Interactive Transcript
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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.
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