Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Neuroscience 🧠 > Chapter 14: Brain Control of Movement > Flashcards

Chapter 14: Brain Control of Movement Flashcards

1
Q

The Major Tracts

Describe the characteristics of the corticospinal tract

A
  • Decussation in medullary pyramids; Contralateral motor control
  • Pathway carrying motor info from primary to secondary motor cortices to the brain stem and spinal cord
  • One of the largest and longest axon tract in the CNS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The Major Tracts

What are the two major pathways and what are the functions?

A
  1. Lateral Pathway - voluntary movement of distal musculature
  2. Ventromedial pathways - control of posture and locomotion; upper motor neurons are in brainstem
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The Major Tracts

Describe the characteristics of the Rubrospinal tract

A
  • Originates in the red nucelus of the midbrain
  • **Receives input from frontal regions that contribute to corticospinal tract **
  • Axons decussate in pons
  • Runs parallel to corticospinal tract
  • Function is largely reduced in humans
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The Major Tracts

What is the Babinki sign and what does it test?

A
  • Easy test for motor tract damage
  • If the toes curl in adults then ur fine but if it doesnt then ur not okay
  • This tests the cortiospinal tract
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

The Major Tracts

What are the four ventomedial pathways?

A

They all originate in the brain stem
1. Vestibulospinal tract
2. Tectospinal trat
3. Pontine Reticulospinal tract
4. Medullary reticulospinal tract

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

The Major Tracts

Describe the Tectospinal tract

A
  • Originates in the superior colliculus (optic tectum) of midbrain
  • Recieves direct projections from retina
  • Orienting response to project image on the fovea
  • Axons decussate after immediately leaving superior colliculus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Motor Cortex

What is area 4?

A

The primary motor cortex (M1)
* Stimulation leads to muscle twitches on contralateral side

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

Motor Cortex

What is area 6?

A

Higher Motor area (Penfield)
- Stimulation leads to more complex movement
- There are two parts
1. Lateral region: premotor area (PMA)
2. Medial Region: Supplementory area (SMA)

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

Motor Cortex

What are mirror neurons?

A

Some neurons in BA6 (PMA) respond when watching another monkey making the same movements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The basal ganglia

What are the characteristics of the basal ganglia?

A
  • Globus pallidus (internal & external )
  • Subthalamic nucleaus
  • Caudate nucleaus + Putamen = Striatum
  • Striatum is the target of cortical input to the bg
  • GP is the source of output to the thalamus
  • Substantia nigra sends DA input to striatum and the process starts over.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The basal ganglia

What does the basal ganglia do?

A
  • Projects to the ventrl lateral (VLo) nucleus of thalamus
  • Provides major input to BA6
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

The basal ganglia

Describe the motor loop

A

Cortex
* Projects back to basal ganglia
* Froms a loop. Cotical-striatal-thalamo-cortical (CSTC)
* Invovled in the selection and initiation of willed moevements
* Cortex—>Basal ganglia—>VLo—>Cortex

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

The basal ganglia

Describe the characteristics of the basal ganglia’s direct pathway

A

Selects appropriate motor actions
Cortical Activation:
* Excites putamen
* Inhibits internal globus pallidus (Gpi–spontaneously active at rest)
* Releases VLo from Gpi
* Acivity in VLo increases activity in BA6

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

The basal ganglia

Describe the characteristics of the basal ganglia’s indirect pathway

A
  • Antagonizes motor functions of the direct pathway
    * Suppresses competing and innapropriate motor programs
  • Includes the GPe and Subthalamic nucleus (STN)
    - cortex activates striatum
    - Striatum inhibits GPe
    - Lead to release of inhibition of GPi and STN
    - Activation by cortex inhibits the thalamus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

The basal ganglia

Summarize the basla ganglia all together

A
  1. Info flows parallel
  2. Regulates motor thalamus
  3. Direct pathway: selects appropriate motor actions
  4. Indirect pathway: suppresses competing and innapropriate motor programs.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Basal ganglia disorders

What are major disorders and describe them

A
  • Parkinsons Disease and Huntington’s Disease
  • Neurodegenerative diseases

Chracterized by:
* Hypokineasia - paucity of movement ( parkinson’s disease)
* Hyperkineasia - excess of movement (huntington’s disease)

