In response to a student request for an overview of neuroanatomy, I happily recorded an hour of dissections designed to provide a neuroanatomical framework. I start with development and proceed to dissections of sheep and human brains to illustrate the parts of the brain and how they fit into the cranium.
Peeling off brain bark In this edition of Lab Videos, we look at horizontal cuts through the human brain. By slicing through the brain, we are able to see all the interesting territory that is normally hidden by the bark or cortex (yes, the word cortex derives from the Latin word for bark; and I am referring to the tree […]
In this installment of laboratory videos, the goal is to compare the sheep and human brains. What we’ll see is the extreme similarity in the basic plan of the sheep and human brains. This is part of our mammalian inheritance, the common evolutionarily derived template that mammals share. In this first video, we look at sheep and human brains side by side and identify the major brain regions in each. Now let’s go inside the sheep brain. The first important point is to see that, as in the human, the telencephalon arches over the diencephalon and brainstem in the sheep. And while the human telencephalic cap covers even more of the rest of the brain than does the sheep cap, the sheep telencephalon is no small potatoes. In fact, the telencephalon is impressive even in smooth-brained (= lissencephalic or lacking sulci and gyri) mammals such as the rat that have relatively small cerebral cortices. By looking at sheep brains, I discovered something surprising; namely that the sheep superior colliculus appears larger than the human superior colliculus. I mentioned this in NeuroMOOC class and several students began to discuss this issue. These clever NeuroMOOCers came up with two intriguing ideas regarding how a large colliculus might render a behavioral or ecological advantage to sheep. First, the sheep with its laterally placed eyes has a wider visual field than does the human with its forward-facing eyes. The sheep can see close to […]
It was quite striking to me how many students in the 2014 NeuroMOOC class of Understanding the Brain appeared to really enjoy the laboratory videos that were included in the class. So I will post versions of those videos here on my blog. I will add more from time to time. But let’s start with those that that were part of NeuroMOOC 2014. I want to emphasize the respect and gratitude that I feel every time I look at tissue from a dead person. The decision to offer up one’s body for scientific study or training is the epitome of generosity and selflessness. I am in awe of those individuals who did so. Please take a moment to be grateful to tissue donors: To start with, we are going to look at the central nervous system which is comprised of the brain and the spinal cord. Now let’s look at the meninges that surround the central nervous system. Now that we know about the meninges, we can talk about “brain tumors” and “brain cancer”. The important point is that none of these are tumors where neurons multiply out of control. Intracranial tumors arise from either glial cells (mostly astrocytomas from astrocytes or Schwannomas from Schwann cells) or from glandular cells (pinealomas in the case of the pineal gland or pituitary adenomas in the case of the pituitary gland). Importantly, neurons are NOT the source of tumors. I should mention that there are […]