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The Brain in Discover magazine

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The Man With Uncrossed Eyes : Neuroskeptic. “GB” is a 28 year old man with a curious condition: his optic nerves are in the wrong place.

The Man With Uncrossed Eyes : Neuroskeptic

Most people have an optic chiasm, a crossroads where half of the signals from each eye cross over the midline, in such a way that each half of the brain gets information from one side of space. GB, however, was born with achiasma – the absence of this crossover. It’s an extremely rare disorder in humans, although it’s more common in some breeds of animals, such as Belgian sheepdogs. Napping Neurons Explain Sleep-Deprived Blunders. When tiredness sets in, poor decisions and clumsiness often follow.

Napping Neurons Explain Sleep-Deprived Blunders

In a study published last April, scientists may have pinpointed the biological basis of such mistakes: tiny clusters of neurons that start napping, even as the brain stays awake. To explore the phenomenon, neuroscientist Giulio Tononi of the University of Wisconsin at Madison tempted lab rats to stay awake longer than usual by supplying them with a steady stream of new toys. At the same time, he measured their brain activity through electroencephalography (EEG). With so much exploring to do, the rats seemed alert, but measurements told a different story.

Though EEG recordings indicated overall wakefulness, small groups of neurons briefly went offline. Our Strange, Important, Subconscious Light Detectors. Studies like Foster’s prompted a number of researchers to look for those missing cells.

Our Strange, Important, Subconscious Light Detectors

The first clue came in 2000, when neuroscientist Ignacio Provencio, now at the University of Virginia, found a light- capturing pigment called melanopsin in the ganglion layer of the retina. It was a bizarre discovery, since the ganglion layer was thought only to relay electric signals from the rods and cones, not catch its own light. But in 2002, Samer Hattar of Johns Hopkins University and David Berson of Brown University identified individual retinal ganglion cells containing melanopsin. They further demonstrated that the cells—called intrinsically photosensitive retinal ganglion cells, or ipRGCs—could detect light. Like the rods and cones, ipRGCs are most sensitive to a particular color: blue, in this case. Hattar and other scientists then set out to determine exactly what ipRGCs do by creating mirror images of Keeler’s blind rodents. Another surprise: Not all ipRGCs are the same. The Brain: The Troublesome Bloom of Autism. Eric Courchesne managed to find a positive thing about getting polio: It gave him a clear idea of what he would do when he grew up.

The Brain: The Troublesome Bloom of Autism

Courchesne was stricken in 1953, when he was 4. The infection left his legs so wasted that he couldn’t stand or walk. “My mother had to carry me everywhere,” he says. His parents helped him learn how to move his toes again. Science's Long—and Successful—Search for Where Memory Lives. During that visit, the three sat down to see if they could figure out the discrepancy in the data.

Science's Long—and Successful—Search for Where Memory Lives

The “problem,” Silva felt, might in fact be an opportunity: a hint of how they could use CREB as a tool not merely to enhance or suppress memories but to explore each new memory’s precise location—to locate the engram. Maybe after all these years, it would be possible to find true tracks of memory in the brain. Perhaps it was actually necessary for only a small percentage of neurons to be involved in forming a memory. Maybe memory formation is a kind of competitive sport. CREB could play an essential role in recruiting the neurons lucky enough to underlie the memories we form. By the time Josselyn’s study was published, in 2001, she had already accepted an invitation extended to her and her husband, Paul Frankland, also a postdoc in neuroscience, to join Silva at UCLA.

But this is where things got seriously strange. Josselyn happens to like Tom Cruise. Yet cautious progress is being made. The Brain: The Connections May Be the Key. There was just one problem: Nobody knew what the connectome looked like.

The Brain: The Connections May Be the Key

MRI scans can capture the entire brain, but they can get down to a resolution of only a few cubic millimeters, not nearly fine enough. Other methods, such as staining, allow scientists to look at one neuron at a time but not to track the broader links between them. The "Interpreter" in Your Head Spins Stories to Make Sense of the World. The left hemisphere specializes in speech, language, and intelligent behavior, and a split-brain patient’s left hemisphere and language center has no access to sensory information if it is fed only to the right brain.

The "Interpreter" in Your Head Spins Stories to Make Sense of the World

The Brain Is Ready for Its Close-Up.