Category Archives: Brain 101

Our Nervous System, explained

I am taking the online course Being Well in a Digital Age – The Science and Practice of Yoga, which partially explains why it has been two years since my last post on this blog. During the first half of 2016 I was studying for my 200-hour yoga teacher certification and blogging at my other web home, Yoga ~ Dance ~ Music ~ Movement. And for large portions of 2015, 2016, and the summer of 2017, my son, daughter-in-law and grandchildren were living with us. Spend time blogging here or with my family; easy decision!

My yoga blog has been the recipient of all yoga-related writing and below is a cross-post of my most recent post, written earlier today. It deals exclusively with the nervous system and how stress impacts and is dealt with by the nervous system. The post is reprinted below.


The lectures by Catherine Spann and Stacy Dockins from Being Well in a Digital Age – The Science and Practice of Yoga have explained the basics of what happens when stress manifests in the human body. A little bit of stress is manageable; a lot of stress begins to break down our capacity to effectively deal with the stress, and that in turn can manifest in the malfunctioning of other body systems.

Our nervous system consists of two parts, the central nervous system and the peripheral nervous system. I use the word “central” to help remember what the central nervous system consists of – it consists of our brain and spinal cord, the part of our nervous system that runs center or central in our body from our head to the bottom of the spine and is housed in our axial skeleton.

The peripheral nervous system is the communications conduit between the central nervous system and the rest of the body. The word “peripheral” means outlying items or those not centrally located. Again, this helps me remember what the peripheral nervous system deals with – the parts of our nervous system peripheral to the brain and spinal cord, the parts of our nervous system that run through our appendicular skeleton.

The peripheral nervous system consists of the somatic nervous system, which are our voluntary actions, and the autonomic nervous system, which are our unconscious actions such as our heart beating (though we can control that to some extent), and the regulation of digestion, respiration, to name a few of the systems.

Finally, the autonomic nervous system is further composed of the sympathetic nervous system and the parasympathetic nervous system. These two have alliterative words to quickly and easily describe their functions. The sympathetic nervous system triggers the fight, flight or freeze response, which Catherine likens to putting a lead foot on a gas pedal.  The parasympathetic nervous system invokes the rest and digest response, which Catherine equates to putting on the brakes. All of these systems interact with the hypothalamus in the brain, which along with the pituitary gland and the thalamus are part of the endocrine system.

The last piece of this puzzle is the vagus nerve, the longest nerve of the autonomic nervous system. Its role as part of the parasympathetic nervous system involves regulating the heart, lungs and digestive tract.

Now we come to stress and how it impacts our nervous system. Stress can be of a short duration, known as acute stress, or it can be chronic stress meaning it is ongoing over a long period of time or simply recurring over and over and over. Our nervous system has a “set point” where it is relatively in balance; this is called homeostasis. Each time our body undergoes some form of stress, our nervous system makes adjustments to return to homeostasis. This adjustment process is known as allostasis. If we are frequently engaged in allostasis it leads to allostatic load, which is the wear and tear on our body systems that often leads to an autonomic imbalance, meaning our sympathetic and parasympathetic nervous systems are out of whack.

Eventually allostatic load causes a cycle that over time makes it difficult to reset our nervous system and find our way back to homeostasis. This is where yoga comes in! Yoga can calm the nervous system and strengthen the ability to self-regulate. A calm nervous system can begin the process of allostasis and correcting for the growing internal imbalances.

One way of calming the nervous system is by stimulating the relaxation response as described by Dr Herbert Benson. Deep, slow breathing stimulates the vagus nerve, which then positively triggers the parasympathetic nervous system. As noted in a prior post, the combination of movement (the physical part of yoga), breath, mindful attention, and relaxation lead to improved mental health. This combination makes for a powerful self-regulation tool that lets you consciously partner with allostasis to reset your body in homeostasis.

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Brainy Henry Markram!

I have just watched this fascinating TED Talk: Henry Markram builds a brain in a supercomputer. (The link goes to a high definition version of his talk.)

Markram is the director of a project that runs on high intensity IBM computers and is called Blue Brain. (Hmm, does the Blue refer to  IBM’s also being known as Big Blue?”) Blue Brain is “a supercomputing project that can model components of the mammalian brain to precise cellular detail – and simulate their activity in 3D.” The graphics, let alone the math and science, are incredibly striking. And after listening to Markram, I couldn’t help but think of a tenth grader at my school who recently attended the Singularity Summit that took place in New York City over the weekend of October 3-4.

The Singularity represents an “event horizon” in the predictability of human technological development past which present models of the future may cease to give reliable answers, following the creation of strong AI [Artificial Intelligence] or the enhancement of human intelligence.

You can read about the Blue Brain Project, also described as “the first comprehensive attempt to reverse-engineer the mammalian brain, in order to understand brain function and dysfunction through detailed simulations.” Or check out this SEED article by Jonah Lehrer, Can A Thinking, Remembering, Decision-Making, Biologically Accurate Brain Be Built From A Supercomputer?

