5.2.1 Central Motor Systems II

Question 1

What is a Jacksonian Seizure?

Answer 1

form of focal epilepsy where epileptic events travel across the homunculus, often beginning at the fingers and then travelling proximally

Question 2

What are the characteristics of syndrome of neglect?

Answer 2

• Caused by lesions in parietal cortex
• Results in inability to respond to stimuli on the contralateral side of body or in the contralateral visual field
• Characteristics:
• Neglect of contralateral arm and objects in contralateral visual field
• Apraxia: difficulty manipulating objects
• Astereognosis: failure to recognize objects placed in hand
• Errors in accuracy of arm movements
• Difficulty performing discrete finger/hand movements requiring visual cues

Bilateral lesions will produce bilateral deficits, and tend to be more severe

Question 3

What is the general pattern for the flow of information in the primary motor cortex

Answer 3

General pattern of information flow: basal ganglia + cerebellum + parietal cortex –> SMA and premotor cortex –> primary motor cortex –> corticospinal output to motoneurons.

Question 4

How does rCBF change in simple repetitive finger flexion?

Answer 4

• Primary Motor Cortex – due to finger movement
• Somatosensory Cortex – due to sensation of fingers touching

Question 5

What is plasticity in regards to the Primary motor cortex?

Answer 5

-Plasticity, or the enlargement of the motor cortex, can be achieved when new motor patterns are learned and practiced

Question 6

How is force encoded by motor cortex neurons?

Answer 6

Question 7

What precedes the movement of a muscle?

Answer 7

Motor cortex discharge

Question 8

What are the characteristics of M1 (Area 4) of the motor cortex?

Answer 8

• Located in the precentral gyrus of the frontal lobe
• Responsible for the execution of movement
• Transfers programmed patterns of outputs to motoneurons in the brainstem and spinal cord to cause voluntary movement

Question 9

Area 7 specifically has the function of?

Answer 9

• controls eye movements
• Neurons issue commands to the frontal eye fields for eye movements to achieve and maintain fixation of objects of interest in extrapersonal space
• Neurons include: saccade related, smooth pursuit related and fixation related

Question 10

How can Cerebral blood flow change?

Answer 10

-Blood flow is increased to the areas of the brain that are most active during a particular task

Question 11

How does rCBF change in Internal Programming Testing?

Answer 11

• SMA ONLY – motor movement was mentally rehearsed but not physically produced

Question 12

What are the characteristics of Supplementary Motor Cortex (Area 6)?

Answer 12

• Programs complex motor sequences
• Active during mental rehearsal (does not require the action to physically occur)

Question 13

Area 5 specifically has the function of?

Answer 13

• controls arm movements
• Neurons issue commands to motor cortex for manual exploration of objects of interest in extrapersonal space

Question 14

What are the characteristics of the premotor cortex (Area 6)?

Answer 14

• Generates the plan for movement and transfers it to primary motor cortex for execution
• Involved in Motor Set
• State of readiness for impending movement

Question 15

What are the general characteristics of the parietal cortex (Areas 5 & 7)?

Answer 15

• Parietal cortex influences movements related to “extrapersonal space”
• Defined as the space external to the body but within reach for exploration
• Using arm and hand movements
• General function in motor control is selective attention to objects of motivational interest

Question 16

Parietal cortex receives input from and can influence what?

Answer 16

Parietal cortex receives input from Sl (Primary somatosensory cortex, Area 1,2,3). Area 7 also receives input from visual cortex.

Parietal areas, basal ganglia and cerebellum can influence motor cortex directly.

Question 17

How does rCBF change in Complex Movement Sequence Testing?

Answer 17

• Primary Motor & Somatosensory Cortex
• SMA – due to need for programming complex sequences

Question 18

Motor cortex firing rate is directly related to?

Answer 18

-Motor cortex firing rate (AP/sec) is directly proportional to muscle force produced

Question 19

What are the characteristics of the motor cortex in regards to function and somatotopy?

Answer 19

1) Motor cortex cells make connections with alpha and gamma motorneurons (UMNs) which initiate voluntary movements or execute commands from the cerebellum/basal ganglia
2) Ordered with somatotopic representation, allowing segregation of neurons

• -Leg is medial, face is lateral
• -Representation is contralateral
• -Distal muscles receive greatest area of representation (fine motor skills)