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Social Neuroscience Advances
Understanding ourselves and how we interact
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Breaking Research: Separable short- and long-term memories can form after a momentous occasion

Breaking Research: Separable short- and long-term memories can form after a momentous occasion | Social Neuroscience Advances | Scoop.it

Imagine that you are a starving fruit fly, desperately searching for food in a new area. Suddenly, you encounter a mysterious new odor and discover a nearby source of life-sustaining food. After a single experience such as this, flies can instantly form an association between that new odor and food, and will follow the odor if it encounters it again (Figure 1-1). Yamagata et al. took advantage of this instinctual behavior to study how the fly brain stores a long-term memory after one event.

They trained groups of flies to associate a particular odor (A) with a sugar reward by presenting them with both stimuli at the same time. They confirmed that the flies formed a memory by giving them a choice between odor A and a different odor (B), and found that flies preferably flocked to an area scented with odor A.

They also identified a large group of dopamine neurons (known as PAM neurons) that were activated by the sugar reward. If the researchers activated the PAM neurons instead of providing sugar when the flies encountered odor A, the flies still associated that odor with a reward (Figure 1-2).

Now the question: how does PAM neuron activity paired with an odor form a long-term memory?  The researchers found that the PAM neurons could actually be grouped into two types. When they activated one type, which they dubbed stm-PAM, the flies only formed a short-term memory. The researchers tested their memory immediately after training and found most of the flies hanging around odor A. But 24 hours later, the memory was gone.

Surprisingly, when the researchers activated the other type of PAM neurons during training (called ltm-PAM), the flies only formed a long-term memory! The flies weren’t particularly interested in odor A immediately after training, but 24 hours later the flies flocked toward it. This incredible result showed that long-term memory doesn’t necessarily require a short-term counterpart. So, instead of the reward pathway forming a short-term memory that later transforms into a long-term memory, this sugar reward formed two complementary memories.


Via Dr. Stefan Gruenwald
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Rescooped by Jocelyn Stoller from Psychology, Sociology & Neuroscience
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Eric Kandel: Unconscious Decision Making

http://bigthink.com/ Nobel Prize winning neuropsychiatrist Eric Kandel describes new research which hints at the possibility of a biological basis to the unc...

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Researchers discover a gene for human brain size - only found in humans

Researchers discover a gene for human brain size - only found in humans | Social Neuroscience Advances | Scoop.it

About 99 percent of human genes are shared with chimpanzees. Only the small remainder sets us apart. However, we have one important difference: The brain of humans is three times as big as the chimpanzee brain. During evolution our genome must have changed in order to trigger such brain growth. Wieland Huttner, Director and Research Group Leader a the Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), and his team identified for the first time a gene that is only present in humans and contributes to the reproduction of basal brain stem cells, triggering a folding of the neocortex. The researchers isolated different subpopulations of human brain stem cells and precisely identified, which genes are active in which cell type. In doing so, they noticed the gene ARHGAP11B: it is only found in humans and in our closest relatives, the Neanderthals and Denisova-Humans, but not in chimpanzees. This gene manages to trigger brain stem cells to form a bigger pool of stem cells. In that way, during brain development more neurons can arise and the cerebrum can expand. The cerebrum is responsible for cognitive functions like speaking and thinking.


Wieland Huttner’s researchers developed a method that isolates and identifies special subpopulations of brain stem cells from the developing human cerebrum. No one has managed to do this so far. The scientists first isolated different stem and progenitor cell types from fetal mice and human cerebrum tissue. In contrast to the big and folded human brain, the brain of mice is small and smooth. After the isolation, the researchers compared the genes that are active in the various cell types and were able to identify 56 genes that are only present in humans and which play a role in brain development. “We noticed that the gene ARHGAP11B is especially active in basal brain stem cells. These cells are really important for the expansion of the neocortex during evolution,” says Marta Florio, PhD student in Wieland Huttner’s lab, who carried out the main part of the study.


The human-specific gene also works in mice: In the further course of the study, the researchers focused on the function of this special gene. The researchers suspected that if it was responsible for a bigger pool of brain stem cells in humans and thereby for an expanded cerebrum, then this human-specific gene should trigger a similar development in the smaller brain of a mouse. They introduced the gene into mice embryos and indeed: Under the influence of the human-specific gene, the mice produced significantly more brain stem cells and in half of all cases even a folding of the neocortex, which is typical for human brains. All these results suggest that the gene ARHGAP11B plays a key role in the evolutionary expansion of the human neocortex.


Via Dr. Stefan Gruenwald
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Rescooped by Jocelyn Stoller from The Next Edge
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Supercooperators: The mathematics of evolution, altruism and human behaviour

"Evolutionary biologist Martin Nowak and author Roger Highfield explain how cooperation and altruism fit into the larger evolutionary puzzle."

 

shared by Gideon Rosenblatt


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