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Let's talk about neuroanatomy and neurophysiology,

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which includes the putamen

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and the caudate nucleus,

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which has a head that we see but also a body and

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a tail that we currently are not following.

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As we go lower,

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we see the lower head of the caudate,

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the lower aspect of the putamen,

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the mid aspect of the head,

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mid aspect of the putamen and the upper aspect of

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the head and the upper aspect of the putamen.

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These are separated by the anterior limb

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of the internal capsule, the genu,

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which blends imperceptibly unless you have iron

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sensitive sequences with the inner and outer

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aspect of the globus pallidus known as

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GPI for inner and GPE for outer,

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GPE for external outer and GPI for inner.

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And these are associated with structures such as

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the subthalamic nucleus which we see below

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the anterior commissure.

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Maybe if we go a little bit forward

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a little more anterior,

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still more of the subthalamic nucleus region

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in here and the substantia nigra.

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Now, the substantia nigra in this young individual

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with tumor factive MS is nicely seen as a somewhat

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darkened stripe. And in Parkinson's disease,

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we're going to look for loss of this

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stripe in the outer aspect of it,

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the so-called swallow tail sign.

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But another thing we like to do is separate out

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the round, dark signal of the red nucleus,

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which is right here from the region of the

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substantia nigra by this stripe.

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And when they bleed together,

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this is usually a sign that something's wrong and

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is actually considered one of the signs

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of Parkinson's disease.

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Now, according to the model of motor loops between the

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basal ganglia thalamus and motor cortical areas,

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GABAergic projections from the inner aspect of the

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globus pallidus modulate activities of other

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structures such as the motor

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nuclei of the thalamus,

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which facilitate movement through excitatory

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glutaminergic projections to

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the cortical motor areas,

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including the premotor cortex and supplementary

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motor area. So, let's take a look at those.

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Most of you already know where the thalamus is.

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It's right here.

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It's a very large complex structure

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with the pulvinar in the back.

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But if we follow the cingulum or cingulate

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sulcus around to the back,

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it becomes the sulcus marginalis

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or supramarginal sulcus.

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Just anterior to that is an oblique-looking sulcus

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and that delimits the motor cortex just in front of it.

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So, this is the motor cortex right here.

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We also mentioned the SMA or supplementary motor

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cortex which is found in the midline.

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That's right here.

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It controls movement,

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especially things like posture and coordination.

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But it's also intimately involved in either

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stimulating or suppressing intrinsic motions that

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are controlled by other structures in the body.

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Now, if we follow this structure out laterally,

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it becomes the prefrontal cortex.

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So, laterally prefrontal cortex in the midline,

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supplementary motor cortex with the motor cortex

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lying immediately behind it in front of

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the region of the sulcus marginalis.

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That's a quick anatomic summary of what's going

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on along with some physiology in the brain.