Chapter 11

Question 1

Somatosensory and motor systems → direction of info

Answer 1

Afferent somatosensory information travels from the sensory organs inward via the somatic nervous system

Movement information travels out of the central nervous system via a parallel efferent motor system

Sensory → Afferent

Motor → Efferent

Question 2

Connections between the nerves and spine

Answer 2

Fibers entering the posterior root bring sensory info from sensory receptors

Fibers leaving the anterior root carry motor info to the muscles

Collateral branches of sensory neurons may cross to the other side and influence motor neurons there

White-matter finer tracts carry info to and from the brain

Posterior → Sensory

Anterior → Motor

Question 3

Dermatome

Answer 3

The spinal cord lies within a series of small bones called vertebrae

Each spinal segment corresponds to a region of body surface called a dermatome

Dermatomes C1-C8 → cervical nerves

Dermatomes T1-T12 → thoracic nerves

Dermatomes L1-L5 → lumbar nerves

Dermatomes S1-S5 → sacral nerves

Question 4

Layering in the neocortex

Answer 4

The 6 cortical layers differ in appearance, characteristics, and functions

Sensory regions have a large input layer, and motor regions have a large output layer

Top → Bottom layering order: integrative functions → Sensory input (Afferent) → output to other parts of brain (efferent)

Motor cortex: frontal lobe, anterior to central fissure

Sensory cortex: posterior to central fissure, extends into parietal lobe

Question 5

Parallel and independent movement control

Answer 5

Movement required for simple actions involves widespread CNS regions → ex: picking up a cup

Forebrain areas must act through lower functional areas: the brainstem and spinal cord

There must be some parallel organization within these areas
↳ you can do other behaviors (ex. Speaking) while picking up a cup

There also must be some independence in the function of these brain regions → movement independent of conscious control

Question 6

Sequentially organized movement

Answer 6

1. Visual info required to locate the target
2. Frontal-lobe motor areas plan the reach and command the movement
3. Spinal cord carries information to the hand
4. Motor neurons carry message to muscles of the hand and forearm
5. Sensory receptors on the fingers send message to sensory cortex saying object has been grasped
6. Spinal cord carnies sensory info to brain
7. Basal ganglia judge grasp forces, and cerebellum corrects movement errors
8. Sensory cortex receives message that the cup has been grasped

Question 7

Forebrain: initiating movement

Answer 7

Lashley (1951) → argued that movements must be performed as motor sequences, with the next sequence held in readiness while the ongoing one is underway (priming)

Motor sequence: movement modules are preprogrammed by the brain and produced as a unit

Ideal motor sequence: movement categories produced from brain as entire preprogrammed sequence

Question 8

Initiating a motor sequence

Answer 8

Frontal lobe regions act hierarchically and in parallel to initiate behavior

Prefrontal cortex: plans complex behavior

Premotor cortex: produces the appropriate complex movement sequences

Primary motor cortex: specifies how each movement is to be carried out

Question 9

Prefrontal cortex → initiating motor sequence

Answer 9

Top of hierarchy → plans behavior

Makes decisions about behavioral goals to select

PFC damage leads to the inability to suppress inappropriate behaviors

Question 10

Promoter control

Answer 10

Premotor cortex receives instructions from the PFC

Produces movements by coordinating body parts

If damaged → no longer able to produce fine motor functions

Question 11

Primary motor cortex → M1

Answer 11

Specializes in producing focal skilled movements, such as those of the arms, hands, and mouth

People with damage to M1 have difficulty reaching and shaping their fingers to perform various hand grasps

Question 12

Simple movement → blood flow in brain

Answer 12

Blood flow increases in hand area of primary somatosensory and primary motor cortex when participants use a finger to push a lever

Question 13

Movement sequence → blood flow in brain

Answer 13

Blood flow increases in promotor cortex when participants perform a sequence of movements

Question 14

Complex movement → blood flow in brain

Answer 14

When participants use a finger to find a route through a maze, blood flow also increases in prefrontal, temporal, and parietal cortex

Question 15

Brainstem: species-typical movement

Answer 15

Species typical movement→ bipedal walking in humans etc.

Brainstem: organizes many adaptive movements → standing upright, coordinating limb movement, walking and swimming, etc.

Question 16

Cerebral palsy

Answer 16

Hard time executing voluntary movement

Disorder primarily of motor function, in which making voluntary movements becomes difficult

Caused by brainstem trauma

Often due to birth complications → lack of oxygen to brain etc.

Question 17

Locked-in syndrome

Answer 17

Condition in which a patient is aware and awake but cannot move or communicate verbally because of complete paralysis of nearly all voluntary muscles except the eyes

Due to brainstem damage

Question 18

Extent of paralysis due to spinal cord injury

Answer 18

Cervical (neck) → quadriplegia

Thoratic (upper back) → paraplegia

Lumbar (lower back) → paraplegia → less extreme or less of lower body

Question 19

Quadriplegia and paraplegia → reflexes

Answer 19

Spinal reflexes still function even though the spinal cord is cut off from communication with the brain

Paralyzed limbs may display spontaneous movements or spasms

The brain can no longer guide the timing of these automatic movements

Question 20

Fritsch and Hitzig

Answer 20

Discovered they could electrically stimulate the neocortex of an anesthetized dog to produce movements of the mouth, limbs, and paws on the opposite side of the dogs body

1st example of controlateral motor control

Question 21

Wilder Penfield

Answer 21

Used electrical stimulation to map the cornices of human patients who were about to undergo neurosurgery

Confirmed the role of the primary motor cortex in producing movement in humans