2-11 Brain Mechanisms Of Movement

Front 1

Objective

Describe the role of the primary motor cortex in controlling movement.

Back 1

The motor cortex has no direct connections to the muscles; its axons extend to the brainstem and spinal cord, which generate the activity patterns that control the muscles.

Front 2

Objective

Distinguish between the dorsolateral and ventromedial tracts.

Back 2

See study guide.

Front 3

Objective

Explain how each of the following contributes to movement.

Back 3

Posterior Parietal Cortex
Prefrontal Cortex
Premotor Cortex
Supplemental Motor Cortex

See study guide.

Front 4

Objective

Discuss the findings on readiness potentials and the conscious control of movement.

Back 4

On average, people report that their decision to move occurred about 200 ms before the actual movement. Before any voluntary movement, the motor cortex produces a particular kind of electrical activity called a readiness potential. The readiness potential begins at least 500 ms before the movement. This finding suggests that brain activity responsible for the movement apparently begins before the person’s conscious decision. If this is true, then our conscious decision does not cause our actions; rather, we become conscious of the decision after the process leading to our action has already been underway for about 300 ms.

Front 5

Objective

Describe the effect of cerebellar damage.

Back 5

The most obvious effect of cerebellar damage is trouble with rapid movements that require accurate aim and timing. For example, people with cerebellar damage have trouble tapping a rhythm, clapping hands, pointing at a moving object, speaking, writing, typing, or playing a musical instrument. They are impaired at almost all athletic activities except a few like weightlifting that do not require aim or timing. Even long after the damage, when they seem to have recovered, they remain slow on sequences of movements and even on imagining sequences of movements. They are normal, however, at continuous motor activity, even if it has a kind of rhythm. For example, they can draw continuous circles. Although drawing circles has a rhythm, it does not require rhythmically starting or stopping an action.

Front 6

Objective

Identify two ways to test the functioning of the cerebellum.

Back 6

See study guide.

Front 7

Objective

Explain how the basal ganglia are connected to other brain areas.

Back 7

The basal ganglia are a group of large subcortical structures in the forebrain that include the caudate nucleus, putamen, and globus pallidus. Input comes to the caudate nucleus and putamen, mostly from the cerebral cortex. Output from the caudate nucleus and putamen goes to the globus pallidus and from there mainly to the thalamus, which relays it to the cerebral cortex, especially its motor areas and the prefrontal cortex.

Front 8

Objective

Describe the role of the basal ganglia in controlling movement.

Back 8

Neurons in the globus pallidus release GABA, an inhibitory transmitter. Input from the caudate nucleus and putamen indicate to the globus pallidus which movements NOT to inhibit. Damage to the globus pallidus results in involuntary, jerky movements.

Front 9

primary motor cortex

Back 9

The precentral gyrus of the frontal cortex, just anterior to the central sulcus, elicits movements

Front 10

dorsolateral tract

Back 10

Set of axons from the primary motor cortex, surrounding areas, and the red nucleus
Axons of the dorsolateral tract extend directly from the motor cortex to their target neurons in the spinal cord
It controls movements in peripheral areas, such as the hands, fingers, and toes

Front 11

red nucleus

Back 11

A midbrain area with output mainly to arm muscles

Front 12

ventromedial tract

Back 12

Includes axons from the primary motor cortex, surrounding areas, and also from many other parts of the cortex; in addition, it includes axons that originate from the midbrain tectum, the reticular formation, and the vestibular nucleus; the ventromedial tract controls mainly the muscles of the neck, shoulders, and trunk and therefore such movements such as walking, turning, bending, standing up, and sitting down

Front 13

vestibular nucleus

Back 13

A brain area that receives input from the vestibular system

Front 14

posterior parietal cortex

Back 14

Area near primary motor cortex; some neurons in the area respond primarily to visual or somatosensory stimuli, others respond mostly to current or future movements, and still others respond to complicated mixture of the stimulus and the upcoming response

Front 15

prefrontal cortex

Back 15

Responds to lights, noises, and other sensory signals that lead to movement; it also calculates probable outcomes of various actions and plans movements according to those outcomes

Front 16

premotor cortex

Back 16

Area that is active during preparations for a movement and somewhat active during the movement itself; it receives info about the target in space, to which the body is directing its movement, as well as info about the current position and posture of the body itself; both kinds of info are necessary to move a body part toward some target; the premotor cortex sends out put to both the primary motor cortex and the spinal cord, organizing the direction of the movements in space

Front 17

supplemental motor cortex

Back 17

Area important for planning and organizing a rapid sequence of movements, such as pushing, pulling, and then turning a stick, in a particular order

Front 18

readiness potential

Back 18

Recordable activity in the motor cortex prior to voluntary movement

Front 19

anosognosia

Back 19

Ignorance of the presence of disease; occurs when someone is paralyzed on the left side but denies having such a problem; it is associated with damage to the motor cortex of the right hemisphere and parts of the surrounding areas

Front 20

basal ganglia

Back 20

Group of large subcortical structures in the forebrain; responsible for learning motor skills, for organizing sequences of movement into a whole, and for the kinds of learning that we cannot easily express in words; for example, when you are first learning to drive a car, you have to think about everything you do; after much experience, you can signal for a left turn, change gears, and turn the wheel all at once in a single smooth movement

Front 21

caudate nucleus

Back 21

Part of the basal ganglia; receives inputs from cerebral cortex and sends outputs to the globus pallidus

Front 22

putamen

Back 22

Part of the basal ganglia; receives inputs from cerebral cortex and sends outputs to globus pallidus

Front 23

globus pallidus

Back 23

Part of the basal ganglia; sends outputs to thalamus, which relays info to the cerebral cortex