Basal Ganglia Flashcards

1
Q

Role of basal ganglia in motor control

A
  • modulation of motor performance via interconnections with the motor cortices.
  • major feedback loop to motor and association cortex
  • in general, serve a role in motor program selection.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Major source of input to basal ganglia

A
  • Cerebral cortex
  • primarily: frontal lobe areas and sensorimotor areas that have a greater role in the planning and initiation of movement.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Characteristics of Parkinson’s disease

A
  • Resting tremor, difficulty initiating movements, slowness
  • etiology: loss of dopamine neurons in the substantia nigra.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Probable mechanism of Parkinson’s

A
  • Substantia nigra sends dopaminergic axons back to the striatum.
  • The action of dopamine in striatum is probably largely excitatory, since Parkinson’s disease, which includes degeneration of substantia nigra neurons and loss of dopaminergic input, is marked by a paucity of movement.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Output of basal ganglia: inhibitory vs. excitatory

A
  • Inhibitory.
  • GPI → (GABA -) @ Thalamus → (Glu +) Cortex.
  • output of the basal ganglia is directed to the thalamus via the pallidothalamic fibers from the GPI which are GABA-nergic and from there back to the cortex.
  • Basal Ganglia provide resting inhibition of the thalamus until a signal comes from the cortex causing the disinhibition of the the thalamus via the direct pathway.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Genetic cause of Huntington’s Disease

A
  • autosomal dominant
  • site of mutation @ short arm of the 4th chromosome.
  • Normal humans have 17-34 CAG repeats, HD have > 40.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Characteristics/presentation of Huntington’s Disease

A
  • Striatal damage produces athetosis or chorea.
    • Chorea = continuous rapid movements of the face, tongue or limbs (usually distal portions).
    • Athetosis indicates slow, writhing, ceaseless movements of hand, sometimes lips, tongue, neck and foot.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

HD impact on basal ganglia

A
  • caudate = most affected region of basal ganglia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

“Direct path” from cortex to basal ganglia and back to cortex

A
  • Cortex → excites through striatum Caudate/Putamen with glutamate
  • glutamate → which inhibits GPI with GABA →
  • stops inhibiting Thalamus with GABA → which can then excite the cortex with glutamate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Stroke @ subthalamic nucleus impact

A
  • subthalamic nucleus = integral piece of the indirect pathway.
  • If stroke that destroyed the STN then a great degree of thalamic inhibition would be lost ==> hemiballismus
    • e.g. stroke @ small ganglionic branch of posterior cerebral artery
  • Disinhibition would rule, hence the flailing of arms and legs on one side.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Type of stimulus used in deep brain stimulation for Parkinson’s patients

A
  • Hyperpolarizing.
  • Main problem in Parkinson’s = STN and GPI cause inhibition of the thalamus.
  • DBS would work to remove such inhibition, otherwise known as encourage disinhibition.
  • Hyperpolarizing the STN or GPI would do just that without the need for medications.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly