Tag Archives: rhesus monkey

This shot shows a scene during the Chinese experiment designed to train monkeys to recognize themselves in the mirror and become aware. Credit: Neng Gong and colleagues/Current Biology 2015

Monkeys can also recognize themselves in mirrors, but only with training

Only humans and great apes can recognize themselves when looking in a mirror, but new findings suggest that it’s possible for rhesus monkeys to realize they’re looking at themselves if trained properly. The findings bear important implications for humans as well, since they suggest patients with impairment of self-recognition can have their condition remedied with training.

To be self aware

This shot shows a scene during the Chinese experiment designed to train monkeys to recognize themselves in the mirror and become aware. Credit: Neng Gong and colleagues/Current Biology 2015

This shot shows a scene during the Chinese experiment designed to train monkeys to recognize themselves in the mirror and become aware. Credit: Neng Gong and colleagues/Current Biology 2015

You might not enjoy looking yourself in the mirror, but believe it or not your ruthless self inspection of pimples, funny moles and crooked teeth is a display of powerful cognitive effort and mental gymnastics that not too many species can boast.  Since the 1970s psychologists have used mirrors to search for signs of self-awareness in both humans and animals. Along the way, they came to believe that humans were almost universally able to pass a mirror-based self-recognition test by 24 months of age. As far as non-human animals go, chimps, gorillas and orangutans have been also found to pass the mirror test, although not all tried specimens pass it and some lost the ability as they aged.

While members of most species of great apes have shown compelling evidence that they recognize themselves, no monkey has done so. In early tests, researchers would put monkeys in front of mirrors of various shapes and sizes starting from early age, yet while the monkeys could learn to use the mirrors as tools for observing other objects they failed to show any signs of self-recognition. Such signs include exploration of otherwise unknown and invisible marks usually applied to the individual’s head. In contrast, great apes display focus and concentration as they use the reflection to pick their teeth, explore their ears, or investigate their genitals. At best, only fleeting/incidental touches near the mark have been reported in a few monkeys during mark tests. No monkey has ever been shown to use its reflection to carefully inspect a directly non-visible body part such as inside its mouth or behind an ear, in spite of repeated attempts to make things easier for monkeys.

Training a monkey to look in the mirror

Neng Gong of the Chinese Academy of Sciences and colleagues weren’t convinced, so they took extra measures. Rhesus monkeys were sat in front of a mirror and had a pesky laser light shined on their faces. They rewarded the monkeys each time they touched the affected area, and after days of training, the researchers switched to a non-irritating red laser light. Two to five weeks in, the monkeys had learned to touch faces areas market by the laser spot they couldn’t feel in front of the mirror. When the mirror was replaced by video images, the monkeys were also apt at noticing the virtual face marks.

Five out of the seven trained monkeys also showed signs of typical self-direct behavior induced by mirrors, like touching the marks on the face or ear then looking and/or smelling at their findings, as if they were communicating to their selves “what’s this on my face?”. They also used the mirrors unprompted by researchers to inspect other body parts that weren’t marked. In effect, the monkeys had passed the mirror test.

“Our findings suggest that the monkey brain has the basic ‘hardware’ [for mirror self-recognition], but they need appropriate training to acquire the ‘software’ to achieve self-recognition,” says Gong said.

The findings suggest that there’s hope for patients inflicted with mental retardation, autism, schizophrenia, or Alzheimer’s disease and who are unable to recognize themselves in the mirror anymore.

“Although the impairment of self-recognition in patients implies the existence of cognitive/neurological deficits in self-processing brain mechanisms, our finding raised the possibility that such deficits might be remedied via training,” the authors write in Current Biology. “Even partial restoration of self-recognition ability could be desirable.”

A rhesus monkey preparing to choose the four and five combination on the panel. (c) PNAS

Monkeys can do math, study proves

rhesus_monkey

Photo: PNAS

It’s long been supposed that monkeys are capable of mental arithmetics, but it was only recently that this was proven for a fact by neuroscientists at the Margaret Livingstone of Harvard Medical School in Boston. The researchers taught three rhesus macaques to identify symbols representing the numbers zero to 25, then when given the choice between two panels, one depicting a number symbol and the other depicting an addition of two other symbols, the monkeys proved they could do math and choose which of the two was bigger. This doesn’t just mean that monkeys are smarter than everyone might have thought; it also raises important questions as to how mammalians brains, including those of us humans, work and engage with our surroundings.

Previously, researchers showed that chimpanzees could add single-digit numbers. The results were nothing short of remarkable, but the study didn’t conclude what process go on in the primate’s brain when this addition was going on. The new study which studied the rhesus monkeys sheds more light on these aspects.

Margaret Livingstone of Harvard Medical School in Boston and colleagues trained three monkeys to associate the Arabic numbers 0 through 9 and 15 select letters with the values zero through 25. To receive food, the monkey had to choose between two boards: one that showed an addition of two symbols and the other only one symbol. If the monkey chose the greater number of the two, it received more tasty food.  Within 4 months, the monkeys had learned how the task worked and were able to effectively add two symbols and compare the sum to a third, single symbol.

So be certain the monkeys were simply memorizing the symbols and all possible combinations (that’s no how arithmetic works, clearly), the researchers introduced an entirely different set of symbols representing the numbers zero to 25 in the form of tetris-like blocks instead of the familiar Arabic numbers and Latin letters. According to the study, all three monkeys were on average capable of choosing the correct answer “well above” 50 percent of the time, which is statistically relevant enough to infer that the rhesus monkeys could actually do the math and not simply rely on chance.

