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Neurobiology > Unit 4 Notes > Flashcards

Unit 4 Notes Flashcards

1
Q

stroke

A
  • brain cells suddenly die because of lack of oxygen

- caused by hemorrhage or ischemia

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2
Q

hemorrhage stroke

A

-weakened or ruptured blood vessel leaks into surrounding brain

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3
Q

ischemia stroke

A
  • obstruction within blood vessel leading to brain

- blockage

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4
Q

prevalence of stroke

A

-most prevalent in southern US b/c of unhealthy eating

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5
Q

photoreceptors

A
  • detect light and convert into neural impulses
  • release nts in response to light detection
  • align retina
  • pint toward back of head
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6
Q

ganglion cells

A
  • transmit info from retina to thalamus (LGN)
  • have long axons that extend to the brain
  • axons from the optic chiasm, optic nerve, and optic tract
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7
Q

rods

A
  • detect dim light
  • no color vision
  • poor resolution
  • don’t give a ton of info
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8
Q

cones

A
  • color vision
  • high acuity b/c neurons linked one to one
  • dense in fovea
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9
Q

fovea

A
  • back of eye at center of retina
  • responsible for sharp central vision
  • dense with cones
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10
Q

cortical representation of fovea

A
  • cortical magnification of fovea even though it is a small structure
  • suggest abundance of photoreceptors (large receptive field)
  • makes sense b/c of fovea role in sharp vision
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11
Q

why no blood vessels near fovea

A

-light can’t penetrate through blood vessels to hit photoreceptors

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12
Q

receptive field

A

-region of space in which the presence of stimuli will alter the firing of neurons

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13
Q

tapetum lucidum

A
  • night vision

- layer of tissue behind retina reflects light back to photoreceptors increasing availability of stimulus

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14
Q

right and left

A
  • right side of each retina projects to right cerebral hemisphere
  • left side of each retina projects to left hem.
  • right side of each retina receives image of visual world on left side of the head
  • left side of each retina receives visual world on right side of head
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15
Q

nasal retina

A
  • part of retinal closest to nasal bones

- visual info that crosses and travels contralaterally to cortex

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16
Q

temporal retina

A
  • part of retina nearest to temporal bone

- visual info that travels ipsilaterally to cortex

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17
Q

optic tract

A

-continuation of optic nerve that runs from optic chiasm to LGN

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18
Q

optic chiasm

A
  • where optic nerves partially cross
  • images of nasal retinal cross
  • images of temporal retina do not
  • half of tracts cross; half don’t
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19
Q

optic nerve

A
  • transmits info from retina to brain
  • cranial nerve II
  • considered part of CNS
  • myelinated axons
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20
Q

lateral geniculate

A
  • primary relay center for visual info received from retina

- located in thalamus

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21
Q

ipsilateral eye projections

A

-hit LGN layers 5, 3, and 2

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22
Q

contralateral eye projections

A

-hit LGN layers 6, 4, and 1

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23
Q

magnocellular layer LGN

A
  • LGN layers 1 and 2
  • large cells with large receptive fields
  • respond to movement, depth, and contrast
  • rods
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24
Q

parvocellular layer LGN

A
  • LGN layers 3-6
  • small cells with small receptive fields
  • respond to position and color
  • cones
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25
Q

koniocellular layer LGN

A
  • zone of small cells between M and P layers of LGN

- provide visual cortex with info about short wavelength color (blue)

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26
Q

on center cell responses

A
  1. ) central illumination
  2. ) annular illumination
  3. ) diffuse illumination
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27
Q

central illumination

A

-on center cells respond best when spot of light shone onto central part of receptive field

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28
Q

annular illumination

A
  • on center response followed by light shone on surrounding area
  • suppresses discharges of on center cells
  • discharges restored when surround turned off
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29
Q

diffuse illumination

A
  • illumination of entire receptive field

- weak discharge becuse center and surround antagonize each other’s effects

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30
Q

optic disk

A
  • where ganglion axons exit eye and converge to form optic nerve
  • no rods or cones present
  • “blind spot”
  • beginning of optic nerve
  • entry point for major blood vessels that supply the eye
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31
Q

off center cell responses

A
  • neuron excited when light shone onto surrounding of off-center receptive field
  • once activated by on surround, response slows or stops when central area of field is illuminated
  • restore signaling when central field is turned off
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32
Q

hermann grid

A
  • grey blobs perceived at intersections of white grid on black background
  • blobs disappear when looking directly at intersection
  • optical illusion caused by lateral inhibition
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33
Q

lateral inhibition

A
  • capacity of excited neuron to reduce activity of its neighbors
  • sharpens response to localized stimulus- contrast
  • rods at center of stimulus send “light” signals to brain
  • rods in periphery of stimulus send “dark” signals to brain
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34
Q

area 17 (V1)

