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.
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. Napping Neurons Explain Sleep-Deprived Blunders. When tiredness sets in, poor decisions and clumsiness often follow.
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). Our Strange, Important, Subconscious Light Detectors. Studies like Foster’s prompted a number of researchers to look for those missing cells.
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. 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.
Courchesne was stricken in 1953, when he was 4. The infection left his legs so wasted that he couldn’t stand or walk. 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.
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. The Brain: The Connections May Be the Key. There was just one problem: Nobody knew what the connectome looked like.
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.
In the case of vision, the optic nerves leading from each eye meet inside the brain at what is called the optic chiasm. Here, each nerve splits in half; the medial half (the inside track) of each crosses the optic chiasm into the opposite side of the brain, and the lateral half (that on the outside) stays on the same side. The parts of both eyes that attend to the right visual field send information to the left hemisphere and information from the left visual field goes to and is processed by the right hemisphere. More than a few years into our experiments, we were working with a group of split-brain patients on the East Coast. The Brain Is Ready for Its Close-Up.