Scientists have created a false memory in mice by manipulating neurons that bear the memory of a place. The work further demonstrates just how unreliable memory can be. It also lays new ground for understanding the cell behavior and circuitry that controls memory, and could one day help researchers discover new ways to treat mental illnesses influenced by memory.
In the study, published in Science on Thursday, the MIT scientists show that they can modify a memory and have a mouse believe it experienced something it didn’t. Susumu Tonegawa, a neuroscientist at MIT, and members of his lab used mice that were genetically modified to allow for certain neurons to be activated with a flash of light; the technique enabled the researchers to activate a memory that caused a mouse to believe it had experienced electrical shocks in a particular box, even though no such thing had happened there. “The process of memory is nothing like a tape recording,” says study co-first author Steve Ramirez. “It’s really malleable and susceptible to the incorporation of new information.”
The results are “really mind-blowing,” says Sheena Josselyn, a neuroscientist at the Hospital for Sick Children in Toronto. “It shows that your memories are really just activities of different cells, and they can take the place of an actual thing that happened by just activating some cells in the brain,” she says. “People have been playing around with this idea for a while, but having a theory and showing it are two different things.”
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Public Service Announcement. Enjoy!
Is it possible to know where you’ve been when you don’t have a brain? Depending on your definition of “know,” the answer may be yes. Researchers have shown that the slime mold, an organism without anything that resembles a nervous system (or, for that matter, individual cells), is capable of impressive feats of navigation. It can even link food sources in optimally spaced networks. Now, researchers have shown it’s capable of filling its environment with indications of where it has already searched for food, allowing it to “remember” its past efforts and focus its attention on routes it hasn’t explored.
And it does this all using, as the authors put it, “a thick mat of nonliving, translucent, extracellular slime.” As you might expect, given the name.
Slime molds are odd creatures: organisms that have a nucleus and complex cells, but are evolutionarily distant from the multicellular animals and plants. When food is plentiful, they exist as single-celled, amoeba-like creatures that forage on the food. But once starvation sets in, the cells send out a signal that causes them to aggregate and fuse. This creates an organism that’s visible to the naked eye and all a single cell, but filled with nuclei containing the genomes of many formerly individual cells. That turns out to be advantageous, because this collective can move more efficiently, and go about foraging for food. In the course of this foraging, the organism leaves behind a trail of slime.
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By decoding brain activity, scientists were able to “see” that two monkeys were planning to approach the same reaching task differently—even before they moved a muscle.
Anyone who has looked at the jagged recording of the electrical activity of a single neuron in the brain must have wondered how any useful information could be extracted from such a frazzled signal. But over the past 30 years, researchers have discovered that clear information can be obtained by decoding the activity of large populations of neurons. Now, scientists at Washington University in St. Louis, who were decoding brain activity while monkeys reached around an obstacle to touch a target, have come up with two remarkable results.
Their first result was one they had designed their experiment to achieve: they demonstrated that multiple parameters can be embedded in the firing rate of a single neuron and that certain types of parameters are encoded only if they are needed to solve the task at hand. Their second result, however, was a complete surprise. They discovered that the population vectors could reveal different planning strategies, allowing the scientists, in effect, to read the monkeys’ minds.
By chance, the two monkeys chosen for the study had completely different cognitive styles. One, the scientists said, was a hyperactive type, who kept jumping the gun, and the other was a smooth operator, who waited for the entire setup to be revealed before planning his next move. The difference is clearly visible in their decoded brain activity.
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Writing today in the Proceedings of the National Academy of Sciences, a team of Wisconsin scientists reports that neurons, forged in the lab from blank slate human embryonic stem cells and implanted into the brains of mice, can successfully fuse with the brain’s wiring and both send and receive signals.
Neurons are specialized, impulse conducting cells that are the most elementaryfunctional unit of the central nervous system. The 100 billion or so neurons in the human brain are constantly sending and receiving the signals that govern everything from walking and talking to thinking. The work represents a crucial step toward deploying customized cells to repair damaged or diseased brains, the most complex human organ.
“The big question was can these cells integrate in a functional way,” says Jason P. Weick, the lead author of the new study and a staff scientist at the University of Wisconsin-Madison’s Waisman Center. “We show for the first time that these transplanted cells can both listen and talk to surrounding neurons of the adult brain.”
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With the help of a hammer-wielding scientist, Jennifer Aniston and a general anesthetic, Professor Marcus du Sautoy goes in search of answers to one of science’s greatest mysteries: how do we know who we are? While the thoughts that make us feel as though we know ourselves are easy to experience, they are notoriously difficult to explain. So, in order to find out where they come from, Marcus subjects himself to a series of probing experiments.
Please note, the whole “left side right side” brain thing is WRONG and we’ve known it has been WRONG for a very long time. Very. Long. Time. The reality is complex and interesting, but it is probably not what you think.
…To get your mind straight!
A group of Japanese neuroscientists is trying to peer into the mind—literally. They have devised a way to turn the brain’s opaque gray matter into a glassy, see-through substance.
The group, based at the government-financed Riken Brain Science Institute in Wako, Japan, has created an inexpensive chemical cocktail that transforms dead biological tissue from a colored mass into what looks like translucent jelly. Soaking brain tissue in the solution makes it easier for neuroscientists to see what’s inside, a step they hope will uncover the physical basis of personality traits, memories and even consciousness.
“I’m very excited about the potential,” said Dr. Atsushi Miyawaki, a researcher on the team, which published its discovery in the journal Nature Neuroscience. More here.
We have five senses but are descended from ancestors with a sixth sense to detect electrical fields in water to find prey and communicate, U.S. scientists say.
A study in the journal Nature Communications says about 30,000 species of land animals — including humans– descended from a common marine ancestor that had a well-developed electroreceptive system.
This ancestor was probably a predatory marine fish with good eyesight, jaws and teeth, and a lateral line system for detecting water movements, visible as a stripe along the flank of most current fish such as sharks that have such a sixth sense, a Cornell University release said Tuesday.
Living about 500 million years ago, it was the common ancestor of the vast majority of about 65,000 living vertebrate land and marine creatures, they said.
Some land vertebrates, including salamanders such as the Mexican axolotl, have electroreception, Cornell evolutionary biologist Willy Bemis said, but adaptation to terrestrial life meant reptiles, birds and mammals lost electrosense. More here.