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Marcos Frank, PhD, Assistant Professor of Neuroscience, at the University of Pennsylvania School of Medicine, along with postdoctoral researcher Sara Aton, PhD, and colleagues have shown that the functions associated with long-term memory formation don’t become active until we sleep.
Optical Brain Maps - Plastic Change
In a cleverly designed series of experiments, the researchers worked with the visual systems of young animals. By covering one eye of the animals with a patch the team studied the electrophysiological and molecular changes that resulted with or without sleep (and compared these to a control group with no patch).
Once triggered to reorganize its neural networks in wakefulness (by visual deprivation, for instance), the brain engages intra- and intercellular communication pathways, releasing a series of enzymes that could reorganize the appropriate neurons.
“To our amazement, we found that these enzymes never really turned on until the animal had a chance to sleep,” Dr. Frank explained, “As soon as the animal had a chance to sleep, we saw all the machinery of memory start to engage.”
(Further, by stopping these enzymes from working in the sleeping brain the normal reorganization of the cortex didn’t happen.)
But perhaps more generally interesting is the insight that the changes in some senses weren’t memory changes — although they were certainly plastic changes. The same mechanism could play a role in all neurological plasticity processes.
In this study, researchers found that a relatively brief period of musical training, just six months, was enough to improve the language aptitude of a group of eight year-olds.
Musical Training Influences Linguistic Abilities in 8-Year-Old Children: More Evidence for Brain Plasticity
Could the environment your mother grew up in affect your likelihood of developing a learning disorder, or protect you from one? This was the intriguing question posed by Larry Feig, PhD, professor of biochemistry at Tufts University School of Medicine and member of the biochemistry and neuroscience programs at the Sackler School of Graduate Biomedical Sciences at Tufts University. He set out to investigate the impact of a mother’s early environment on her offspring. He found that if a mother had a stimulating environment with novel objects and unforced exercise when she was young, the benefits of such an environment carried over to her offspring, even if they were raised by a foster mother. (This was all done with mice.)
This ‘inheritance of acquired characters,’ first proposed by Lamarck goes against pure Mendelian genetics and points to a much more rapid generic mechanism for conferring benefits or deficits across generations. Feig concludes that the mechanism may have evolved to protect infants from circumstancial sensory deprivation.
This report appeared in the Reading Eagle covering a study to be published tomorrow in the Journal of Neuroscience.
Norman Doidge: The Brain That Changes Itself
The fourth and sixth chapters of Norman Doidge’s “The Brain That Changes Itself” deal with the subject of compulsion, inclination, and habit from different perspectives. In some parts of these chapters Doidge lose some of his objectivity and lets his personal judgments and beliefs creep into the text. In most cases these subjective moments don’t detract from the point being made and are easily enough ignored. But overall they tend to cloud the central argument that Doidge is making: Our psychology is written through plastic change and can be rewritten through plastic change.
As an example from his psychology practice Doidge uses sexual compulsion and addiction to make the case that such things as addiction to pornography result from plastic change that gradually desensitizes the subject, leading to the desire for more gratification. The most interesting thing about Doidge’s reflections on this kind of addictive behavior is the information that being aware of this kind of plastic change can help us to rewrite it, reversing the behavior pattern.
With alcohol and narcotics, however, the problem is amplified by the chemical trigger.
Doidge: “By hijacking our dopamine system, addictive substances give us pleasure without our having to work for it.”
And later, refering to a study by Eric Nestler of the University of Texas: “A single dose of many addictive drugs will produce a protein, called delta-FosB, that accummulates in the neurons. Each time the drug is used more delta-FosB accummulates, until it throws a genetic switch, affecting which genes are turned on or off.”
But then there’s an example of Doidge’s overreaching. He draws the conclusion that once flipped the damage is irreversible. But he makes no argument to substantiate this conclusion. In several places Doidge refers to “harmful” or “unpleasant” plastic change as permanent in a way that seems to reveal a certain personal distaste or bias.
Doidge makes the point that learning a new association involves a different process and a different chemical change from unlearning.
Whereas children learn during a critical period of plastic change — absorbing new information like sponges — through the action of BDNF (brain derived neurotrophic factor) critical periods of unlearning are associated with the release of oxytocin.
Massive unlearning happens when we fall in love and when we begin parenting. It’s also released in smaller quantities during orgasm.
Neuroscientists from Johns Hopkins University School of Medicine have identified one of the mechanisms at work in the process of new brain cell generation. They found that cell growth involves a change in gene expression (an epigenetic change).
