Tag Archives: macaque

Scientists jump-start consciousness in brains of monkeys

Consciousness is just weird. We don’t know which parts of the brain are responsible for a conscious state. A new study, however, is making good progress after scientists identified an “engine of consciousness” — a region of the brain that, when stimulated, woke up monkey subjects even when they were under anesthesia.

Credit: Pixabay.

Research in the past showed that staying in a conscious state involves activity across the entire brain. However, some brain regions seem to play a more important role in this regard than others.

Take, for instance, the case of a patient who for months was in a “minimally conscious state” (a condition of severely altered consciousness that is distinguished from the vegetative state) following a brain injury. During this state, the man was mostly unaware of his surroundings although he would have some bouts of consciousness from time to time. In many ways, it was as if his mind was on some other planet.

In August 2007, researchers at the Weill Cornell Medical College in New York City implanted electrodes in the patient’s central thalamus, which contains neurons sensitive to eye position and which plays a critical role in forebrain arousal and organized behavior. The patient’s level of consciousness improved dramatically after this procedure.

This landmark study suggested that it is possible to switch wakefulness on and off with the right stimuli.

In a new study, researchers at the University of Wisconsin-Madison took this a step further, performing experiments on sleeping or anesthetized macaques.

“We decided to go beyond the classical approach of recording from one area at a time,” says senior author Yuri Saalmann, an assistant professor at the University of Wisconsin, Madison. “We recorded from multiple areas at the same time to see how the entire network behaves.”

The researchers implanted electrodes in various areas of the monkeys’ brains and sent mild electric impulses through them while the animals were either asleep or sedated.

The monkeys stayed asleep during most stimulation apart from the time when the impulse stimulated the central lateral thalamus at a specific frequency. At that time, the monkeys woke up even when they were under deep anesthesia.

Sleep and anesthesia have different mechanisms of action, so the fact that the monkeys became awake following the electrode stimulation suggests that a shared brain circuit is involved in wakefulness.

After monitoring the monkeys as they went back and forth between conscious and unconscious states, the researchers were able to identify two brain pathways that trigger a wakeful state when activated.

One of the circuits carries sensory information from the thalamus to the cerebral cortex, the outermost layered structure of the brain and controls higher brain functions such as information processing. The other pathway that needs to be activated to trigger consciousness is involved in making predictions, attention priorities, and goals.

“We found that when we stimulated this tiny little brain area, we could wake the animals up and reinstate all the neural activity that you’d normally see in the cortex during wakefulness,” Saalmann says. “They acted just as they would if they were awake. When we switched off the stimulation, the animals went straight back to being unconscious.”

There’s a big caveat though: once the stimulation stopped, the monkeys’ consciousness also slipped away.

In this study, consciousness does not refer to the individual awareness of one’s unique thoughts, memories, feelings, sensations, and environment. How this kind of consciousness, or sentience, arises is a complex question, which the study’s authors did not attempt to answer. In this context, consciousness refers to being awake (i.e. not asleep) and able to interact with one’s environment.

The newly identified link between the thalamus and the cortex may have important medical implications. For instance, the insight could lead to improvements in anesthesia and new treatments for people with consciousness disorders, such as the 2007 patient mentioned earlier.

There are also some study limitations, such as the fact that only two monkeys were examined. In the future, similar studies that employ a higher sample and work with other animal models (i.e. mice) could strengthen the study’s findings.

“The overriding motivation of this research is to help people with disorders of consciousness to live better lives,” says first author Michelle Redinbaugh, a graduate student in the Department of Psychology at the University of Wisconsin, Madison. “We have to start by understanding the minimum mechanism that is necessary or sufficient for consciousness, so that the correct part of the brain can be targeted clinically.”

“There are many exciting implications for this work,” she says. “It’s possible we may be able to use these kinds of deep-brain stimulating electrodes to bring people out of comas. Our findings may also be useful for developing new ways to monitor patients under clinical anesthesia, to make sure they are safely unconscious.”

The study appeared in the journal Neuron.

Macaque tool-use patterns help us understand how early humans went about it

A new study on macaques at Thailand’s Ao Phang Nga National Park is helping us understand how early humans developed the use of stone tools.

Image credits Heiko S / Flickr.

Macaques tend to rely pretty heavily on stone tools, especially percussive (striking) tools, during their daily forage for food. This allows them access to more varied food sources — shellfish, in the case of the two groups of macaques that made the object of this study. The results indicate that while the environmental context definitely plays a part in tool use and development, cultural factors also matter.

Cracking oysters

“We observed differences among macaques on two different islands, in relation to tool selection and the degree of tool re-use when foraging for marine prey,” says co-author Dr. Tomos Proffitt from the University College London Institute of Archaeology.

