Kantak - Basal Gang/Sara Bellum

Question 1

What are the four parts/functional nuclei of the basal ganglia and what are their respective divisions? Which of these parts makes up the lentiform nucleus? Which of these parts makes up the striatum?

Answer 1

Caudate Nucleus
Globus Pallidus (External/Internal)
Substantia Nigra (Pars Reticulata/Compacta)
Subthalamic Nucleus

Lentiform Nucleus = Putamen + Globus Pallidus

Striatum = Caudate Nucleus + Putamen

Question 2

What are the four roles of the basal ganglia?

Answer 2

Action Selection, Cognition, Mood + Vigor, Motor + Non-motor Habit Formation aka, Reward Based Behavior OR the anticipation of reward

Question 3

Where does the BG receive afferent input from?

Answer 3

Cortex, Thalamus, Brain Stem

Question 4

Where does efferent output from the BG go?

Answer 4

Thalamus, Brain Stem

Question 5

What are the two major output nuclei of the BG?

Answer 5

Globus Pallidus Internus + Substantia Nigra Pars Reticulata

Question 6

What part of the BG is the major receiver of input?

Answer 6

Striatum

Question 7

Describe the Direct Pathway and name what receptor directs it.

Answer 7

D1 Receptors on the Substantia Nigra Pars Compacta are activated through the Direct Pathway.

Info from the Thalamus goes to the Cortex, this excites the Striatum (Putamen), inhibits the Gpi and therefore inhibits the thalamus. The some total of this is that the thalamus is disinhibited and facilitation of movement occurs.

Question 8

Describe the inDirect Pathway and name what receptor directs it.

Answer 8

D2 Receptors on the Substantia Nigra Pars Compacta are activated through the Direct Pathway.

Info from the Thalamus goes to the Cortex, this excites the Striatum (Putamen), inhibits the Gpe, inhibits the Gpi, and therefore inhibits the thalamus and inhibits movement.

Question 9

What is the effect of dopamine on the direct pathway?

Answer 9

all channels facilitated, more mvmt.

Question 10

What is the effect of dopamine on the indirect pathway?

Answer 10

inhibits the indirect pathway = more mvmt.

Question 11

Which neurotransmitter is released where in the basal ganglia circuit?

Answer 11

Cortex: Glutamate (facilitatory)
Striatum (Putamen): GABA (inhibitory)
GPi + Pars Reticulata: GABA
Pars Compacta: Dopamine (either fac/inhib)
Subthalamic nucleus: Glutamate

Question 12

What are the parallel circuits for the BG?

Answer 12

Skeletomotor: Motor Planning: Putamen
Oculomotor: Saccadic Eye Mvmt: Caudate
Executive: Associative: Caudate
Limbic: Emotion/Motivation: Ventral Striatum

Question 13

What is more used at the beginning of learning vs. acquisition as far as parallel circuits within the BG? What parts of the striatum does this entail?

Answer 13

Pre-frontal Cortical-Basal Ganglia @ Beginning THEN Skeletomotor once automaticity has occurred. The shift moves from caudate to putamen.

Question 14

What is the difference between hypokinetic and hyperkinetic basal ganglia pathologies?

Answer 14

Hypokinetic involved slow movement (akinesia/rigidity), reduced tone, and examples of this are PD, drug-induced PD, multiple systems atrophy, progressive palsy.

Hyperkinetic involve excessive uncontrolled movement (dyskinesias) and examples of this are chorea, myoclonus, tics.

Question 15

What 3 things is Parkinsonism characterized by?

Answer 15

1. Bradykinesia
2. Resting Tremor / Rigidity
3. Postural Instability

Question 16

What are the diagnostic criteria for PD and how many of them do you need to have?

Answer 16

You need to have 3.

1. Resting Tremor
2. Unilateral Onset (though, can be bilateral)
3. Progressive
4. Good response to L-dopa
5. Severe L-dopa induced chorea
6. L-dopa response for +5 years
7. Clinical Course > 10 years

Question 17

What are the negative symptoms of PD? Positive?

Answer 17

Negative: Bradykinesia/Akinesia, Postural Instability

Positive: Resting Tremor (suppressed to initiate movement), Rigidity (not velocity dependent!)

Question 18

What are the scales used to classify PD?

Answer 18

Hoehn Yahr (Stage 1 = unilateral, Stage 2 = bilateral)

UPDRS (4 parts)

Question 19

What are the pharmacological agents used to treat PD and how do they generally act?

Answer 19

1. Increase amount of available dopamine (L-dopa, Carbidopa / Sinemet) - these can also cause hallucinations, chorea, and an increase in postural sway.
2. Dopamine Agonists (these act like dopamine)
3. Anticholinergics (block Glutamate)
   or. .. ultimately surgery (DBS)

Question 20

Where does the cerebellum receive input from?

Answer 20

1) Cortex
2) Brain Stem
3) Spinal Cord

Question 21

Where does the cerebellum send info to?

Answer 21

1) Cortex
2) Brain Stem
NOT THE SPINAL CORD

Question 22

What connects the brain stem to the cerebellum bilaterally?

