Organization & Planning of Movements

Question 1

_______ information includes the position, velocity, and acceleration of the hand, joint angles, and lengths of muscles without reference to the forces that cause the movement

Answer 1

Kinematic

Question 2

______ information is concerned with the forces generated or experienced by our body.

Answer 2

Kinetic

Question 3

______ is the ability of a force to cause rotation on a lever. Muscle activations produces forces which act around a joint centre – joint torque

Answer 3

Torque

Question 4

Explain image

Answer 4

Coritcol voluntary control of behavior

The issue is that there is a lot of unconscious control of movement

The data does not occur in a serial manner

Question 5

Explain each image

Answer 5

A: Spatial orientation

B: Movement planning

C: Inverse kinematic transformation: calculation of a set of joint angles that can achieve the endpoint

D:Inverse dynamic transformation: calculation of joint torques to achieve the motion

Question 6

Understand the pathway of the motor cortex

Question 7

What are the characteristics of M1, primary motor cortex?

Answer 7

• part of a distributed network of cortical motor areas
• contains a heterogeneous population of neurons that contribute to the several operations required to convert a plan of action into the motor commands that execute the plan

Question 8

Explain this diagram

Answer 8

Corticomotorneurons activate complex muscle patterns through divergent connections with spinal motor neurons that innervate different arm muscles

• Single corticomotoneuron axon often branches and terminates on spinal motor neurons for several different agonist muscles (•can also influence the contractile activity of other muscles through synapses on spinal interneurons)
• This organization produces coordinated patterns of activity (muscle synergies: excitatory input to extensors and inhibitory input to flexors (and vice versa))

Question 9

What are the 4 principles of motor map organization?

Answer 9

1.Fractured somatotopy: individual movements are represented multiple times- facilitates formation of new muscle synergies to achieve different functional goals

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2.Area equals dexterity: movements that require greater skill occupy a larger portion of the map

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3.Interconnectivity: adjacent neurons are highly interconnected directly and via interneurons - facilitates formation of new muscle synergies

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4.Plasticity: the motor map is highly dynamic and influenced by training

Question 10

What are the functions of motor maps?

Answer 10

•Maturation of motor maps is associated with increased skill in motor performance during development

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•Disrupting the circuitry of motor maps (loss of synapses, interference with protein synthesis) without directly damaging the neurons causes inability to perform skilled movement

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•Rehabilitation and training restore the motor maps, which is associated with improved motor skill

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• Animals with high dexterity have proportionally larger motor maps
• Digit representation in primates
• Whisker representation in rats

Question 11

Explain this image

Answer 11

Activity of a motor cortex neuron correlates with changes in the direction and amplitude of muscle forces during wrist movements

Monkey flexes wrist under 3 load conditions. No load, the neuron fires before and during flexion.

Load opposed = activity and flexor of neuron increases

Load assist: both fall silent

The activity of motor cortex neuron is better related to the direction and level of forces during movement as opposed to wirst displacement

Question 12

Explain this image

Answer 12

The firing rates of many primary motor cortex neurons correlate with the level and direction of force exerted in an isometric task

Plotting neuronal acting when monkey doing isometric directional task

Neuron is mostly active when monkey is performing to the right

Question 13

Explain this image

Answer 13

The activity within the population of neurons shifts systematically with movement direction so that the vectorial sum of the activity of all cells is a population vector that closely matches that of the direction of movement

Question 14

Explain this image

Answer 14

• The population vector activity precede the hand displacement vectors by approximately 100 ms
• Encoding direction and speed of movement

Question 15

What are the characteristics of SMA proper and Pre SMA? (Supplementary motor area)

Answer 15

• discharge before and during voluntary movements.
• Readiness potential recorded over the SMA during self-generated movements: 0.8 –1 s before movement onset (Intention to move?)

Question 16

True or False: activity of most SMA neurons is less tightly coupled to particular actions of a specific part of the body

Answer 16

True, and instead appears to be associated with more complex, coordinated motor acts, and action sequence

Question 17

How does SMA may have a key role in contextual control of voluntary behavior

Answer 17

• selecting and executing actions deemed appropriate on the basis of different combinations of internal and external cues as well as withholding inappropriate actions
• SMA may have a direct influence on the long latency reflexes (LLR) and/or ‘presets’ M1 activity according to task instruction prior to perturbation onset (Scott 2015)

Question 18

Explain this image

Answer 18

Reaching movement is represented differently in the premotor and primary motor cortex during planning and execution of movement

Shows the directional sensitivity of a neuron

Premotor cortex neuron is active regardless of which hand is moving

The primary motor cortex is active more in the contralateral movement

Question 19

Explain this image

Answer 19

Neural processes related to movement planning and movement execution

B: In the instructed delayed cue, in the delay period many premotor cells show directionally tuned changes in activity that signal the direction of the impending movement

Question 20

Reaching is in the ____ premotor area and grasping is done in the _____ pre motor area

Answer 20

dorsal, ventral

Question 21

Explain this image

Answer 21

Some neurons in the parietal and premotor cortex respond to both tactile and visual stimuli

VIP important for things coming close to our body

Question 22

Explain image

Answer 22

PMv (ventral premotor) neuron

Activatged more by ring shape

Question 23

Explain this diagram

Answer 23

PMv is involved in operations required to choose a motor response based on sensory information

Green shows the correlation with f1, red the correlation with f2, black the interaction between f1and f2, and blue the correlation with the difference between f2–f1.

Question 24

What are mirror neurons

Answer 24

Neuron active when monkey graspa an object, same neuron excited when monkey observes another onkey grab object, activated when human grabs the object

Question 25

Explain diagram

Answer 25

Mirror neurons in the IPL of monkey are activated when monkey observes a motor act, more storngly when grassped to eat

Question 26

What are the three major categories of neurons in the anterior intraparietal area?

Answer 26

Motor dominant, visuomotor, visual dominant

Question 27

Explain image

Answer 27

The activity of functionally distinct parietal motor neurons varies with the purpose of grasping action

Question 28

Explain

Answer 28

Motor Control Processes Contributing to Skillful Motor Performance

A: Feedforward generates a motor command based on desired state

B: Feedback control, the desired and sensed states are compared to generate a error signal, which helps shape motor command

Question 29

Explain image

Answer 29

Inverse model: calculates motor outputs from sensory inputs

Forward model estimates future sensory inputs based on motor outputs

If the parameter value of forward and inverse model are correct, the output of the forward model (ie predicted behaviour) will be the same as the input to the inverse model

Question 30

Know diagram