Cerebellum Up Close

The Cerebellum is my favorite part of the brain. I like the sound of the word, which means “little brain” in Latin; though if you check the meaning of cere and bellum, you might be surprised at their individual meanings. How they come together to form “little brain” is all a matter of Latin semantics.

In dissecting a sheep’s brain, I see why the cerebellum is described as resembling cauliflower. (The cauliflower is on the left.) Unlike a head of cauliflower, though, the human cerebellum is quite a bit smaller, about the size of a golf ball or a fist. I’ve also seen it described as two halves of a peach and as “two clams side by side”.

The cerebellum is located in the rear of the brain, below the occipital lobes and attached to the brain stem. The white mass, which branches out tree-like, is the “white matter” and consists of nerve axons. There is so much white matter because the cerebellum has so many neurons. The darker, brownish tissue is “gray matter” and consists of nerve cell bodies. The Purkinje cells, which comprise the third of three layers of the cerebellum, “are the most complex nerve cells and interact with perhaps as many as 100,000 other nerve fibers, making more connections than any other cells in the brain.”

Like the rest of your brain, the cerebellum has two halves that are connected by a thick bundle of nerves. It comprises only ten percent of the brain’s physical size, but contains more than 50 percent of all the neurons, which translates to more nerve cells than any other area of the brain.

“Information is constantly being fed to the cerebellum, which makes modifications as needed.” Messages from the muscles, tendons, and joints are “sent to the cerebellum, which does not initiate movement, but monitors and modifies the progress of movements.” The cerebellum sends information to the cerebrum, which then determines if anything needs to be changed and relays that information back to the cerebellum, which makes the changes. The cerebrum and cerebellum work together much like a pilot and copilot.

This mini-brain has huge responsibilities, many of which call out to me as a teacher. The idea of kids or adults sitting still for long periods of time while trying to learn makes no sense to me, given the tasks ascribed to the cerebellum. Anyone who teaches should aim to take advantage of this powerful portion of the brain. Here is what the cerebellum does:

• handles motor patterns
• coordinates muscle movement
• maintains bodily equilibrium (posture, balance)
• handles cognitive patterns (speaking)
• automates certain repetitive tasks (breathing, heartbeat)
• responds to novelty

Resources:

• Neuroscience for Kids has a Flash fly–through of the brain. The cerebellum makes its entrance about two-thirds of the way through.
• At KidsHealth you can read and interact with information about the cerebellum and Your Brain & Nervous System.

Most of the quoted information in this post comes from these two books:

• The Complete Idiot’s Guide to Understanding the Brain, by Arthur and Mitchell Bard, is a clearly written explanation of how the brain functions. While some may scoff at the title, I found the book most helpful for getting me started on the anatomy of the brain, and continue to reference and reread parts.
• The Great Brain Book – An Inside Look at the Inside of Your Head, by HP Newquist, may have been written for young adults, but I found it a highly accessible story of the brain, from the history of its study to the way it works. There is a wonderful two-page spread that details what happens in your brain while you are watching a movie. I suspect most of us rarely “think” about how we think in such detail!

Pictures at a Dissection

Well, last weekend I dissected a preserved sheep brain. The previous week a colleage (a Science teacher with whom I co-teach the elective “Frontiers in Science”) brought me a fresh-from-the-butcher sheep brain, and we spent 20 minutes exploring it. The brain was soft and squishy. Having been partially frozen, as it melted it became almost like goop. Wish I had my camera, as it was easy to pick up or point out individual parts.

The preserved brain I dissected over the weekend was quite firm, making it easy to cut and hold, yet because it was preserved the brain seemed more like a plastic model. On May 3rd the “Frontiers in Science” class will dissect sheep brains, and the brains we will provide will be half from the butcher and half preserved brains.

My next goal is to further study individual brain parts, and for this I am hoping to borrow a microscope from school.

Pre-Dissection

Searching for “brains for dissection”, I discovered the NKU Cognitive Neuroscience blog post of September 24, 2006, and this enticing blurb:

Check out this fascinating video of brain dissection (Dissection 15), which I first learned about from Mind Hacks. The video is used for an anatomy class, not neuroscience, so the level of detail is rather course, but for those of us who never had the opportunity to saw off the top of someone’s skull and run our fingers through a human brain, this is a real eye-opener.

From there it was an easy hop to the University of Wisconsin Medical School’s Department of Anatomy. The Department has an extensive set of Anatomy Dissections, 27 at last count, consisting of videos ranging in length from 5.5 minutes to 35 minutes. The video quality is excellent, providing bird’s eye views of the dissections of parts of the human anatomy, coupled with technical explanation by the person doing the dissection.

I was fascinated and disappointed by Dissection 15, the 26 minute dissection of the Brain. Fascinated to see the dissection, plain and simple. Disappointed because it focused on the blood supply and surrounding structures, and did not highlight the actual brain parts. I wanted to see the corpus callosum, the hypothalamus, the amygdala, the cerebellum in greater detail, and more of the inner workings of this magnificent and amazing body part. Nonetheless, for a first time view, amazing!