A rhesus monkey preparing to choose the four and five combination on the panel. (c) PNAS

A rhesus monkey preparing to choose the four and five combination on the panel. (c) PNAS

What’s interesting to note is that after the researchers analyzed their findings in greater deal they began to understand why the monkeys weren’t right most of the time with their calculations. Apparently, they tended to underestimate a sum compared with a single symbol when the two were close in value—sometimes choosing, for example, a 13 over the sum of eight and six. Basically, when the monkey was adding two numbers, it paid close attention to the large of the two and then added only a fraction of the lesser number to make up the sum; which obviously came out wrong from the real answer.

This peculiar, since one prevailing theory on how the brain processes number representations is that it underestimates the value of larger numbers in a systematic and unchangeable way. The present findings contradict this idea and may help researchers better understand how human beings process numbers. Also, the findings could also help shed light on dyscalculia (similar to dyslexia, only it involves failing to perform mathematical operations instead of reading – an interesting piece about it worth reading here). It’s not that people with dyscalculia have an intellect comparable with rhesus monkeys – far from it, apart from their disability to perform arithmetic, they’re totally cognitively functioning human beings. Estimating values, the present study suggests, may be key to how addition works.

Results were published in the journal PNAS.

brain structure human

Human brain found to have unique brain structures from other primates

brain structure humanHumans were granted with an evolutionary edge that differentiated us from other primates and may have helped us become the dominant species on planet Earth. A recent study which scanned the brains of humans and rhesus monkeys found that humans have at least two functional brain networks absent in rhesus monkeys.

Previous genetic research concluded that our ancestors split from those that lead to the evolution of rhesus monkeys some 25 million years ago, and since then brain networks have been added, disappeared or changed function. It’s rather obvious that we humans are capable of much more than our primate relatives, which lead scientists to claim that humans possess specific brain functions that are unique, however conclusive evidence has been absent until now.

The study was conducted by neurophysiologist Wim Vanduffel and colleagues at KU Leuven and Harvard Medical School, and involved functional Magnetic Resonance Imaging scans to visualise brain activity by detecting changes in blood flow while participants (humans and rhesus monkeys) performed various tasks. Oxygen and blood content delivered to a particular area of the brain differs according to a particular task, thus brain activity can be monitored. Professor Vanduffel explains:

“We did functional brain scans in humans and rhesus monkeys at rest and while watching a movie to compare both the place and the function of cortical brain networks. Even at rest, the brain is very active. Different brain areas that are active simultaneously during rest form so-called ‘resting state’ networks. For the most part, these resting state networks in humans and monkeys are surprisingly similar, but we found two networks unique to humans and one unique network in the monkey.”

“When watching a movie, the cortex processes an enormous amount of visual and auditory information. The human-specific resting state networks react to this stimulation in a totally different way than any part of the monkey brain. This means that they also have a different function than any of the resting state networks found in the monkey. In other words, brain structures that are unique in humans are anatomically absent in the monkey and there no other brain structures in the monkey that have an analogous function. Our unique brain areas are primarily located high at the back and at the front of the cortex and are probably related to specific human cognitive abilities, such as human-specific intelligence.”

Findings were published in the Journal of Neuroscience.

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The rhesus monkey twins, Roku and Hex ("six" in Japanesse and Greek respectively, since they were made from six distinct genetic entities), in sound health posing for the researchers. (c) OHSU

First chimera monkeys presented by scientists

The rhesus monkey twins, Roku and Hex ("six" in Japanesse and Greek respectively, since they were made from six distinct genetic entities), in sound health posing for the researchers. (c) OHSU

The rhesus monkey twins, Roku and Hex (“six” in Japanesse and Greek respectively, since they were made from six distinct genetic entities), in sound health posing for the researchers. (c) OHSU

In Greek mythology, the chimera is a fire breathing beast composed of several animal parts (lion body, snake-head tail, a goat head hanging from its back and so on), which has spurred the imagination of man for thousands of years. Though it is fairly clear that such an abomination never existed, apart from the infinite recesses of human imagination, scientist at the Oregon National Primate Research Centre have successfully bred, not one, but three chimera monkeys – each of them made up of tissue that came from up to six distinct genetic entities.

Of course, the scientists worked only with a single species, so that means no monkeys with rhino horns or giraffe ears. The three animals, two twins and a singleton, were bred after several different rhesus monkey embryos were stuck together in their early stage of development. These were later implanted in five female rhesus monkeys, all of which became pregnant. Thus, the chimera monkeys had tissue made up of cells that came from each of the contributing embryo.

“The cells never fuse, but they stay together and work together to form tissues and organs,” said Shoukhrat Mitalipov, who led the research. “The possibilities for science are enormous.”

This isn’t the first time a chimeric animal has been bred, far from it. The first successful attempts of this kind were made in the 1960s when one by one scientists managed to give life in the lab to chimeric rats, sheep, rabbits or cattle.  In time, this kind of research proved to be invaluable for scientists’ ongoing stem cell research efforts. Understanding how during embryonic development one particular cell develops into a particular tissue in the organism is crucial.

“If we want to move stem cell therapies from the lab to clinics and from the mouse to humans, we need to understand what these primate cells can and can’t do. We need to study them in humans, including human embryos,” said Mitalipov.