Basal Ganglia Animation
description
Transcript of Basal Ganglia Animation
Basal Ganglia Animation
May 2012
Movement in the body is controlled by the brain. Working in conjunction with motor neurons (neurons that connect to muscles), the brain sends signals to muscles to contract. A combination of these signals results in either a wanted movement or the stopping of an unwanted movement.
Brain
Motor Neurons
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Show movement when “signal” reaches the hand
Show signal going from brain to hand (brain to
motor neurons to hand)
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The motor cortex sends out signals to control voluntary movements in the body via motor neurons that cause muscle to contract.
Motor Neurons
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Show movement when “signal” reaches the hand
Show signal going from brain to hand (motor cortex to motor neurons to hand)
Motor Cortex
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The control of voluntary movement by the motor cortex, however, is regulated by other brain circuits. One of these is called the basal ganglia, a group of interconnected structures in the middle of the brain. Specifically, the basal ganglia participate in the initiation and termination of voluntary movements by suppressing unwanted movements and permitting desired and appropriate movements .
Motor Neurons
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Show movement when “signal” reaches the hand
Show signal going from brain to hand (motor cortex to spinal cord, spinal cord to motor neurons, motor neurons to arm and hand muscles AND back and forth between motor cortex and basal ganglia)
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Basal Ganglia
Motor Cortex
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Transition from prior screen: Zoom in on brain and fade basal ganglia area to the actual structures
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Basa
l Gan
glia
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The basal ganglia consists of the striatum (caudate nucleus and putamen),
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Striatum
global pallidus (external and internal segments),
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subthalamic nucleus,
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Even though I “cut” out the structures, I would recommend just fading them and highlighting the structure being addressed.
and substantia nigra reticulata.
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The basal ganglia receives information from most parts of the cerebral cortex and sends information specifically to the motor cortex, to execute movement, through the thalamus.
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So, how does this process work? Messages are sent from various parts of the cerebral cortex to the
basal ganglia, here let’s consider messages from the motor cortex to the striatum, the input structure of
the basal ganglia.
Striatum
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Motor Cortex
Striatum
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The basal ganglia also has output structures, the globus pallidus internal segment and the substantia nigra reticulata, which control the motor
cortex through the thalamus. (N.B. erase big arrow and unhighlight the striatum and highlight the SNr and Gpi as output structures with an arrow going to the thalamus and another arrow going to the motor
cortex.)
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The globus pallidus internal segment and the substantia nigra reticulata control the motor cortex through the thalamus.
1. Have these be dynamic, dashed arrows that appear first and then highlight the thalamus.
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The striatum controls the output structures through two different pathways.
Striatum
Global pallidus external segment
Subthalamic Nucleus
Global pallidus internal segment/Substantia
nigra reticulata
Indirect Pathway: Suppresses unwanted or inappropriate movements.
Direct Pathway: Promotes wanted or desired movement
In the indirect pathway, the striatum sends a message to the global pallidus external segment .
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Striatum
Global pallidus external
Striatum
Global pallidus external segment
The global pallidus external then sends a signal to the subthalamic nucleus.
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Global pallidus external
Global pallidus external segment
Subthalamic nucleus
Striatum
The subthalamic nucleus then sends a message to the global pallidus internal and substantia nigra.
Subthalamic nucleus
Global pallidus internal segment/Substantia
nigra reticulata(Output)
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Subthalamic nucleus
Global pallidus internal segment
Substantia nigra reticulata
Global pallidus external segment
Striatum (Input)
The striatum also sends messages through the direct pathway. In this pathway, the striatum sends a message directly to the global pallidus internal and the substantia nigra.
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Striatum
Global pallidus internal segment/substantia nigra
reticulata
Now the global pallidus internal and the substantia nigra have received
messages from both the indirect and direct pathway. Motor cortex
Striatum
Global pallidus external
Subthalamic nucleus
Global pallidus internal/Substantia nigra
Direct Pathway
Indi
rect
Pat
hway
The global pallidus internal and substantia nigra then send a
message on to the thalamus.
Substantia nigra
Global pallidus internal
Thalamus
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Motor cortex
Striatum
Global pallidus internal/Substantia
nigra
Thalamus
Indirect pathway
Direct pathway
The thalamus then sends a message t o the motor cortex.
Thalamus
Motor Cortex
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Motor cortex
Striatum
Global pallidus internal/Substantia
nigra
Thalamus
Direct pathwayIn
dire
ct p
athw
ay
The motor cortex then sends the appropriate
message out to the body.Motor Cortex Highlight first
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