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.
Show signal going from
brain to hand (brain to
motor neurons to
hand)
Brain
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solid (not
see through)
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Motor Neurons
Show movement when “signal”
reaches the 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.
Show signal going from
brain to hand (motor
cortex to motor
neurons to hand)
Motor Cortex
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solid (not
see through)
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Motor Neurons
Show movement when “signal”
reaches the 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
Basal Ganglia
group of
interconnected
structures in the
Show signal going from brain to
middle of the brain.
hand (motor cortex to spinal cord,
Specifically, the basal
spinal cord to motor neurons,
motor neurons to arm and hand
ganglia participate in
muscles AND back and forth
the initiation and
between motor cortex and basal
ganglia)
termination of
voluntary movements
by suppressing
Show movement when “signal”
unwanted movements reaches the hand
and permitting
desired and
appropriate
movements .
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solid (not
see through)
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Motor Neurons
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Basal Ganglia
Transition from prior
screen: Zoom in on
brain and fade basal
ganglia area to the
actual structures
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lines
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,
Even though I
“cut” out the
structures, I
would
recommend
just fading
them and
highlighting the
structure being
addressed.
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and substantia nigra
reticulata.
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half only)
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.
Motor Cortex
Striatum
Fill in motor cortex
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Striatum
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Keep the highlighting cycling until
student moves on to next section.
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.
4. Highlight this
Third – make this a dynamic,
dashed line.
2. Highlight second.
1. Have these be
dynamic,
dashed arrows
that appear first
and then
highlight the
thalamus.
The striatum controls the output structures through two different pathways.
Striatum
Indirect Pathway:
Suppresses
unwanted or
inappropriate
movements.
Global pallidus
external segment
Direct Pathway: Promotes wanted or
desired movement
Subthalamic Nucleus
Global pallidus internal
segment/Substantia
nigra reticulata
In the indirect pathway, the striatum sends a
message to the global pallidus external segment .
Striatum
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Global pallidus
external segment
Striatum
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Global pallidus
external
The global pallidus external
then sends a signal to the
subthalamic nucleus.
Striatum
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Global pallidus
external segment
Subthalamic
nucleus
Global
pallidus
external
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Subthalamic
nucleus
Striatum (Input)
The subthalamic nucleus then sends a message to
the global pallidus internal and substantia nigra.
Global pallidus external
segment
Subthalamic nucleus
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Global pallidus internal
segment/Substantia
nigra reticulata
(Output)
Subthalamic
nucleus
Global pallidus
internal segment
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Substantia nigra
reticulata
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
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Motor cortex
Striatum
Global pallidus
external
Subthalamic
nucleus
Direct Pathway
Indirect Pathway
Now the global pallidus internal and
the substantia nigra have received
messages from both the indirect and
direct pathway.
Global pallidus
internal/Substantia nigra
The global pallidus internal and
substantia nigra then send a
message on to the thalamus.
Motor cortex
Striatum
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Direct
pathway
Indirect
pathway
Global
pallidus
internal
Substantia
nigra
Global pallidus
internal/Substantia
nigra
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Thalamus
Thalamus
Motor cortex
The thalamus then
sends a message t o
the motor cortex.
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Motor
Cortex
Direct pathway
Indirect pathway
Striatum
Global pallidus
internal/Substantia
nigra
Thalamus
Thalamus
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The motor cortex then
sends the appropriate
message out to the body.
Motor Cortex
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second
End arrow here