Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

PN3313 > Motor Systems > Flashcards

Motor Systems Flashcards

1
Q

What are the 3 main categories of motor systems?

A

Reflexive - involuntary in response to peripheral stimuli
Rhythmic - occilating controlled by brain stem and spinal cord
Voluntary - goal directed, higher centres involved

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How is the motor system hierarchally organised?

A

spinal cord -> brain stem -> cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How does the brainstem feedback to other motor systems?

A
  • Feedback to cortex and spinal cord to regulate planning and execution
    (affected in Parkinsons, Huntington’s and Cerebral ataxia)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the two areas of output of the spinal cord?

A

Dorsal -> sensory

Ventral -> motor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the two different categories of motor neurons?

A

Lateral - limb buds

Medial - axial muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are local interneurons?

A

Confined to the same or adjascent segments, local networks and rythmic neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are propriospinal neurons?

A

Axons that project to distant segments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are projection neurons?

A

Axons that ascend to higher brain areas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the medial brainstem pathways?

A
  • Control basic posture control
  • Vestibulospinal, reticulospinal and tectospinal tracts
  • Terminate on ventromedial interneurons and some medial interneurons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the lateral brainstem pathways?

A
  • Goal directed
  • Lateral motorneurons
  • Dosolateral interneurons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does the cortex control?

A
  • Coordination of individual joint and whole limb actions
  • Complex goal directed and precise movements
  • Code parameters such as direction and force
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does the ventral corticospinal tract control?

A

Posture, ventral medial motor neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does the lateral corticospinal tract control?

A

Activates lateral neurons (limbs)

Loss of these affects fine digit control

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do the axons of the primary motor cortex ennervate?

A
  • Single neuron synapses with motor neurons innervating a number of muscles
  • Different groups activate different combinations of spinal interneuron networks
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are premotor areas influential in?

A

Complex movements, motor planning and learning

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are mirror neurons?

A
  • Discharge when motor act is performed and done by another individual
  • Activated also by sounds of task
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe the role of the basal ganglia in motor systems

A

Gets input from cortex which it relays through the thalamus
striotum - major recipient of inputs
globus pallidus - major output projections of the basal ganglia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the direct pathway?

A

Facilitates desired movement

  • inhibits GPi input (thalamus) and allows more activity in the cortex
  • Absent in Parkinsons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the indirect pathway?

A
  • Inhibits GP less

- Inhibits movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Define locomotion

A

Rythmic and alterating movements of the body which generate propulsion involving functional agonists

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

In limbed animals what are the two modes of locomotion?

A

Power stroke - stance (extensor)

Return stroke - swing (flexor)

22
Q

What were the earliest studies of locomotion?

A

Marey and Muybridge used high speed photography to show that horses had all legs off the ground at point during a gallop

23
Q

What changes during the different gaits in the locomotion of quadripeds?

A

Swing phase changes a little however stance phase becomes much shorter with speed

24
Q

What did Charles Sherrington propose?

