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NEUR2020 > Quiz 2 - Non-visual sensory, motor control, neuroplasticity > Flashcards

Quiz 2 - Non-visual sensory, motor control, neuroplasticity Flashcards

1
Q

What is the function of the auditory system?

A

To transduce sound energy into a neural signal, to transmit the neural signal to the brain and to process the neural signal to provide meaningful auditory information.

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2
Q

What does frequency and amplitude translate to?

A

Frequency translates to pitch and amplitude translates to loudness.

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3
Q

What is the threshold for sound detection in humans? What pitch do we lose later in life?

A

20 - 20,00 Hz - we lose pitches above 16,000 Hz after the age of 16

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4
Q

What are the three sections of the outer ear?

A

Auricle/ pinna, the auditory canal and the tympanic membrane.

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5
Q

What does the tympanic membrane do, and what is it attached to?

A

The tympanic membrane vibrates in response to air pressure changes from sound waves, and is attached to the middle ear ossicles.

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6
Q

What is the function of the ossicles?

A

The middle ear ossicles concentrate the vibrations of the tympanic membrane onto the oval window.

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7
Q

What is the overall increase in pressure from the middle ear to the inner ear oval window?

A

22 fold increase from the vibrations on the tympanic membrane.

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8
Q

What si the name of the membrane in the inner ear, and how is it structured?

A

The basilar membrane, and it has tonotopic structure - thicker at the beginning, high frequency sound, larger and thinner at the apex, low frequency sound.

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8
Q

How does the sound transduce to a nerve signal?

A

In response to a sound, the basilar membrane will move at a specific location, causing the hair cells in the Organ of Corti to move. The mechanical motion of the hair causes ion flow for sodium and potassium (sodium floods into the cell), causing an action potential to trigger down the auditory nerve.

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8
Q

What is the pathway of the auditory nerve?

A

Ipsilateral cochlear nuclei -> medial geniculate nucleus (in the thalamus) -> primary auditory cortex

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9
Q

What role do the superior olives play in audition?

A

The superior olives play a part in localising sound by detecting the sound differences and intensity coming into both ears.

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10
Q

Define interaural time difference, and the structure that detects it.

A

The time difference between sound coming in to the different ears. The medial superior olive detects and creates a map of time differences.

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11
Q

What is interaural intensity difference, and what structure detects it?

A

Interaural intensity difference is when the intensity of sound is different in each ear - the head can act as a block for sound to one ear. The lateral superior olives detects it.

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12
Q

How is the auditory cortex arranged?

A

Tonotopically, in line with the basilar membrane/ cochlear.

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13
Q

What are the three types of deafness that can arise as a result of auditory dysfunction?

A

Conduction deafness, sensorineural deafness and central deafness.

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14
Q

What structures are damaged to result in conduction deafness, and what are the treatments?

A

The external and/or middle ear are damaged, and hearing aids or bone conduction implants are treatments.

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15
Q

What structures are damaged to result in sensorineural deafness? What treatments are available?

A

The inner ear is damaged, causing the auditory nerve fibres to not be stimulated properly. Cochlear implants are the treatment, bypassing hair cells to stimulate the auditory nerve fibres directly.

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16
Q

What structures are damaged to result in central deafness?

A

The temporal cortex and brainstem are damaged by brain lesions.

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17
Q

What does the vestibular system do? Where is it located?

A

Vestibular system transduces signals about balance and position of the head and body. It is located in the inner ear.

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18
Q

What are the structures of the vestibular system, and what do they detect?

A

5 receptor organs that have hair cells that bend when we move, sensing accelerations of the head
3 semicircular canals (sense head rotations)
2 otolith organs (utricle and saccule) sense linear acceleration - horizontal movement and tilt

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19
Q

How does the semicircular canals detect head rotations?

A

The inertia of the endolymph fluid in the ampulla exerts force on the hair cells - the hair cells deforming either create depolarisation (incresae impulse frequency) or hyperpolarisation (decrease impulse frequency).

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20
Q

What is the vestibular-ocular reflex?

A

Head movements illicit compulsory eye movements to maintain fixation.

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21
Q

What receptor types are fastest and slowest?

A

Fastets - Non-stroking mechanoreceptors
Slowest - affective touch and slow burn nociceptors.

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22
Q

What is the dorsal column somatosensory pathway? What type of nerves do they have, and what speed of receptor does it detect?

A

Nerves come in to dorsal root of the spine -> travels up the dorsal column (ascends ipsilaterally) -> decussates in the hindbrain -> travels up the medial lemniscus to the thalamus -> projects to somatosensory area. It carries information about touch and proprioception - fast, large myelinated.

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23
Q

What is the anterolateral somatosensory pathway? What information does it carry, and what speed of receptor does it detect?

A

Enters spine from dorsal roots -> decussates immediately and travels up the spinothalamic tract (ascends contralaterally) -> feeds into thalamus then somatosensory cortex. It carries information about pain and temperature (slow, small myelinated or unmyelinated).

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24
Q

What type of organisation occurs in the somatosensory cortex?

A

Somatotopic organisation (when a specific part of the body is associated with a distinct location in the central nervous system) in both S1 and S2. - essentially homunculus

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25
Q

What is the purpose of the anterior and posterior Insular cortex?

A

Anterior IC - processes complex emotional and social cognitive processes
Posterior IC - processes sensation of heat, pain, nausea

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26
Q

What is a motor unit?

A

The motor neuron and the muscle fibres it innervates.

27
Q

What neurochemical is released to the muscles from the motor end plate?

A

Acetylcholine

28
Q

What do the dorsolateral tracts allow you to move?

A

Distal contraleteral parts of the body, such as independent movement of limbs. In monkeys, when this was cut, they could move their whole body but not independent limb movements (reaching for something).

29
Q

What do the ventromedial tracts allow you to move?

A

Posture and whole body movements.

30
Q

Where do signals descend to the muscles in the spinal cord?

A

Through two dorsolateral regions and 2 ventromedial regions.

31
Q

what are the two types of dorsolaterla tracts, and what are their differences?

A

The corticospinal tracts - direct tracts that decussate in the medulla.
Corticorubrospinal tracts - indirect tracts that decussate in the red nucleus of the midbrain tegmentum. These send signals to the contralateral face muscles.

32
Q

What are the two types of ventromedial tracts, and where do they decussate?

A

Ventromedial corticospinal - direct.
Cortico-brainstem-spinal - indirect.
They both decussate in the ventral horn of the spinal cord.

33
Q

What is the physiological cause of Parkinson’s disease?

A

Loss of neurons in the Substantia Nigra that project onto the putamen, meaning that dopamine signals are not released as well.

34
Q

What are the positive symptoms of Parkinson’s disease?

A

Tremor while resting, rigidity (resulting in a resistance to passive movements and a loss of righting reflexes), leaning (either backwards or forwards).

35
Q

What are the negative symptoms of Parkinson’s disease?

A

Hypokinesia (reduction in spontaneous movement), akinesia (slow initiation of movement), reduced range and scale of motion, hypophonia (dull, weak voice without inflections, slow speech), un-emotional expression.

36
Q

What are the two treatments for Parkinson’s disease?

A

L-Dopa pill and deep brain stimulation.

37
Q

How does the L-Dopa pill work, and what are the side effects?

A

L-Dopa is a precursor for dopamine, and works by compensating for the lack of dopamine from the Substantia Nigra. The side effects are disorientation, nausea and hypotension.

38
Q

What is deep brain stimulation, and how does it work?

A

Deep brain stimulation involves inserting an electrode into the subthalamic nucleus to adjust the electrical stimulation through the neurons. This releases more neurotransmitters, making up for the loss of cells in the Substantia Nigra.

39
Q

What is the physiological cause of Huntington’s disease?

A

Destruction of GABA-ergic neurons in the striatum (caudate and putamen). This results in progressive striatal atrophy, in which the medial caudate atrphies, then the putamen, then the tail of caudate.

40
Q

What are the first symptoms of Huntington’s disease?

A

Depression, anxiety, irritability, impulsivity, aggression.

41
Q

What are later onset symptoms of Huntington’s disease?

A
  • restlessness
  • poor coordination,
  • forgetfulness,
  • personality changes,
  • altered speech and writing,
  • poor motor dexterity,
  • athetosis and chorea.
42
Q

What is the physiological cause of Tourette’s syndrome?

A

An imbalance of GABAergic activity in the basal ganglia. Symptoms include intermittent involuntary tics and echolalia (involuntary voice outbursts).

43
Q

What is the management of severe Tourette’s?

A

Neuroleptics (drugs that block dopamine binding) such as haloperidol and risperidol.

