 Let's talk about neuroanatomy and neurophysiology, which includes the putamen and the caudate nucleus, which has a head that we see, but also a body and a tail that we currently are not following. As we go lower, we see the lower head of the caudate, the lower aspect of the putamen, the mid-aspect of the head, mid-aspect of the putamen, and the upper aspect of the head and the upper aspect of the putamen. These are separated by the anterior limb of internal capsule, the genu, which blends imperceptibly unless you have iron-sensitive sequences with the inner and outer aspect of the globus pallidus, known as GPI for inner and GPE for inner, GPE for external outer and GPI for inner. And these are associated with structures such as the subphalamic nucleus, which we see below the anterior commissure. Maybe if we go a little bit forward, a little more anterior, still more of the subphalamic nucleus region in here, and the substantia nigra. The substantia nigra in this young individual with tumor-factive MS is nicely seen as a somewhat darkened stripe, and in Parkinson's disease, we're going to look for loss of this stripe in the outer aspect of it, the so-called swallowtail sign. But another thing we'd like to do is separate out the round dark signal of the red nucleus, which is right here from the region of the substantia nigra by this stripe. And when they bleed together, this is usually a sign that something's wrong and is actually considered one of the signs of Parkinson's disease. Now, according to the model of motor loops between the basal ganglia thalamus and motor cortical areas, GABA-ergic projections from the inner aspect of the globus politus modulate activities of other structures such as the motor nuclei of the thalamus, which facilitate movement through excitatory glupaminergic projections to the cortical motor areas, including the premotor cortex and supplementary motor area. So let's take a look at those. Most of you already know where the thalamus is. It's right here. It's a very large complex structure with a pulvanar in the back. But if we follow the singulum or singulate sulcus around to the back, it becomes the sulcus marginalis or super marginal sulcus. Just anterior to that is an oblique-looking sulcus, and that delimits the motor cortex just in front of it. So this is the motor cortex right here. We also mentioned the SMA or supplementary motor cortex, which is found in the midline. That's right here. It controls movement, especially things like posture and coordination, but it's also intimately involved in either stimulating or suppressing intrinsic motions that are controlled by other structures in the body. Now, if we follow this structure out laterally, it becomes the prefrontal cortex, so laterally prefrontal cortex in the midline supplementary motor cortex with the motor cortex lying immediately behind it in front of the region of the sulcus marginalis. That's a quick anatomic summary of what's going on along with some physiology in the brain.