Exercise boosts your brain

New research is showing some of the molecular reasons why keeping fit also keeps you sharp, and it has to do with your brain’s untapped potential for growth.

Dr. Fred Gage and collaborators have been publishing a variety of papers describing the molecular pathways by which exercise leads to brain growth. Gage’s work in the 90’s showed that our brains have a store of stem cells that lie largely dormant, waiting for some stimulus to initiate cell division. A growth factor called bone morphogenetic protein (BMP) works to control cell division throughout the body, including in the brain. The more BMP, the less growth. Regulatory factors like BMP are essential to a healthy body; studies have shown that the absence of BMP activity is linked to colon cancer.

But as we get older, higher counts of BMP accumulate in the brain and keep our neural stem cells asleep. This is where exercise comes in. Within one week of being given an exercise wheel, mice showed half as much BMP signaling in their brains. The mice also showed increased levels of the protein Noggin (yes, I know), which acts as a BMP-antagonist. There are still questions as to whether exercise directly decreases BMP, or does so indirectly via Noggin production. Either way, stem cells begin to divide and new neurons are born.

Google: the perfect crack machine

For humans, this desire to search is not just about fulfilling our physical needs. Panksepp says that humans can get just as excited about abstract rewards as tangible ones. He says that when we get thrilled about the world of ideas, about making intellectual connections, about divining meaning, it is the seeking circuits that are firing.

The juice that fuels the seeking system is the neurotransmitter dopamine. The dopamine circuits "promote states of eagerness and directed purpose," Panksepp writes. It's a state humans love to be in. So good does it feel that we seek out activities, or substances, that keep this system aroused—cocaine and amphetamines, drugs of stimulation, are particularly effective at stirring it.

Ever find yourself sitting down at the computer just for a second to find out what other movie you saw that actress in, only to look up and realize the search has led to an hour of Googling? Thank dopamine. Our internal sense of time is believed to be controlled by the dopamine system. People with hyperactivity disorder have a shortage of dopamine in their brains, which a recent study suggests may be at the root of the problem. For them even small stretches of time seem to drag. An article by Nicholas Carr in the Atlantic last year, "Is Google Making Us Stupid?" speculates that our constant Internet scrolling is remodeling our brains to make it nearly impossible for us to give sustained attention to a long piece of writing. Like the lab rats, we keep hitting "enter" to get our next fix.

Multitasking is eating our brains


  • Did a significantly worse job filtering out the irrelevant information.
  • Took longer than non-multitaskers to switch among tasks.
  • Less efficient at juggling problems.
  • Tended to search for new information rather than accept a reward for putting older, more valuable information to work.
  • Process visual and auditory input less efficiently.
  • Become reliant on more a more simplistic, and often inferior, thought process, and can thus fall prey to perceptual decoys.

Maybe multitasking gives the illusion of productivity without achieving higher volume...

Changing your mind--with magnets

MIT neuroscientists have now shown that they can influence those judgments by interfering with activity in a specific brain region--a finding that helps reveal how the brain constructs morality. In the new study, published in Proceedings of the National Academy of Sciences, the researchers used a magnetic field to disrupt activity in the right temporoparietal junction (TPJ). The stimulation appeared to influence subsequent judgments that required an understanding of other people's intentions.

The findings offer "striking evidence" that the right TPJ, located at the brain's surface above and behind the right ear, is critical for making moral judgments, says Liane Young, the paper's lead author and a postdoctoral associate in brain and cognitive sciences. It's also startling, since normally people are very confident and consistent in such judgments, she adds. "You think of morality as being a really high-level behavior," Young says. "To be able to apply [a magnetic field] to a specific brain region and change people's moral judgments is really astonishing."

read more at technologyreview.com

Are you a super-Turing quantum gravitic computer?

The average human’s resting heat dissipation is something like 2000 kilocalories per day. Making a rough approximation, assume the brain dissipates 1/10 of this; 200 kilocals per day. That works out (you do the math) to 9.5 joules per second. This puts an upper limit on how much the brain can calculate, assuming it is an irreversible computer: 5 *10^19 64 bit ops per second.

Considering all the noise various people make over theories of consciousness and artificial intelligence, this seems to me a pretty important number to keep track of. Assuming a 3Ghz pentium is actually doing 3 billion calculations per second (it can’t), it is about 17 billion times less powerful than the upper bound on a human brain. Even if brains are computationally only 1/1000 of their theoretical efficiency, computers need to get 17 million times quicker to beat a brain.

The model of the Antikythera mechanism shown here is one of the clearer I've seen. I'm fascinated by analog computers, but figure we need an entirely new category for "organic" models.

