Basal Nuclei - Lec12

Question 1

What is agnosia? What lesion is associated with it?

Answer 1

lesions of the posterior parietal cortex

inability to accurately perceive objects through normally functioning sensory mechanism

Question 2

Basal nuclei

Answer 2

Striatum
-caudate nucleus 
-putamen
Globus pallidus
Substantia nigra
Subthalamic nucleus

Question 3

Corpus Striatum

Answer 3

Caudate nucleus - large subconscious movements of skeletal muscle

Lentiform nucleus - (lens shaped)

• Putamen: large subconscous movements of skeletal muscles
• Globus pallidus: regulates muscle tone

Question 4

Putamen Circuit

Answer 4

(Direct pathway)

Primarily excitatory and the subconscious execution of learned patterns of movement

Cerebral cortex (+ actylch or glutamate) 
And substania nigra compacta

• > putamen (-GABA, +dopamine (d1 R))
• > globus pallidus (-GABA) and substania nigra reticularis
• > thalamic relay nuclei (+glutamate)
• > primary motor cortex

Bypasses caudate nucleus.

Question 4

Dopamine is ______ in the indirect pathways and uses which receptor? And for the direct pathway?

Answer 4

Inhibitory in indirect pathway using D2 R

Excitatory in direct pathway using D1 R

Question 5

Lesion in globus pallidus

Answer 5

Results in inability to maintain postural support

Results in continuous spontaneous writing movements of a hand, arm, neck or face (athetosis)

Question 6

Lesions in subthalamic nuclei

Answer 6

Results in the release of inhibition on the contralateral side

Sudden, flailing movements on an entire limb - hemiballismus

Question 7

Lesions in the striatum

Answer 7

Release of inhibition

Flickering movements in hands, face or else where - chorea

Huntingtons

Question 8

Lesions in substantia nigra

Answer 8

Caused by destruction of dopaminergic neurons

Parkinson’s disease

Results in rigidity, akinesia and tremors

Destroying dopaminergic neurons resultsin overall inhibitory effect

Question 9

Caudate circuit

Answer 9

Indirect pathway

Major role in cognitive control of motor activity

Overall inhibitory to decrease motor activity

Cerebral cortex (+ achl and glumatate) and the substantia nigra compacta (- dopamine)

• > caudate nucleus (- GABA)
• > Globus Pallidus external (acts on the GP internal) -GABA
• > Thalamic relay nuclei
• > premotor and supplementary motor cortex

Question 10

Hungtingtons Disease

Answer 10

GABA neurons in caudate nucleus are destroyed and the indirect pathway loses the inhibitory effect on the direct pathway causing an increase in motor activity

Characters:

• flicking movements of individual muscles
• progressive severe distortional movements of entire body
• severe dementia
• motor dysfunction

Ach also lost in some parts of brain in addition to the GABA neurons (normal fucntion to inhibit partso f globus pallidus and s. Nigra)

Question 11

Parkinson’s Disease

Answer 11

AKA paralysis agitans

Destruction of the substania nigra compacta

• loss of dopaminergic pathways to cauddate nucleus and putamen
• so both indirect and direct pathways
• decreased motor activity

Characters:

• rigidity of much body musculature
• involuntary tremors
• akinesia: difficulty in intiating movement
• postural instability
• dyphagia, speech disorders, gait distrurbances and fatigue

Question 12

Name the neurotransmitter:

Subtania nigra to caudate nucleus and putamen

Answer 12

Dopamine, both inhibitory and excitatory respectfully

Question 13

Name the neurotransmittter

Caudate nucleus and putamen to globus pallidus and s. Nigra

Answer 13

GABA - inhibitory

Question 14

Name the nuerotransmitter from the cortes to the caudate nucleus or putament

Answer 14

Acetylcholine or glutamate (excitatory)

Question 15

what is personal neglect syndrome?

Answer 15

severe damage to right posterior parietal cortex causing an inability to percieve stimulus on their left and spatial coordination. (clock drawing example) -agnosia

Question 16

athetosis

Answer 16

writhing movements of hand, arm, neck or face

caused by lesions to globus pallidus

Question 17

hemiballismus

Answer 17

flailing movements of entire limb

caused by lesions in subthalamus

Question 18

chorea

Answer 18

flicking movements of the hands, face, etc.

small lesions in the putamen