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NEUR 321 > Final Exam 1 > Flashcards

Final Exam 1 Flashcards

1
Q

How fast do sounds move?

A

340m/s

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2
Q

What is frequency?

A

Vibration rate
How many cycles/unit time
Corresponds to our perception of pitch
Measured in Hz = wl/sec

Human can hear anywhere from 20 -20000 Hz

The higher the frequency, the shorter the wavelength

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3
Q

Doppler Effect

A

The perceived pitch of a sound is higher as a sound approaches us and lower as the sound moves away from us

Sound is produced at a particular frequency, it is just the perceived frequency that changes.

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4
Q

Amplitude

A

Difference in intensity of sound (loudness)
Measured in decibels (dB)

Hitting a tuning fork harder or softer changes the loudness but not the frequency. Wavelength is the same, but the amount of air moved is greater when the fork is hit harder

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5
Q

What is tinnitus?

A

The perceived continuous sound after a loud noise

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6
Q

What is a simple sound?

A

pure tone - only produces one frequency
ex. tuning fork

But most sounds are complex

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7
Q

Complex sounds

A

Made up of a combination of frequencies - one fundamental frequency plus many overtones (multiples of the fundamental frequency, each with its own amplitude)
COMPLEX TONES ARE PERIODIC

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8
Q

Noise

A

Aperiodic complex sounds.

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9
Q

Can the pinna enhance certain frequencies?

A

It sure can!

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10
Q

Tympanic membrane

A

Vibrates based on the frequency of sound waves

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11
Q

Ossicles

A

Malleus, Incus, Stapes
Hammer, Anvil, Stirrup

Stapes hits the OVAL WINDOW

Smallest bones in the body - they amplify vibrations

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12
Q

Eustachian tube

A

Connects the muddle ear to the nasal-sinus cavity
Ensures that the pressure is equal between the middle and outer ear

Pressure equalization here is important for the ear drum to work efficiently

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13
Q

What connects in the inner ear to the brain?

A

The auditory nerve (Vlllth cranial nerve)
Inner ear = cochlea + vestibular organ + semicircular canals

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14
Q

Structure of the Organ of Corti

A

Organ of corti lies on top of the basilar membrane, tectorial membrane lies on top

The organ of corti has inner and outer hair cells with stereocilia

Outer hair cells are connected to the tectorial membrane

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15
Q

Base of the basilar membrane and pitch?

A

The basilar membrane maximally vibrates in response to high pitches (high frequencies)

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16
Q

Apex of the basilar membrane and frequency?

A

The apex responds to lower pitches (lower frequencies)

Get the highest neural response in hair cells located at the part of the basilar membranes where the most displacement occurs (depends on the frequency)

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17
Q

Shape of the basilar membrane

A

Narrow and thick near the oval window (responds to HIGH frequencies)
Thin and broad near the apex (responds to lower frequencies)

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18
Q

How is frequency coded at the Apex?

A

Not coded in a tonotopic fashion (everywhere else on the BM is coded in a tonotopic fashion)
This is the region sensing frequencies below 200 Hz

Here, the action potential rate is proportional to frequency such that the higher frequencies get more firing.
Volley theory

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19
Q

Inner and outer hair cells

A

1 row of inner hair cells that are responsible for hearing. these are connected to the tectorial membrane 3500
3 rows of outer cells 12000
Mechanically-amplify low-level sound entering the cochlea
CONNECTED TO THE TECTORIAL MEMBRANE

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20
Q

How to movement of the BM lead to APs?

A

Displacement of the BM leads to movement of the hair cells against the tectorial membrane. The movement causes the cilia on the hair cells to move - opening channels via the movement of tiplinks (connect stereocilia together)

When the steriocilia bend, they pull open cation channels .

K+ channels open - leads to influx of potassium ions - depolarization - this leads to the activation of voltage gated Ca2+ channels - INCREASE IN NT RELEASE -

When the cilia bend the other way - no channels open - hyperpolarization - decreased NT released

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21
Q

What do the outer hair cells do?