Good sleep, good learning, good life

"This article attempts to produce a synthesis of what is known about sleep with a view to practical applications, especially in people who need top-quality sleep for their learning or creative achievements. Neurophysiology of sleep is an explosively growing branch of science. Many theories that are currently contested will soon be forgotten as a result of new findings. Consequently, this text is likely to grow old very quickly. Yet some basic truths about sleep are well-established, and practical conclusions can be drawn with the benefit to human creativity and intellectual accomplishment. In this text, I provide some links to research papers and popular-scientific articles that advocate disparate and contradictory theories. Please consult other sources to be certain you do not to get a one-sided view! This article includes some indications on how to use free running sleep in the treatment of insomnia, hypersomnia, advanced and delayed phase shift syndromes, and some other sleep disorders."

The web shatters focus, rewires brains

Dazzled by the Net’s treasures, we are blind to the damage we may be doing to our intellectual lives and even our culture.

What we’re experiencing is, in a metaphorical sense, a reversal of the early trajectory of civilization: We are evolving from cultivators of personal knowledge into hunters and gatherers in the electronic data forest. In the process, we seem fated to sacrifice much of what makes our minds so interesting.

Kurzweil’s next book: creating an artificial mind

Ray Kurzweil is working on another book, this one to explore the principles of human level intelligence in machines. Titled How the Mind Works and How to Build One, the new book will explore all the amazing developments in reverse engineering the brain that have come along since his last book, the Singularity is Near was released in 2005. Whether or not you agree with Ray Kurzweil’s predictions, the inventor and author stands out as one of the foremost futurists of our time.

Just a note to remind myself...

'Thirst for knowledge' may be opium craving

The brain's reward for “getting” a concept is a shot of natural opiates

Neuroscientists have proposed a simple explanation for the pleasure of grasping a new concept: The brain is getting its fix.

The "click" of comprehension triggers a biochemical cascade that rewards the brain with a shot of natural opium-like substances, said Irving Biederman of the University of Southern California. He presents his theory in an invited article in the latest issue of American Scientist.

"While you're trying to understand a difficult theorem, it's not fun," said Biederman, professor of neuroscience in the USC College of Letters, Arts and Sciences.

"But once you get it, you just feel fabulous."

The brain's craving for a fix motivates humans to maximize the rate at which they absorb knowledge, he said.

"I think we're exquisitely tuned to this as if we're junkies, second by second."

Biederman hypothesized that knowledge addiction has strong evolutionary value because mate selection correlates closely with perceived intelligence.

Only more pressing material needs, such as hunger, can suspend the quest for knowledge, he added.

The same mechanism is involved in the aesthetic experience, Biederman said, providing a neurological explanation for the pleasure we derive from art.

"This account may provide a plausible and very simple mechanism for aesthetic and perceptual and cognitive curiosity."

Biederman's theory was inspired by a widely ignored 25-year-old finding that mu-opioid receptors – binding sites for natural opiates – increase in density along the ventral visual pathway, a part of the brain involved in image recognition and processing.

The receptors are tightly packed in the areas of the pathway linked to comprehension and interpretation of images, but sparse in areas where visual stimuli first hit the cortex.

Biederman's theory holds that the greater the neural activity in the areas rich in opioid receptors, the greater the pleasure.

In a series of functional magnetic resonance imaging trials with human volunteers exposed to a wide variety of images, Biederman's research group found that strongly preferred images prompted the greatest fMRI activity in more complex areas of the ventral visual pathway. (The data from the studies are being submitted for publication.)

Biederman also found that repeated viewing of an attractive image lessened both the rating of pleasure and the activity in the opioid-rich areas. In his article, he explains this familiar experience with a neural-network model termed "competitive learning."

In competitive learning (also known as "Neural Darwinism"), the first presentation of an image activates many neurons, some strongly and a greater number only weakly.

With repetition of the image, the connections to the strongly activated neurons grow in strength. But the strongly activated neurons inhibit their weakly activated neighbors, causing a net reduction in activity. This reduction in activity, Biederman's research shows, parallels the decline in the pleasure felt during repeated viewing.

"One advantage of competitive learning is that the inhibited neurons are now free to code for other stimulus patterns," Biederman writes.

This preference for novel concepts also has evolutionary value, he added.

"The system is essentially designed to maximize the rate at which you acquire new but interpretable [understandable] information. Once you have acquired the information, you best spend your time learning something else.

"There's this incredible selectivity that we show in real time. Without thinking about it, we pick out experiences that are richly interpretable but novel."

The theory, while currently tested only in the visual system, likely applies to other senses, Biederman said.