Motor Systems

Question 1

What did wolpert argue is the reason we have brains? What animal exemplifies this ideaology?

Answer 1

-we have brains to move
-the sea squirt when juvenile swim around looking for a comfortable rock to sit on where they can passively extract food from the water for the rest of their adult lives
-once they settle in the first thing they do is eat their own brains

Question 2

Since movement is critical to an animals survival and reproduction what does wolpert also argue? What does this help us with understanding?

Answer 2

that perception attention learning and memory evolved to support movement
-helps us with understanding how the motor systems can help us think differently about these other systems

Question 3

What three things is the motor system good at?

Answer 3

I. Hierarchically structured movement control
-reflexes are coded in central pattern generators
-some adaptation based on sensory feedback is also spinally mediated but much involves the cerebellum
-initiation/gating and goal related feedback related to action goals involves the basal ganglia

II. Prediction
-why you cant tickle yourself
error correction and motor learning

III. Representation
-response representations in motor cortex
-how you understand people

Question 4

Why do we need a motor cortex if the basal ganglia and the cerebellum are there?

Answer 4

goal plans

Question 5

What and where are central pattern generators?

Answer 5

-they are in the spinal cord and they can generate simple reflexive actions

Question 6

What was done on the study investigating investigating central pattern generators?

Answer 6

hindlimbs are disconnected from the brain via transection of the spinal cord but sensory feedback about relative position (the force of the ground on the paw the extension of muscles by stretching out on the treadmill) is coupled with rhythm generation to produce walking behavior without intervention from above the level of the spinal cord

Question 7

What controls non cerebral movement?

Answer 7

the cerebellum and the basal ganglia
- a wide variety of relatively complex and motivated behavior can be carried out without the cerebral cortex

Question 8

What did decerebrate cats exhibit?

Answer 8

multiple gait patterns

Question 9

What does controlled movement generally involve? How does this coordination seemingly appear, but what does it actually require?

Answer 9

coordination of a large number of muscles and joints
-this coordination seemingly appears effortless and ballistic, but actually requires considerable sensory feedback from proprioceptive, tactile, and visual sensory information

Question 10

What does damage to the cerebellum due to brain injury reveal in regards to the role of sensory feedback for voluntary movement in the cerebellum?

Answer 10

damage to the cerebellum due to a brain injury or disease reveals a critical role for cerebellar feedback for smooth volitional movements

Question 11

What is observed as a result of impaired cerebellar feedback due to a unilateral lesion of the cerebellum?

Answer 11

tremors are observed
-one hand is tremor and there is overcorrection and then have to undershoot and this correction is mediated by the cerebellum - has overall ataxia of right limbs

Question 12

What is the basal ganglia and what does it play a direct role in?

Answer 12

basal ganglia - caudate and SNr
-plays a direct role in motor initiation and selection

Question 13

What is another term for the caudate of the basal ganglia?

Answer 13

the striatum

Question 14

What is another term for the substantia nigra of the basal ganglia?

Answer 14

pallidum

Question 15

What does activity in the caudate do?

Answer 15

inhibits the substantia nigra

Question 16

What does inhibition of the substantia nigra cause?

Answer 16

tonically inhibits the superior colliculus a midbrain regions involved in eye movements

Question 17

What does the loop between the caudate and SN and superior colliculus and eye movements characterize?

Answer 17

the basal ganglia’s role in controlling a wide variety of behaviors

Question 18

What do some other complex loops involve?

Answer 18

the thalamus and cortex

Question 19

What is the relationship between the basal ganglia and reward feedback?

Answer 19

the basal ganglia are involved in encoding reward value as well as habit learning tasks
-that is why motor learning tasks are not a good test of learning in individuals with PD

Question 20

Since feedback in motor movements almost function as an error signal what are the two types of feedback present?

Answer 20

cerebellum - is my arm where i expected it to be? if not adjust
basal ganglia - did my movement result in an expected reward if nor adjust
CANNOT HAVE EXPECTATION WITHOUT SOME PREDICTION - SO SENSORY OUTCOMES CAN PREDICT THIS

Question 21

In the blakemore et al study in which you cannot tickle yourself what did it provide evidence for?

