7. Cognitive/Motor Flashcards
(139 cards)
1
Q
state of consciousness
A
level of arousal
2
Q
how is state of consciousness measured?
A
by behaviour and brain activity
3
Q
conscious experience
A
capacity to experience one’s existence
4
Q
what does ElectoEncephaloGraph (EEG) measure?
A
mainly measures activity of neurons located near the scalp in grey matter of cortex
5
Q
EEG components
A
frequency and amplitude
6
Q
what does frequency refer to in EEG
A
levels of responsiveness
7
Q
what does amplitude refer to in EEG
A
synchronous neural activity
8
Q
relaxed EEG characteristics
A
slow frequency with big amplitude
9
Q
alert EEG characteristics
A
high frequency with small amplitude: less synchrony
10
Q
stage 1 NREM sleep characteristics
A
low amplitude
11
Q
stage 4 NREM sleep characteristics
A
high amplitude, low frequency, more synchrony
12
Q
what happens to amplitude and frequency from NREM stage 1 to 4?
A
amplitudes become bigger and frequencies smaller
13
Q
REM sleep
A
- Rapid Eye Movement
- deepest sleep
- dreaming phases
14
Q
characteristics of REM sleep
A
- increased eye movement
- increased skeletal muscle inhibition = low muscle tone
- increased heart rate and respiration
15
Q
how does REM sleep appear on EEG?
A
low amplitude, high frequencies: resembles awake state
16
Q
sleep apnea
A
sudden reduction in respiration in REM sleep due to high muscle relaxation: tongue falls back, blocking respiration and wakes person up
17
Q
sleep cycle
A
- spend 30-45 min cycling through NREM stages of sleep
- go into REM sleep
- cycle again
18
Q
the amount of REM sleep we get decreases with…
A
age
19
Q
what regulates the state of consciousness?
A
the circadian rhythm
20
Q
Circadian rhythm is mediated by…
A
hypothalamus and Reticular Activating System
21
Q
awake state regulations from hypothalamus and reticular activating system
A
- reticular activating system activates aminergic neurons: norepinephrine and serotonin
- acetylcholine production deactivated
- hypothalamus increases histamine production
22
Q
Asleep state regulations from hypothalamus and reticular activating system
A
- reticular activating system activates cholinergic neurons: acetylcholine
- norepinephrine and serotonin production deactivated
- hypothalamus inhibits histamine production
23
Q
what mediates behaviour?
A
motivation and emotions
24
Q
what is the mesolimbic pathway?
A
reward pathway, motivation
25
what is the limbic system?
controls our emotions
26
what does the mesolimbic pathway involve?
- dopamine as primary neurotransmitter
- anatomically: locus ceruleus in reticular activating system + midbrain + prefrontal cortex
27
anatomy involved in limbic system
- olfactory bulb
- amygdala = emotional response
- hippocampus = memory
28
declarative memory
conscious experiences that can be put into words
29
knowing faces, names and facts is an example of what memory?
declarative memory
30
where is short-term declarative memory located?
hippocampus + other temporal lobe structures
31
where is long-term declarative memory located?
cerebral cortex
32
procedural memory
skilled behavior
33
learning how to juggle or ride a bike are examples of which memory?
procedural memory
34
where is short-term procedural memory located?
widely distributed
35
where is long-term procedural memory located?
basal nuclei + cerebellum + premotor cortex
36
which hemisphere is language most located on?
left hemisphere
37
brain areas involved in language
- Broca's area
- Wernicke's area
38
Broca's area is responsible for language...
production, articulation
39
Wernicke's area is responsible for language...
comprehension (written + spoken)
40
aphasia
language deficit
41
parietal damage can lead to
sensory neglect of contralateral side of the world
42
sensory neglect
sensory information processed normally but is ignored/doesn't exist in their visual field
43
limb extension..
increases the angle around the joint
44
extensor and flexor muscles during extension
- extensor muscle contracts (agonist)
- flexor muscle relaxes (antagonist)
45
limb flexion...
decreases the angle around the joint
46
extensor and flexor muscles during flexion
- flexor muscle contracts (agonist)
- extensor muscle relaxes (antagonist)
47
antagonist
relaxing muscle
48
agonist
contracting muscle
49
how is limb position maintained so there is no movement?
there's a balance between flexor and extensor muscle tension
50
motor neurons key points
- excitatory only
- release acetylcholine
- receive inputs mostly from interneurons in grey matter of spinal cord
51
2 types of motor neurons
- alpha
- gamma
52
what do alpha motor neurons innervate?
skeletal/extrafusal muscle
53
what do gamma motor neurons innervate?
