Gordon Johnson: Doctor let’s talk about the basal ganglia.
Dr. Erin Bigler: So now I’m going to pull this apart a little bit further. So, I’m going to do an interesting – I’m going to put you on the spot, okay? So I’m going to pull this, structure out right here and, what does that look like to you?
Gordon Johnson: It looks like a pebble.
Dr. Erin Bigler: If you were to eat it. If it was something that you were going to –
Gordon Johnson: It looks like a pepper.
Dr. Erin Bigler: Or a lima bean.
Gordon Johnson: It’s too big for a lima bean, but, maybe, it’s red, so I’m thinking pepper.
Dr. Erin Bigler: Okay, well, my, my little experiment didn’t work all that well.
Gordon Johnson: Okay.
Dr. Erin Bigler: So think of it as a lima bean.
Gordon Johnson: Alright.
Dr. Erin Bigler: Okay, nice big, the biggest the lima bean you’ve ever seen. So, when the early anatomists looked at this and dissected it out, it has more gray matter so it, it looks distinct in the brain and they referred to this as like a lentil, a bean.
Gordon Johnson: Okay.
Dr. Erin Bigler: So this is the lenticular nucleus.
Gordon Johnson: Alright.
Dr. Erin Bigler: The outer side of it is the putamen; the inner side of it is globus pallidus.
Gordon Johnson: Okay now the outer side on your model is an orangest red and the inner side is a much deeper red. Is there a reason why they have those in different colors? I know that’s not the actual color of the brain, but, why do they give us that in different colors in the model?
Dr. Erin Bigler: Well, it, it actually relates to different connections that these brain structures are involved in. There’s more white matter that’s in the globus pallidus, but these structures here have complex networks with motor function, motor control and also emotional, areas. That insular cortex that sits just on the outside of where the putamen is located that insular cortex is activated when there are versa things like if you see something that’s very disgusting, this outer part of cortex is activated and it involves this area as well. But these colors don’t necessarily mean anything other than distinguishing between this outer part and this inner part.
Dr. Erin Bigler: So, now, here we have what’s called the internal capsule. It’s the white matter projections. The motor neurons that are going from motor cortex in the frontal lobe down pass through here and the somata sensory, tracks that are going up to the parietal cortex from the thalamus pass through here.
Gordon Johnson: Somata se –
Dr. Erin Bigler: Somata sensory, so touch, so the touch sensory, information, joint sense and those things, they synapse in the thalamus which we are going to look at in just a minute and then they project up to the parietal cortex. Now if we look here this shows the caudate. We’ll unveil the caudate over here in just a moment. So this is the head of the caudate, the body and the tail of the caudate as it bends around and it will actually interface with the amygdala. But then you can see this is the putamen, the outer aspect of the putamen and you see these striations here. So these are the striations that go from the putamen to the caudate. So this is the striatum, is this part and we’ll now pull this. This shows you the inner side view of the caudate and how it has a head, a body and then a tail. Remember at the end of the tail it connects to the amygdala.
So I’m going to pull this apart just a little bit here. Now I’m losing some of my little anatomical numbers for the anatomy test that I gave just a little bit ago. This is showing you a very nice side view of the ventricle. So here is the anterior horn, the body, the occipital horn, and the temporal horn of the lateral ventricle.
Gordon Johnson: And again the ventricle is the water balloon.
Dr. Erin Bigler: It is the water balloon located internally and now I’m going to pull this apart and put the ventricle aside and so here we have that head of the caudate, body, tail, putamen. I’m going to now pull this off and you can see there’s that globus pallidus structure again.
Gordon Johnson: And what is the caudate?
Dr. Erin Bigler: So the caudate is another part of the basal ganglia. The caudate is again involved in some aspects of background motor control. It’s also involved in some aspects of emotional control and regulation, motivation, drive. And now if we turn this again, we’re looking at the brain stem and you get this other nice view. The brain stem is no bigger than your thumb. So you have all of these weighty structures sitting on this very small aspect of the brain stem. At this point here this area right in here, this whole thing that we’re looking at is the term that you used earlier, the diencephalon – so diencephalon is the thalamus and the hypothalamus. So this is the thalamus, this is the hypothalamus.
Gordon Johnson: Let’s break and do the diencephalon separately.
Dr. Erin Bigler: Okay.