The study assessed a total of 115 stone tools recovered from two islands (Boi Yai Island and Lobi Bay) located about 15 kilometers apart in southern Thailand, and are both part of the national park. Each island houses a population of wild long-tailed macaques, provides virtually the same tool-making resources (primarily limestone), and harbor the same prey species.

In such a context, the team expected both populations to develop similar, if not identical, tools. However, they found that the macaques on Boi Yai Island select heavier tools than their counterparts on Lobi Bay, while the latter’s tools show signs of repeated use on several species of prey.

Stone tools used to crack open oysters on Boi Yai tend to be larger than those used on Lobi Bay. While the team notes that oysters on Boi Yai Island are, in general, larger than those Lobi Bay, they believe that this is a learned rather than practical behavior.

“The theory is that if the environmental factors are the same—the only reasonable conclusion is that one island has developed its own tool using culture either through genetics or through passing down through a learning mechanism. While the other group exhibits a tool use culture which is more ephemeral and ad hoc,” says Dr. Proffitt.

Seeing how other primates develop and use tools today can help inform us about how our ancestors went about the same process. Lead author, Dr. Lydia Luncz (Institute of Cognitive and Evolutionary Anthropology, University of Oxford), said:

“That we find a potential cultural behavior in macaques is not surprising to us. The interesting part is that the same foraging behavior creates distinct tool evidence in the environment. This might be useful to keep in mind when we look at the archaeological record of human ancestors as well”.

The paper “Group-specific archaeological signatures of stone tool use in wild macaques” has been published in the journal eLife.

Monkey business: A group of monkeys in Indonesia will steal your wallet and sell it back to you — for a cracker

The Monkey Mafia is acting up in Indonesia.

“Hey boss, you got something good for me?” Image credits: McKay Savage.

Researchers have identified and described a nasty but fascinating behavior of monkeys. By themselves, they’ve learned to steal the valuables of tourists and then sell it back for a profit.

The long-tailed macaques (Macaca fascicularis) living near the Uluwatu temple in Indonesia are not picky — they’ll steal anything: wallets, cash, hats, cameras, anything that looks like it’s valuable. Then, they’ll run off to the temple staff to sell their ill-gotten goods for a tasty treat. This behavior has been discussed anecdotally for years, but it hasn’t been properly studied. So Fany Brotcorne, a primatologist at the University of Liège in Belgium, set out to see how the macaques act, and what drove them to act this way.

“It’s a unique behaviour. The Uluwatu Temple is the only place in Bali where it’s found,” she says, which suggests it is a learned behaviour rather than an innate ability.

She spent four months around the temple, documenting the monkeys’ behavior — which I can only imagine was a unique experience in itself.

She learned that it’s a learned behavior because when a new group of macaques moved to the area, they too observed the other monkeys and soon copied the behavior. There were other clues as well. Aside from monkeys learning from one another, young males (who are more prone to taking risks) were observed to exhibit this behavior more than others. Basically, this appears to be a cultural behavior, transmitted from generation to generation and from monkey to monkey. In other words, it’s more like a human behavior than an animal behavior.

“This indicates that it can indeed be a new behavioural tradition in primates and one that teaches us that new traditions can involve robbing and bartering with a different species,” he says.

In fact, Brotcorne believes that this could actually help us understand a thing or two about ourselves and how our own cognitive abilities developed.

“Bartering and trading skills are not well known in animals. They are usually defined as exclusive to humans,” she says.

Amusingly, she also said that she herself fell victim to the monkeys — not once, but several times.

“Oh, so many times,” she says. “The monkeys were always trying to steal my hat, my pen, even my research data!”

It’s not the first time monkeys exhibit a surprising behavior. In a separate experiment, researchers taught monkeys the concept of money. Not long after, the first prostitute monkey appeared.

Journal Reference: Fany Brotcorne, Gwennan Giraud, Noëlle Gunst, Agustín Fuentes, I. Nengah Wandia, Roseline C. Beudels-Jamar, Pascal Poncin, Marie-Claude Huynen, Jean-Baptiste Leca — Intergroup variation in robbing and bartering by long-tailed macaques at Uluwatu Temple (Bali, Indonesia). DOI: 10.1007/s10329-017-0611-1

Japanese macaque. Credit: Wikimedia Commons

Monkeys have the vocal hardware required for speech but lack the brains

Japanese macaque. Credit: Wikimedia Commons

Japanese macaque. Credit: Wikimedia Commons

Macaques and likely other monkeys, as well as apes, are technically capable of vocalizing vowel sounds and even whole sentences, not much different from how humans do it. This was revealed by a new study which found no anatomical limitations to keep monkeys from being able to speak. However, macaques lack the neuro-cognitive machinery to generate speech. It’s an important distinction that will be of great use in our quest to unravel the origin of speech.

