final Flashcards

1
Q

Acoustic radiation

A

Axons leaving the mgn project to auditory cortex via the internal capsule in an array called acoustic radiation

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2
Q

Damage to auditory areas and hearing

A

A normal degree of hearing can be retained after unilateral lesions in the auditory cortex (this is not the same for hearing). But because of tonotopic organization in A1, its possible to make a restricted cortical lesion that destroys neurons with characteristic frequencies within a limited range

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3
Q

Mcgurk effect

A

Our hearing is largely based on vision

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4
Q

Strips of neurons running across a1 contain neurons that have fairly similar characteristic frequencies

A

Isofrequency bands

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5
Q

Auditory receptive fields vs visual receptive fields

A

We cannot place auditory receptive fields into simple/complex categories like visual fields

Cortical neurons have different temporal response patterns, some have a transient response to a brief sound while others have a sustained response

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6
Q

stimuli that evokes the strongest response in higher auditory

A

tend to be more complex than those that best excite neurons.

Some neurons are intensity tunes and give a peak response to a particular sound intensity

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7
Q

Isofrequency bands

A

Strips of neurons running across a1 contain neurons that have fairly similar characteristic frequencies

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8
Q

Example of tonotopy

A

Moving from base to the apex of the cochula, a progressive decrease in frequency that produces a maximal deformation of the basilar membrane

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9
Q

Tonotopy

A

When the baslair membrane resonates with a particular frequency in a particular spot
Tonotopic organization also occurs within the primary auditory cortex.

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10
Q

How different frequencies are represented by brain stem neurons

A

At low frequencies, phase locking is used
At intermediate frequencies, both phase locking and tonotopy are used
At high frequencies, tonotopy must be used to indicate sound frequency

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11
Q

Phase locking

A

Constant firing of cell at the same phase of a sound wave(at low frequencies some neurons fire action potentials every time the sound is at a particular phase. This makes it easy to determine the frequency of sound since it is the same as the firing frequency of the neurons action potential

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12
Q

How is frequency represented in Specific Movement of basliar membrane

A

Hair cells near apixal basilar membrane have characteristics of low frequencies
Hair cells near basal basilar membrane have high characteristic frequencies
There is a map of basilar membrane within cochlear nuclei

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13
Q

Auditory nerve fibers fire faster to same sound frequencies when the intensity is increased. What does this do to the basilar membrane

A

Produces movements of basilar membrane over greater distance and leads to activation of more hair cells. Increase in activated hair cels cause a broadening of the frequency range to which the fiber responds.

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14
Q

Loudness we perceive is correlated with..

A

Number of active neurons in the auditory nerve and their firing rate

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15
Q

Characteristic frequency

A

A neuron has characteristic frequency when it is most responsive to one frequency. Its less responsive to neighboring frequencies

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16
Q

Nature of input from the neurons in the spinal ganglion of the cochlea

A

Most spiral ganglion cells receive input from a single inner hair cell at a particular location on the baslar membrane.

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17
Q

Each Cochlear nucleus receives input from

A

Just one ear on the ipsilateral side (all other auditory nuclei in brain stem receive input from both ears)

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18
Q

Ways for extensive feedback for auditory pathways

A

Auditory cortex sends axons to MGN and inferior colliculus

Brainstem sends axons that contact outer hair cells

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19
Q

Projections from brainstem to other auditory pathways

A

Inferior colliculus sends axons to superior colliculus

Cerebellum

Outer hair cells

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20
Q

Axons in superior olive then intervate to..

A

Inferior colliculus in midbrain

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21
Q

Where does integration of auditory and visual information occur

A

Superior colliculus (inferior colliculus sends axons here)

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22
Q

Cells in ventral cochlear nucleus send axons to..

A

Superior olive (on both sides of brain stem)

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23
Q

Medullas sound processing structures

A

Dorsal cochlear nucleus

Ventral cochlear nucleus ipsilateral to the cochlea where the axon is originated)

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24
Q

Protein essential for outer hair cells motor and cochlear amplifer functioning

A

Prestin

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25
Q

Decending input from brain to cochlea

A

Regulates auditory sensitivity

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26
Q

Effect of outer hair cells on the response of inner hair cells can be modified by..

A

Neurons outside the cochlea

Theres also fibers projecting from the brain stem to the cochlea

They can synapse onto outer hair cell and release Ach (this can change shape of outer hair cell and therefor affect response of inner hair cell

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27
Q

stages of amplification by outer hair cells

A

starts with motor proteins in membranes of outer hair cells

bending of stereocilia acauses K to enter hair cell and depolarizes it

this triggers motor proteins to activate and change length of hair cell

this increases the flexing of basilar membrane

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28
Q

Conchular amplifier

A

Outer hair amplify movement of baslar membrane during low intensity sound stimuli

  • They involve motor proteins (only found in membrane of outer hair)
  • Outer hair cells respond to sound by both receptor potential and change in length
  • When outer hair amplify response of baslar membrane, inner hair cells bend more and produces a greater response in the auditory nerve
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29
Q

What does the spiral ganglion mostly communicate with

A

Inner hair cells (less than 5% receive output from outer hair even though they are more abundant)

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30
Q

are inner hair cells or outer hair cells more abundant

A

outer hair. 3/1.

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31
Q

Displacement of cilia in one direction..

A

Increases tension on tip link and increases amount of K movement

-Entry of k causes cell to depolarize (different from normal neurons because of high k concentration in endolynph)

this entry of k causes volted gated calcium channels to open

-incoming calcium lead to release of NT from synaptic vesicle then diffuses to postsynaptic neurite from spinal ganglion

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32
Q

Ion channel and tip of stereocilium

A

Ion channel opens and closes when stereocilium is bent

They only have two channels at the tip and the entire hair cell may only have 100

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33
Q

What happens with extremely loud sound..

A

Receptor potential of hair cell is saturated and tips of stereocilia move about 20nm to the side. This can cause damage

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34
Q

Lateral motion of the reticular membrane bends stereocilia on outer hair one way or the other…

A

One direction depolarizes while the other hyperolerizes

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35
Q

When baslar membrane moves up…

A

Lamina moves up and toward the modiolus (opposite happens when it it moves down)

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36
Q

how to restore hearing when auditory nerve is still intact

A

cochlear implant artificial cochlea)

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37
Q

whats the most common case of deafness

A

hair cell damage

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38
Q

what happens when basilar membrane moves in response to a motion at the stapes

A

entire foundation supporting the hair cells move because the basilar membrane, rods of corti, reticular lamina and hair cells are rigidly connected

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39
Q

spiral ganglion

A

bipolar neurites extending to the bases and sides of the hair cells where they receive synaptic input

-axons from these cells enter the auditory vestibular nerve which projects to the cochlear nuclei in the medulla

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40
Q

what kinds of cells are hair cells

A

specialized epithelial cells

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41
Q

outer hair cells location

A

farther out than rods of corti

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42
Q

critical event for transduction of cells into neural signals

A

bending of celia

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43
Q

organ of corti and its function/structures

A

place in ear where neurons are first involved. Converts mechanical energy into change of membrane depolarization
has hair cells with stereocilia extending from top

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44
Q

response of basilar membrane to sound

A

high frequency sound produce waves traveling wave which dissipates near the arrow and stiff base of the basilar membrane

low frequency-wave propagates all the way to the apex of basilar membrane before disssapating

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45
Q

Tonotopy

A

Systematic organization of sound frequency within an auditory structure
(like retinotopy in visual system)

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46
Q

Hebbian synapses

A

Neurons that fire together wire together

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47
Q

Apoptosis

A

Expression of cell death genes cause neurons to die. This process is apropos

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48
Q

Neurotrophins

A

A family of Tropic proteins. Nerve growth factors was one of these.

Neurons compete with one another for limited quantities of trophies factors produced by target neurons

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49
Q

Tropic factors

A

Life sustaining substances that are provided in limited quantities by target cells

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50
Q

Auditory pathway

A

Auditory receptors (cochlea/ganglion)

Superior olive (brain stem)

Inferior colliculus?

MGM

auditory cortex

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51
Q

Visual pathway

A

Photoreceptors

Retinal neurons

Lgn

Visual cortex

52
Q

Outer hair cells

A

Receive signals from the brain and serve as mini biomechanics amplifier

Attention

Loud noises damage cells

53
Q

Inner hair cells

A

Carry nerve signal of sound along the auditory to the brain

54
Q

What are the ossicles

A

Mallius

Incus

Stapes

55
Q

What happens during protective attenuation reflux

A

The tensor tympani muscle and stafpedius muscle lock down the middle ear within 50-100ms

56
Q

Ganglion cells combine to form the receptive field of…

A

A single LGN cell

57
Q

The receptive fields of many LGN cells combine to form the receptive field of..

