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The Brain in Three Dimensions

[ 1 ] October 28, 2010

MRI scans of the brain display colorful splotches in areas where there is a higher-than-usual level of activity, which calls for increases in bloodflow to that region (MRI machines tracks the magnetism of iron in our blood as it moves through the brain). These images are classically two-dimensional. As valuable as MRI imaging has been, showing a flat perspective of a structure than can only be understood in three dimensions is eventually quite limited in its medical applications.

Now, researchers at Eindhoven University of Technology have developed a software tool that doctors can use to convert MRI scans into three-dimensional images, such as the image seen below.

Imaging tools like this one should increase the accuracy of diagnosing brain disfunction and allow doctors to pinpoint regions for surgery with greater precision. Read more in the official press release here. (Special thanks to TBB reader Maarten Boos for the tip).

Losing an Overlooked Gift

[ 9 ] October 24, 2010

A virus destroyed Ian Waterman’s kinesthetic and other mechano-cutaneous nerves when he was 19 years old. Lacking proprioception, the sense of knowing the relative position of various part of the body, Ian was bound to a wheelchair for a long time. Now, he relies on vision to know where his limbs are. If there is no light, he cannot tie his shoes, walk up or down stairs, or clap his hands. At one point in his life, he was stuck in an elevator, with the lights off. He was unable to remain standing and could only stand when the lights turned back on. Proprioception is one of many senses we take for granted, being able to know where your limbs are, even while closing your eyes. Here’s a less than scientific, but informative, video about Ian Waterman.

You can read more in Jonathon Cole’s book, Pride and a Daily Marathon.

Tooling Around

[ 0 ] October 21, 2010

Tool use is extremely important to humans.  Much research has suggested a complex neural underpinning of tool-using behavior: it involves real-time 3D mapping of objects, extreme tactile sensitivity, planning ahead, and, well, patience.

Like language, humans have a special knack for tool-making.  And, also like language, this knack is represented in specialized neural circuits.  “Tool circuits” would presumably be designed for manipulating objects in meaningful, complicated, and even artful ways.  Research published earlier this year in Psychological Science revealed that individuals who are born blind may have the neural architecture in place for tool manipulation, even though they have never seen a tool.  When a sighted individual thinks about a tool, say a hammer, circuits in the left parietal cortex light up, and these same circuits fail to light up when the imagined object is not tool-like (i.e. a bed, a dog, etc).  Interestingly, individuals who have never actually seen tools show this same pattern of activation.

This research suggests that our neural representations are not shaped only by experience.  Tools have been vital for our species for so long –  evolution has likely built into our brains the necessary architecture to treat tools with special attention, whether we can actually use them or not.

Now, Where Was I?

[ 0 ] October 17, 2010

In an experiment by Foster and Wilson (2006), researchers placed a rat into a long narrow corridor and taught it to walk down to each end, where it would find a treat. The rat repeated this, and it enjoyed the treat. It was being fed, after all. But researchers noticed something unusual. The rat would get to one end, eat its treat, then just stop and sit there for a moment. When the researchers plotted the activity of “place cells” (which, in theory fire according to where the rat is in a particular environment) in the rat’s hippocampus, they exhibited bursts of activity when the rat was stationary. The researches expanded a split second’s worth of this strange firing:

You can see that there is successive activation from place cell #19-#1. What they found was that the rat’s brain was actually firing the place cells in such a way that it was repeating the course it had just run, and repeating it backwards. It was as if the mouse was thinking “ok, I just got this treat by walking down this hallway…how did I get here? Where was I?” Perhaps even more interesting is that when the rat was asleep, it continued to do this, except much much faster, theoretically because it was redoing what it had learned but without physical limitations; it could walk down that corridor as fast as its neurons allowed it.

Smelling Attraction

[ 5 ] October 10, 2010

Pheromones have almost gained a mythological status in popular culture, thanks to the goat extract at the gas station or perfumes that supposedly uses pheromones to make you irresistible. (Side note: perfumes often use glandular excretions from other animals as one of their main ingredients.) But there is some credence to the layers of fantasy. Several tests have been conducted that provide good evidence that humans can indeed sense pheromones from other humans. But there is still the mystery of what the sensory organ is for pheromones. One theory is that cranial nerve zero is at least in part responsible for our responses to pheromones. This nerve is barely noticeable and often destroyed during dissection, which is why it is not included in many textbooks yet.
Scientists have even found this nerve in whales, an animal that, through evolution, has long lost its olfactory cranial nerves. This supports the idea that cranial nerve zero is separate from the olfactory system. But more importantly, it underlines an evolutionary importance of cranial nerve zero, withstanding millennia of evolution.

Scientists’ Double Lives

[ 0 ] October 4, 2010

NOVA has a great new online series called “The Secret Life of Scientists.” The videos take a look at some leading scientists’ alternative, non-science lives – much like neuroscientist and Beautiful Brain contributor Joe Ledoux’s musical project, the Amygdaloids.

Here’s one of my favorite videos, featuring Joe DeGeorge, who is a physics student and lead singer/songwriter of the great Harry-Potter themed indie rock band Harry and The Potters.