The uniqueness of human vocalized communication is difficult to pin down. For one, speech requires a precise coordination of the vocal anatomy, which includes the tongue, lips, and larynx. This is only half the picture, though, because having a vocal range is not enough. You also require dedicated brain regions that are meant for processing speech.

It was never clear if our evolutionary edge is due to vocal anatomy, brain wiring, or a combination of both. An international team of researchers has now simplified the picture by effectively singling out one of these assumptions.

“Now nobody can say that it’s something about the vocal anatomy that keeps monkeys from being able to speak—it has to be something in the brain. Even if this finding only applies to , it would still debunk the idea that it’s the anatomy that limits speech in nonhumans,” said Asif Ghazanfar, a Princeton University professor of psychology and the Princeton Neuroscience Institute, and of the study’s co-authors.

“Now, the interesting question is, what is it in the human brain that makes it special?”

Ghazanfar and colleagues used sophisticated imaging technology based on X-rays to trace all the subtle movements of the macaque’s vocal anatomy. The recorded footage was then turned into a model by researchers from the VUB Artificial Intelligence Laboratory in Belgium which could simulate a macaque’s vocal range based on the physical attributes recorded by X-ray.

X-rays were used to trace the movements of the different parts of a macaque's vocal anatomy. Asif Ghazanfar, Princeton Neuroscience Institute.

X-rays were used to trace the movements of the different parts of a macaque’s vocal anatomy. Asif Ghazanfar, Princeton Neuroscience Institute.

We are able to carry out meaningful conversations because of words. Words start off with a source sound produced by the vocal box, which is then altered by the lips or tongue. For instance, the words “bat” and “bot” have the same vocal source. Its frequencies, however, are then altered by the movements of the mouth and tongue.

When a macaque’s grunt or source sound was plugged into the computer model, the researchers found comprehensible vowel sounds can be formed. Were the monkey able to direct its vocal anatomy, it could utter complete sentences. But it would not sound similar to a human, the researchers warn in the paper published in Science Advances.

“This new result tells us that there’s still a big mystery concerning where human speech came from,” said Laurie Santos, a psychology professor at Yale University who is familiar with the research but had no role in it.

Though the study has only be made included macaques, it’s likely the findings apply to other primate species. Being older in the evolutionary tree than apes, it’s also likely that species like gorillas or chimps also share the same vocal capabilities. “I think that means we’re in for some exciting new answers soon,” Santos said.

What will likely happen next is a more in-depth look into monkey and app brains to see what they’re missing that makes them unable to speak. More sophisticated models might also help us unravel the origin of speech in humans.

“Their value as a model system for studying the parts of the brain that directly control the biomechanics of orofacial movements during speech and other vocal behaviors will increase,” Ghazanfar said. “Moreover, it’s going to force us to think more carefully about how speech evolved, how our brain is uniquely human and how we can use these model animals in the future to understand what goes wrong when we are unable to speak.”

Monkey Business: Popular Girls Have Less Lice

It pays off to have many friends, especially if you’re a macaque.

Grooming is an important aspect of the macaque social structure. Photo by Noneotuho.

Lice infestations can be a huge problem for humans and animals alike. But it’s easier to get by with some help from your friends. For instance, popular macaque girls benefit from extra grooming from their friends. The more at the center of a social network a female is, the more grooming she gets, which reduces the number of lice on her body.

“We thought that since grooming is one of the most common types of contact that occurs between macaques, this behavior should facilitate the transmission of lice,” says lead author Julie Duboscq, who conducted the research at the University of Strasbourg and currently based at Kyoto University. “At the same time, grooming might also constrain the spread of lice because louse eggs are removed during grooming, which reduces future generations of lice.”

He and his colleagues observed grooming patterns and egg-picking to estimate how many lice each macaque had. They expected more grooming to equal fewer parasites, but this wasn’t nearly the case – the relationship between social status turned out to be more complex.

Basically, the more popular a macaque is, the more he or she interacts with others — which increases the likelihood of it getting new parasites.

“The link between sociality and parasitism is not always straightforward,” says Andrew MacIntosh, a senior author of the paper and a researcher at Kyoto University’s Primate Research Institute. “Increased centrality in social networks is often linked to increased parasite load and disease risk.”

In a previous study, they found that central females are more likely to suffer from intestinal worms, but in this case, the risk is mitigated by grooming.

The paper “Network centrality and seasonality interact to predict lice load in a social primate” appeared Feb. 26, 2016 in Scientific Reports, with doi: 10.1038/srep22095