A

That simple reflexes are the basic units of movement

25
What did T. Graham Brown find?
- Isolated spinal chords can still produce rythmic motor activity - Central pattern generators -> half centre hypothesis
26
What has been the more recent addition to the half-life hypothesis?
- Reflexes integrated with cpg to produce adaptive movements e. g sstimulation of high threshold, small diameter afferents in cat spinal chords treated with L-DOPA led to rythmic activity
27
What is the function of the mesencephalic locomotor region?
- Exites interneurons in the medial reticular formation - Axons descend to the spinal locomotor system via the ventrolateral funiculus - Increasing stimulation strength changes gait and speed of circuit
28
What are the descending pathways of locomotion in the brain?
- MLR activates locomotion - Processing of afferent signals involving the cerebellum refines the motor pattern - Limb movements guided by visual input
29
What are central pattern generators?
Rhythm generating networks which may be conveyed to pattern forming circuits for appropriate spatial and temporal muscle pattern activity
30
What is the output of central pattern generators determined by?
- Intrinsic properties e.g ion channels, neurotransmitters - Synaptic connectivity between neurons - Synaptic properties - Neuromodulation
31
Where is rostro-caudal delay found?
In invertebrates
32
What can the rhythmicity of a CPG reflect?
- Occilating neural networks | - Endogenous bursters (pacemaker cells)
33
What is the half-centre hypothesis?
Idea of 2 neurons that receive tonic exitation also exite inhibitory neurons connecting the two resulting in occilating activity (reciprocal inhibition) where the inhibitory neuron fatigues
34
What is the hyperpolarisation-activated inward current (Ih)?
- Mixed cationic (N+/K+) current activated by hyperpolarisation - Activates and deactivates slowly causing slow depolarisation - Can give rise to a post-inhibitory rebound potential
35
What are low voltage activated calcium currents(ILVA)?
- Transient (inactivating) Ca2+ currents activated at low v - Can also mediate post-inhibitory rebound potentils - Can boost membrane depolarisation threshold
36
What are transient K+ channels (IA)?
- Transient outward current - Require hyperpolarisation to remove inactivation - Can delay spike and burst initiation
37
What are persistent Na+ currents (INAP)?
- Non-inactivating persistent - Low activation threshold - Can contribute to plateau potentials - Help initiate depolarisation and are then important for maintenance
38
What are high voltage activated calcium currents (IHVA)?
- Activated by depolarisation from resting potential - Various subtypes with slow/little activation - Mediate persistent inwards currents which contribute to plateau potentials - Help initiate and main depolarisation and maintain it
39
What are slow non-selective cationic current (ICAN) ?
- Calcium activated current - Non-inactivating and persistent with no voltage sensitivity - Maintains depolarisation
40
What are two channels which contribute to the termination of action potential firing?
- Inactivation of fast inactivating sodium currents (INA) which inactivate when depolarised - KCa channels which produce long hyperpolarising pauses in activity
41
What is the Calcium activated K current (IKCA)?
- Activated by Ca2+ entry via voltage activated channels - Underlies post action potential hyperpolarisation (AHP) - Can control spike timing leading to spike frequency adaptation
42
How are isolated rodent spinal cords used to study locomotion?
- Early spinal tissue kept alive - Motor activity induced by stimulating brainstem or applying NMDA and serotonin or dopamine (older) - Attach electrodes to ventral roots of left and right extensor (L2 )and extensor (L5) - See alternating burst of activity
43
Where is the vertebrate CPG believed to be located?
- In the ventral horn of the spinal cord | - Distributed along the lumbar cord however has a rostrocaudal exitability gradient
44
How are interneurons studied in the vertebrate spinal cord?
- Identification of transciption factors involved in the differentiation of specific types of spinal neurons - Labeling of specific interneurons with fluorescent markers
45
What are genetic knock-outs?
Knock-outs of specific genes using homologous recombination to replace gene of interest with an inoperable version
46
How does the cre-lox system work?
- Cre mediates recombination between two loxP sites - Pair gene of interest with Cre and flank gene we want to cut out with loxP - Can be used for conditional deletion and expression at the level of specific tissues
47
What are the criteria for rhythm generating neurons in vertebrates?
Must be ipsilaterally projecting glutaminergic excitatory neurons
48
Why might HB9 expression neurons be rhythm generating?
- Glutaminergic with intrinsic bursting (revealed by TTX) - Rhythmically active in time with fictive locomotion - Coupled by gap junctions (allows coordination) - Ipsilaterally projecting neurons
49
What are the characteristics of Dbx-1 (V0) expressing interneurons and what might they be involved in?
- Have monosynaptic connections with motor neurons - knockout of these leads to increased number of cobursts between left and right - Could be involved in left-right coordination
50
What are V1 motor neurons and what do they appear to control?
- Express Pax6 and En1 - Inhibitory and ipsilareally projecting - When deleted locomotor burst duration increases and rhythm slows - could therefore control speed
51
What is the advatage of inducible silencing techniques?
Avoids compensation
52
What do deletions of activity during fictive locomotion suggest?
A layered organisation of the CPG with a central rythm generator (clock) and a bottom pattern forming layer which distribute this rhythm

PN3313 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions