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NEUR 321 > Final exam > Flashcards

Final exam Flashcards

1
Q

General senses

A

Somatic, tactile, thermal, pain, proprioceptive (receptors throughout the body)

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2
Q

Special senses

A

smell, taste, vision, hearing, balance (receptors located in sense organs such as eye, ear, etc)

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3
Q

Which species sense magnetic fields?

A

Fish, birds, butterflies, and bats to orient and migrate

All contain magnetite in their brains (sensitive to magnetic fields)

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4
Q

Labeled lines hypothesis

A

Holds that the CNS determines the type of stimulus receiving input from all sensory cells activated by that stimulus

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5
Q

What is transduction?

A

Changing a physical stimulus (analog signal) into a neural (digital) signal

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6
Q

Pacinian corpuscle

A

A free nerve ending surrounds by onion-like structure
Stretching the membrane opens stretch-activated ion channels
Vibrations produce graded potentials

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7
Q

Sensitive range

A

In general, is wider than the response repertoire of a single cell
- Get the entire range by having multiple parallel neurons with different thresholds - then with higher intensity - get more cells recruited

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8
Q

Range fractionation

A

Coding intensity - in general, the sensitive range is wider than the response repertoire of a single cell
- Solution - multiple parallel neurons with different thresholds. Higher intensity stimulus - more cells will be recruited (range fractionation)
ie low medium high threshold neurons - if all recruited, neural firing rate is very high

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9
Q

Sensory adaptation

A

detect initial change, but ignore changing events
This limits the amount of (unnecessary) sensory information to process.
Phasic receptor - change the frequency of firing when there is a constant stimulus (fire with change)

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10
Q

Phasic receptors

A

Change frequency of firing with constant stimulus
Only fire in response to change in the stimulus

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11
Q

Tonic receptors

A

Continues to fire as long as the stimulus is present

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12
Q

Thalamus role in sensory pathways

A

Thalamus receives most of the sensory input (except sometimes olfaction)
- Sends it to the cortex (there are specific cortical regions for each sense)

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13
Q

receptive field

A

the region of the sensory organ to which a particular neuron will respond.
Neurons at each level of the hierarchy have receptive fields. Progressively more complex

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14
Q

What are the two forms of sensory suppression?

A
  1. Use of an accessory organ to decrease input (ie. closing eyes)
  2. Descending pathways - neural inhibition of the receptor’s activity
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15
Q

What two parts of the brain are involved in focusing?

A

Cingulate cortex
Posterior parietal (association) cortex
Has polymodal cells
damage is called NEGLECT (causes people to have trouble focusing)
usually contralateral neglect *only on one side of the body

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16
Q

Olfactory receptors

A

6 million total in 2 cm squared area
Each receptor has a long dendrite that extends to the epithelial layer (many fine cilia along the surface)
Fine UNMYELINATED axons - project through the cribiform plate, synapse in the olfactory bulb.
Constantly replaced throughout life
~1000 receptors but only about 400 are functional (others are spares)
GPCR all!

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17
Q

Olfactory Glomerulus

A

Where the receptor cells synapse with the mitral cell within the OLFACTORY bulb

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18
Q

Perception of olfaction

A

We only use 400 R’s but can smell 5000 diff odours –PATTERN CODING
Each particular smell activates an array of receptors - get a specific smell when specific array is activated.

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19
Q

What cells do olfactory receptors innervate?

A

Mitral cells in particular glomeruli in olfactory bulb
Only one type of olfactory receptor neurons inputs to each glomerulus

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20
Q

Which is the only sense which sensory info does not need to go through the thalamus on the way to the cortex?

A

Olfaction

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21
Q

What is the prepyriform cortex?

A

Part of the primary olfactory cortex
The cortical brain regions that receive the mitral cell axon projections

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22
Q

COVID affecting smell

A

Virus binds ACE2 receptors on support (sustentacular cells) - damages epithelium, major loss of cilia

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23
Q

Taste

A

The perception of the sensory cells in your taste buds

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24
Q

Flavour (what you understand)

A

Aroma (what you smell) + what you taste = flavour

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25
Q

Where are taste receptors found?

