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

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

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

Where are they found?

 

Betz cells

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

2

What are the two main tracts of the pyramidal system?

  1. Corticonuclear/-bulbar ( ---> CN nuclei)
  2. Corticospinal ( ---> ventral horn)

3

How do the corticospinal tract fibers travel in the brainstem?

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

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

crossed fibers (90%) - lateral funiculus

uncrosed fibers (10%) - anterior funiculus

5

What are the 5 components of the basal ganglia?

  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

What are the functions of the basal ganglia?

  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

Most of the cerebral cortex communicated with the basal ganglia.

What two parts do not?

  1. Primary Auditory Cortex
  2. Primary Visual Cortex

A image thumb
8

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

And what is their function/neurotransmitter?

Medium Spiny Neurons

inhibitory neurons using GABA

A image thumb
9

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

  1. Direct Pathway - increases movement
  2. Indirect Pathway - decreases movement

10

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

Its neurotransmitter?

Pre-motor cortex

Glutamate

 

A image thumb
11

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

Via what neurotransmitter/receptor?

What's the effect?

Substantia Nigra

Dopamine + D1 Receptor on medium spiny neuron

activating effect

12

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

Its neurotransmitter?

a medium spiny neuron in the putamen

- inhibitory effect with GABA and Substance P

A image thumb
13

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

Its neurotransmitter?

Globus Pallidus, internal segment

GABA

14

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

Lenticular Fasciculus

- connects globus pallidus and thalamus

15

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?

Thalamus VA/VL

glutamate

- synapses in the motor cortex 

16

What is the direct pathway from start to finish?

4 neurons, their neurotransmitters + 1 regulatory input

  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

A image thumb
17

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?

 

- medium spiny neuron in the putamen

GABA and Enkephalin

18

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

Its neurotransmitter?

Globus Pallidus Externus

GABA

 

19

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

Its neurotransmitter?

Subthalamic Nucleus of Luysi

Glutamate

20

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

Its neurotransmitter?

Globus Pallidus Internus

GABA

21

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

Its neurotransmitter?

Thalamus VA/VL

Glutamate

22

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

6 neurons, their NTs + 1 regulatory input

  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