First Evidence that Animals Can Mentally Replay Past Events Found

Many innovations and breakthroughs have been based on or inspired by better understandings of animals, such as understanding bats leading to sonar and understanding scorpion venom leading to the development of new medicines. Perhaps animals have different mental processes than humans to remember past events, but in any case, there’s likely benefits to this research still unseen.

Neuroscientists at Indiana University have reported the first evidence that non-human animals can mentally replay past events from memory. The discovery could help advance the development of new drugs to treat Alzheimer’s disease.

The study, led by IU professor Jonathon Crystal, appears today in the journal Current Biology.

“The reason we’re interested in animal memory isn’t only to understand animals, but rather to develop new models of memory that match up with the types of memory impaired in human diseases such as Alzheimer’s disease,” said Crystal, a professor in the IU Bloomington College of Arts and Sciences’ Department of Psychological and Brain Sciences and director of the IU Bloomington Program in Neuroscience.

Under the current paradigm, Crystal said most preclinical studies on potential new Alzheimer’s drugs examine how these compounds affect spatial memory, one of the easiest types of memory to assess in animals. But spatial memory is not the type of memory whose loss causes the most debilitating effects of Alzheimer’s disease.

“If your grandmother is suffering from Alzheimer’s, one of the most heartbreaking aspects of the disease is that she can’t remember what you told her about what’s happening in your life the last time you saw her,” said Danielle Panoz-Brown, an IU Ph.D. student who is the first author on the study. “We’re interested in episodic memory — and episodic memory replay — because it declines in Alzheimer’s disease, and in aging in general.”

Episodic memory is the ability to remember specific events. For example, if a person loses their car keys, they might try to recall every single step — or “episode” — in their trip from the car to their current location. The ability to replay these events in order is known as “episodic memory replay.” People wouldn’t be able to make sense of most scenarios if they couldn’t remember the order in which they occurred, Crystal said.

To assess animals’ ability to replay past events from memory, Crystal’s lab spent nearly a year working with 13 rats, which they trained to memorize a list of up to 12 different odors. The rats were placed inside an “arena” with different odors and rewarded when they identified the second-to-last odor or fourth-to-last odor in the list.

The team changed the number of odors in the list prior to each test to confirm the odors were identified based upon their position in the list, not by scent alone, proving the animals were relying on their ability to recall the whole list in order. Arenas with different patterns were used to communicate to the rats which of the two options was sought.

After their training, Crystal said, the animals successfully completed their task about 87 percent of the time across all trials. The results are strong evidence the animals were employing episodic memory replay.

Additional experiments confirmed the rats’ memories were long-lasting and resistant to “interference” from other memories, both hallmarks of episodic memory. They also ran tests that temporarily suppressed activity in the hippocampus — the site of episodic memory — to confirm the rats were using this part of their brain to perform their tasks.

Crystal said the need to find reliable ways to test episodic memory replay in rats is urgent since new genetic tools are enabling scientists to create rats with neurological conditions similar to Alzheimer’s disease. Until recently, only mice were available with the genetic modifications needed to study the effect of new drugs on these symptoms.

“We’re really trying push the boundaries of animal models of memory to something that’s increasingly similar to how these memories work in people,” he said. “If we want to eliminate Alzheimer’s disease, we really need to make sure we’re trying to protect the right type of memory.”

Platypus Milk Could Help Fight Antibiotic Resistance

An important finding through studying animals reveals itself again, and the fight against antibiotic resistance is among the most serious issues of the 21st century.

Researchers previously discovered that platypus milk confers antimicrobial protection to the species’ young, and now a new study led by scientists at Australia’s CSIRO has figured out what it is about platypus milk that’s so effective against bacteria.

“Platypus are such weird animals that it would make sense for them to have weird biochemistry,” says one of the team, molecular biologist Janet Newman.

“By taking a closer look at their milk, we’ve characterised a new protein that has unique antibacterial properties with the potential to save lives.”

[…]

It’s possible, the team thinks, the platypus evolved to produce its antimicrobial Shirley Temple curls, as a defence against bacteria attracted to this exposed milk, ensuring the pups got fed, not bugs in the environment.

That’s just a hypothesis at the moment, but now that we know about the molecular structure of this natural antimicrobial structure, the team says we might be able to replicate the protein for antibiotic medications – providing us with a new means of fighting the growing scourge of antibiotic resistance.

It’s not the first time this unusual animal has come to our aid. In 2016, researchers discovered a hormone contained in platypus venom could actually help us develop new kinds of diabetes treatments.

Not bad for a wacky hybrid of stitched-together animal parts that’s probably just a joke somebody’s playing on us. Not bad at all.

