Taken by Robert Ludlow of the University College London’s Institute of Neurology, this is a rare shot of a living brain, revealing the cerebral cortex of an epileptic patient during surgery. Oxygenated blood flushes bright red in a web of small arteries while larger veins, tucked in the sulci or crevices of the brain, carry away purplish, deoxygenated blood. Gray matter (so-dubbed because that’s its color after death) is pink with life.
The image won a 2012 Wellcome Trust award for photography.
Your Brain on Alcohol (submitted by mitchellmoffit, thanks!)
In the 1950s and 60s, a fatal epidemic called kuru swept through the South Fore tribe of Papua New Guinea, killing over 1,000 people. Kuru means “shaking death” which is consistent to the first symptoms of the victims: tremors, headaches and loss of motor skills, since the disease affected the cerebellum, which is responsible for co-ordinarting movement. Soon the victims weren’t able to stand or eat, they sometimes lost speech and developed open sores, and then finally died six to twelve months later. It was discovered that the epidemic was linked to the tribe’s ritual of mortuary cannibalism—consuming the brains of the recently deceased. Kuru began to disappear when cannibalism was outlawed, and yet a few cases still occurred up into the 2000s, suggesting that the disease has an incubation period of up to 50 years. Kuru belongs to a class of neurodegenerative diseases that also includes what is commonly known as “Mad Cow Disease,” and is caused by abnormally folded proteins called prions. These proteins are present in all cells in their normal form, but the abnormal ones are infectious agents, able to ‘flip’ other proteins into the abnormal prion shape that then flip others, and on and on like dominoes. They gradually cause nerve cells to degenerate and die—and since nerve cells cannot be replaced, the brain tissue takes on a sponge-like appearance as it slowly dies. So, Kuru was originally caused by the victims consuming infected brain material, which then infected their own brain tissue and turned it to spongy mush.
Memories are made of this
Synapses that form at the contacts between a cultured hippocampal neuron expressing YFP-actin and neurons expressing CFP-actin.
Picture credit : Michael Colicos, UCSD
Split brain is a term used to refer to someone who has had the corpus callosum (a white fiber tract connecting the two sides of the brain, discussed in the last post) severed. Therefore, the two sides of the brain cannot communicate with each other. The reason that this would be done is usually in very severe cases of epilepsy. Seizures are caused by brain activity synchronizing at extremely high levels. Therefore, you can prevent seizures by preventing the whole brain from being able to synchronize its neuronal activity.
Split brain patients act entirely normally during normal life. It is only when doing tasks, such as those that only use one side’s visual field, that you can notice abnormal behavior. The left side of the brain contains all of the language centers. Therefore, whatever is in the left visual field (above: “RING”) can be spoken aloud. The right side of the brain is more abstract- relating to more “artistic” things- like spatial reasoning. Therefore, whatever can be seen in the right visual field (above: “KEY”) can be drawn or picked out, but it cannot be verbalized. This becomes extra cool when you ask the patient, “Why did you pick up the key?” In asking verbally, you are talking to the left side of their brain, which did not see the word KEY (They will say they only saw the word RING). Instead, they will come up with some logical reason (For instance, they might say something like “Oh, I was thinking about when I get to go home- I’ll need to grab my keys.” or “I liked the texture of the key.” or “I saw RING, and thought of my key ring.”). The reason depends on the person, but the mind can come up with a reasonable explanation (albeit inaccurate) for any behavior. Split brain research helped us to realize that this sort of reasoning happens in the left hemisphere.
Additionally, the right hand (which receives input from the left brain) is terrible at drawing or spatial reasoning tasks (matching a pattern of blocks for instance) in split brain patients who don’t have the normal communication, which helped us to learn that this behavior is localized to the right hemisphere. I was lucky enough to see a talk by Gazzaniga who is one of the pioneers of split brain research a few years ago. He showed a really interesting video of a patient having to put together a set of blocks in a pattern. He had them sit on the left hand and do the task with the right. The right hand would just make a mess of the blocks. The left hand of one patient kept trying to come in and fix what the right hand was making such a mess of. Kind of like a “No, no, you’re doing it wrong- let me!” response. It was really fascinating. I’ll show more about this in my next post.
A multi-wavelength, three dimensional, wide-field immunofluorescence image of a fixed neuron. The projection was generated using an extended depth of field algorithm. Cell body labeled for tubulin is shown in blue, F-actin in green, and presynaptic protein in Red. Specimen courtesy of Natalie Dowell-Mesfin BMS-PhD student.