How the brain learns to read: development of the “word form area”

By Emilie Reas The ability to recognize, process and interpret written language is a uniquely human skill that is acquired with remarkable ease at a young age. But as anyone who has attempted to learn

When Biology and Policy are Moving Targets: The complex case of a potential success story

Listing and delisting of species under the endangered species act (ESA) is a delicate political and scientific dance that can play out over decades. Anyone who has paid attention to the listing, reintroduction, and delisting

Sensory Anthropology Meets Neuroanthropology

By Alexis Winter

Greg Downey, in his recent post on language and smell, opened a carton of expiring milk and poured himself into an exploration of cross-cultural variation in sensory experience.

While humans have evolved into primarily visual beings, …

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Developing a Neuroanthropology of Social Space: Implications for North American Archaeology

By Trevor Duke

A few days ago I was walking around Ybor City, a place near downtown Tampa known for its eclectic feel and mix of restaurants, alternative shops, and party spots. While Ybor is often associated with divergence from …

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Vision and Culture: A Neuroanthropological Approach

By Farah Britto

Eye image
What do you see when you watch TV? A movie? Do you perceive staring into a screen that when not lit up is simply a dark, flat abyss? Or, when deeply absorbed in a film you are …

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Breaking in Order to Build

Image courtesy of the Journal of Cell Biology

Image of labeled (red) DNA breaks in a single cell courtesy of the Journal of Cell Biology

Do you ever think about how every time you encounter something new your brain adjusts and rewires and makes molecular changes so you can remember this new object in the context of what you already know? I know I do, though that may be a by-product of my neuroscience upbringing. Even if you don’t think about it, it’s happening. Complex changes in the numbers and amounts of gene expression are critical to developing and maintaining memories. And as it turns out, breaking the DNA in your brain cells into pieces is also part of the process.

Seems a bit counter-productive right? Even downright dangerous? Cancer is caused by random DNA damage in other kinds of cells. New work in Nature Neuroscience shows that some level of DNA breakage (Double-Strand Breaks, DSB) in neurons accompanies the exposure of an animal to a new environment. As the animal explores its new environment and learns the layout of the enclosure, new memories are being generated and DSBs are observed at a high level in the dentate gyrus, known to be involved in learning and memory. These breaks can be observed throughout the brain at a low level, but they are increased in frequency in the part of the brain devoted to learning and memory. This result is highly unexpected so the group performing the study confirmed their results with several different assays that activate neurons. They provided visual stimulus to immobilized mice and they specifically activated regions of the brain with light activated ion channels. Each of these methods caused DSBs in DNA in response. These breaks seem to be repaired within 24 hours of the exposure to a new environment, suggesting the normal DNA repair machinery is acting efficiently and that these breaks are truly associated with the exposure stimulus.

As we age, both normally, and when affected by neurodegenerative diseases the number of these breaks tends to increase. Mouse models of Alzheimer’s disease have higher numbers of DNA breaks earlier in their lifetime. Eventually, this burden of repairing DNA can overwhelm the neurons and the cells can begin to malfunction. It’s really intriguing that activities like reading and doing crossword puzzles which are thought to be protective in cases of dementia, would also cause these DSBs, which seem to be related to disease progression. So   more breaks are good? Or are more breaks bad? If we can figure out the role these breaks play in healthy neurons, it could help us understand how to lessen the burden in cases of Alzheimer’s. It’s also possible that these breaks are related to the cellular stress of a large influx of calcium each time the neurons are activated and don’t actually contribute to learning and memory directly. Either way, it’s fascinating to speculate about why breaking neuronal DNA into pieces is happening all the time.


Smarter mice are safer than smarter sharks

deep blue seaI don’t know if you’re familiar with the cinematic gem Deep Blue Sea, but as far as ridiculous neuroscience sci-fi horror movies go, it is awesome. Let me summarize the plot for you. A group of researchers is working in an underwater lab trying to cure Alzheimer’s. Their proposal involves genetically engineering three Mako sharks to enlarge the size of their brains. Somehow, the researchers plan to harvest these huge brains and then use the tissue to cure Alzheimer’s…  Lets just say, they didn’t cure Alzheimer’s and spoiler! Samuel L. Jackson gets eaten in one of cinema’s greatest death scences.

It turns out that not all neuroscientists are familiar with Deep Blue Sea and the consequences of tinkering around with their lab animal’s brains. A new study recently published in Cell Stem Cell, discovered that when human glial progenitor cells are grafted into mouse’s brains the mice become “smarter”. A glial progenitor cell is a type of stem cell that is capable of maturing into an astrocyte, which is a cell that supports neurons, and is the most abundant type of cell in the brain. These human astrocytes distributed evenly throughout the brain of the recipient mouse and even generated their typical structures which previously had only been observed in humans and apes.

Astrocytes don’t normally participate in the electrical activity of the brain but they do send signals via fluctuations of calcium. These human astrocytes respond to changes in calcium level much faster than mouse astrocytes. These quick responses to calcium enhance how the mouse neurons signal electrically. After observing these physical changes in the chimeric human-mouse brains, the  next question is, do these changes change how well the mouse brain functions?

The mice participated in several classic learning and memory tests, auditory fear conditioning, contextual fear conditioning, Barnes mazes, and Object-location memory tasks. On every test, the mice with human glial cells outperformed control mice. So it appears that adding these glial cells has made these animals “smarter”.

If I were those researchers, I would be a little worried about my lab mice turning on me. At least they can’t run 35 mph or have enormous jaws….yet.