Basal ganlgia

Question 1

what are the 5 major nuclei in Basal ganlgia

Answer 1

• caudate nucleus
• putamen
• globus pallidus
• subthalamic nucleus
• substantia nigra

Question 2

What makes up the corpus striatum?

Answer 2

• Corpus striatum = caudate + lentiform
• Lentiform = putamen + globus pallidus

**Striatum is “INPUT GATE” to basal ganglia**

Question 3

what makes up the striatum

Answer 3

• Striatum = putamen + caudate nucleus

Question 4

What nucleus make up basal ganlgia?

Answer 4

• corpus striatum + substantia nigra + subthalamic nuclues

Question 5

• primary function of caudate nucleus?
• primary function of putamen?
• Primary function of nucleus accumbens?

Answer 5

• Cuadate = cognitive information
• Putamen = motor functions (“OUTPUT GATE” from basal ganglia)
• Nucleus accumbens = emotional and motivational aspects of motor function

Question 6

Function of the motor loop circuit in basal ganglia

Answer 6

• motor loop relays information from basal ganglia to motor cortical areas

–> influence upper motor neurons of corticospinal, corticonuclear and other motor tracts

Question 7

Function of association circuit of the basal ganglia

Answer 7

• Cognitive = planning and direction of movement

Question 8

Function of the oculomotor circuit of the basal ganglia

Answer 8

• Integration of eye movements and visual guidance

Question 9

Function of limbic circuit with basal ganglia

Answer 9

• Emotional and motivational influences on movements

Question 10

What information does the VA and VL thalamic nuclei relay

Answer 10

• Relays signals related to movement

Question 11

What information does the mediodorsal thalamic nuclei relay

Answer 11

• relays signals to frontal and limbic cortex

Question 12

describe the direct pathway through the basal ganglia

Answer 12

• Facilitates the flow of information though the thalamus resulting in greater excitation of the cortex
• Function is to release (DISINHIBIT) the thalamus from tonic pallidal inhibiton allowing VOLUNTARY MOVEMENTS
• FACILITATION = HYPERKINESIA

Question 13

Describe the indirect pathway though the basal ganglia

Answer 13

• Decreases activity in the THALAMUS (INCREASED INHIBITON) lessening excitatory output to the cortex
• Function = TONIC SUPPRESSION of inappropriate movements, but also to terminate volitional movements
• INHIBITION = HYPOKINESIA

Question 14

Describe the Closed circuit of the MOTOR LOOP

Answer 14

1) Supplementary motor cortex (area 6)
2) caudate nucleus and putamen (STRIATUM)
3) globus pallidus and substantia nigra (PALLIDUM)
4) Ventral lateral nucleus of the thalamus
5) Supplementary motor cortex (area 6)

–> receives open loops from Somatosensory cortex, primary motor cortex and premotor cortex (corticostriate fibers)

Question 15

Describe the Close loop of the ASSOCIATION LOOP

Answer 15

1) Prefrontal Cortex (area 9 and 10) (plan and decide)
2) Caudate nucleus (STRIATUM)
3) globus pallidus and substantia nigra (PALLIDUM)
4) Ventral anterior nucleus and dorsomedial nucleus of the THALAMUS
5) Prefrontal cortex
- Recieves open loop from Premotor cortex (orientation) and posterior parietal cortex (visual guidance)

Question 16

Describe Close loop of the oculomotor loop

Answer 16

1) Frontal eye field (area 8 - visual tracking)
2) Vaudate nucleus (Striatum)
3) globus pallidus and substantia nigra (Pallidum) –> sends projections to superior colliculus (visual reflex)
4) ventral anterior nucleus and dorsomedial nucleus of the thalamus
5) frontal eye field
- Recieves open loop fibers from prefrontal cortex (plan and decide) and posterior parietal cortex (visual guidance)

Question 17

describe the closed loop of the limbic circuit

Answer 17

1) Anterior cingulate gyrus and Orbitofrontal cortex
2) Ventral striatum and caudate nucleus (Striatum)
3) Ventral pallidum and globus pallidus and substantia nigra (PAllidum)
4) ventral anterior nucleus and dorsomedial nucleus of the thalamus
5) anterior cingulate gyrus and orbitofrontal cotex
- recieves input into STRIATUM from Medial and lateral temporal lobe, Hippocampus (memory), amygdala (emotions) and Entorhinal area (olfactory info)

Question 18

Sings and symptoms of basal ganglia lesion

Answer 18

• Referred to as EXTRAPYRAMIDAL SYNDROME
• Example = Parkinson’s disease

–> Rigidity, slowness of movement, slumped posutrue = excessive inhibiton with lack of facilitation

–> Resting tremor = lack of suppression of involuntary movement

–> proximate cause = Death of dopaminergic cells in pars compact of substantia nigra

**NO PARLYSIS with LESION**

Question 19

define chorea

Answer 19

• jerky involuntary movements affected especially the shoulders, hips and face

Question 20

Define Athetosis

Answer 20

• abnormal muscle contractions cause involuntary writhing movements
• affects some people with cerebral palsy, impairing speech and use of hands

Question 21

Define dyskinesia

Answer 21

• abnormality or impairment of voluntary movement

Question 22

define bradykinesia

Answer 22

• extreme slowness of movements and reflexes
• sign of parkinsons

Question 23

define hemiballismus

Answer 23

• violent uncontrollable movemetns of one lateral half of the body due to LESION IN THE SUBTHALAMIC NUCLEUS OF THE CONTRALATERAL SIDE OF THE BODY

Question 24

What two signs must be present to define Tourette’s and what one sign, in particular, makes it unique among all extrapyramidal syndromes

Answer 24

• repetitive, stereotyped, involuntary movements
• vocalizations called tics