Answer 21

evidence for motor based sensory prediction

Question 22

What is the primary idea behind the blakemore et al study in which you cannot tickle yourself?

Answer 22

when you try to tickle yourself your motor system generates a prediction about the tactile consequences of your movements
-experience provides you with a pretty good model of what its going to feel like to touch your own palm so there no discrepancy between predicted and observed stimulation so no tickliness

Question 23

What was seen in the the blakemore et al study in which you cannot tickle yourself when they used a robot arm and got participants to tickle themselves by proxy?

Answer 23

-participants manipulate a tickling rod and a robot arm holding an identical rod over their other hand generates movement in real time
-at zero delay it is like they are tickling themselves but it you increase the delay you get a greater tickling sensation - so that by 200-300ms they are just tickled as if they are not producing the movement themselves (same as externally produced tickle)

Question 24

What as seen in the blakemore et al study in which you cannot tickle yourself when they rotated the angle of the robot arm?

Answer 24

also created a prediction error leading to a greater tickling sensation where 90 degrees is the same as externally produced

Question 25

In the blakemore et al study in which you cannot tickle yourself where in the brain was there increased activity when they caused tickling with delay and changed the rotation angle of the arm?

Answer 25

increased activity in the cerebellum

Question 26

What is prediction error a key component of?

Answer 26

-in procedural learning in the basal ganglia and midbrain dopmainergic system

Question 27

What are error signals generated by the cerebellum involved in?

Answer 27

learning new motor skills

Question 28

When people talk about muscle memory what are they talking about?

Answer 28

learning involving the cerebellum

Question 29

What was done in the Imamizu et al study where people had to learn to use a new tool in an fmri experiment? What was the tool?

Answer 29

-the tool was a mouse that moves obliquely to the direction of movement so moves 120 degrees away from how you move it

-initially activity is observed throughout the cerebellum which is thought to reflect the large error signal - after training a subset of cerebellar regions remain active even relative to the an error equalized baseline condition - they forced participants to go faster
-this is thought to reflect the acquisition of a new cerebellar circuit for this tool

Question 30

In the study conducted by graydon et al where they trained people to use a joystick which functioned normally or transformed their movements by 90 degrees (motor learning what did they see?

Answer 30

activity in the putamen was observed in addition to activity in the cerebellum during motor learning - aka there is cooperation between the basal ganglia and cerebellum in motor learning
-there are interactions between maintaining balance and doing complex cognitive behaviors

Question 31

What is the basal ganglia key for?

Answer 31

selection and initiation of motor outputs and for learning from reward feedback

Question 32

What is the cerebellum key for?

Answer 32

integrating online sensory feedback and for learning new motor skills

Question 33

If we have a cerebellum and basal ganglia why do we have a big chunk of cortex given to motor representations?

Question 34

What does the primary motor cortex have a direct line to? What do modules in motor cortex represent?

Answer 34

primary motor cortex has a direct line to spinal motor neurons
-modules in the motor cortex are organized to represent articulators rather than individual muscles

Question 35

What is over represented in motor cortex?

Answer 35

fingers lips jaw and tongue which relative to the trunk which is much larger but has little use for fine motor control

Reorganization of body parts - monkey sewn two finger together goes all the way down to motor cortex

Question 36

When recalling the roitman and shalden study in decision making what was a higher level of coherence in random dot motion display associated with?

Answer 36

activity encoding related to decision making in the LIP - also the fef and all the way down to the superior colliculus

Question 37

What was seen when gold and shalden combined random dot displays with stimulation in the fef?

Answer 37

-the gren arrow indicates the usual uniased direction of movement evoked by stimulation whereas the red (up) and blue (down) arrows show how the direction of movement is influenced by direction of coherent motion in dot display
-the magnitude of bias was directly related to coherence of motion

-SHOWS THAT information coming from world about the movement gets summed as a vector to make a new pattern of movement

Question 38

What was seen when gold and shalden combined random dot displays with stimulation in the fef for 0% coherence?

Answer 38

there is some deviation what is plotted is the magnitude of deviation so it is possible there is some drift during the random displays