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Neuroscience > Lecture 10 Special Senses > Flashcards

Lecture 10 Special Senses Flashcards

1
Q

What and where is Meyer’s Loop?

A
  • 3rd order neurons from lateral geniculate nuclei to primary visual cortex
  • upper goes through Parietal lobe
  • lower goes through Temporal lobe
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2
Q

Describe how visual fields are represented with regards to upper and lower visual. Field hemispheres and central versus peripheral vision within the primary visual cortex.

A
  • Upper and lower - below calcarine fissure and more rostral is outer upper field of contralateral side and as you move caudally it is more central vision. Vice versa for above calcarine fissure and lower field of contralateral side
  • calcarine fissure separates central visual field from peripheral visual field and as you move caudally towards occipital pole the more central vision you get
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3
Q

What are the two ways the primary visual cortex communicates with its association cortices? What information is travelled between each of these two pathways?

A
  • Parieto-occipital association cortex - WHERE? - spatial relationships between objects, are they moving? Staying together? How far away are they from me?
  • Occipitotemporal association cortex - WHAT? - form, shape, size, colors, are there letters?
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4
Q

What type of visual loss will we see with damage to the optic nerve?

A

ipsilateral blindness

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5
Q

What type of visual loss will we see with damage to the optic chiasm with bilateral lateral compression?

A

binasal hemianopia

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6
Q

What type of visual loss will we see with damage to the optic chiasm with midsagittal transection/pressure?

A

bitemporal hemianopis

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7
Q

What type of visual loss will we see with damage to the left optic tract?

A

right hemianopia

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8
Q

What type of visual loss will we see with damage to the left optic radiation in the lower division?

A

right upper quadrantanopia

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9
Q

What type of visual loss will we see with damage to the left optic radiation in the upper division?

A

right lower quadrantanopia

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10
Q

What type of visual loss will we see with damage to the both division of left optic radiations?

A

right hemianopia with macular sparing

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11
Q

What muscles do the oculomotor nerve innervate? What are their muscle actions?

A
  • medial rectus - adduction
  • superior rectus - elevation and intorsion
  • inferior rectus - depression and extorsion
  • inferior oblique - extorsion and elevation
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12
Q

What muscles do the trochlear nerve innervate? What are their muscle actions?

A

superior oblique - intorsion and depression

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13
Q

What muscles do the abducens nerve innervate? What are their muscle actions?

A

lateral rectus - abduction

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14
Q

What is the role of the medial longitudinal fasciculus?

A
  • keeps ability for left eyes to talk to right eyes and have them move together which keeps vision fixated
  • Stops vision from getting blurry and double vision as eyes move
  • connects fibers from oculomotor, trochlea, abducens, and vestibular nuclei
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15
Q

How does our CNS control horizontal eye movements? What structures are involved and how are they connected?

A
  • muscles - medial and lateral rectus
  • abducens and oculomotor nuclei are connected through medial longitudinal fasciculus
  • abducens nuclei control abducens nerve and contralateral communication to oculomotor so when you look left your left eye abducts (abducens) and right eye adductus (oculomotor)
  • Paramedian Pontine Reticular Formation - “back seat driver” - regulate info from cortex, superior colliculus, and other descending cortical drive
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16
Q

How does our CNS control vertical eye movements? What structures are involved and how are they connected?

A
  • muscles - superior and inferior oblique
  • trochlear and oculomotor nuclei are connected through medial longitudinal fasciculus in pretectal area so as one moves one direction the other move in that direction as well on contralateral side
  • rostral midbrain reticular formation is the “back seat driver”
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17
Q

What are saccades?

A

Rapid, voluntary eye movements that function to bring targets of interest into field of view

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18
Q

What is smooth pursuit?

A

Slow following of a visual target while allowing for stable viewing of moving targets

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19
Q

What are the cortical regions involved in eye control and what are their basic functions?

A
  • frontal eye fields - generate contralateral saccades
  • parieto-occipito-temporal cortex - generate ipsilateral smooth pursuit
  • basal ganglia - oculomotor loop
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20
Q

What structures are found in the external ear

A
  • auricle (pinna)
  • external auditory canal
  • ear drum (tympanic membrane)
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21
Q

What structures are found in the middle ear?

A
  • auditory ossicles (malleus, incus, stapes)
  • oval and round window
  • tensor tympani and stapedius muscles
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22
Q

What structures are found in the inner ear?

A
  • bony and membranous labyrinth (semicircular canals, vestibule, cochlea)
  • auditory apparatus
  • vestibulocochlear nerve (CN 8)
23
Q

What is the sensory receptor organ for hearing? Describe in basic details how it responds to sound.

A
  • spiral organ of corti
  • contains hair cells (stereocilia) between tectorial and basilar membrane and the stereocilia and basilar membrane move in response to sound vibrations
  • movement of the the stereocilia propagates AP
24
Q

What is the basic pathway that sound takes between entering the outer ear and when it reaches the cochlea?

A

1) Sounds waves strike tympanic membrane and cause it to vibrate
2) Vibration is amplified and send through oval windows by auditory ossicles
3) Perilymph fluid moves in cochlea in response to vibration
4) Movement of perilymph fluid makes hair cells move
5) Depending on which direction these hair cells move, they will become depolarized or hyperpolarized
6) Cochlear nerve activated

25
Q

What is the function of the vestibular system?

A
  • equilibrium by estimating body position and movement, postural control, and control of eye movements
26
Q

What role does the peripheral vestibular system take on function?

A

1) Stabilize visual images on the fovea of the retina during head movement allow for clear vision
2) Maintain postural stability, especially during movement of head
3) Provide information for spatial orientation

  • mainly responsible for relaying information
27
Q

What is the bony labyrinth of the vestibular apparatus?

