Basal Ganglia

Question 1

What is the basal ganglia

Answer 1

• group of gray matter nuclei in cerebrum, diencephalon, & midbrain: (located deep within white matter)
• 5 Nuclei =Caudate, Putamen, Globus Pallidus, Subthalamic Nucleus, Substantia Nigra
• caudate, putamen and globus pallidus are in the cerebrum
• influnce function of movemetn

Question 2

What are the non motor circuits of the basal ganglia

Answer 2

• Goal directed or executive circuit
• Social-behavioral
• emotion or limbic

Question 3

Goal Directed or Executive circuit function

Answer 3

• decision-making loop regarding goal directed behavior (Ex: late-yellow light. Brake or accelerate?);
• puts actions in context (Same example-at same light, but not in a hurry, ease gas, etc)

Question 4

Social Behavioral circuit function

Answer 4

recognition of

• social disapproval,
• self-regulatory control,
• selecting relevant knowledge from irrelevant,
• maintaining attention,
• stimulus-response learning

Question 5

Emotional or limbic circuit

Answer 5

• links limbic, cognitive, and motor systems
• involved in reward-guided behavior;
• concerned with seeking pleasure;
• involved with facial expression

Question 6

Motor circuits of the basal ganglia

Answer 6

Oculomotor circuit
motor circuit

Question 7

Oculomotor circuit

Answer 7

makes decisions about eye movement and spatial attention; initiation of fast eye movement

Question 8

Motor circuit of basal ganglia

Answer 8

circuit-regulates

• muscle contraction,
• muscle force,
• multi-joint movements,
• sequencing of movements;
• movement selection and action

Question 9

Caudate nucleus

Answer 9

c-shaped and adjacent to the lateral ventricle

• Head=Anterior
• Body=participates in motor control-part of the oculomotor loop
• Posterior=tail=successful learning

Question 10

Anterior portion of the caudate nucleus importance

Answer 10

• Executive function/goal directed behavior Loop
• evaluates info for making perceptual decisions, planning, and choosing actions in context
• NOT involved with controlling movement
• active in learning and changes its activity before the cortex when reward contingencies are reversed;
• caudate head is first to learn new contingency=executive function

Question 11

Lentiform nucleus

Answer 11

• putamen + Globus Pallidus
• coordinates small, precise muscle movements
• Putamen-forms lateral portion of basal ganglia
• Globus pallidus-”pale globe”-many myelinated fibers

Question 12

What does the putamen do

Answer 12

Putamen receives input from premotor and motor cortex-forms lateral portion of basal ganglia

Question 13

What does the globus pallidus do

Answer 13

Globus pallidus sends output to motor areas of the cerebral cortex (maintains muscle tone)=motor circuit

Question 14

What is the striatum

Answer 14

• Caudate + putamen
• contributes to motor control-virtually all inputs to the basal ganglia arrive via striatum
• Join anteriorly=ventral striatum= limbic/Emotion circuit
• role in emotions and motivation
• acts as a link between the limbic, cognitive, and motor system

Question 15

Neurotransmitters of the basal ganglia

afferent

Answer 15

• glutamate from cerebral cortex=excitatory
• glutamate and ACh from PPN=excitatory
• Serotonin from dorsal raphe nuclei=inhibitory

go into the basal ganglia

Question 16

Neurotransmitters of the basal ganglia as efferent signals

Answer 16

• Efferent signals leaving the basal ganglia=GABA-inhibits thalamus, PPN, and reticular formation
• Dopamine from substantia nigra to the striatum adjusts signals to output nuclei so these nuclei provide the appropriate level of inhibition to target cells

Question 17

Basal ganglia pathways

Answer 17

• “the Go pathway disinhibits the motor thalamus, thereby facilitating specific movements.” (direct pathway)
• “No-Go pathway activity is suppression of unwanted movements.” (Indirect pathway)
  With dysfunction, movement is either insufficient(akinesia) or excessive due to lack of inhibition (tremor, postural instability)

Question 18

Motor control from the internal globus pallidus

Answer 18

• motor thalamus => motor areas of cortex => corticospinal tracts => LMNs voluntary movement (Glutamate excitatory)
• pedunculopontine nucleus => (GABA) reticulospinal tracts => LMNs of posutral (Glutamate)
• Midbrain locomotor region => (acH) reticulospinal tracts => (glutamate) stepping pattern generator