A

A single V1 cell

58
Q

What are the five vertebrae regions

A

Cervical nerves

Thoracic nerves

Lumbar nerves

Sacral nerves

59
Q

What are the three cuts

A

Midsaggital

Horizontal

Coronal

60
Q

Basal telencephalon function

A

Helps with initiating voluntary movement. Cortex communicates with neurons in basil ganglia, a collection of cells in basal telencephalon

Amygdela is located here which is involved in fear and emotion

61
Q

Thalamus function

A

Send axons to the cortex via internal capsule .

It’s considered gateway to cerebral cortex because of sensory pathways serving vision and audition and somatic sensation relays in thalamus

62
Q

Hypothalmus function

A

Controls autonomic nervous system and regulates body function in response to organ

Fight or flight response

Hormones

63
Q

Pon function

A

Connection cerebral cortex to cerebellum

64
Q

Medulla function

A

Relay information from spinal chord to thalamus such as taste and feeling.

65
Q

Telencephalon

A

Deals with high level processing

66
Q

Diencephalon/thalamus

A

Supports mammalian brain, parenting and four basic f’s

67
Q

Midbrain

A

Helps keep us safe. Deals with visual orientation and motor reflexes

68
Q

Hindbrain

A

Controls physiological needs and homeostasis

69
Q

Tract

A

CNS axons

70
Q

Nerve

A

PNS axons

71
Q

Locus

A

Well defined group of cells

72
Q

Ganglion

A

Collection of neurons in PNS

73
Q

Substantia

A

Less distinct borders of group of neuron

74
Q

Nucleus

A

Well defined group of neurons

75
Q

Corner function

A

Acts as first lens and has focusing power by refracting light.

76
Q

Where is central part of vision located

A

Back of brain

77
Q

Where is perennial areas of visual field located

A

More Anteriorly

78
Q

Top part of visual field is located ____

Bottom is located ____

A

Top-lower part

Bottom-upper part

79
Q

Where is central part of vision located

A

Back of brain

80
Q

Where is perennial areas of visual field located

A

More Anteriorly

81
Q

Top part of visual field is located ____

Bottom is located ____

A

Top-lower part

Bottom-upper part

82
Q

Number of rods

A

100 million

83
Q

Number of cones

A

5-6 million

84
Q

Number of ganglion cells

A

It has about 50 rods and cones. In fovea ganglion cells gave 12-20 of them for high definition

85
Q

What is center surround receptive fields

A

Two concentric areas with antagonistic responses to light on and light off

86
Q

What is reFLECtion

A

Light rays bouncing off a surface

87
Q

Only retinal neurons that fire action potentials

A

Ganglion cells

88
Q

What is a receptive field

A

Area of retina that when stimulated with light, changes a cells membrane potential

89
Q

What is dark current

A

Photoreceptors are depolarizer in the dark because of a steady influx of sodium ions

90
Q

What is focal distance

A

Refractive surface to point where parallel rays converge

91
Q

I why do we say that ganglion cells are mainly responsive to differences in illumination that occur within receptive field

A

Center surround ganglion cells respond best when a light or dark edge falls at boundary between the center and surround regions of receptive field

92
Q

Which layer of retinal neurons has axons leave retina

A

Ganglion cells

93
Q

Spatial sensitivity of green cone pigment

A

530 nm

94
Q

What is meant by phototransduction

A

Process that occurs hen photoreceptors convert light energy in neuronal membrane potential

95
Q

Why is retina said to be duplex

A

It works under both scotopic and photopic lighting conditions

96
Q

Distinguish between m cells and p cells

A

M cells respond with transient burst of action potentials and p cells respond with a sustained discharge

97
Q

What is visual acuity

A

Ability of the eye to distinguish two nearby points

98
Q

Choroid plexus

A

Produce CSF and form blood CSF barrier

99
Q

Nucleus

A

A clearly distinguishable mass of neurons usually deep in the brain

Substantia is like this but with less defined borders

100
Q

What does Weber’s law state

A

The brighter the light, the more change in brightness is required for us to notice a difference

101
Q

What does Weber’s law state

A

The brighter the light, the more change in brightness is required for us to notice a difference

