Midterm 2: Basal Ganglia + Motor Pathways (Ben) Flashcards Preview

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Flashcards in Midterm 2: Basal Ganglia + Motor Pathways (Ben) Deck (22)
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1
Q

What are the first neurons sending signals in the pyramidal system ?

Where are they found?

A

Betz cells

  • large, pyramidal neurons in the 5th layer of the cortex of the pre-central gyrus
2
Q

What are the two main tracts of the pyramidal system?

A
  1. Corticonuclear/-bulbar ( —> CN nuclei)
  2. Corticospinal ( —> ventral horn)
3
Q

How do the corticospinal tract fibers travel in the brainstem?

A

in the pyramids of the medulla…

  • 90% decussate (@ pyramidal decussation) and join the lateral/cruciate corticospinal tract
  • 10% remain uncrossed and join the anterior corticospinal tract
4
Q

How do the fibers of the corticospinal tract travel in the spinal cord?

A

crossed fibers (90%) - lateral funiculus

uncrosed fibers (10%) - anterior funiculus

5
Q

What are the 5 components of the basal ganglia?

A
  1. Striatum - caudate nucleus + putamen
  2. Pallidum - globus pallidus int/ext segment
  3. Ventral Pallidum - nucleus accumbens + olfactory tubercle
  4. Substantia Nigra - pars compact + reticulata
  5. Subthalamic Nucleus
6
Q

What are the functions of the basal ganglia?

A
  1. Motor Regulation
  2. Eye Movement Control (SNr —> sup. collicle)
  3. Motivaton - dopamine
  4. Cognitive Function - basal nucleus, ACh
  5. Emotional Reaction - amygdala > ventral striatum
7
Q

Most of the cerebral cortex communicated with the basal ganglia.

What two parts do not?

A
  1. Primary Auditory Cortex
  2. Primary Visual Cortex
8
Q

What kind of neurons receive and send information in the striatum?

And what is their function/neurotransmitter?

A

Medium Spiny Neurons

- inhibitory neurons using GABA

9
Q

What are the two movement-regulating circuits of the basal ganglia and their functions?

A
  1. Direct Pathway - increases movement
  2. Indirect Pathway - decreases movement
10
Q

Where is the first neuron in the direct pathway of the basal ganglia?

Its neurotransmitter?

A

Pre-motor cortex

Glutamate

11
Q

What basal ganglia structure has a modifying effect on the direct pathway?

Via what neurotransmitter/receptor?

What’s the effect?

A

Substantia Nigra

  • Dopamine + D1 Receptor on medium spiny neuron
  • activating effect
12
Q

Where is the 2nd neuron in the direct pathway of the basal ganglia?

Its neurotransmitter?

A

a medium spiny neuron in the putamen

  • inhibitory effect with GABA** and **Substance P
13
Q

Where is the 3rd neuron in the direct pathway of the basal ganglia?

Its neurotransmitter?

A

Globus Pallidus, internal segment

  • GABA
14
Q

What is the pathway formed by the axon of the 3rd neuron in the direct pathway of the basal nuclei called?

A

Lenticular Fasciculus

  • connects globus pallidus and thalamus
15
Q

Where is the fourth neuron in the direct pathway of the basal ganglia?

What is its neurotransmitter?

And where does it synapse, ending the pathway?

A

Thalamus VA/VL

  • glutamate
  • synapses in the motor cortex
16
Q

What is the direct pathway from start to finish?

4 neurons, their neurotransmitters + 1 regulatory input

A
  1. Premotor Cortex - Glu
  2. Putamen - GABA + Substance P
    1. Substantia Nigra - DA + D1 receptor (+)
  3. Globus Pallidus Internus - GABA
  4. Thalamus VA/VL - Glu
  5. Ends in the motor cortex

- 2 inhibitory neurons in the path cancel out = activation

17
Q

The first neuron in the indirect pathway is the same as in the direct.

Where is the second neuron in the indirect pathway?

Its neurotransmitter?

A
  • medium spiny neuron in the putamen
  • GABA** and **Enkephalin
18
Q

Where is the 3rd neuron in the indirect pathway of the basal ganglia?

Its neurotransmitter?

A

Globus Pallidus Externus

  • GABA
19
Q

Where is the 4th neuron in the indirect pathway of the basal ganglia?

Its neurotransmitter?

A

Subthalamic Nucleus of Luysi

  • Glutamate
20
Q

Where is the 5th neuron of the indirect pathway of the basal ganglia?

Its neurotransmitter?

A

Globus Pallidus Internus

  • GABA
21
Q

Where is the 6th neuron in the indirect pathway of the basal ganglia?

Its neurotransmitter?

A

Thalamus VA/VL

  • Glutamate
22
Q

What is the indirect pathway of the basal ganglia from start to finish?

6 neurons, their NTs + 1 regulatory input

A
  1. Premotor Cortex - Glu
  2. Putamen - GABA + Enkephalin
    1. Substantia Nigra - DA + D2 (-)
  3. Globus Pallidus Externus - GABA
  4. Subthalamic Nucleus (Luysi) - Glu
  5. Globus Pallidus Internus - GABA
  6. Thalamus VA/VL - Glu
  • 3 inhibitory neurons = inhibition
  • dopaminergic inhibition of inhibition = activation