What reaction do you have to this possibility? To the stunningly vibrant images?

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.

Imagination: Ramachandran

Phantoms in the Brain is an engaging tale of individuals who have odd and curious brain quirks, often resulting from a malfunction in their brain such as a stroke, which display in sometimes unbelievable manifestations.

Ramachandran begins with an overview of the brain’s physiology, coupled with sharing how he approaches study of the brain. He likens the work to that of Sherlock Holmes and Dr Watson in the pursuit of solving mysteries. As a youngster, Ramachandran was intrigued by science, concocting unusual experiments with simple tools, and with “being drawn to the exception rather than to the rule in every science” he studied. He believes that “the odd behavior of these patients can help us solve the mystery of how various parts of the brain create a useful representation of the external world and generate the illusion of a “self” that endures in space and time.”

Once explained, the experiments that Ramachandran designed sounded deceptively simple and logical. What impressed me was his imaginative insight in concocting them in the first place.

Chapter Five describes patients who have discrepancies between what they visually see, and what they believe they see. Damage to some portion of the visual cortex can result in hallucinations, and depending upon the type of damage, the hallucinations can impact specific portions of the visual field, such as the lower half or the left half. As an example, there is the story of one patient who sustained damage to his eyes and optic nerves as the result of an auto accident. Greatly, though not wholly, recovered, he had visual hallucinations in just “the lower half of his field of vision, where he was completely blind. That is, he would only see imaginary objects below a center line extending form his nose outward.”

Ramachandran goes on to describe how the patient discerns between what is real and what is an hallucination. At one point, the patient says he sees a monkey sitting on Ramachandran’s lap. The patient notes that while “it looks extremely vivid and real”, “it’s unlikely there would be a professor here with a monkey sitting in his lap so I think there probably isn’t one.” The patient goes on to state that the images “often look too good to be true. The colors are vibrant, extraordinarily vivid, and the images actually look more real that real objects, if you see what I mean.” The hallucinations tend to fade fairly soon after being “seen”, and while they usually blend in with the rest of what is actually being seen, the patient knows that they are part of his visual imagination. He enjoys the surprise of what he conjures up, and is more concerned about his partial blindness.

By the end of this chapter, which has a number of other interesting and curious vision tales, Ramachandran hypothesizes that “all these bizarre visual hallucinations are simply an exaggerated version of the processes that occur in your brain and mine every time we let our imagination run free. Somewhere in the confused welter of interconnecting forward and backward pathways is the interface between vision and imagination. … what we call perception is really the end result of a dynamic interplay between sensory signals and high-level stored information about visual images from the past.”

What starts to emerge is an explanation of imagination as a combination of that which we have visually seen, processed and stored in memory, coupled with crafting something new based upon those conceptions. Interesting questions arise…

  • If we had no prior knowledge, would we be able to imagine?
  • Do we consciously conjure our imagination, or is it a subconscious process, or a little of both depending upon the situation?
  • When we are feeling stymied and need a nudge to get our imagination going, how do we do that under our own power?
  • When we totally zone out (like I do when getting in the groove of swimming laps), how is it that thoughts can just “pop” into my head?

Phantoms in the Brain by V.S. Ramachandran & Sandra Blakeslee

Phantoms in the Brain was listed someplace as one of the books that must be read by any serious student of neurology. Having quite enjoyed watching Ramachandran give his TED Talk, of course I had to snap up the book!

If you are like me, and found this talk entertaining, lively and informative, then you will not be disappointed in reading Phantoms in the Brain.

Phantoms can be approached from any number of angles. Read it for the science, and you will come away with a deeper understanding of how parts of our brain function. Indeed, Ramachandran’s approach reminded me of an exercise we did with Robert Greenleaf this past August. Designed to teach the concept of verbs, the exercise had us rewriting a fairy tale but we had to leave out all verbs. One way to learn what a verb is, is to have to write without using any verbs. And one way to learn about our brains is to study the oddities of the brain.

phantoms.pngRead it for the experiments and tinkering, and you will come away with an appreciation for how simple experiments can be used to find answers to complex questions. You are also sure to be impressed by the imaginative methods employed in devising these experiments.

Read it as a medical sleuth and join Sherlock Ramachandran as he attempts “to share the sense of mystery that lies at the heart of all scientific pursuits and is especially characteristic of the forays we make in trying to understand our own minds.”

Read it as a psychologist or philosopher to try and find neurological underpinnings for how we are who we are.

Read it as a novel filled with emotion, mystery, conflict, people’s lives, and pursuit of the unknown.

I appreciated it on all counts, and took note of his commentary on imagination, attention, left and right hemispheres, cognitive neuroscience, creativity, and the need for doing experiments, all of which will be covered in a future post!

By the way, no need to take just my word for it. On the amazon page for this book, there are 84 customer reviews; 67 folks give the book 5 stars, and the remaining 10 folks rate it 4 stars. The first three reviews (Matteson, Hills and Peterzell) provide an in-depth overview of the book’s content and style.

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 atfmricharlierose.jpg 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