A

Touch the tectorial membrane
Have afferent and efferent associations with the brain - receive feedback and regulate their activity

Change the stiffness of the regions of the BM - sharpens tuning for some frequencies

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22
Q

What cells do hair cells synapse on?

A

Bipolar cells!

Each bipolar cell gets input from ONLY ONE hair cell
The axons of the bipolar cells form the 8th cranial nerve

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23
Q

What part of the brainstem do bipolar cells contact in the auditory system?

A

The ipsilateral (same side brainstem)
-aka the cochlear nucleus

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24
Q

How is the phase of a sound wave codes by the brain?

A

Bursting pattern of the firing corresponds to the wavelength

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25
Q

Sizing of Wernicke’s area

A

In righties, it is bigger on the left
In lefties - 70% bigger on the left

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26
Q

Dorsal stream in the auditory pathway

A

GOES TO THE POSTERIOR PARIETAL CORTEX
Plays a role in auditory control of MOVEMENT (where?)

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27
Q

Ventral stream in the auditory pathway

A

To further TEMPORAL LOBE areas. Plays a role in identifying auditory stimuli (what?)

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28
Q

How is pitch coded for in the brain?

A

Tonotopic arrangement - Place coding

1:1 ratio of hair cells to bipolar cells – this makes sure that the brain knows exactly where on the membrane the hair cell was activated - identify the pitch

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29
Q

Which parts of the CNS is the frequency map involved in?

A

Inferior colliculus
Primary and secondary auditory cortices

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30
Q

Coincidence detection

A

Occurs in the medial superior olivary nuclus
Receives signals from both the left and the right ears

Helps to identify where a sound came from

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31
Q

Sound shadows

A

High frequency sounds get blocked and this creates a sound shadow on the distal side of our head
- Sound is perceived as less loud on this shadowed ear and the brain uses this to calculate direction

Low frequency sound localization - Low frequ sounds will bend around our heads quite easily - both ears will perceive the same loudness.

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32
Q

Which type of hearing loss can be corrected?

A

Conductive hearing loss
Some problem in mechanics ie ossicle failure, eardrum failire

Ear infections are the most common cause of temporary hearing loss in children

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33
Q

Can sensorineural hearing loss be corrected?

A

Not really - need cochlear implants or auditory brainstem implants
PROBLEM WITH TRANSDUCTION

Gentamicin kills hair cells…high aspirin dose temp dysfunction

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34
Q

Cochlear implants

A

Some types of hearing loss can be treated with a cochlear implant BECAUSE of the TONOTOPIC arrangement of the BM and of the auditory system

Electrodes inserted into the cochlea
Stimulates BM - required intact auditory nerve and brain structures

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35
Q

What are the Otolith organs?

A

utricle and saccule

Utricle - detects linear acceleration in the horizontal plane
Saccule detects linear acceleration in the vertical plane

36
Q

What type of motion to semicircular canals detect?

A

They detect angular force, like ROTATION

37
Q

Transduction of info regarding gravity and acceleration of the head

A

Done by hair cells - they are arranged in specific orientations to respond to acceleration in a particular direction.

38
Q

Transduction in the semicircular canals

A

Endolymph resists changes in momentum - activation of hair cells in the ampulla when movements of the head and the fluid are different
- left and right ear respond differently

endolymph initially stays still when the head moves
keeps moving when the head stops

39
Q

Somatosensation

A

sense of touch
the ability to feel hot and cold, to recognize an object by touch alone, to respond to pain, etc.

40
Q

What do receptors for hapis detect?