A

In special cells called taste cells

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26
Q

Taste bud

A

Onion like structure formed by many taste cells which are formed from many taste cells

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27
Q

Papillae on the tongue

A

Upper surface of tongue. thousands of taste buds are found in nipple-like structures called papillae

Each papillae has one or more taste buds… Each taste bud has 50-150 cells

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28
Q

Where are taste receptors found?

A

In our throat and gut and tongue

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29
Q

Taste receptor types

A

Sweet, salty, sour, bitter, unami
Each receptor responds to a different chemical components of food

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30
Q

What are the 3 different papillae?

A
  1. Fungiform (most numerous (one bud/papillae)
  2. Foliate
  3. Circumvallate

Each participate in transduction of all tastes

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31
Q

Fungiform Papillae

A

Most numerous type
One bud/papillae
Found mostly at the tip of the tongue

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32
Q

Foliate papillae

A

On the side of the tongue

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33
Q

Circumvallate papillae

A

On the back of the tongue

34
Q

Salty taste transduction

A

Binding of Na+ to the Na+ channel causes opening of the Na+ channel and Na+ enters the cell - cell depolarizes - AP

35
Q

Sour taste transduction

A

H+ ions from the food block K+ leak channels - cells depolarizes

36
Q

Sweet taste transduction

A

Special GPCR’s cause the closure of K+ channels - get depolarization of cell

37
Q

Bitter taste transduction (lots of Rs)

A

GPCR - diff then for sweet though. Reduce K+ channel opening - leading to cell depolarization
(30 diff receptor subtypes)

38
Q

Umami

A

Type of GLUTAMATE receptor - GPCR - has a high affinity glutamate binding domain
Responds to certain amino acids
MSG - activates these receptors

39
Q

What are the cranial nerves involved in taste transduction?

A

Facial nerve, glossopharyngeal, vagus

40
Q

Taste transduction

A

Not as simple as labeled lines - pattern coding (more complex than olfaction) instead.
The relative activity of the different incoming signals will determine the end taste.

41
Q

What must the retina do?

A

Must convert (transduce) light energy into APs
Must discriminate different wavelengths
Must work over a wide range of light intensities
Must perceive minute details

42
Q

Optic disc

A

Where the blood vessels and axons that make up the optic nerve leave the eye
Blind spot - no photoreceptors here

43
Q

Fovea

A

Only cones
Better ratio of photoreceptor cells to ganglion cells in the fovea (1:1)

44
Q

How many different photopigments are there?

A

Four
Rhodopsin (496 nm) and one for each type of cone
Each best activated at specific wavelengths

45
Q

Phototransduction

A

Opsin = GPCR that is bound to a light - absorbing chromatophore.
G-protein= transducin

Light hits - activates transducin - activates PDE -reduce cGMP - results in the CLOSURE of Na+ channels - causes HYPERPOLARIZATION - less glutamate is released

46
Q

Glutamate released from photoreceptors

A

An inhibitory NT
INHIBITS on-centre bipolar cells and activates off-centre bipolar cells

Light - less Glu released - bipolar depol
Dark - more Glu released - bipol hyperpol

47
Q

Ganglion cells

A

Don’t see shapes
They have very small dots as receptive fields
centre/surround receptive field

One photoreceptor can contribute to many receptive fields

48
Q

Detection of edges

A

Get the largest change in response (largest response) at the edge of the on centre ganglion cell))

49
Q

Visual field to cortex processing

A

The right cortex sees the left visual field (left side of both eyes) and the left cortex sees the right visual field (right side coming into either eye)

50
Q

Corpus callosum connections in the occipital lobe?

A

Almost no connections!
Except for the cells that lie along the midline of the visual field

51
Q

What are the two types of retinal ganglion cells?

A

They project from the retina to the brain
M cells (magnocellular) - receive input from rods
P cells (parvocellular) - receive input from cones

These pathways are segregated throughout the visual system

52
Q

What are the major targets of the retinal ganglion cells?

A

Superior colliculus (midbrain - coordinates and detect movements)
Lateral geniculate LGN (thalamus; vision)
Suprachiasmatic nucleus SCN (hypothalamus; circadian clock)
Pretectum (pupil and lens reflexes)

53
Q

Coding retinal location

A

Ganglion cells project to the brain in an orderly fashion, preserving their spatial arrangement

54
Q

What are the main routes to the visual brain?

