → relief of pain

101
Q

What is the function of the endogenous opioid system?

A

Provide modulatory influence on cortical pain process

102
Q

What are 3 endogenous molecules that physiologically activate opioid receptors?

A

1) Enkephalins
2) Endorphins
3) Dynorphins

103
Q

How does the endogenous
opioid system provide analgesia?

A

Release of (i) enkephalins (ii) endorphins (iii) dynorphins
→ activation of opioid receptors
→ inhibit Ca2+ and/or open K+ channels
→ hyperpolarisation + ↓neuronal excitability

104
Q

What are the 4 types of pain?

A

1) Radicular
- dermatome

2) Referred
- viscerosomatic convergence

3) Phantom pain
- pain in absent of insensate (by nerve severance) part of body

4) Central pain
- from lesion in thalamus or cortex → pain in corresponding mapped body part

105
Q

What is the difference between aphasia, dysarthria, speech ataxia and cognitive-communication defects?

A

Aphasia:
- impaired ability to understand and produce language

Dysarthria:
- ↓intelligibility due to weakness in speech muscles

Speech apraxia:
- difficulty coordinating the movements needed for speech, despite having no weakness in the speech muscles themselves

Cognitive-communication defects:
- difficulties in communicating in higher level with corresponding deficits in cognitive functions and pragmatics

106
Q

Which germ layer and part of the pharyngeal apparatus is the external ear canal from?

A

Ectoderm

1st pharyngeal cleft

107
Q

Which germ layer and part of the pharyngeal apparatus is the tympanic membrane from?

A

Mesoderm of 1st arch

108
Q

Which germ layer and part of the pharyngeal apparatus is the eustachian tube from?

A

Endoderm

1st pharyngeal pouch

109
Q

Which part of the pharyngeal apparatus are the ear ossicles from?

A

Malleus + Incus’ short process and body ← 1st arch

Incus’ long process + Stapes cura ← 2nd arch

110
Q

How does the external ear help us with hearing?

A

Amplification and localisation

111
Q

Why is impedance matching important in hearing?

A

Reflection coefficient for terrestrial animals very high (specific acoustic impendence difference very big between air and liquid in cochlear) → need matching to transmit more energy to inner ear for sensing

112
Q

What are 3 features of the middle ear that help with impedance matching?

A

1) Tympanic membrane to oval window ratio (high→20x)

2) Lever action of ossicles
- malleus 30% longer than incus → 1.3x by lever action

3) Buckling action of tympanic membrane
- 2x amplfication

Total: 2x20x1.3=52x amplification

113
Q

Which part of the inner ear are cochlear hair cells located?

A

Organ of Corti

114
Q

How are the cochlear hair cells arranged?

A

3 outer rows:
- amplify sound
- signal modulation

1 inner row
- main signal transducer

115
Q

Describe the tonotropic arrangement of the cochlear.

A

Hair cells sensitive to higher pitch → base

Hair cells sensitive to lower pitch → apex

116
Q

Which lobe is the auditory cortex found in?

A

Temporal

117
Q

The cochlear nucleus receives (ipsi/contra/bilateral) contribution before decussating.

A

Bilateral

118
Q

How would a px with age-related hearing loss commonly present on an audiometry?

A

Sloping, hearing loss accentuated at higher frequencies

119
Q

What are 4 forms of hearing tests?

A

1) Audiometry
2) Auditory brainstem response (ABR) testing
3) Otoacoustic emission (OAE) testing
4) Weber’s test
5) Rinne’s test

120
Q

What are 2 treatment modalities for conductive hearing loss?

A

1) Myringotomy and tube insertion (if effusion into middle ear)

2) Ossiculoplasty (if ossicles absent)

3) MAHA (bone conduction device)

121
Q

What are 2 treatment modalities for sensorineural hearing loss?

A

1) Cochlear implants
2) Hearing aids

122
Q

What are the transparent mediums of the eye?