Adult Neural Stem Cell Neurogenesis
Since an epigenetic change persists through cell division, the scientists believe that further unravelling of this mechanism may shed light on the processes by which memories are formed and behaviors and skills are learned.
“How is it that when you see someone you met ten years ago, you still recognize them? How do these transient events become long lasting in the brain, and what potential role does the birth of new neurons play in making these memories?” says Hongjun Song, Ph.D., an associate professor of neurology and member of the Johns Hopkins Institute of Cell Engineering’s NeuroICE. “We really want to understand how daily life experiences trigger the birth and growth of new neurons, and make long-lasting changes in the brain.”
Scientists have been discovering the process by which we learn as we observe. By monitoring the firing of neurons as an animal watches an activity, they find that the neurons fire in the same pattern as they do when the animal performs the same activity.
That we learn by watching doesn’t seem so surprising. But the mechanism itself is intriguing.
I’m reading Norman Doidge’s book — The Brain That Changes Itself — in which he describes the parallels between doing and thinking of doing. Subjects imagining that they are stressing a muscle for a set period each day actually increase muscle strength. Likewise mental practice of a piece of music results in improved proficiency at playing the music.
As Doidge points out, the brain responds to our being in the physical world, but can also operate and send messages without direct stimulation from from the physical world.
With this in mind, visualization and imagination become powerful tools in learning and practicing skills and proficiencies.
Scientists at the University of British Columbia have discovered the mechanism that controls and suppresses neural sprouting and brain plasticity in adults. The adult brain is less plastic than a child’s brain, which helps to maintain the (presumably helpful) connections that have been formed over the years. But in cases of injury or disease this process inhibits healing and regrowth.
The team found that a protein called calpain inhibits the plasticity of neural connections. In animal models, when they reduced the impact of calpain, the neural connections became plastic again.
The trick to devising a drug therapy from this finding will be to stimulate plasticity for healing without risking the good connections that have been so long in the making.
When I saw an article in the MIT Technology Review called “Making an Old Brain Young: Scientists are developing new ways to manipulate the brain’s normal plasticity” I thought to myself “oh, good, more evidence of useful, natural therapies that can leverage plasticity.”
But the second sentence of the article begins “Drugs that target these mechanisms might eventually help treat neurological disorders …”
Not that the medical world shouldn’t be evaluating drugs that leverage plasticity. What concerned me about the article was the complete absence of reference to therapies that might not require drugs. Meanwhile, the Australian Alzheimer’s Association has endorsed brain training exercises as a non-pharmacalogical mechanism for delaying or preventing the onset of Alzheimer’s symptoms. The most effective therapies for stroke victims leverage plasticity through non-drug therapies. Progressive learning specialists are working with brain exercises to mitigate or correct learning dysfunctions. And other research has shown that the generation of new nerve cells in the dentate gyrus helps combat depression — something that can be assisted with exercise and brain exercise…
If our newfound knowledge of plasticity can teach us anything surely it should be teaching us that there are many remarkable alternatives to drugs.
A story today in the Toronto Star hints at society’s changing perspectives on learning dysfunctions.
After reporting that Barbara Arrowsmith’s program has been operating for 30 years, The Star nevertheless describes the program as “controversial” because it “goes against the conventional notion that learning disabilities are lifelong and children should be taught to work around them with accommodations.” One would think that thirty years would be sufficient time for us to begin to integrate a new perspective into our ”conventional” wisdom.
Although many educational establishments and learning specialists are unaware of or unconvinced by the idea that learning dysfunctions can be corrected through appropriate mental exercise, a sizeable and growing number schools and practitioners already use Arrowsmith’s findings and methods.
I was speaking recently, for instance, to a learning specialist who works on the West coast. In her practice and her broader referral network the use of brain training tools to correct or mitigate learning dysfunctions is commonplace. The only drawback is the expense of some of these tools.
Norman Doidge - The Brain That Changes Itself
Conventional wisdom, however, tends to be a tenacious beast. Despite our information rich lifestyles, good news can take an awfully long time to get around.
We can only hope that Doidge’s book and similar information resources popularize the new wisdom so that another generation of children won’t have to suffer accommodations for their learning dysfunctions when they could be getting help to correct them.
mouse on a treadmill
For some reason the term “middle-aged mice” amuses me. As reported in the Journal of Applied Physiology, North Korean researchers put them on a treadmill and measured the effect on the generation of new brain cells in the dentate gyrus. They found that five weeks of treadmill running increased proliferation of neural stem/precursor cells and the number of immature neurons as well as promoting the maturation and survival of immature neurons.
More evidence of the beneficial effects of exercise for brain health, and more evidence of adult brain neurogenesis and neuroplasticity…
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