A

Fine touch, pressure

41
Q

Subcutaneous

A

Hypodermis
Not really part of the skin

42
Q

Pacinian Corpuscles

A

Free nerve ending surrounded by an onion-like capsule
Detects vibrations
Rapid deformations of the structure lead to stretching of the free nerve ending - opening of SODIUM Na+ channels

large receptive fields

Fast adapting , RESPOND TO CHANGES IN STIMULUS

43
Q

FAST ADAPTING

A

Respond to changes in the stimulus

44
Q

Slow adapting

A

Fire whenever the stimulus is present

45
Q

Merkel’s discs

A

Densely packed in skin areas with fine spatial resolution
Respond to very light touch
Slow adapting
Great spatial resolution

46
Q

Meissner’s Corpuscle

A

More numerous and also densely packed then Merkel’s discs
Fine spatial resolution
FAST adapting - low threshold
Important for determining texture detail and edges

47
Q

Ruffini’s endings

A

Respond to indentation/stretches in the skin when body part is moved
SLow adapting
Low spatial resolution

48
Q

What are the slow adapting touch receptors?

A

Ruffin’s endings, merkel’s discs

49
Q

Fast adapting touch receptors?

A

pacinian corpuscles
Meissner’s corpuscle

50
Q

Which are the best detectors for Braille?

A

Merckel’s discs - second is meissner’s corpuscles

51
Q

Where does somatosensory dorsal ventral combination occur

A

In the secondary cortex

52
Q

Purpose of pain?

A

Withdraw from a source of injury
Promote restorative behaviours (sleeping, grooming, feeding)
Social signal (elicit care-giving behaviour from others)

53
Q

Pain signal pathway

A

Tissue damage causes the release of chemicals - activates adjacent nerve fibres - produce NT’s - Activate nociceptors - chemical or temp receptors in the membrane of nerve fibres

CRosses to the contralateral side IN THE SPINAL CORD

54
Q

where does the pain signal cross to the contralateral side in the spinal cord?

A

in the spinal cord, before the signal reaches the brain.

55
Q

Ascending and descending pain pathways

A

Pain goes up to brain in the primary afferent - synpases on second order neuron and inhibitory interneuron - this can change the perception of pain

WANT TO BLOCK THE ASCENDING PATHWAY WHEN TREATING PAIN
The inhibitory interneuron is very important with the control of pain

56
Q

Examples of general anaesthetics

A

GABA a receptor agonist
NMDA receptor antagonist
2-pore K+ channel activator

Prevents brain from processing pain!

57
Q

C fibres

A

unmyelinated - thin
- temp and pain receptors

58
Q

A delta fibres

A

mylelinated - thickish
tempp and pain

59
Q

A beta fibres

A

thick and fast, myelinated fibres
fine touch and pressure sensitive

60
Q

TRPV1

A

Nociceptor group - channels ( 1 is a subtype of the group)
Vanilloid receptor - ion channel receptor
Activated by different stimuli - physical, mechanical, chemical, acidic, various ligands, heat
CAPSAICIN (ingredient in hot peppers)

receptor responds to both pain and heat - explains feeling when eating spicy peppers

61
Q

Can a receptor be activated by both hot and cold?

A

No they are each on separate fibres - different receptors involved
heat r’s - ex = TRPV1

62
Q

What receptor is responsible for the initial sharp pain?

A

Vanilloid-like receptor (on large fibres)
activated at a higher temp

63
Q

Cold receptor

A

CMR1
TRPm8

activated by menthol
on small fibres

64
Q

Gate control theory

A

There is the same inhibitory interneuron involved in some touch and pain signal pathways

Painful stimuli - activate slow small C-fibres which turns OFF the inhibitory interneuron - get activation of the pain pathway- feel the pain

Touch stimuli .ex. rubbing - activates the fast and large alpha beta fibres - activates the inhibitory interneurons - INHIBITION PAIN PATHWAY

65
Q

Do internal organs have their own pain pathways to the brain?

A

NO - there is instead referred pain.
They synapse on spinal neurons that receive nociceptive information from body’s surface. So there is one set of neurons but two sets of inputs

Can’t tell the difference between pain in the left arm and pain in the heart.

66
Q

What is proprioception?

A

Information about body movement and position
Guides, refines, coordinates movements

67
Q

Muscle spindles

A

detects stretch

68
Q

gOLGI tendon organ

A

detects the tension at the end of the msucle

69
Q

what is another word for stretch reflex?