“There’s a quote from [Louis] Pasteur which is ‘Chance favours the prepared mind’,” Newman told Radio NZ.

“You can find discoveries in all sorts of places.”

Venomous Animals Found to Sometimes Change Their Venom Recipe

The careful study of animals has often yielded positive results for humans. Studying bats helped lead to the development of radar and also is beneficial for flying aircraft better, for example. These findings on venomous animals are important, however, because there’s actually a fair amount of medicine that’s made from venom. Last year scorpions were found to be able to adjust their venom depending on the situation, so this study with sea anemones adds further evidence to venom being different than thought in past years.

For a long time scientists believed that an animal’s venom was consistent over time: once a venomous creature, always a venomous creature. However, through a close study of sea anemones, Dr. Yehu Moran of Hebrew University’s Alexander Silberman Institute of Life Science, found that animals change their venom several times over the course of a lifetime, adapting the potency and recipe of their venom to suit changing predators and aquatic environments.

“Until now, venom research focused mainly on toxins produced by adult animals. However, by studying sea anemones from birth to death, we discovered that animals have a much wider toxin arsenal than previously thought. Their venom evolves to best meet threats from predators and to cope with changing aquatic environments,” explained Dr. Yehu Moran.

To track these changes, Moran’s team labeled the sea anemone’s venom-producing cells and monitored them over time. The researchers also recorded significant interactions that Nematostella had over their lifetime — first as prey and later as predators.

These findings are significant for several reasons. First, venom is often used in medicines and pharmacological compounds. This study suggests that for animals with a complex life cycle there are many venom components that have remained unknown to researchers since, until now, researchers have only studied venom from adult sea anemones, missing out on the unique compounds that exist in larvae venom. These “new” compounds could lead to new medicines and drugs. Second, sea anemones, jellyfish and coral play a significant role in marine environments. A better understanding of their venomous output and effect on marine life ecology is crucial.

Strong Evidence for “Speciation Reversal” Phenomenon Found Through Ravens

An important finding for the study of animal history worldwide, all the better that it’s shown through wonderful corvids.

WonderfulRavens

For over a century, speciation — where one species splits into two — has been a central focus of evolutionary research. But a new study almost 20 years in the making suggests “speciation reversal” — where two distinct lineages hybridize and eventually merge into one — can also be extremely important. The paper, appearing March 2 in Nature Communications, provides some of the strongest evidence yet of the phenomenon, in two lineages of Common Ravens.

“The bottom line is [speciation reversal] is a natural evolutionary process, and it’s probably happened in hundreds or almost certainly thousands of lineages all over the planet,” said Kevin Omland, professor of biological sciences at University of Maryland, Baltimore County (UMBC) and co-author on the new study. “One of our biggest goals is to just have people aware of this process, so when they see interesting patterns in their data, they won’t say, ‘That must be a mistake,’ or, ‘That’s too complicated to be correct.'”

“We examined genomic data from hundreds of ravens collected across North America,” said Anna Kearns, the study’s first author and a former postdoctoral fellow at UMBC, who is now a postdoc at the Smithsonian Center for Conservation Genomics. “Integrating all of the results across so many individuals, and from such diverse datasets, has been one of the most challenging aspects of this study. Next-generation genomic techniques are revealing more and more examples of species with hybrid genomes.”

[…]

The best explanation based on the team’s analysis is that the California and Holarctic lineages diverged for between one and two million years, but now have come back together and have been hybridizing for at least tens of thousands of years.

“The extensive genetic data reveals one of the best supported examples of speciation reversal of deeply diverged lineages to date,” said Arild Johnsen, professor of zoology and evolutionary biology at University of Oslo and another leader of the study. “The biggest thing is the degree to which we’ve caught them in the act.”

How does this relate to people? Humans are also a product of speciation reversal, Omland notes, with the present-day human genome including significant chunks of genetic material from Neanderthals and Denisovans, another less well-known hominid lineage. Recent genetic studies have even indicated a mysterious fourth group of early humans who also left some DNA in our genomes.

“Because speciation reversal is a big part of our own history,” Omland said, “getting a better understanding of how that happens should give us a better sense of who we are and where we came from. These are existential questions, but they are also medically relevant as well.”

[…]

Co-author John Marzluff, professor of wildlife science at the University of Washington, summed up the experience of being part of the study: “It is fascinating to me that this complex history of raven speciation has been revealed. For decades my students and I held and studied ravens throughout the West and never once suspected they carried evidence of a complex past,” he said. “Thanks to collaborations among field workers and geneticists, we now understand that the raven is anything but common.”