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Observations of predator behavior further piqued his interest. While filming and playing back his videos, he noted how cats stack their bodies behind their faces when they’re hunting. He interprets this, he said, as cats “trying to hide their heat” with their cold noses. He has also observed barn owls twisting as they swoop down, perhaps to shield their warmer parts — legs and wingpits — with cooler ones.

Maybe, he thought, “predators have to conceal their infrared to be able to catch a mouse.”

Eventually, these and other musings led Dr. Baker to place mouse hairs under a microscope. As it came into view, he felt a strong sense of familiarity. The guard hair in particular — the bristliest type of mouse hair — contained evenly-spaced bands of pigment that, to Dr. Baker, closely resembled structures that allow optical sensors to tune into specific wavelengths of light.

Thermal cameras, for instance, focus specifically on 10-micron radiation: the slice of the spectrum that most closely corresponds with heat released by living things. By measuring the stripes, Dr. Baker found they were tuned to 10 microns as well — apparently homed in on life’s most common heat signature. “That was my Eureka moment,” he said.

In support of that idea, half a dozen Nobel laureates and other prominent scientists are working with two small companies offering NR supplements.

This time his lab made headlines by reporting that the mitochondria in muscles of elderly mice were restored to a youthful state after just a week of injections with NMN (nicotinamide mononucleotide), a molecule that naturally occurs in cells and, like NR, boosts levels of NAD.

It should be noted, however, that muscle strength was not improved in the NMN-treated mice

a single dose of NR resulted in statistically significant increases” in NAD in humans—the first evidence that supplements could really boost NAD levels in people.

When NAD levels drop, as they do with aging, SIRT1 activity falls off, which in turn makes the crucial signals fade, leading to mitochondrial dysfunction and all the ill effects that go with it.

NAD boosters might work synergistically with supplements like resveratrol to help reinvigorate mitochondria and ward off diseases of aging

Test-tube and rodent studies also suggest that pterostilbene is more potent than resveratrol when it comes to improving brain function, warding off various kinds of cancer and preventing heart disease.

Even before Sinclair's paper, researchers had shown in 2012 that when given doses of NR, mice on high-fat diets gained 60 percent less weight than they did on the same diets without NR. Further, none of the mice on NR showed signs of diabetes, and their energy levels improved. The scientists reportedly characterized NR's effects on metabolism as "nothing short of astonishing."

The Sinclair group's NAD paper drew attention partly because it showed a novel way that NAD and sirtuins work together. The researchers discovered that cells' nuclei send signals to mitochondria that are needed to maintain their normal operation. SIRT1 helps insure the signals get through. When NAD levels drop, as they do with aging, SIRT1 activity falls off, which in turn makes the crucial signals fade, leading to mitochondrial dysfunction and all the ill effects that go with it.

Test-tube and rodent studies also suggest that pterostilbene is more potent than resveratrol when it comes to improving brain function, warding off various kinds of cancer and preventing heart disease.

DARPA hopes to do that with an implanted device that will take over some functions of the brain's hippocampus, an area that's important to memory. The agency has already used a device that does this in rodents, Ling said, and the goal is to move on to people quickly.

We believe that the tools and technologies that will come from this initiative will actually enable all brain scientists to do their work better, faster and with more impact,"

For several years now, people with Parkinson's have been able to reduce their tremors with a treatment known as deep brain stimulation.

But Dr. Tom Insel, director of the National Institute of Mental Health, said it's important to remember that the immediate goal of the BRAIN Initiative isn't developing treatments, but understanding the inner workings of the most complex system in the universe.

"They're interested in the brain as a way to understand who we are, what makes us different and what is special about the human brain."

a growing number of scientists are using autonomous robots to interrogate animal behavior and cognition. Researchers have designed robots to behave like ants, cockroaches, rodents, chickens, and more, then deployed their bots in the lab or in the environment to see how similarly they behave to their flesh-and-blood counterparts.

robots give behavioral biologists the freedom to explore the mind of an animal in ways that would not be possible with living subjects, says University of Sheffield researcher James Marshall, who in March helped launch a 3-year collaborative project to build a flying robot controlled by a computer-run simulation of the entire honeybee brain.

“I really think there is a lot to be discovered by doing the engineering side along with the science.”

Not only did the bots move around the space like the rat pups did, they aggregated in remarkably similar ways to the real animals.3 Then Schank realized that there was a bug in his program. The robots weren’t following his predetermined rules; they were moving randomly.

