Lecture 12

Question 1

What is the function of the basal nuclei?

Answer 1

Help to plan and control complex patterns of muscle movement, controlling relative intensities of the separate movements, directions of movements, and sequencing of multiple successive and parallel movements

Question 2

The basal nuclei plan and execute motor commands in concert with which cortex?

Answer 2

Cerebral

Question 3

What do the basal nuclei help the cortex execute?

Answer 3

Subconscious but learned pattern

Question 4

T or F: The basal nuclei control simple patters of motor activity.

Answer 4

False. The basal nuclei control complex patterns of motor activity.

Question 5

Where do the basal nuclei receive most of their input?

Answer 5

From cerebral cortex

Question 6

Where do the basal nuclei return most of their output?

Answer 6

Cerebral cortex

Question 7

What is the principle role of the basal nuclei?

Answer 7

Work with corticospinal system to modulate thalamic output to the motor cortex to plan and execute smooth movements

Question 8

What kind of nuclei do the basal nuclei consist of?

Answer 8

Paired

Question 9

List the paired nuclei of the basal nuclei.

Answer 9

Striatum, globus pallidus, substantia nigra, subthalamic nucleus

Question 10

What are the 2 major basal nuclei circuits?

Answer 10

Putamen circuit and caudate nucleus circuit

Question 11

Which of the major basal nuclei circuits is direct and which is indirect?

Answer 11

Direct = putamen circuit 
Indirect = caudate nucleus circuit

Question 12

Describe the function of the putamen circuit.

Answer 12

Function isn’t clear, but inhibits athetosis or non-volitional movements, suppresses rigidity

Question 13

What is the caudate nucleus circuit responsible for?

Answer 13

Motor planning (activating muscles in sequence for motor patterns 5 seconds ahead or more)

Question 14

Connections between the striatum and the substantia nigra use ___ as their neurotransmitter.

Answer 14

Dopamine

Question 15

Which receptor does dopamine use on the indirect pathway? Is this excitatory or inhibitory?

Answer 15

D2 receptors; Inhibitory

Question 16

Which receptor does dopamine use on the direct pathway? Is this excitatory or inhibitory?

Answer 16

D1 receptors; Excitatory

Question 17

Is the overall action of dopamine excitatory or inhibitory?

Answer 17

Excitatory

Question 18

Exciting the putamen inhibits what? What does this allow?

Answer 18

Inhibits IGP/SubNigRet; Allows thalamus to send excitatory signals to motor cortex

Question 19

The IGP/SubNigRet is normally active and send inhibitory signals to where?

Answer 19

Thalamus

Question 20

What does a lesion in the globus pallidus result in?

Answer 20

Inability to maintain postural support; Athetosis

Question 21

What is athetosis?

Answer 21

Continuous spontaneous writing movements of a hand, arm, neck, or face

Question 22

What does a lesion in the subthalamic nuclei result in?

Answer 22

Release of inhibition of contralateral side; Hemiballismus

Question 23

What is hemiballismus?

Answer 23

Sudden, flailing movements of an entire limb

Question 24

What does a lesion in the striatum result in?

Answer 24

Release of inhibition; Chorea

Question 25

What is chorea?

Answer 25

Flicking movements in hands, face, or elsewhere

Question 26

T or F: Chorea occurs in patients with Huntington's disease.

Answer 26

True.

Question 27

What are lesions in the substantia nigra caused by?

Answer 27

Destruction of dopaminergic neurons

Question 28

What does a lesion in the substantia nigra result in?

Answer 28

Ridigity, akinesia, tremors

Question 29

Why does the destruction of dopaminergic neurons result in an overall inhibitory effect?

Answer 29

Dopamine inhibits the indirect (inhibitory) pathway and excites the direct (excitatory) pathway

Question 30

Which pathway plays a major for in the cognitive control of motor activity?

Answer 30

Caudate circuit (indirect pathway)

Question 31

T or F: The caudate circuit tends to increase motor activity.

Answer 31

False. The caudate circuit tends to decrease motor activity.

Question 32

Which neurotransmitter is used between the substantia nigra to the caudate nucleus and putamen?

Answer 32

Dopamine (inhibitory)

Question 33

Which neurotransmitter is used between the caudate nucleus and putamen to the globus pallidus and substantia nigra?

Answer 33

GABA (inhibitory)

Question 34

Which neurotransmitter is used between the cortex to the caudate nucleus and putamen?

Answer 34

Acetylcholine (excitatory)

Question 35

Which pathways from the brain stem use norepinephrine, serotonin (inhibitory), and enkephalin?

Answer 35

Multiple pathways from the brain stem

Question 36

Which neurotransmitter provides most of the excitatory signals?

Answer 36

Multiple glutamate pathways

Question 37

What does Parkinson's disease result from?

Answer 37

Widespread destruction of pars compacta of substantia nigra that sends dopaminergic fibers to caudate nucleus and putamenm

Question 38

In Parkinson's disease, which pathways to the direct and indirect pathways are lost?

Answer 38

Dopaminergic

Question 39

Describe what is lost in the direct and indirect pathways in Parkinson's disease.

Answer 39

Direct pathway loses some of its excitatory input; Indirect pathway loses some of its inhibitory input

Question 40

What are the characteristics of Parkinson's disease?

Answer 40

Rigidity of much of body musculature, involuntary tremors of involved areas even at rest at a fixed rate, serious difficulty in initiating movement (akinesia), postural instability, dysphagia, speech disorders, gait disturbances, fatigue

Question 41

When does Huntington's disease usually become symptomatic?

Answer 41

Around 30-40 years of age

Question 42

What are the characteristics of Huntington's disease?

Answer 42

Flicking movements of individual muscles, progressive severe distortional movements of entire body, severe dementia, motor dysfunctions

Question 43

What are the abnormal movements of Huntington's disease probably caused by?

Answer 43

Loss of most of cell bodies of GABA-secreting neurons of caudate nucleus and putamen and of Ach neurons in other parts of brain

Question 44

How is Huntington's disease inherited?

Answer 44

Autosomal dominant

Question 45

Describe the direct and indirect pathways in Huntington's disease.

Answer 45

Indirect pathway no longer has inhibitory influence on the direct pathway and motor activity is increased

Question 46

In Huntington's disease, which neurons typically inhibit parts of the globus pallidus and substantia nigra?

Answer 46

GABA

Question 47

What protein is produced due to mutations in the HTT gene?

Answer 47

Huntingtin

Question 48

What does the huntingtin protein cause?

Answer 48

DNA segment CAG repeats that appear multiple times in a row

Question 49

What is agnosia? With what lesion is it associated?

Answer 49

Inability to accurately perceive objects through normally functioning sensory mechanisms; Associated with lesions of posterior parietal cortex

Question 50

What is personal neglect syndrome?

Answer 50

Depending on side of lesion (such as right), patient will try to avoid using the left side of the body for performance tasks. Patient almost doesn’t know that those parts of the body exist.