The Brain is Full of Surprises

New research suggests the brain is more organized than previously thought and alsothat a full memory can reside within only a few neurons

The brain is more grid than tangle of spaghetti.
The brain is more grid than tangle of spaghetti. Image courtesy of Human Connectome Project

Maybe you heard about the study published last week that compared the brain’s wiring to the streets of Manhattan. It made me wonder if this had anything to do with how active my brain’s fear center gets when I’m in the back of a New York taxi, but apparently the scientists did not see the value of this line of research.

They did, however, find that the connections in our brains seem to follow a fairly basic design, that instead of resembling a bowl of tangled spaghetti, as once thought, they’re laid out like a grid. (Well, that’s reassuring.) And, says the study’s lead author, Van Wedeen, of Harvard Medical School, that helps clarify how a relatively small number of genes can produce a blueprint for something so complex. It also explains how the basic brain of a flatworm could evolve into a stunningly complicated human mind. To extend Wedeen’s Manhattan analogy, it’s a case of adding a lot more streets to the grid.

The value of the study, along with other major brain mapping undertakings, such as the Human Connectome Project, is that they’ll help scientists see what goes wrong to cause disorders such as autism and Alzheimer’s disease.

Where memory lives

But as impressive as that research is, another brain study, also published last month, may be even more momentous. A team of MIT scientists found that it’s possible to activate a memory on demand by stimulating a few neurons with light. Which suggests that a full memory can reside in only a handful of brain cells.

The researchers used an innovative technique called optogenetics, through which genetically-modified neurons can be controlled with a brief pulse of light–an approach to altering neurons that’s considerably more precise than either electrical stimuation or drugs.

Working with mice, they first identified a specific set of cells in the hippocampus–the part of the brain identified with memory–that were active only when a mouse was learning about a new environment. Next they coupled those cells with genes that create light-activated proteins. Finally, they gave the mouse a mild shock on its foot and it did what mice do–it froze in a defensive posture.

Then came the test. With the mouse in a completely different environment, the researchers directed light on the neurons connected with the initial memory. And the mouse froze, its memory of the shock revived.

It’s a long way, of course, from activating an unpleasant flashback in a mouse to conjuring up one of our old favorite memories with a pulse of light. But the likelihood that a complete memory lives within only a few neurons will undoubtedly help scientists better understand how complex memories take shape in the first place. And it’s one more piece to the intricate and vexing puzzle inside our heads.

Our brain may follow a grid, but it remains full of mysterious corners.

A mind of its own

Here are other recent studies that revealed a bit more about how our mind works–and doesn’t:

  • Two languages are better than one: More research suggests that a person who is bilingual has a better chance of delaying dementia and Alzheimer’s than someone who speaks only one language. The latest study, by scientists at the University of York in Toronto, found that signs of dementia started three or four years later in people who spoke at least two languages.
  • Flabby muscle memory: People with sleep apnea, which often results in fragmented sleep, have a harder time maintaining motor or “muscle” memory, according to a new study.
  • Is it foggy in here? Or is it just me?: Research at the University of Rochester Medical Center confirmed that the “brain fog” about which menopausal women often complain is real. It’s also more likely to affect their ability to receive new information and manipulate it in their heads–such as figuring out a tip–and in holding focus on a challenging task, such as doing their taxes.
  • Attack of the math monster: The brains of kids who have anxiety about math function differently from the brains of those who don’t. Brain scans of second and third graders showed different parts of the brain were active for the math-phobic kids working on addition and subtraction problems from those who didn’t get anxious.
  • Is that real friends or Facebook friends?: A study by professor Robin Dunbar of the University of Oxford concludes that the larger a person’s frontal lobe, the more friendships they’re able to manage.

Video bonus: Can’t believe that light can be used to control specific neurons in the brain? Here’s a little tutorial on optogenetics.

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