Animal experiments are still needed to advance neuroscience.” But, he adds, robots may prove to be an indispensable new ethological tool for focusing the scope of research. “If you can have good physical models,” Prescott says, “then you can reduce the number of experiments and only do the ones that answer really important questions.”

animal-mimicking robots is not easy, however, particularly when knowledge of the system’s biology is lacking.

However, when the researchers also gave the robots a sense of flow, and programmed them to assume that odors come from upstream, the bots much more closely mimicked real lobster behavior. “That was a demonstration that the animals’ brains were multimodal—that they were using chemical information and flow information,” says Grasso, who has since worked on robotic models of octopus arms and crayfish.

some sense, the use of robotics in animal-behavior research is not that new. Since the inception of the field of ethology, researchers have been using simple physical models of animals—“dummies”—to examine the social behavior of real animals, and biologists began animating their dummies as soon as technology would allow. “The fundamental problem when you’re studying an interaction between two individuals is that it’s a two-way interaction—you’ve got two players whose behaviors are both variable,”

building a robot that animals will accept as one of their own is complicated, to say the least.

handful of other researchers have also successfully integrated robots with live animals—including fish, ducks, and chickens. There are several notable benefits to intermixing robots and animals; first and foremost, control. “One of the problems when studying behavior is that, of course, it’s very difficult to have control of animals, and so it’s hard for us to interpret fully how they interact with each other

, the rodent displayed a heightened fear response, although no foot shock had ever been given in that location. The mice eventually became conditioned to the false memory, and would freeze in Box A even in the absence of pulsing light.

“The brain mechanisms for forming and recalling the false memories are not distinguishable from those underlying genuine memories,” said Tonegawa.

hypothesized that a similar mechanism could be behind the formation of false memories in humans and said the findings underscore the problematic nature of eyewitness testimony in court proceedings.

“We hope this kind of research will reinforce the need to look at eyewitness testimony carefully,” said Tonegawa, “so that innocent people will not be incriminated.”

Tonegawa said he thinks that false memories with positive connotations likely form in the same way—a hypothesis he hopes to test with future experiments. In addition, given that false memories appear robust enough to compete with real memories, Tonegawa said he plans to investigate the factors that affect the relative strengths of the two types of memory.

The rodent at the top of this story is being studied with a technique called optogenetics, which Deisseroth pioneered.

genetically engineered the mouse so that its brain cells turn certain genes on or off when scientists shine laser light onto them. The light enters the mouse's brain through that optical fiber you see in the photo.

For example, say 20 percent of people with autism don't have Gene A, but scientists aren't sure what Gene A does. They could turn off Gene A in a mouse's brain and see what happens next. The mouse's reaction could provide a clue about what Gene A does in people and why it's missing in certain patients

chemical communication between humans in laboratory experiments

Whether pheromones play a role in human life outside the lab remains unknown. In animals pheromones affect the whole panoply of behavior - mating, aggression and fear.

rats that fear change have shorter lives than their more flexible counterparts, and that social isolation can also affect the longevity of rodents

the social and psychological world changes the fundamental mechanisms of biology, and vice versa

I've tried to situate biology in a rich social and psychological context and make it simple.

the chemosignal. Molecules produced by a person or animal that can change behaviors of others, even though they are not detected as an odor.

for two months, we exposed nonlactating women to this breast-feeding compound, which is found naturally in nursing mothers and infants. Women with regular sex partners reported a 24 percent increase in sexual desire; those without partners increased their sexual fantasies by 17 percent

These past studies of exercise and neurogenesis understandably have focused on distance running. Lab rodents know how to run. But whether other forms of exercise likewise prompt increases in neurogenesis has been unknown and is an issue of increasing interest

new study, which was published this month in the Journal of Physiology, researchers at the University of Jyvaskyla in Finland and other institutions gathered a large group of adult male rats. The researchers injected the rats with a substance that marks new brain cells and then set groups of them to an array of different workouts, with one group remaining sedentary to serve as controls.

They found very different levels of neurogenesis, depending on how each animal had exercised. Those rats that had jogged on wheels showed robust levels of neurogenesis. Their hippocampal tissue teemed with new neurons, far more than in the brains of the sedentary animals. The greater the distance that a runner had covered during the experiment, the more new cells its brain now contained. There were far fewer new neurons in the brains of the animals that had completed high-intensity interval training. They showed somewhat higher amounts than in the sedentary animals but far less than in the distance runners. And the weight-training rats, although they were much stronger at the end of the experiment than they had been at the start, showed no discernible augmentation of neurogenesis. Their hippocampal tissue looked just like that of the animals that had not exercised at all.

“sustained aerobic exercise might be most beneficial for brain health also in humans.”

Just why distance running was so much more potent at promoting neurogenesis than the other workouts is not clear, although Dr. Nokia and her colleagues speculate that distance running stimulates the release of a particular substance in the brain known as brain-derived neurotrophic factor that is known to regulate neurogenesis. The more miles an animal runs, the more B.D.N.F. it produces. Weight training, on the other hand, while extremely beneficial for muscular health, has previously been shown to have little effect on the body’s levels of B.D.N.F.

As for high-intensity interval training, its potential brain benefits may be undercut by its very intensity, Dr. Nokia said. It is, by intent, much more physiologically draining and stressful than moderate running, and “stress tends to decrease adult hippocampal neurogenesis,” she said.

These results do not mean, however, that only running and similar moderate endurance workouts strengthen the brain, Dr. Nokia said. Those activities do seem to prompt the most neurogenesis in the hippocampus. But weight training and high-intensity intervals probably lead to different types of changes elsewhere in the brain. They might, for instance, encourage the creation of additional blood vessels or new connections between brain cells or between different parts of the brain.

forgetting seems to be an active mechanism that is constantly at work in the brain.

“To have proper memory function, you have to have forgetting.

Different types of memory are created and stored in varying ways, and in various areas of the brain.

Neurons communicate with each other through synapses — junctions between these cells that include a tiny gap across which chemical messengers can be sent

The more often a memory is recalled, the stronger its neural network becomes. Over time, and through consistent recall, the memory becomes encoded in both the hippocampus and the cortex

Because the hippocampus is not where long-term memories are stored in the brain, its dynamic nature is not a flaw but a feature

Neuroscientists often refer to this physical representation of a memory as an engram. They think that each engram has a number of synaptic connections, sometimes even in several areas of the brain, and that each neuron and synapse can be involved in multiple engrams

The brain is always trying to forget the information it’s already learnt,

Hardt’s lab showed that a dedicated mechanism continuously promotes the expression of AMPA receptors at synapses.

To forget certain things, it seemed that the rat brain had to proactively destroy connections at the synapse. Forgetting, Hardt says, “is not a failure of memory, but a function of it”.

Paul Frankland, a neuroscientist at the Hospital for Sick Children in Toronto, Canada, had also found evidence that the brain is wired to forget

Frankland was studying the production of new neurons, or neurogenesis, in adult mice. The process had long been known to occur in the brains of young animals, but had been discovered in the hippocampi of mature animals only about 20 years earlier. Because the hippocampus is involved in memory formation, Frankland and his team wondered whether increasing neurogenesis in adult mice could help the rodents to remember.

Eventually, it exists independently in the cortex, where it is put away for long-term storage.

Researchers think that the human brain might operate in a similar way

Studies of people with exceptional autobiographical memories or with impaired ones seem to bear this out

People with a condition known as highly superior autobiographical memory (HSAM) remember their lives in such incredible detail that they can describe the outfit that they were wearing on any particular day

Those with severely deficient autobiographical memory (SDAM), however, are unable to vividly recall specific events in their lives

As a result, they also have trouble imagining what might happen in the future

By better understanding how we forget, through the lenses of both biology and cognitive psychology, Anderson and other researchers might be edging nearer to improving treatments for anxiety, PTSD and even Alzheimer’s disease

Hardt thinks that Alzheimer’s disease might also be better understood as a malfunction of forgetting rather than remembering

But more memory researchers are shifting their focus to examine how the brain forgets, as well as how it remembers

In the past decade, researchers have begun to view forgetting as an important part of a whole

Why do we have memory at all? As humans, we entertain this fantasy that it’s important to have autobiographical details,

Forgetting enables us as individuals, and as a species, to move forwards.

In contrast to a previous study6, they observed a robust lifespan extension in male mice fed a BCAA-restricted diet throughout life, equal to the benefits of dietary protein restriction.

Interestingly, female mice showed no lifespan extension from BCAA or dietary protein restriction, and if BCAA restriction was started during middle age, the benefits on males were greatly reduced. Thus, both studies collectively point to mTOR as a primary mediator of the benefits associated with BCAA restriction (Fig. 1).

A clear picture is emerging of how specific amino acids are sensed by sestrin to regulate mTOR signalling and autophagy and so preserve the function of intestinal stem cells during ageing.

Genetic background is crucial in the response to dietary restriction, with an identical low-calorie regimen increasing lifespan in some mouse strains but shortening it in others

There is also evidence that dietary restriction initiated later in life might have reduced benefits in rodents and, in some cases, result in premature death

Taken together, these observations suggest that although protein- and BCAA-restricted diets are a powerful research tool for exploring the fundamental mechanisms of ageing, it is premature to recommend adoption by the general population.