ch. 14 - brain control of movement Flashcards
(63 cards)
1
Q
the brain influences activity of…
A
the spinal cord
- voluntary movements
2
Q
strategy
A
association areas of neocortex, basal ganglia
3
Q
tactics
A
motor cortex, cerebellum
4
Q
execution
A
brain stem, spinal cord
5
Q
sensorimotor system
A
sensory info used by all levels of the motor system
6
Q
lateral pathways
A
- voluntary control of distal musculature
- under direct cortical control
7
Q
ventromedial pathways
A
- control of posture and locomotion
- under brain stem control
8
Q
coritcospinal tract (pyramidal tract)
A
- crosses at junction of medulla and spinal cord
- terminate in dorsolateral region of ventral horns and intermediate gray matter
9
Q
rubrospinal tract
A
- starts in midbrain at the red nucleus
- crosses over in pons
- travels with axons of corticospinal tract
- role reduced in humans
10
Q
lesions in lateral pathways cause…
A
- deficit in fractionated movement of arms and hands
- paralysis on contralateral side after stroke
11
Q
ventromedial pathways
A
- originate in brain stem
- terminate on spinal interneurons controlling proximal and axial muscles
- use sensory info to maintain balance
12
Q
vestibulospinal tracts
A
- head movements and balance
- from vestibular nuclei of the medulla
- one projects bilaterally down spinal cord to cervical circuits (head and back muscles)
- other ipsilaterally to lumbar spinal cord (upright and balanced posture)
13
Q
tectospinal tract
A
- from superior colliculus (input from vision, somatosensory, auditory)
- produces orienting response
14
Q
pontine reticulospinal tract
A
- originate from reticular formation of the brainstem,
- controlled by cortex
- enhances antigravity reflexes of the spinal cord
15
Q
medullary reticulospinal tract
A
- originate from reticular formation of the brainstem,
- controlled by cortex
- liberates antigravity muscles from reflex
16
Q
what areas make up the motor cortex?
A
4 and 6
17
Q
area 4
A
primary motor cortex or M1
18
Q
area 6
A
higher motor area
19
Q
premotor area (PMA)
A
- lateral region
- connects to reticulospinal neurons that innervate proximal motor units
20
Q
supplementary motor area (SMA)
A
- medial region
- axons to distal motor units directly
21
Q
before motor actions, must have info from…
A
- somatosensory
- visual
- proprioceptive
22
Q
area 5 receives input from…
A
areas 3, 1, 2
23
Q
area 7 receives input from…
A
higher order visual cortical areas (like MT)
24
Q
anterior frontal lobes
A
abstract thoughts, decision making, and anticipating consequences of action
25
area 6
actions converted into signals specifying how actions will be performed
26
per roland
monitored cortical activation accompanying voluntary movement (PET)
27
evarts
demonstrated importance of area 6 in planning movement
28
"ready"
parietal and frontal lobes
| attention and alertness
29
"set"
SMA and PMA
| strategies devised
30
"go"
area 6
31
basal ganglia is made up of..
- caudate nucleus
- putamen
- globus pallidus
- subthalamic nuclei
- substantia nigra
32
basal ganglia aids in...
selection and initiation of willed movements
33
basal ganaglia: input and output
- striatum receives input from cortex
| - globus pallidus output to thalamus
34
basal ganglia gives input to..
VL nuclues
35
basal ganglia motor loop
cortical activation of putamen excites SMA and gives "go" signal
36
hypokinesia
increased inhibition of the thalamus by basal ganglia
37
hyperkinesia
decreased output of basal ganglia
38
parkinson's
- hypokinesia
| - trouble initiating willed movements due to increased inhibition of thalamus (VL) by basal ganglia
39
symptoms of parkinson's
- bradykinesia (slow)
- akinesia (difficulty starting)
- rigidity and tremors of hand and jaw
40
organic basis of parkinson's
degeneration of dopaminergic substantia nigra inputs to striatum, so no release of VL from inhibition
41
dopa treatment
facilitates production of dopamine to increase SMA activity
42
huntington's disease symptoms
- hyperkinesia
- dyskinesia (abnormal movement)
- dementia
- impaired cognitive ability
- personality disorder
43
chorea
spontaneous, uncontrollable and purposeless movements with fast irregular flow, flicking movements
44
hemiballismus
- hyperkinesia
| - violent, flinging movement on one side of the body
45
general role of basal ganglia
- focus activities from widespread regions of the cortex onto the SMA
- serve as filter to prevent inappropriate movements from being expressed
46
M1
lowest threshold for elicitation of movement by electrical stimulation (strong connections to motor neurons and spinal interneurons)
47
betz cells
pyramidal cells in cortical layer 5
48
sources of input to betz cells
- cortical areas ( 6 and 3, 1, 2)
| - thalamus (which relays info from the cerebellum)
49
betz cells project to...
spinal cord and brain stem
50
force and direction of movement is encoded by...
activity from several neurons in M1
51
where are all cells active for every movement?
motor cortex
52
activity of each cells represents
a single vote
53
direction of movement
determined by a tally and averaging
54
malleable motor map - experimental rats
- microstimulation of M1 cortex normally elicits whisker movement
- cut nerve that supplies whisker movement
- microstimulation now causes forelimb movement
55
cerebellum
control sequence timing of muscle contractions
56
cerebellar lesions produce
- ataxia
- uncoordinated
- inaccurate movements
57
dysynergia
decomposition of synergistic multijoint movements
58
dysemtria
overshoot or undershoot target
59
anatomy of cerebellum
- folia and fissures increase surface area
- divided into 10 lobules
- 10% of brain volume, more than 50% of neurons
60
vermis
- divides hemispheres
| - sends output to brain stem area that contribute to ventromedial pathways (axial musclature)
61
cerebral hemispheres
contribute to lateral pathways, especially cerebral cortex
62
motor loop through lateral cerebellum
- layer V pyramidal in sensorimotor cortex project to pons
- potine nuclei project to cerebellum
- lateral cerebellum projects back to motor cortex via thalamus
63
importance of motor loop through lateral cerebellum
- proper execution of planned voluntary multijoint movements
- movement, direction, timing, force