A

1) Cornea
2) Lens

123
Q

How is the transparency of the cornea maintained?

A

Regular arrangement of collagen layers
- by constant level of hydration between evaporation and active transport by carbonic anhydrase pump of endothelium

124
Q

The lens is a bi(concave/convex) structure that is manipulated by the ciliary body and suspensory ligaments to allow for focusing.

A

Biconvex

125
Q

What it the “near triad” for viewing near objects?

A

1) Accommodation
- ciliary muscles contract → suspensory ligaments relax → lens more convex (↑AP diameter → ↑refraction)

2) Convergence

3) Miosis

126
Q

What are 3 forms of refractive error in the eye?

A

1) Myopia
- axial length too long/refractive medium too strong → light focused in front of retina → distant blur
- correct with divergent lens

2) Hyperopia
- axial length too short → light focused behind retina → accommodation needed for distant vision → near/distant blur
- correct with convergent lens

3) Presbyopia
- failure in accommodation → near/far blur
- correct with convergent lens

4) Astigmatism
- refractive surfaces have different radii of curvature → 2 points of focus
- correct with cylindrical lens

127
Q

What does the retinal pigment epithelium layer do?

A

1) Contains melanin → absorbs light and reduces scatter

2) Vitamin A cycle
- regeneration of visual pigment (11-cis-retinal)

128
Q

Describe the biosignalling mechanism when light strikes the retina.

A

1) Light strikes Rhodopsin
11-cis-retinal → all-trans-retinal

2) Hyperpolarisation of photoreceptors

3) ↓inhibitory NTs to bipolar cells → depolarisation

4) Bipolar synapse with retinal ganglion cells → AP to brain

129
Q

What does 6/6 vision mean?

A

A subject can, at 6m, read a letter that subtends 5’/arc

130
Q

The different cones have the same ___________ but different __________, leading to different maximum sensitivity to RGB wavelengths respectively.

A

Same vitamin A chomophore
Different opsin protein

131
Q

What visual defect is caused by vitamin A deficiency?

A

Night blindness
- insufficient chromophore/retinal → loss of night vision

132
Q

What visual defect is caused by macular edema/submacular hemorrhage?

A

Loss of normal acuity but not blindness

133
Q

What visual defect is caused by rod-cone dystrophies?

A

Genetic defects in opsin protein
- inability to detect light → poor night vision and visual acuity

134
Q

What are 5 functional brain areas for vision?

A

V1: 1° visual cortex
V2: 2° visual cortex
V3: Dorsal → motion, Ventral → colour
V4: Extrastriate → colour
V5: Middle temporal cortex/lingual gyrus → motion, facial recognition

6) Inferotemporal cortex → shapes
7) Hippocampus → visual memory

135
Q

What is the primary action of the medial rectus?

A

Adduction

136
Q

What is the primary action of the lateral rectus?

A

Abduction

137
Q

What are the (i) primary (ii) secondary and (iii) tertiary actions of the superior rectus?

A

i) Elevation
ii) Intorsion
iii) Adduction

138
Q

What are the (i) primary (ii) secondary and (iii) tertiary actions of the inferior rectus?

A

i) Depression
ii) Extorsion
iii) Adduction

139
Q

What are the (i) primary (ii) secondary and (iii) tertiary actions of the superior oblique?

A

i) Intorsion
ii) Depression
iii) Abduction

140
Q

What are the (i) primary (ii) secondary and (iii) tertiary actions of the inferior rectus?

A

i) Extorsion
ii) Elevation
iii) Abduction

141
Q

What are 2 forms of anisocoria?

A

1) Parasympathetic/ constriction failure
- more apparent in light
- eg. Adie’s tonic pupil, CNIII palsy, pharmacologic

2) Sympathetic/ dilation failure
- more apparent in dark
- eg. physiologic, Horner’s

Nervous System (14 decks)

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