I also found a number of online stores that sell sheep brains, and have purchased a sheep brain for dissection from Home Science Tools. I also purchased their Brain Mammal Dissection Guide. There are a number of sites with directions and information about sheep brain dissections:

• Exploratorium – Sheep Brain Dissection: The Anatomy of Memory
• Home Science Tools Sheep Brain Dissection
• Dr Burnett’s Sheep Brain Dissection at Clayton State University
• The Sheep Brain Dissection Guide from the Hanover College Psychology Department

I am quite looking forward to the arrival of my sheep brain (it shipped this past Wednesday) and am hoping it arrives in time for a weekend dissection. (It did! More on that in future posts.) At any rate, my plan is to take pictures of the brain parts and post them here coupled with explanations about the parts. Think of this as the next step in my Brain 101 posts. {This post was written prior to the dissection but posted after the dissection, which is why the dating is out of sequence.}

By the way, in early May I will be giving a talk to a high school Frontiers In Science class. This is a one semester elective that covers the latest discoveries and advances in science. The topics include stem cells, twenty first century spy technology, chemistry of love, teleportation, germ warfare, robotics, synthetic organs, invisibility, the nuclear age, SETI, the brain, and ongoing technology talks. I am giving the talk on the brain, and as part of the first day’s Introduction to the Brain, we will be dissecting sheep brains. I’ll keep you posted!

Brain Imaging from a New Perspective

In this almost four minute talk, Christopher deCharms provides a peek at the technology available to look inside your own brain and use what you see to make changes! His company, Omneuron, is looking at ways to use this technology to assist “patients, physicians, researchers, and subjects to visualize and control the functioning of the brain using non-invasive methods based on MRI, and is exploring applications of functional brain imaging.”

And how did I learn about Christopher deCharms? Why, from a TED talk!

Brain Imaging from the Inside–>Out

This morning I clicked on over to Garr Reynolds’ Presentation Zen blog, the way I do most mornings. His post, Dr. Jill Bolte Taylor’s amazing TED presentation, describes Dr. Taylor as a brain scientist who will move you to tears. That was all it took – the combination of a brain scientist and something emotional – for me to sit glued to my computer screen at 6:32 this Saturday morning.

I’ve watched Jill’s talk and I was moved to tears. And now, before the sun has even tickled the horizon, the birds are chirping. This Wednesday past, true as clock work, the Osprey who summer on the creek behind our house returned to their perches. And I thought of my Dad at King Street Nursing Home…how his brain is humbled by Alzheimers but his heart still smiles with song. Unable to speak many words, he tells me he wants to go home, and he can still respond to family news with “That’s wonderful.” And Frank Sinatra or any of the Columbia University fight songs can still elicit from him a hum or a phrase of song and a twinkle of recognition.

Brain Imaging from the Outside–>In

My husband sent me a link for the Charlie Rose Science Series, sponsored by Pfizer. Charlie Rose is a public television talk show host, and this series consists of twelve conversations between Charlie and numerous scientists as they explore a range of topics, beginning and ending with the brain. I watched the first part, From Freud to the mysteries of the human brain and the last part, From Potential of the Mind to Diseases of the Brain. (While all the talks are nicely organized on the Pfizer site, they played more reliably from the Rose site.) We had a snow day on February 22 (meaning school was canceled), and these video conversations, complete with a cup or two of tea, made for a delightful afternoon’s journey.

The format of both talks was similar, with Eric Kandel helping to steer the round table conversations. Kandel was awarded the Nobel Prize in Physiology or Medicine in 2000 and is a Professor of Physiology & Cellular Biophysics at Columbia University. I was especially interested in the discussion about seeing the brain in action. Thanks to improved imaging techniques, we are able to view a brain in “real time”. MRI highlights the structure and details of the brain, while a PET scan or fMRI allows the mapping of brain function. Brain functions tend to be localized to regions or combinations of regions in the brain. What brain imaging does is measure the “change in blood flow to the active part of the brain”. (As noted by Nancy Kanwisher, MIT Professor.)

According to Steven Johnson, author of Mind Wide Open, “you have to have roughly 500,000 neurons active in an area for the scan to register them”. He writes about his own fMRI in chapter six, which is what gave me the urge to want to see my own brain in action. You can see a really quick movie of a portion of a brain scan here.

Eric Kandel, whose interest is learning and memory, believes that psychotherapy is a learning experience. Therefore, he would like to see the mapping of a brain prior, during and after psychotherapy, with the goal being to see what anatomical changes may be occurring as the brain goes through the process.

For more on these imaging techniques see:
MRI (magnetic resonance imaging)
fMRI (functional magnetic resonance imaging)
PET (positron emission tomography)

and this wonderfully informative and well-designed site fMRI 4 Newbies – A Crash Course in Brain Imaging by Jody Culham, Robarts Centre for Functional & Metabolic Mapping in London, Ontario

Image and movie: Charlie Rose site