17
Q

Basal ganglia disorders

Go more in-depth about Parkinson’s disease

A
  • Trouble initiating willed movements
  • Symptoms: Hypokinesia Bradykinesia (slowness of movement), rigidity, temors of hand and jaw
  • Lack of DA input to striatum
  • Increased inhibition of the thalamus by basal ganglia
  • Sustained tonic inhibition from GPi to thalamus
  • Thalamus is less likely to excite motor neurons
  • Inhibition wins
18
Q

Basal ganglia disorders

Go more in-depth about Huntington’s Disease

A
  • Polyglutamine disease
  • Symptoms: Chorea, hyperkineasia, dyskinesias, dementia, personality changes
  • Loss of neurons in caudate nucleus, putamen, globus pallidus
  • consequent loss of inhibitory input to the thalamus
    *Excitation wins
19
Q

Basal ganglia disorders

desribe huntington’s disease BG circuit

A
  • Projection from striatu to GPe is diminished
  • Increases inhibition to STN & GPi
  • Thalamic excitation is increased
  • Excitation wins
20
Q

Control of Movement in Primary Motor Cortex

Why is broadman’s area 4 designated as PMC or Primary Motor Cortex?

A

It has the lowest threshold for eliciting movements from electrical stimulation.

21
Q

Control of Movement in Primary Motor Cortex

What happens in Cortical layer V?

A

It is the pathway where motor neurons activate LMNs.
Betz Cells
* Largest pyramidal cells
* Projects to pools of LMNs (lower motor neurons) and excites them
* Branches and excites local inhibitory interneurons
* Provides reciprocal inhibition or flexors qand extensors of the muscle/joints.

22
Q

Control of Movement in Primary Motor Cortex

How are the commands to perform precise movements encoded in the activity of the upper motor neurons?

A
  • We record pyramidal cells during visually guided reaching movements then observe a burst of activity immediately before and during voluntary movement.
  • Encodes both force and direction
  • **Movement direction tuning of individual M1 neurons is broadly tuned so cells can respond best to a particular direction of motion. **
23
Q

Control of Movement in Primary Motor Cortex

What encoded movement of direction?

A
  • Collective Activity of neurons -** Population coding **
  • Motor cortex: most cells active for every movement
    * Activity of each cell represents a “vote” and the direction of movement is determined by an average of all votes by each cell in the population
  • the larger the population of neurons representing a type of movement, the finer the potential control.
24
Q

Control of Movement in Primary Motor Cortex

Can M1 cells switch from participating in one type of task to another?

A

Yes!
**Plasticity ** in the adult motor cortex
* For example, if we cut a mouse whisker then the there would still be microstimulation that causes eye or forelimb movements.

25
Q

The Cerebelllum

What is the anatomy of the Cerebellum?

A
  • Folia and lobules which serve to increase surface area
  • Deep cerebellar nuclei which relays cerebellar cortical output to brain stem structures
  • Vermis: midline ‘bump’
  • axial musculature
  • contributes to ventromedial pathways
  • Cerebellar hemispheres: limb movements
  • Contributes to lateral pathways
26
Q

The Cerebelllum

What is the function of the cerebellum?

A
  • Coordinate a detailed sequence of muscle contractions
  • maintains fluidity of muscles
27
Q

The Cerebelllum

What are the three cerebellar lesions?

A
  1. Ataxia: uncoordinated and inaccurate movements (Looks like u drunk)
  2. Dyssynergia: Decomposition of synergistic multi-joint movement (move like a lil barbie)
  3. Dysmetria: Overshoot or undershoot target
    - Dyssynergia and dysmetria are characteristic of alcohol intoxication.
28
Q

The Cerebelllum

Describe granule cells

A
  • Tiny excitatory neurons
    *dominate cells in cerebellum
29
Q

The Cerebelllum

What are purkinje cells?

A
  • Largest neurons in the cerebellum
    *** Recieves excitatory input from granule cells in the moleculr layers
  • Sends inhibitory axon to deep cerebellar nuclei. **
30
Q

The Cerebelllum

Describe the motor loop through the lateral cerebellum

A

Input to pontine nuclei
* Axons from layer V pyramidal cells in the sensorimotor cortex send massive projections to pons which then go to the cerebellum for processing called the corticopontocerebellar projection
* The cerebellum then projects back to the motor cortex via deep cerebellar nuclei and VL thalamus and then projects back to mtor cortex.

31
Q

The Cerebelllum

Why is the cerebellum a sit of motor learning?

A
  • Instructs the primary motor coretx
  • Uses past experience to make predictions about outcome

Neuroscience 🧠 (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions