Biochemists Create Enzyme-Based Memory Capable of Learning
Electronic processors are highly efficient at certain types of computation. For example, a standard PC can vastly outperform any human at arithmetic. However, computer scientists have long been fascinated by the ability of biological systems to do tasks, such as face recognition, at speeds and a power efficiency that put the most powerful supercomputers to shame.
Clearly, biology is able of computing in ways that traditional processors have failed to capture, which is why there is a significant interest in unconventional methods of computing that explore new ways of processing information.
One form of unconventional computing is biochemical and involves using molecules to encode information and using chemical reactions to process it. Nature has developed highly complex machinery for doing this so much of the focus has been on exploiting biological molecules for this task, using proteins, DNA and the like.
Today, Vera Bocharova and a few pals at Clarkson University in Potsdam, New York, say they ‘ve used a set of enzymes to create a memory system that can “learn” to produce a specific output given a certain input. They says this system can even “unlearn” again later. “We report the first realization of a simple variant of associative memory in an enzymatic biochemical process,” they say.
(via First Enzyme-Based Memory Created in the Lab | MIT Technology Review)
Cocaine-Addled Monkeys With Ceramic Brain Implants Use Electronic Prosthetics to Aid Memory
The monkeys’ neural activity was recorded by a tiny ceramic-enclosed electronic device and relayed to an external computer. In the first part of the experiment, the researchers analyzed the brain activity they had recorded from the cortex.
But then came the hard part. Memory is formed when one set of neurons processes the signals from another set, but how can you replicate this processing in an electronic device? First, you have to figure out the code the brain is using.
From the initial recordings, the research team was able to extrapolate what’s called a MIMO model—short for multi-input/multi-output. This type of mathematical model can characterize the neural firing patterns detected by the electrode implant and, after processing the patterns, spit out the signals that instruct other neurons to form the appropriate memory.
To demonstrate that their model worked, the researchers gave the monkeys cocaine. The cocaine-addled monkeys had trouble remembering the correct image. But with the implant in place and the MIMO model translating the incoming signals and feeding data back to another set of neurons, they were able to pick out the right picture about as reliably as usual, if not slightly more so.
Brainless Slime Molds Shed Light On The Evolution of Memory
“We have shown for the first time that a single-celled organism with no brain uses an external spatial memory to navigate through a complex environment,” said Christopher Reid from the University’s School of Biological Sciences.
…“Results from insect studies, for example ants leaving pheromone trails, have already challenged the assumption that navigation requires learning or a sophisticated spatial awareness. We’ve now gone one better and shown that even an organism without a nervous system can navigate a complex environment, with the help of externalized memory.”
The research method was inspired by robots designed to respond only to feedback from their immediate environment to navigate obstacles and avoid becoming trapped. This “reactive navigation” method allows robots to navigate without a programmed map or the ability to build one and slime molds use the same process.
When it is foraging, the slime mold avoids areas that it has already “slimed,” suggesting it can sense extracellular slime upon contact and will recognize and avoid areas it has already explored.
…“We then upped the ante for the slime molds by challenging them with the U-shaped trap problem to test their navigational ability in a more complex situation than foraging. We found that, as we had predicted, its success was greatly dependent on being able to apply its external spatial memory to navigate its way out of the trap.”
(via Brainless slime mold uses external spatial ‘memory’ to navigate complex environments | KurzweilAI)
Scientists Implant Synthetic Short-Term Memories Directly into Rat Brains
For the first time, scientists have implanted false memories directly into pieces of cut-out rodent brain tissue, storing different types of short-term memory and proving the brain cells can store information about specific contexts. The memories lasted 10 seconds inside in vitro brain tissue, meaning brain tissue stored in a test tube was able to remember — albeit very briefly.
Neuroscientists at the Case Western Reserve University School of Medicine took slices of rodent brain and stimulated neural pathways in the hippocampus to introduce patterns of activity. The neural circuits maintained the memory of this simulated input for more than 10 seconds, the researchers say. They could tell because the brain cells were behaving differently, and in a way that called to mind monkey brain activity in a different short-term memory study…
“This is the first time anyone has found a way to store information over seconds about both temporal sequences and stimulus patterns directly in brain tissue,” said the lead author, neuroscientist Ben Strowbridge, in a statement. “This paves the way for future research to identify the specific brain circuits that allow us to form short-term memories.”
(via Scientists Plant False Short-Term Memories Directly In Rodent Brains | Popular Science)
Dream Engineering: Scientists Manipulate Dream Content in Rats Using Audio Tones
The researchers accomplished their dream manipulation by training rats to run through a maze during the day, using audio tones to guide them. One tone indicated that a left turn would lead the rats to food, with the other tone indicating a right turn would be met with reward. While the rats did this, the researchers logged all their neural activity. Then, exhausted from a full day of left- and right-turning, the rats went to sleep.
Scientists have long known that while we sleep, our hippocampus replays many of the day’s events and consolidates what happened into memories. It works the same way for rats, and the researchers wanted to know if they could use the audio cues embedded in the day’s memories to influence the progression of a dream. It turns out they can.
Analysis showed that when lab rats dream (at least these lab rats), they dream of mazes. And if the researchers played the audio chimes to the rats while they were dreaming, they would immediately begin dreaming of the section of the maze associated with that particular chime. So the content of the rats’ dreams was altered, essentially by cuing specific memories from the previous day using a trigger—in this case the audio chime. They think this finding could lead to new kinds of dream manipulation that could also be used to edit the memory consolidation process—basically enhancing, numbing, or blocking out memories—which in turn could aid in the treatment of things like PTSD.
(via Researchers Manipulate the Dreams of Rats, Opening the Door to ‘Dream Engineering’ | Popular Science)
Researchers Record, Play Back Rat Memories with Electronic Media
In this current study the scientists had rats learn a task, pressing one of two levers to receive a sip of water. Scientists inserted a microchip into the rat’s brain, with wires threaded into their hippocampus. Here the chip recorded electrical patterns from two specific areas labeled CA1 and CA3 that work together to learn and store the new information of which lever to press to get water.
Scientists then shut down CA1 with a drug. And built an artificial hippocampal part that could duplicate such electrical patterns between CA1 and CA3, and inserted it into the rat’s brain.
With this artificial part, rats whose CA1 had been pharmacologically blocked, could still encode long-term memories. And in those rats who had normally functioning CA1, the new implant extended the length of time a memory could be held.
The next step is to test the device in monkeys, and then in humans.
Of course at this early stage a breakthrough like this brings up more questions than solutions. Memory is hugely complex, based on our individual experiences and perceptions. If we have the electrical pattern for the phrase, See Spot Run, mentioned above, would this mean the same thing for you as it does for me?
How would such a device work within context? As writer Gary Stix asked in the Scientific American article, “Would “See Spot Run” be misinterpreted as laundry mishap instead of a trotting dog?” Or as the science journalist John Horgan once put it, you might hear your wedding song, but I hear a stale pop tune.
(via The Matrix reality: Scientists successfully implant artificial memory system | SmartPlanet)
Electrodes Implanted in Epileptic Brains Help Neuroscientists Decode Recorded Memory Patterns
The brain recordings necessary for the study were made possible by the fact that the participants were epilepsy patients who volunteered for the study while awaiting brain surgery. These participants had tiny electrodes implanted in their brains, which allowed researchers to precisely observe electrical signals that would not have been possible to measure outside the skull.
While recording these electrical signals, the researchers asked the participants to study lists of 15 randomly chosen words and, a minute later, to repeat the words back in which-ever order they came to mind.
The researchers examined the brain recordings as the participants studied each word to home in on signals in the participant’ brains that reflected the meanings of the words. About a second before the participants recalled each word, these same “meaning signals” that were identified during the study phase were spontaneously reactivated in the participants’ brains.
Because the participants were not seeing, hearing or speaking any words at the times these patterns were reactivated, the researchers could be sure they were observing the neural signatures of the participants’ self-generated, internal thoughts.
Critically, differences across participants in the way these meaning signals were reactivated predicted the order in which the participants would recall the words.In particular, the degree to which the meaning signals were reactivated before recalling each word reflected each participant’s tendency to group similar words (like “duck” and “goose”) together in their recall sequence. Since the participants were instructed to say the words in the order they came to mind, the specific se-quence of recalls a participant makes provides insights into how the words were organized in that participant’s memory.
(via Mind reading from brain recordings? ‘Neural fingerprints’ of memory associations decoded, ht Big Think)
Researchers Affect Memory Consolidation During Deep Sleep, Improving Learning
In the Northwestern study, research participants learned how to play two artificially generated musical tunes with well-timed key presses. Then while the participants took a 90-minute nap, the researchers presented one of the tunes that had been practiced, but not the other.
“Our results extend prior research by showing that external stimulation during sleep can influence a complex skill,” said Ken A. Paller, professor of psychology in the Weinberg College of Arts and Sciences at Northwestern and senior author of the study.
By using EEG methods to record the brain’s electrical activity, the researchers ensured that the soft musical cues were presented during slow-wave sleep (deep sleep, not REM sleep, or dreaming), a stage of sleep previously linked to cementing memories.
Participants made fewer errors when pressing the keys to produce a melody that had been presented while they slept, compared to the melody not presented.
“We also found that electrophysiological signals during sleep correlated with the extent to which memory improved,” said lead author James Antony of the Interdepartmental Neuroscience Program at Northwestern. “These signals may thus be measuring the brain events that produce memory improvement during sleep.”
(via How to reinforce learning while you sleep | KurzweilAI)
Switching the Magnetism of Individual Molecules Could Shrink Size of Memory 1000x
Using a scanning tunneling microscope, Kiel scientist Dr. Thiruvancheril Gopakumar was able to switch individual molecules between two magnetic states. Despite their dense packing in a molecular layer, he was able to target individual molecules for switching.
The next step will be to switch molecules with light instead of electrons and at higher temperatures.
(via Switchable nanomagnets could led to computer memory 1,000 times smaller | KurzweilAI)
Researchers Trigger Memories by Stimulating Individual Neurons:
MIT researchers have shown, for the first time ever, that memories are stored in specific brain cells. By triggering a small cluster of neurons, the researchers were able to force the subject to recall a specific memory. By removing these neurons, the subject would lose that memory.
As you can imagine, the trick here is activating individual neurons, which are incredibly small and not really the kind of thing you can attach electrodes to. To do this, the researchers used optogenetics, a bleeding edge sphere of science that involves the genetic manipulation of cells so that they’re sensitive to light. These modified cells are then triggered using lasers; you drill a hole through the subject’s skull and point the laser at a small cluster of neurons.
(via MIT discovers the location of memories: Individual neurons | ExtremeTech)