A
  • protective case of perilymphatic fluid and supportive connective tissue
28
Q

What makes up the membranous labyrinth of the vestibular apparatus?

A

Vestibule - otolith organs and semicircular canals

Cochlea

29
Q

What types of movements are the otolith organs sensitive to? What two organs are part of this system?

A

utricle - movement in horizontal plane

saccule - movement in vertical plane

30
Q

Explain how the otoliths respond to head movements with regards to their receptor cells and the supportive structures involved.

A
  • kinocilium - tallest of stereocilia
  • Movement of stereocilia towards kinocilium: EXCITATORY
  • Movement of stereocilia away from kinocilium: INHIBATORY
31
Q

How do the otoliths cover all planes of linear acceleration/head tilt?

A

Kinocilium are pointing in different directions so there is response no matter what direct our head turns

32
Q

What are our semicircular canals? What type of movements are they sensitive to? What is found within them?

A
  • canals filled with endolymph that displaces when movement occurs causing hair cells to move and either depolarize or hyperpolarize
  • sensitive to angular velocity
33
Q

Where are the receptor cells found in the semicircular canals? Explain how this process occurs.

A
  • in the cupula which is in ampula - bulbous formation at start or finish of canal
  • as head rotates, endolymph fluid displaces and causes cupula to move to one side o or another which activates hair cells
34
Q

Where doe the anterior and posterior semicircular canal lie in regards to the sagittal plane? What movement are they sensitive to?

A

45 degrees off of midsagittal plane

forward and backward rotation, especially at a 45 degree angle

35
Q

What plane is the middle semicircular canal in? What movement is it sensitive to?

A

horizontal

horizontal rotation, shaking your head no

36
Q

What are semicircular canal positions compared to each other? How are they paired?

A
  • all 90 degrees from each other

- paired contralaterally - When moving forward, anterior canal is paired with contralateral posterior canal

37
Q

When we move our head ipsilaterally in a plane of movement that a canal is sensitive to, does that canal become excited or inhibited? How about when we move contralaterally?

A

Ipsilaterally - depolarization (excited)

Contralaterally - hyperpolarized (inhibited)

38
Q

What is the function of the vestibulo-ocular reflex (VOR)?

A

Stable vision during head motion

39
Q

Explain the reflexive loop that allows for our VOR to function. What structures are involved?

A

ex: righthead rotation

+ R horizontal semicircular canal  R vestibular nucleus  L abducens nucleus  L abducens nerve to contract L lateral rectus and R oculomotor nucleus (MLF) to oculomotor nerve to contract R medial rectus

  • L horizontal semicircular canal  L vestibular nucleus  R abducens nucleus  R abducens nerve to inhibit R lateral rectus and L oculomotor nucleus (MLF) to oculomotor nerve to inhibit L medial rectus
40
Q

What are the general types of information being relayed throughout vestibular nuclei?

A
  • eye movement control for gaze stability
  • postural control and movement
  • spatial orientation
  • autonomic nervous system control
41
Q

What are the 4 sets of subnuclei in the vestibular nuclei?

A
  • lateral (dieter’s) nucleus
  • Medial nucleus
  • Superior nucleus
  • Inferior nucleus
42
Q

What are the outputs of the lateral (dieter’s) nucleus?

A

outputs to the cerebellum (feedback) and to lateral vestibulospinal tract to facilitate extensors (posture; muscles of trunk and legs)

43
Q

What are the outputs of the medial nucleus?

A

provides descending output to muscles of head and neck via medial longitudinal fasciculus (MLF; head position)

44
Q

What are the outputs of the superior nucleus?

A

provides ascending output (via MLF) to oculomotor nuclei (CN III, IV and VI; VOR)

45
Q

What are the outputs of the inferior nucleus?

A

outputs to the cerebellum (feedback), to the reticular formation (arousal and ANS) and to the oculomotor nuclei (CN III, IV and VI; VOR)

46
Q

What type of information does the lateral vestibulospinal tract carry?

A

travels to the thoracic spinal cord to extensor musculature for:

  • Head & body position in space
  • Walking upright
  • Righting and equilibrium reactions
47
Q

What is the pathway for the lateral vestibular tract?

A

(1⁰) Lateral Vestibular Nuclei (pons) project ipsilaterally to medial intermediate zone
(2⁰) exit spinal cord via ventral horn to extensor muscles

48
Q

What type of information does the medial vestibulospinal tract carry?

A

travels bilaterally to the cervical cord to extensor musculature for:

  • head movements
  • integrating head and eye movements
49
Q

What is the pathway for the medial vestibulospinal tract?

A

(1⁰) Medial Vestibular Nuclei (medulla) project BILATERALLY to medial intermediate zone
(2⁰) exit spinal cord via ventral horn to extensor muscles

50
Q

How does our cerebellum impact our vestibular system?

A

Responsible for postural and gaze stabilization by:

  • modulating VOR
  • Providing and receiving feedback from postural muscles on balance and equilibrium
51
Q

What areas of the cortex are thought to be involved with our vestibular integration?

A
  • Parieto-Insular Vestibular Cortex: PIVC
  • Medial Superior Temporal Region
  • Ventral Intraparietal Region
52
Q

What is the role of the Parieto-Insular Vestibular Cortex: PIVC?

A
  • Junction of parietal and insular lobe

- Receives input from from cerebellum and vestibular nuclei via the thalamus

53
Q

What is the role of the Medial Superior Temporal Region?

A
  • Visuo-vestibular integration

- Self-motion perception

54
Q

What is the role of the Ventral Intraparietal Region?

A
  • Multisensory spatial coding

- Proprioceptive, auditory, visual, tactile, vestibular

Neuroscience (16 decks)

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