A

Tectopulvinar system
Geniculostriate system
Retinohypothalamic tract

55
Q

Striate cortex

A

Primary visual cortex = V1
Processes simple forms
Also involved in forming mental images - activated during imagining a visual object

56
Q

Dorsal visual stream

A

Visual processing pathway from V1 to parietal lobe - HOW

57
Q

Ventral visual stream

A

visual processing pathway from V1 to temporal lobe
WHAT - identifies stimulus

58
Q

What processing structures are within V1?

A
  • Cortical Columns
  • Blobs
  • Interblobs

the segregation is preserved from V1 to V2

59
Q

Blobs

A

Clusters of cells in the V1 that respond to colour

60
Q

Interblobs

A

Clusters of cells that respond to form and motion

61
Q

V1 simple cells

A

Act as orientation detectors
Fire more when bars of light are presented in a particular orientation

FOUND IN PRIMARY VISUAL CORTEX

62
Q

V1 complex cells

A

Maximally excited by bars of light moving in a particular direction (in a particular orientation)

63
Q

Hypercomplex cells

A

like complex cells, but have both excitatory and inhibitory portions of the visual field

64
Q

Area V2

A

Extrastriate cortex
Responds to many aspects of vision
Higher order integration - will respond to complex relations among parts of the visual field
Response to illusory contours

65
Q

Which part of the brain responds to illusory contours?

A

Extrastriate cortex; area V2

66
Q

V3A

A

Dorsal stream - receives inputs from V2 and from the primary visual area
Projects to the posterior parietal cortex
Processing of global motion and form

67
Q

V3B

A

Ventral stream
Weaker connections from the primary visual area, stronger connections with the inferior temporal cortex
Colour and dynamic form (forms that change)

68
Q

Inferior temporal cortex

A

These neurons receive input from the visual cortex (V3B) from the VENTRAL stream
Maximally excited by complex visual stimuli like hands and faces
Fusiform Gyrus forms part of it
Neurons are very specific in their responses - cells arranged with columns respond to slightly different forms of the object

69
Q

Fusiform gyrus

A

Faces, facial expressions
When this area is damaged - called prosopagnosia = face blindness - cannot recognize ppls faces

Found within the inferior temporal cortex

70
Q

Faceblindness

A

Prosopagnosia
Results when the fusiform gyrus, a part of the inferior temporal cortex, is damaged.

71
Q

Area V4

A

Extrastriate cortex part
Responds to colour and complex sinusoidal stimuli

72
Q

Area V5

A

Part of the extrastriate cortex
Responds best to dynamic motion
Damage - akinetopsia - motion blindness - picture motion

73
Q

Akinetopsia

A

Motion blindness
Damage to V5 (involved in processing of dynamic form)
See moving stimuli as a series of strobe like images - see visual trails moving behind objects

74
Q

Difference between robust and feeble dichromatic vision

A

Both have 2 cones but with feeble, there are less cones (cats)

75
Q

Nocturnal animals

A

Often have minimal colour vision - they are active in the dark so they dont really need to see colour

76
Q

What is the most common type of human colour blindness?

A

Deuteranopia
Red-green colourblindness is the most common (esp in males)
Can’t distinguish between reds and greens.

77
Q

3 colours combined in the trichromatic theory?

A

Red, green and blue
Combination of these three can create the entire range of colour visible to humans
Thought that each is a labeled line into the brain (maintained into primary and secondary cortices)

LEVEL OF THE PHOTORECEPTORS

78
Q

How to see white light in according to the trichromatic theory?

A

Full 100% activation of each type of cone

79
Q

Deep red?

A

Only 5% activation of long cones
NO activation of the short or medium cones

80
Q

Opponent process theory

A

Proposed by Hering that colours are perceived in a balance of 3 pairs
Red/Green, Blue/yellow, and black/white (brightness)

LEVEL OF THE GANGLION CELLS
some of the cells are excited by one of the opponent colours and inhibited by the other

Centre -surround arrangement.

81
Q

Which part of the extrastriate cortex processes colour?

A

V4 - Cells in V4 deal with perceived colour
One function: COLOUR CONSTANCY. Objects maintain their colour relative to one another despite change in lighting intensity.

Brain might perceive a certain colour by unconsciously assuming that the object is in a particular type of light.

NEUR 321 (6 decks)

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