Psy 256 Movement

Question 1

Describe the general sequence of activation in the different brain areas involved in movement.

Answer 1

-the prefrontal cortex of the frontal lobe plans movements, the premotor cortex organizes sequences of
movements, the motor cortex executes specific movements

Question 2

Is sensation necessary for movement? What sensory areas are critical? What is apraxia and ataxia?

Answer 2

-key sensory areas for movement are primary somatosensory cortex (S1, post central gyrus) and the
posterior parietal cortex (PPC; space)
-Damage to PPC can cause apraxia (inability to initiate voluntary movements), ataxia (lack of
coordination and accuracy), and spatial neglect.

Question 3

Name the 4 main regions of the spinal cord. What condition would be produced by a complete cut to
the middle of the thoracic region?

Answer 3

-Five major regions of spinal cord: cervical, thoracic, lumbar, sacral and coccygeal
- a cut to the middle of the thoracic would lead to brain commands no longer would reach the lumbar nerves
controlling the legs. (legs would be paralyzed)

Question 4

What is the difference between upper and lower motor neurons?

Answer 4

-upper motor neurons (from brain to spinal cord)
-lower motor neurons (from spinal cord to muscles)

Question 5

What are alpha motor neurons, where do they originate, and from what part of the spinal cord do they
emerge?

Answer 5

alpha motor neurons (1 of 3 main kinds of lower motor neurons) exit at different regions of the spinal cord to control movement of different body parts

Question 6

What is the corticospinal (pyramidal) tract? Is it white natter or grey matter?

Answer 6

-main pathway from voluntary motor movements
-white matter

Question 7

Define neuromuscular junction and motor unit.

Answer 7

-neuromuscular junction is where a neuron & muscle fiber synapse; motor unit is a set of muscle fibers
innervated by one motor neuron (gross=many, fine=fewer)

Question 8

What NT and what receptor type is used at the NMJ to
trigger muscle contractions? What enzyme is used to deactivates this NT?

Answer 8

-NT that triggers muscle contractions is Acetylcholine (Ach)
-Acetylcholinesterase is the enzyme that breaks down Ach to stop its effect on target muscle

Question 9

What is a muscle fiber? A tendon? Flexors & extensors? Antagonistic vs synergistic muscles?

Answer 9

-skeletal (striatal) muscles are made up of thousands of muscles fibers and are attached to the bones by
tendons
- some muscles (biceps) bring bones together (flexor), others (triceps) move them apart (extensors)
-antagonistic muscles move in opposite directions; synergistic muscles work together to complete some action (push-up)

Question 10

What are muscles spindles and Golgi tendon organs? What do they do?

Answer 10

-muscle spindle help with strength and length detection
-Golgi tendon organs help with tendon tension

Question 11

Described the crossed extensor reflex.

Answer 11

-crossed extensor reflex allows us to keep our balance when we must quickly withdraw a leg (e.g. injury),
this is mediated by the local spinal cord neurons within the spinal cord

Question 12

What does this reflex tell us about the organization of our motor
system? What are local spinal cord neurons & central pattern generators. Are they under PFC control?

Answer 12

-central pattern generators mediate repetitive behaviors such as walking, chewing, and breathing
-shows how the motor system is organized hierarchically

Question 13

What are corticospinal vs corticobulbar neurons?

Answer 13

-corticospinal neurons send signals from the primary motor cortex to the spinal cord; corticobulbar
neurons send signals from the primary motor cortex to the brainstem and cranial nerves to control head, neck, & face movements

Question 14

Where do corticospinal neurons become contralateral?

Answer 14

-axons of most corticospinal neuron’s cross sides in the medulla and then continue down the spinal cord. So the left motor cortex primarily controls right-side body movements and vice versa

Question 15

Where is the primary motor cortex (M1) located?

Answer 15

-primary motor cortex (M1) is in the precentral gyrus

Question 16

How many layers are there in the cortex? From which layer do motor neurons project out of M1?

Answer 16

-6 layers in the cortex
-neurons project out of V and VI layers

Question 17

What does it mean to say that M1 has a somatotopic organization?

Answer 17

-somatotopic organization means the amount of tissue reflecting the amount of motor control
associated with the relevant body part

Question 18

What is the motor homunculus?

Answer 18

-motor homunculus is a topographic representation of the body parts and its correspondents along the
precentral gyrus of the frontal lobe

Question 19

What happens when regions of this homunculus (M1) are stimulated
for a prolonged (.5 s) period of time. What does that suggest about the organization of M1?

Answer 19

-monkeys carried out a particular behavior; hand movement to the mouth as eating; eyes closed and
hand raised as if defending against threat; and other behaviors
-specific behavior depended upon which cortical area was being stimulated

Question 20

What brain regions make up Premotor areas? What appears to be the main functions of these areas?

Answer 20

-the premotor areas are anterior to M1 and include the dorsal& ventral premotor areas, and
Supplementary Motor Area (SMA)

Question 21

What happens when neurons in the SMA are stimulated?

Answer 21

-When neurons in the SMA are stimulated when a person feels the desire to make a specific movement, increased activity/stimulation of that area leads to actual motor movement

Question 22

What are the frontal eye fields, and how are they related to the superior colliculus?

Answer 22

-Frontal eye fields (BA8) which control voluntary eye movements related to current (PFC-based) goals
(cf. the superior colliculus)

Question 23

What happens when the SMA or inferior parietal cortex are stimulated?

Answer 23

-Electrical stimulation of the inferior parietal lobe (IPL) produces feelings of “wanting to move” but
additional stimulation doesn’t not trigger movement

Question 24

What happens when the SMA or inferior parietal cortex are
damaged?

Answer 24

-Damage to SMA or IPL may show a reduced desire to carry out motor actions or alien hand syndrome

Question 25

What is alien-hand syndrome?

Answer 25

-alien hand syndrome is a condition in which their hand or other body part makes movements that are
not intended when this occurs M1 is active but SMA and IPL aren’t

Question 26

What are mirror neurons? Where were they first discovered? To what abilities are they related?

Answer 26

-mirror neurons provide a bridge between observation and action, thus a mechanism for imitation
-discovered in monkeys, mirror-neuron-like activity is also observed in humans e.g. in premotor areas
linked to smiling

Question 27

Where is the PFC; how is it defined?

Answer 27

-PFC is critical for stopping/inhibiting behaviors which is necessary both to avoid errors and to allow less
automatic actions to be performed

Question 28

What is utilization
behavior?

Answer 28

-Utilization behavior refers to cases where a part usually with frontal lobe damage
automatically/impulsively uses objects put in front of them (pens,glasses,etc.)

Question 29

What 3 structures make up the basal ganglia? Which 2 are together known as the striatum? What
behaviors are mediated by the BG? What does it mean to say that the BG form a “loop”? What are
the structures in this loop? What NT is key to BG function and from what area is this NT projected?

Answer 29

-3 structures are the Caudate & Putamen (striatum) which act as main input to basal ganglia circuitry,
and Globus Pallidus which is main output structure.
- behaviors mediated by basal ganglia is movement, behavior, and emotions
-loop (cortex>striatum>GP>thalamus>motor areas of front lobe) modify signals sent to muscle
-Dopamine is a key neurotransmitter for the BG and is supplied by substantia nigra, lack of DA input, as in PD, causes difficulties with voluntary movements

Question 30

Describe the 3 major functions of the cerebellum. What is predictive processing?

Answer 30

-3 major functions are increasing coordination and accuracy of movements, timing of movements,
predicting consequences of actions (predictive processing) and signaling when those predictions are
wrong (error detection)