44
Q

Where is the primary motor cortex located, and what movement does it control for?

A

The primary mtor cortex is located on the precentral gyrus of the frontal lobe, and is a convergence point of cortical motor signals. It controls simple movements (twitches).

45
Q

How is the primary motor cortex arranged?

A

In a homunculus formation (different body parts on different sections).

46
Q

What may result in damage to the primary motor cortex?

A

Hemiplegia, categorised by a loss of power in the body part represented at the point of damage - typically effects more distal parts of the body.

47
Q

Where is the secondary motor cortex in relation to M1, and what does it contain?

A

The secondary motor cortex is anterior to the primary motor cortex, and contains broca’s area.

48
Q

Where does the secondary motor cortex recieve signals from, and where does it send signals to?

A

It recieves signals from the association cortex and send signals to the primary motor cortex.

49
Q

What is the posterior parietal apart of (in motor systems), and where does it receive information?

A

It is a part of the sensorimotor association cortex, and receives signals from the sensory systems.

50
Q

What does the posterior parietal do?

A

It integrates knowledge of (positions of) objects, knowledge of position of body parts and directs attention.

51
Q

What deficits can result from damage in the posterior parietal?

A

Ataxia and impaired body representation.

52
Q

Where does the posterior parietal send information to?

A

Dorsolateral prefrontal association cortex, secondary motor cortex and the frontal eye fields

53
Q

What deficits occur after damage of the output from the posterior parietal?

A

Apraxia and contralateral motor neglect.

54
Q

What does the dorsolateral prefrontal association cortex do?

A

It is involved in the decision to make an action - it is not involved in the execution of the action itself.

55
Q

From where does the dorsolateral prefrontal association cortex receive it’s signals, and where does it send signals?

A

Receives from the posterior parietal cortex and sends to the secondary motor and primary motor cortex, and frontal eye fields.

56
Q

What is ataxia, when does it occur and what are the symptoms?

A

Ataxia is the inability to use visual infomation to guide movement of hands. The deficit is more severe in the periphery of the visual field. It occurs after parietal damage>
Symptoms - incorrect/ awkward movements, errors in accuracy.

57
Q

What is apraxia, and when does it occur?

A

Apraxia is the inability to move the body in a purposeful manner - disorder of skilled movement. The deficit follows parietal lobe damage.

58
Q

What is anterograde neural degeneration?

A

Degeneration from the point towards the synaptic terminals (the distal segment) - occurs quickly due to separation from metabolic centre

59
Q

What is retrograde neural degeneration?

A

Degeneration from the point back to the cell body (the proximal segment) - slow process

60
Q

What is trans-neural degeneration?

A

When damage spreads to neurons that are linked synaptically.

61
Q

What are the effects (physically and physiologically) of a concussion?

A

Physical effects: confusion, temporary unconsciousness, behavioural and cognitive issues
Physiological: Microtubules fracture, affecting neurotransmitter transport

62
Q

What are some cumulative effects of a concussion, and what syndrome mimics this?

A

Internal bleeds and linear and rotational forces that can lead to cell death. Punch-drunk syndrome - typically seen in boxers that demonstrate general cognitive deterioration.

63
Q

What are some of the effects of a closed head injury?

A
  • contusions -> bruises when the brain slams against the skull
  • haematomas -> bleeds, due to the shearing of blood vessels
  • damage the brain due to pressure -> Oedema - swelling due to pressure
  • cause midline shifts
  • loss of consciousness - downward pressure on brain stem, but also when brain moves forward, it tends to twist in the skull, disrupting brain stem functions including consciousness
  • epilepsy -> disrupted tissue can start to produce impaired neuronal activity
64
Q

How can a penetrating head injury lead to epilepsy?

A

The brain can become damage either through an internal mechanism (swelling, haematomas, bruises), through infections or the penetrating object -> all of which can lead to scarring, which leads to epilepsy

65
Q

What are the effect of strokes on the brain?

A

Strokes can infarcts (areas of dead tissue) - these areas are surrounded by the penumbra, which is alive but dysfunctional.

66
Q

What does cerebral hypoxia cause?

A

Cerebral hypoxia (a lack of oxygen to the brain) causes dysfunctions in the mitochondria, leading to neurotransmitter dysfunction and neuron death.

67
Q

Which can regenerate better and faster - the CNS or PNS?

A

PNS

NEUR2020 (4 decks)

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