Answer 22

Superior, Middle, Inferior Cerebellar Peduncles

Question 23

The cerebellum plays a role in which three functions?

Answer 23

1. Motor Control / monitoring/planning
2. Motor Learning
3. Cognitive Aspects of Human Behavior

Question 24

Which side of the body does the cerebellum control? For what regions of the cerebellum do tracts double cross to achieve this?

Answer 24

Ipsilateral.

Ventral Spinal Cerebellar Tract
Cerebrocerebellar

Question 25

Where do the inputs of the cerebellum come from? Howsabout the outputs?

Answer 25

Inputs: The Cortex (usually, a movement plan). Ventral Spinocerebellar Tract (how did the plan go?) Outputs: Motor / Premotor Cortex Brainstem

Question 26

What are the different presentations for removal of the cerebellum vs. damage?

Answer 26

W/ removal there is no sensation or strength loss. W/ damage, there is a loss of accuracy of movement, balance + tone, motor learning and cognitive function.

Question 27

What are the effects of BG lesions to each of these locations: Substantia Nigra, Putamen, Subthalamic Nucleus, and Caudate Nucleus.

Answer 27

PD Chorea Hemiballism Emo/Cognitive Issues

Question 28

What are all the deep cerebellar nuclei and where are they located? What is their significance?

Answer 28

Vermis: Fastigial Intermediate: Interposed Lateral: Dentate The Vestibular Nuclei are not in the cerebellum. They are the main outputs of the cerebellum.

Question 29

What are the fxal roles of the regions of the cerebellum and where are they located structurally within the cerebellum?

Answer 29

Cerebrocerebellum: higher order planning, the lateral portion of the longitudinal fissures of the cerebellum. Spinocerebellum: in the intermediate hemispheres more limb specific, in the vermis, more head and trunk specific. Vestibulocerebellum: flocconodular lobe specific, controls balance, head/gaze control (so, smooth pursuit/saccade effected if damaged), proprio of neck and coordination of vision/head.

Question 30

What are the 3 main repercussions of damage to the spinocerebellum?

Answer 30

1) loss of planning/speed 2) feed forward w/ loss of timing of agonist/antagonist (intention/terminal tremor) #dysmetria 3) interactive torques #ataxia

Question 31

What are the 3 layers of the cerebellar cortex and how do these interact with the cerebral cortex?

Answer 31

1) Molecular 2) Purkinje 3) Granular The Deep Cerebellar Nuclei send output to the Mossy Fibers constantly. This output arises from granule cells in the granular layer to the parallel fibers of the molecular layer. These parallel fibers effect the purkinje fibers at a constant state. Contrarily, the Purkinje Fibers directly synapse to the deep cerebellar nuclei and also have interactions with Climbing Fibers. Climbing Fibers arise from the inferior olivary nuclei and go directly to the molecular layer to effect the Purkinje Fibers with a complex signal that only fires when needed OR open recognition of discrepancy from Biomechanical Links to the Cortex.

Question 32

What is the difference between the dorsal spinocerebellar tracts and the ventral?

Answer 32

Dorsal is somatosensory info (mostly from legs). Ventral is the state of SC during active movements.

Question 33

Which parts of the contemporary model of motor control are linked with the BG vs. the CB?

Answer 33

Action Selection:BG | Execution/Inverse/Forward Model: CB

Question 34

What are the differences in reactive postural control bw PD & CB?

Answer 34

PD have coactivation (and so experience rigidity or akinesia) CB have magnified responses in either direction and a lack of coordination between agonists and antagonists.

Question 35

How do you distinguish cerebellar ataxia from sensory ataxia?

Answer 35

CB lesion: cannot stand w/ feet together with EO or EC. DCML lesion: can stand together with EO, but not EC.

Question 36

What is the physiological effect of HIT training and how might we define HIT in the clinic?

Answer 36

The effect is that more D2 receptors arise on the striatum. FITT (frequency, intensity, timing, type).

Question 37

What are the three primary functions of the thalamus?

Answer 37

1. Weigh station for all sensory info - olfactory. 2. Voluntary Motor Activity (given connections to the BG/CB) 3. Limbic System Connections

Question 38

What is the function of the Internal Medullary Lamina and External Medullary Lamina of the Thalamus?

Answer 38

Internal serves to 1) separate thalamus into anterior/medial/lateral sections, 2) connects fibers that connect thalamic nuclei together. External serves to 1) separate the reticular nucleus from the thalamic mass, and 2) contains the thalamocortical and corticothalamic fibers.

Question 39

What are the differences between the Ventral Anterior Nucleus, Ventral Lateral Nucleus, and Ventral Posterior Nucleus?

Answer 39

VAN = motor activity based, receives info from GPi and SN, sends info to premotor and supp motor cortex. VLN = motor activity based, receives info from GPi and SN, also dentate nucleus and primary motor cortex, sends info to primary motor cortex. VPN = chief sensory relay station, receives info from contralateral head/neck/body, sends to primary somatosensory info.