102
Q

Henninger synapses

A

Synapses that can be modified

103
Q

Hebbian modifications

A

Synaptic rearrangement

104
Q

Retinal activity and synapses

A

Whenever a wave of retinal activity drives a postsynaptic LGN neuron to fire an action potential, the synapse between them are stabilized

105
Q

Cells of V1

A

They detect direction of certain properties (lines, orientation, edges)

They are automatic and fast

106
Q

Simple cells

A

Have excitatory and inhibitory areas

They respond most to lines or bars of orientated light

107
Q

Complex cells

A

No fixed excitatory or inhibitory areas

They respond most to a moving line or bar

108
Q

Hyper complex cells

A

Primary stimuli is a moving bar of light like the complex cells except the bar has an end

Located in V1 and v2

109
Q

Hyper complex cells

A

Primary stimuli is a moving bar of light like the complex cells except the bar has an end

Located in V1 and v2

110
Q

What does the peripheral nervous system (PNS) consist of?

A

Nerves and ganglion outside of the brain and spinal cord. Its not protected by bone or the blood brain barrier like the CNS so its more exposed to toxins and mechanical injuries

111
Q

What is a way to avoid spine bediphia

A

Folic acid

112
Q

What are the divisions of the PNS?

A

Somatic nervous system-associated with body under voluntary control. (cell bodies of somatic motor neurons are in CNS but axons in PNS) (somatic sensory neurons lie outside of spinal cord in clusters called dorsal root ganglia. There is a dorsal root ganglia for each spinal nerve)
Autonomic nervous system-involuntary control over smooth muscle and glands. Also called visceral PNS. It rings info about visceral functions to CNS such as oxygen content in blood.

113
Q

Somatic nervous system

A

associated with body under voluntary control. (cell bodies of somatic motor neurons are in CNS but axons in PNS) (somatic sensory neurons lie outside of spinal cord in clusters called dorsal root ganglia. There is a dorsal root ganglia for each spinal nerve)

114
Q

Autonomic nervous system

A

involuntary control over smooth muscle and glands. Also called visceral PNS. It rings info about visceral functions to CNS such as oxygen content in blood.

115
Q

What are the divisions of the autonomic nervous system?

A

Sympathetic nervous system-fight or flight (stimulatory)

Parasympathetic nervous system-rest and digest (inhibitory)

116
Q

What happens if dura is ruptured?

A

Blood can collect in between dura and arachnoid which is called a subdural hematoma. This buildup of fluid can disrupt brain function by compressing parts of CNS. This can be fixed by drilling a hole in the skull

117
Q

What is the binocular visual field?

A

The central portion of both left and right hemifields put together

118
Q

Ocular dominance columns

A

Bands of cells extending through the thickness of the striate cortex. They contain neurons with input dominated by one eye and the columns alternate between left and right eye

119
Q

Orientation selectivity

A

Neurons that prefer a particular orientation. Thee neurons can be in columns called orientation columns. Their greatest response is given to a bar with a particular orientation

120
Q

Organization of the lgn

A

Its arranged in six distinct layers of cells. Different types of retinal info are being kept separate at this synaptic relay

121
Q

How do neurons of retinal ganglion cells and lgn cells respond to stimulation pf their receptive field centers?

A

Increase in the frequency of action potentials.

122
Q

How to record a ganglion cells receptive field

A

Record the neurons axon in the optic nerve
Small spot of light projected onto retina
Receptive field consist of locations that increase or decrease cells firing rate
Move light to map region of the visual field that causes spiking in the ganglion cell
(light anywhere outside of its field will have no firing rate)

123
Q

What is the membrane potential of rods photoreceptos in the dark

A

-30mV

124
Q

steps of transduction of light by rods

A

light bleaches rhodopsin
g protein is stimulated
effector enzyme is activated
PDE (the effector enzyme) reduces cGMP level
Na+ channels close and cell membrane hyperpolarizes

125
Q

Role of calcium in light adaptation

A

Ca2+ enters a cone through he same cGMP channels as Na. it inhibits the synthesis of cGMP

126
Q

what happens when dark in ganglion cells hits middle receptive field vs when its in the areas that surround the center of receptive field?

A

Center-cell depolarizes
Surround-hyperpolarize
If darkness fills the surrpund, the center response is canceled