Question 19

Blood supply to caudate

Answer 19

anterior cerebral
anterior choroidal

Question 20

blood supply

putamen

Answer 20

Lenticulostriate branches of middle cerebral

Question 21

blood supply

Substantia nigra

Answer 21

Basilar, posterior cerebral, superior cerebellar

Question 22

blood supply to

subthalamic nucleus

Answer 22

posterior cerebral

Question 23

Basal ganglia disorders

Answer 23

hypokinetic
hyperkinetic

Result from dysfunction in the motor pathways within the basal ganglia and in the PPN

Question 24

# Basal ganglia disorders hypokinetic

Answer 24

- Too little movement - Excessive basal ganglia inhibition of the motor thalamus, PPN, and midbrain locomotor region (MLR)

Question 25

# Basal ganglia disorders hyperkinetic | not specific examples

Answer 25

- Excessive movement - Inadequate inhibition of the motor thalamus, PPN, and MLR

Question 26

Parkinsons disease

Answer 26

- Hypokinetic - Related to decrease in dopamine - dopamine lost in substantia nigra

Question 27

# PD symptoms

Answer 27

- Bradykinesia/ - akinesia - Tremor-unilateral, resting - Postural instability - rigidity - gait abnormalitis (freezing, shuffling) - visual perceptive impairments (diffculty with doorways or changes) - masked fascial expression

Question 28

# PD types

Answer 28

1. tremor dominant 2. postural instability/gait diffculty

Question 29

# PD non motor dysfunction symptoms

Answer 29

- depression - Psychosis=visual hallucinations - Dementia=deterioration of intellectual function (planning, goal direction, decision making) vs. memory with Alzheimer’s - Autonomic=constipation, orthostasis

Question 30

Parkinsons treatment

Answer 30

* Medications (not a complete list) * Increase dopamine levels via levadopa (L-dopa/ Sinemet) * Other meds * Mirapex (Dopamine agonists) * Comtan (Prolongs effects of levodopa) * Amantadine (short term mild symptoms or to enhance leva dopa)

Question 31

Dyskinesia

Answer 31

Involuntary, erratic, writhing movements of the face, arms, legs or trunk (too much Sinemet)

Question 32

Goal of PD medications

Answer 32

- goal is to increase on time and decrease off time (symptoms) - keep side effects at bay

Question 33

Other treatments for PD

Answer 33

* Surgery: deep brain stimulation pallidotomy and thalamotomy, fetal tissue transplant * PT, OT, Speech therapy…multidisciplinary approach * Moderate to high intensity-PWR, LSVT * Tai Chi, wellness exercise, boxing, dance ## Footnote Pallidotomy/Thalamotomy-liquid nitrogen or lasers used destroy a small precise region of the thalamus(tremor) or globus pallidus (akinesia). For treatment of dyskinesia and tremor

Question 34

Atypical presentation of PD

Answer 34

- multple system atrophy - progressive supranuclear palsy - dementia with lewy bodies - corticobasal degeneration

Question 35

Secondary parkinsonism

Answer 35

- results from another disease or event - traumatic - toxic - infectious - drug-induced

Question 36

Red flags with possibel PD case

Answer 36

- early postural instability - rapid progression, - respiratory dysfunction, - abnormal postures, - emotional lability, - cerebellar signs, - voluntary gaze dysfunction

Question 37

Progressive supranuclear palsy (PSP)

Answer 37

PSP-Corticobrainstem tract –motor function on eyes=downward gaze palsy

Question 38

# Atypical PD Multi system atrophy

Answer 38

* Akinetic/rigid syndrome * Cerebellar signs: uncoordinated speech and ataxia * Autonomic dysfunction: * Corticospinal tract dysfunction * Decreased goal-directed cognition and difficulty with attention * progressive degenerative disease - Cause unknown - affects the basal ganglia and cerebellar and autonomic systems; the peripheral nervous system; and the cerebral cortex.

Question 39

# Atypical PD Dementia with lewy bodies

Answer 39

* EARLY, generalized cognitive decline * Visual hallucinations * Postural instability * Gait dysfunction

Question 40

# Atypical PD Corticobasal degeneration

Answer 40

* progressive atrophy of the cerebral cortex and basal ganglia. * Motor signs similar to PD * visuospatial and cognitive impairments, apraxia, dysphagia, speech hesitancy, and myoclonus.

Question 41

# Hyperkinetic disorders huntington's disease

Answer 41

* Genetic disorder * “hyperkinetic” disorder * Symptoms: chorea, athetosis, possible dementia * Degeneration: ↓activity in output nuclei; Disinhibition of thalamus & PPN * ↑ activity in lateral tracts ## Footnote Chorea-literal meaning=dance. Continuous involuntary movements that have a jerky/fluid quality (low amplitude might be mistaken for fidgeting)