A
  • primary visual field
  • located posteriorly in occipital lobe
  • striate cortex- myelinated axons visible
  • processes info about static and moving objects
  • pattern processing
  • 6 layers
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35
Q

part of retina detecting right visual field

A
  • left temporal

- right nasal

36
Q

part of retina detecting left visual field

A
  • right temporal

- left nasal

37
Q

retinotopic maps

A
  • info from 6 layers of LGN maintain topography when traveling to 6 layers of area 17
  • integration of info from many neurons
  • increase in complexity of processing further into cortex
38
Q

damage to right LGN

A

-become blind in left visual field (right temporal and left nasal)

39
Q

notable thing about human visual cortex

A
  • subdivision of layer 4

- where most LGN fibers end

40
Q

4C alpha and 4B layer of visual cortex

A

-receive input from magnocellular layers of LGN

41
Q

circle of Willis

A
  • vascular structure under brain
  • common location of aneurism
  • arrangement of arteries creates redundancies, which allows for vascular “back-up” if an artery were to become blocked
42
Q

aneurysm

A
  • abnormal widening or ballooning of portion of an artery due to weakness of the vessel wall
  • dangerous if ruptures
43
Q

pituitary tumor

A
  • midline structure
  • tumor puts pressure on middle of optic chiasm
  • suppresses nasal retina input
  • limits peripheral vision b/c nasal detects lateral vision
  • pituitary also secrets prolactin, so abnormal levels would indicate
44
Q

layer IV C of striate cortex

A
  • innervates superficial (higher layers)- II and III

- binocular processing (info from both eyes) begins

45
Q

ocular dominance columns

A
  • portions of visual cortex that get input from one one verses the other
  • variation in eye preference
  • observable with radioactive tracer injected into animal eye and carried from retina to LGN to cortex
  • cells in one layer of LGN project to aggregates of target cells in layer 4 that are separate from those supplied by the other eye
46
Q

what generates ocular dominance columns

A

-axons from LGN segregation and crossing after layer IV of cortex

47
Q

orientation selectivity

A
  • simple cells of striate cortex respond to certain orientation of bars of light
  • setting up edge detection
48
Q

simple cells

A
  • found mainly in layers 4 and 6 of visual cortex
  • respond to pattern of light in certain orientation in a small receptive field
  • each cell has distinct and specific response
  • degree of response dependent on bar of light width and angle orientation
49
Q

cortical fields derived from fovea

A

-most excited by narrower bars of light b/c “represents” an on-center stimuli and of center surround

50
Q

orientation pinwheels

A
  • range of different orientations that drive cells maximally
  • orientation organization laid on top of visual dominance patterns
  • each portion of cortex sensitive to certain orientation
  • visual cortex has LOTS of organized layers
51
Q

synthesis of simple cell get receptive field

A
  • produced from convergence of inputs from LGN neurons
  • LGN neurons have receptive fields in retina that are aligned identical to receptive fields of simple cells in cortex
  • LGN cells that project to particular simple cell in particular fashion that simple cell is sensitive to
  • get receptive fields from many LGN cells
52
Q

4C beta and 4A of visual cortex

A

-receive input from parvocelluar LGN

53
Q

complex cells

A
  • in layers 2, 3, 5, and 6
  • receive input from the simple cells
  • sensitive to orientation of light/dark border (edges)
54
Q

binocular fusion

A

-simple cells in visual cortex respond to similar visual stimuli in either eye

55
Q

demonstrating ocular dominance columns

A
  • destroy small group of cells in one layer of the LGN and examine cortex for degenerating terminals
  • can also be changed by removing eye
  • eye or LGN cells that are still there has an increase in ocular dominance
56
Q

haptic sense

A
  • recognizing objects through touch

- complex task further downstream in cortex

57
Q

complex cells and importance of orientation

A
  • cells are sensitive to specific edge (ex: horizontal, vertical, etc)
  • if completely invert stimulus, cell has inhibitory response as opposed to excitatory
58
Q

complex cells and relative unimportance of position

A

-cell responds vigorously to every vertically oriented edge, no matter where in the receptive field