muscle spindle/intrafusal muscle
54
spinal interneurons
receive information from many neurons to be transmitted to motor neurons in dorsal root
55
information received at spinal interneuron (6)
- tension monitoring
- pain
- proprioceptive feedback
- voluntary movements
- coordinate complex movements
- length monitoring
56
sensory afferent pathway
proprioception pathway: up the ipsilateral dorsal columns, branching at interneuron for inhibition
57
motor efferent pathway
1. descending motor commands (from brain) reach interneuron
2. then passed to motor neuron in ventral horn
3. motor efferent exits through ventral root
58
purpose of withdrawal reflex
to protect limbs from injury
59
2 parts of the withdrawal reflex
1. flexion withdrawal
2. cross extensor reflex
60
Withdrawal reflex
Flexion withdrawal
1. painful stimulus: nociceptors activated
2. nociceptors go through pain pathway, branching before the midline
3. ipsilateral extensor inhibited, ipsilateral flexor excited
cross extensor reflex
4. nociceptors at branching cross the midline
5. contralateral extensor excited, contralateral extensor inhibited
61
withdrawal reflex: ipsilateral extensor...
is inhibited: extensor muscle relaxes
62
withdrawal reflex: ipsilateral flexor...
is excited: flexor muscle contracts
63
withdrawal reflex: contralateral extensor...
is excited: extensor muscle contracts
64
withdrawal reflex: contralateral flexor...
is inhibited: flexor muscle relaxes1
65
irradiation
increase in rate and magnitude of withdrawal response with increased stimulus strength due to recruitment of interneurons
66
afterdischarge
difficulty to re-extend limb even after pain stimulus removed due to feedback loops in spinal cord maintaining withdrawal
67
withdrawal reflex is polysynaptic or monosynaptic?
polysynaptic: interneurons present between sensory input and motor output
68
is withdrawal reflex contralateral or ipsilateral?
both: ipsilateral on withdrawal reflex (same side as nociceptive input) and contralateral on cross extensor reflex
69
purpose of stretch reflex
to control muscle length
70
stretch reflex steps
1. tap below knee cap gently
2. activation of stretch receptor
3. stretch receptor pulls on patella, pulling on stretch extensor muscle
4. muscle length reported through proprioception pathway: ipsilateral dorsal columns
5. monosynaptic and polysynaptic branching in grey cortex:
- excitatory synapse on motor neurons innervating ipsilateral extensor
- inhibitory synapse through interneuron inhibiting ipsilateral flexor
6. leg kicks
71
how is muscle length reported?
- muscle spindle is in parallel with extrafusal muscle fiber so both are always the same length
- muscle lengthens = muscle spindle lengthens = increase in muscle spindle afferent activity
- reported to CNS
72
extrafusal muscle fibers are activated by...
alpha motor neurons
73
intrafusal muscle fibers are activated by...
gamma motor neurons
74
what do extrafusal muscle fiber produce?
force creating movement
75
Ia primary afferents
signal dynamic changes in muscle length due to stimulus changes
--> rapidly adapting
76
II secondary afferents
signal static muscle length (position)
--> non-adapating
77
which afferent (Ia or II) mediates the stretch reflex?
Ia primary afferents
78
how is muscle flexion generated?
- alpha motor neuron activity commands muscles to shorten
- muscle spindle also shortens
- muscle spindle collapses: sensitivity reduced so receptor stops working
79
how is spindle sensitivity maintained?
by alpha-gamma coactivation: gamma motor neurons cause intrafusal fibers to contract, stretching the muscle spindle
80
properties of stretch reflex
- resists changes in muscle length: sets muscle tone
- mono and polysynaptic
- feedback from muscle spindles
81
properties of muscle spindles
- report muscle length
- in parallel with extrafusal muscle fibers
- intrafusal muscle fibers maintain muscle spindle sensitivity
- alpha-gamma coactivation
- Ia and II afferents
82
purpose of inverse stretch reflex
to control muscle tension (voluntarily)
83
organ involved in inverse stretch reflex
golgi tendon organ
84
organ that responds to tension
golgi tendon organ
85
properties of golgi tendon organ
- in series with extrafusal muscle fibers
- reports muscle tension
- Ib afferents
- underlines inverse stretch reflex
86
how does golgi tendon organ control muscle tension?
when tension increases, collagen fibers looping around the free nerve endings pinch the free nerve endings, activating mechanically-gated ion channels
87
inverse stretch reflex steps
1. muscle contracts, increasing tension in extensor muscle
2. activation of golgi tendon organ
3. causes increased Ib afferent activity sending AP through dorsal root/column
4. branching in grey matter:
- excitation of motor neurons innervating ipsilateral flexor
- inhibition of motor neurons innervating ipsilateral extensor
88
inverse stretch reflex is polysnaptic or monosynaptic?