A

Myotatic reflex
The contraction of a muscle in response to its passive stretching

70
Q

Corticospinal tract

A

Pathway between the motor cortex and brain stem/spinal cord’

Most of the axons that form the tract originate from pyramidal cells in layer V of the primary motor cortex

Descend into the brain stem
- most cross over to the contralateral side and continue down the lateral corticospinal tract
- however some stay ipsilateral and continue down the ventral cortical spinal tract,

71
Q

Motor sequences

A

how complex behaviours are broken into according to Lashley,

they are movement modules preprogrammed by the brain and produced as a unit. ex. scratching the head

72
Q

Closed loop control in Executive control of movement

A

FOR SLOW MOVEMENTS
Uses feedback, maximizes accuracy
Usually involved in slow, smooth, sustained movements
move, adjust, repeat

73
Q

Open -loop system for executive control of movements

A

For faster movements - ballistic movements

Preprogammemd control that can be adjusted through learning

high firing rates and velcoities etc

74
Q

What happens when there is a lesion in the premotor area?

A

The premotor area coordinates simultanous motor programs - lesions abolish this coordination

All of the movements are still possible, just lose th coordination between them

75
Q

Primary motor cortex

A

Responsible for executing skilled movements with fine detail
Complex movements rely on the primary motor cortex
EXECUTES ACTIONS
ex. pincher grasp - highly skilled, requires the primary motor cortex, coordinates

but the power grasp is a low dexterity task and persists even if there is damage to the primary motor cortex.

76
Q

Which structures are involved in the modulation of movement?

A

Basal ganglia and the cerebellum

77
Q

What do the basal ganglia play a role in for movement?

A

Amplitude and direction of movement
Modulates patterns of activity generated in other cortical regions (MODULATORS)
Guide memory influenced behaviours

78
Q

Huntington’s

A

A HYPERKINETIC (fast movements) disorder
Damage to the caudate or putamen nuclei
Leads to unwanted movements (involuntary exaggerated movements - jerking, twitching, etc)

Larger lateral ventricles in these individuals

Genetic - trinucleotide repeat

79
Q

Parkinson’s

A

HYPOKINETIC DISORDER (slow/reduced movements)
loss of dopaminergic cells in the substantia nigra
Decreased output to caudate and putamen
Inabability to produce normal movements - hard to initiate movements

Treatments

L-DOPA , deep brain stimulation

80
Q

Muscular atrophy

A

Movement disorder
Muscle wasting
Duchenne’s disease - X linked trait, early onset

81
Q

Myasthenia Gravis

A

aUTOIMMUNE, movement disorder
Attack of ACh receptors (essential for motor junctions and initiating movements)
Causes muscle weakness (head and face first, speech and breathing later)

Treat with immune system suppressors

82
Q

Amyloid Lateral Sclerosis (ALS)

A

Lou Gehrig’s Disease
Destroys motor neurons in the spinal cord and brain stem (without them, cannot move, muscles weaken)
Muscles will waste away without input
Cause is unknown (~10% hereditary)
Aging, toxins, virus, autoimmune, endocrine

83
Q

Acute flaccid paralysis

A

Spinal Damage
Affects mainly lower motor neurons
Reflexes absent and muscles waste
Various potential causes

84
Q

Approaches to spinal cord severing repair

A

Stem cells, central glial bridge
Neurotrophins - generate a healthy environment
Peripheral nerve bridge
If you have a peripheral nerve injury - help axons regrow

85
Q

Movement therapy

A

Following loss of function
Constraint induced
-Strengthen existing pathways (still-functioning pathways)
-Enhance cortex

86
Q

Brain computer interface therapy

A

fOLLOWING INJURY
Record brain activity, control muscles or exoskeleton
Train people to move their arm with their brain - have electrodes that report the brain activity - connected to the muscles
Cortex size dedicated to area moved will get larger with therapy/rehab

NEUR 321 (6 decks)

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