59
Q

end stopping

A
  • cells respond more vigorously when whole stimulus fits in receptive field
  • if extend beyond receptive field, don’t fire as much
  • back edge of stimulus causes cell to respond more vigorously
60
Q

simple and complex example

A
  • multiple simple cells respond to vertical line (in specific position)
  • all vertical simple cell projections lead to single complex cells
  • target complex cells respond best to any vertical line within its receptive field
61
Q

binocular cells

A
  • first see in visual cortex superficial to layer 4

- where integration of two eyes is occuring

62
Q

beyond striate cortex pathways

A
  1. ) dorsal stream
  2. ) ventral stream
    * outer layers of brain
63
Q

dorsal stream

A
  • focused on spatial processing
  • how things are moving around
  • where things are in space
  • “where” pathway
  • V1, V2, V3, MT, other dorsal areas
64
Q

ventral stream

A
  • focused on object shape and color
  • “what” pathway
  • recognizing face
  • V1, V2, V3, V4, IT, other ventral areas
  • DON’T process motion
65
Q

originate at V1

A
  • > V2 -> V3 -> MT or V4
  • if MT -> MST -> dorsal areas
  • if V4 -> IT -> ventral ventral areas
66
Q

MT

A
  • middle temporal (V5)

- critical area in primates for processing visual motion

67
Q

lesion to MT

A
  • extreme difficulty perceiving motion
  • snapshots, rather than fluid motion
  • every now and then new view
  • really choppy
  • Ex: overshoot when pouring coffee
68
Q

MST

A
  • medial superior temporal
  • getting most input in MT
  • role in visual motion and navigation
  • involved in optic flow
69
Q

IT

A
  • inferior temporal cortex
  • complex objects
  • face recognition
70
Q

V4

A
  • big role in color

- simple geometric objects

71
Q

optic flow

A
  • things flowing past eyes
  • generated as you are moving
  • shifts if turning
72
Q

why see ground move when playing guitar hero

A
  • during play MST is fired up (optic flow)
  • even when stimulus stops, MST still active for a bit
  • habituation- habitual activity with MST, so don’t notice optic flow
73
Q

para-hypocampal place area (PPA)

A
  • area of brain that identifies landmarks
  • experiment with response to houses
  • ventral stream structure
74
Q

fusiform face area

A
  • behind PPA
  • recognize faces
  • ventral stream structure
75
Q

grandmother cells

A
  • hypothetical neuron that represents a complex but specific concept or object
  • activated when person see or hears
  • sensibly discriminates
  • big role in face recognitions
76
Q

vision

A
  • perception combines individually identified properties of visual objects
  • achieved by simultaneous parallel processing of visual pathways
77
Q

parallel processing

A
  • ability to carry out multiple operations or tasks simultaneous
  • ability of brain to divide and interpret visual input by color, motion, shape, and depth
78
Q

MEG

A
  • used to identify zones of activity

- sensitive machine that detects tiny brain waves

79
Q

MUA

A
  • multi unit activity
  • used to identify receptive fields
  • rarely used in humans b/c requires sticking electrode in brain
80
Q

EEG

A

-focuses on surface of brain activity

81
Q

fMRI at rest with eyes closed

A
  • how much of brain using when doing absolutely nothing
  • brain is still very active
  • already using more than 10% doing nothing
  • at rest using 15% of brain
82
Q

fMRI when telling traumatic story out loud

A
  • trying to see all of brain firing at once
  • frontal, temporal, limbic, and occipital firing
  • using 30% of brain
83
Q

to determine importance of structure

A
  1. ) correlation
  2. ) necessity
  3. ) sufficiency- can it generate behavior by itself
84
Q

neurons and behavior

A

-is there a correlation between activity and behavior

85
Q

large giant interneuron

A

-role in flip behavior response to sneaking up on crawdad

86
Q

limitation of fMRI

A

-can’t see individual neurons

Neurobiology (4 decks)

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