polysynaptic
89
stretch reflex is polysnaptic or monosynaptic?
both
90
inverse stretch reflex: ipsilateral flexor
contracts
91
inverse stretch reflex: ipsilateral extensor
relaxes
92
motor control hierarchy
1. higher centres consciously initiate movement
2. 2 main pathways down brainstem and spinal cord
3. motor neurons innervate muscle fibres or cranial muscles in brainstem
93
sensorimotor cortex =
primary motor cortex + somatosensory cortex
94
middle level composed of:
- sensorimotor cortex
- basal nuclei
- thalamus
- brainstem
- cerebellum
95
local level
brainstem and spinal cord
96
why is there an involuntary component to voluntary movements?
- to execute individual muscle contractions
- to make corrections based on sensory information while the movement is being executed
97
2 major pathways down the spinal cord
- corticospinal
- extrapyrimidal
98
Corticospinal pathway contols
skilled movements
99
Extrapyrimidal pathway controls
trunk and posture
100
voluntary control of movement steps
1. consciously initiate a movement
2. at premotor cortex: motion decomposed into individual muscle contractions required
3. at primary motor cortex neurons send information down spinal cord
4. somatosensory cortex regulates movement to sensory information received
101
central sulcus separates... from...
primary motor cortex from somatosensory cortex
102
somatotopic motor representation
size of body structures in primary motor cortex is proportional to the number of neurons dedicated to their motor control and to the degree of skill required to operate that area
103
corticospinal descending pathway
- originates in primary motor cortex
- compact, discrete fiber tract direct to spinal cord: directly involves alpha and gamma motor neurons and branching at interneuron
- crossed at medulla --> controls contralateral muscles
- extremities: mostly hands and feet
- controls skilled movements
104
corticospical descending pathway is mono or polysynaptic?
both
105
corticospinal controls ipsilateral or contralateral muscles?
contralateral
106
extrapyramidal descending pathway
- originates from neurons in brainstem
- diffused and indirect: several descending tracts via brainstem, only innervating interneurons in spinal cord
- crossed and uncrossed --> controls contralateral and ipsilateral muscles
- trunk + postural muscles
- controls upright posture, balance, and walking unconsciously
107
extrapyrimidal descending pathway is mono or polysynaptic?
polysynaptic
108
extrapyramidal controls ipsilateral or contralateral muscles?
both
109
muscle tone
resistance of skeletal muscle to stretch
110
how is normal muscle tone reflected on stretch reflex?
slight and uniform reflex
111
consequences of damage to motor descending pathways
- hypertonia
- spasticity
- rigidity
112
hypertonia
abnormally high muscle tone
113
spasticity
overactive motor reflexes
114
rigidity reflects
constant muscle contraction
115
why is stretch reflex much stronger when there is damage to descending pathways?
descending pathway branches into interneurons, which are mostly inhibitory
--> damage means no more inhibition of those interneurons
116
consequences of damage to motor neurons
- hypotonia
- atrophy
- decreased or missing reflexes
117
hypotonia
abnormally low muscle tone
118
atrophy
loss of muscle mass
119
basal nuclei
collection of cell bodies in CNS
120
basal nuclei function
helps determine specific movements needed to accomplish a desired action
121
2 basal nuclei movement disorders
- Parkinson disease
- Huntington disease
122
Parkinson disease
reduced dopamine input to basal nuclei
123
Parkinson's symptoms
- akinesia
- bradykinesia
- muscular rigidity
- resting tremor
124
akinesia
reduced movements
125
bradykinesia
slow movements
126
resting tremor
tremor stops only when person makes a movement with that shaking limb
127
Parkinson disease treatment
increasing dopamine concentrations in the brain
-> no cure
128
Huntington disease
genetic mutation that causes widespread loss of neurons in the brain, mostly in the basal nuclei
129
Huntington's symptoms
- hyperkinetic disorder
- choreiform movements
130
hyperkinetic disorder
excessive motor movements
131
choreiform movements
jerky, random involuntary movements of limbs and face
132
cerebellum functions
movement timing, planning and error correction + learning new motor slills
133
how is cerebellum linked to sensation?
it receives sensory information that goes through the brainstem (next to each other so information shared)
134
cerebellar deficits
- asynergia
- dysmetria
- ataxia
- intention tremor
135
asynergia
Smoot movements broken down into their individual components
136
dysmetria
unable to target movements correctly when trying to reach for something
137
ataxia
incoordination of muscle groups --> awkward gate
138
intention tremor
tremor only during voluntary movements
139
what is a symptom that isn't seen in patients with cerebellar deficits?
paralysis or weakness
--> still independent but can't learn skilled movements
