Tag Archives: #monkeys

Monkeys Experience the Visual World The Same Way People Do (Neuroscience)

When humans look out at a visual landscape like a sunset or a beautiful overlook, we experience something — we have a conscious awareness of what that scene looks like. This awareness of the visual world around us is central to our everyday existence, but are humans the only species that experiences the world consciously? Or do other non-human animals have the same sort of conscious experience we do?

Scientists and philosophers have asked versions of this question for millennia, yet finding answers — or even appropriate ways to ask the question — has proved elusive. But a team of Yale researchers recently devised an ingenious way to try to solve this riddle.

Writing on March 29 in the Proceedings of the National Academy of Sciences, they make the case that one non-human species — the rhesus macaque — also has a conscious awareness of the world around it.

“People have wondered for a long time whether animals experience the world the way we do, but it’s been difficult to figure out a good way to test this question empirically,” said Moshe Shay Ben-Haim, a postdoctoral fellow at Yale and first author of the paper.

Researchers have known for a long time that people can be influenced by unconscious subliminal cues — visual stimuli presented just outside of our threshold for conscious awareness, said Laurie Santos, a professor of psychology at Yale who is co-senior author of the study along with her colleague Steve Chang, associate professor of psychology and of neuroscience, and Ran Hassin of Hebrew University.

“We tend to show different patterns of learning when presented with subliminal stimuli than we do for consciously experienced, or supraliminal stimuli,” she said.

If monkeys show the same “double dissociation” pattern that humans do, it would mean that monkeys probably experience the supraliminally presented stimuli in the same way as people do — as a conscious visual experience.

Ben-Haim, Santos, and their team thought of a novel way to explore whether macaques also exhibit a difference in learning when stimuli are experienced consciously versus non-consciously.

In a series of experiments, they had monkeys and humans guess whether a target image would appear on the left or right side of a screen. Before the target appeared, participants received a visual cue — a small star— on the side opposite of where the target would subsequently appear. The researchers varied whether the cue was presented supraliminally or subliminally. When the cue was presented for a few seconds, human participants successfully learned that the target would appear in the opposite location from the cue. But when the cue was presented subliminally — quickly enough that it escaped people’s conscious perception — participants showed a different pattern of performance; they continued to choose the side that was subliminally cued, failing to learn the rule that the cue predicted the opposite side.

Surprisingly, the researchers found that monkeys showed exactly the same response patterns as the people did: like humans, macaques were able to successfully look to the target location when the cues were presented consciously, but showed the reverse pattern for subliminal cues. This striking result suggests that monkeys have two levels of processing just as humans do, one of which must be conscious.

“These results show that at least one non-human animal exhibits both non-conscious perception as well as human-like conscious visual awareness.” said Ben-Haim. “We now have a new non-verbal method for assessing whether other non-human creatures experience visual awareness in the same way as humans.”

Other authors of the paper are Yarrow Dunham, Olga Dal-monte, and Nicholas Fagan of Yale.

Featured image credit: stock.adobe.com

This science news is confirmed by us from Yale

Provided by Yale University

Stimulating Brain Pathways Shows Origins of Human Language and Memory (Neuroscience)

Scientists have identified that the evolutionary development of human and primate brains may have been similar for communication and memory.

Although speech and language are unique to humans, experts have found that the brain’s pathway is similarly wired in monkeys which could signify an evolutionary process dating back at least 25 million years.

In a study, published in the journal Neuron, teams led by Newcastle University and the University of Iowa, compared auditory cortex information from humans and primates and found strong links.

Professor Chris Petkov, from Newcastle University’s Faculty of Medical Sciences, said: “Our language abilities help us to crystallise memories and make them vivid, such as ‘the singer sounded like a nightingale’.

“Therefore, it’s often thought that the human language and memory brain systems went through a substantial transformation during our recent evolutionary history, distinguishing us from every other living animal.

“We were astounded to see such striking similarity with other primates, and this discovery has substantial importance for science and neurological disorders.”

This discovery has substantial importance for science and neurological disorder. 

— Professor Chris Petkov

Stimulating auditory cortex

Scientists used information from neurosurgery patients being monitored for treatment. With humans, stimulation of a specific part of the brain can be visualized if brain imaging is used at the same time.

The experts also compared the results from stimulating auditory cortex and visualising areas important for language and memory in monkeys.

The brain stimulation highlighted a previously unseen ancestral brain highway system that is deeply shared by humans and monkeys, one that is likely to have been present in ancestral primates to both species.

The finding is important because brain stimulation is a common treatment for neurological and psychiatric disorders. However, how brain stimulation works is not well understood and requires work that cannot be conducted with humans. Work with non-human primates has paved the way for current brain treatments, including Parkinson’s disease.

Inspiring new research

The study has generated unique new brain scanning information that can now be globally shared to inspire further discovery by the international scientific community.

Professor Matthew Howard III, chief neurosurgeon at the University of Iowa Carver Medical Center, USA, co-author of the study, said: “This discovery has tremendous potential for understanding how brain stimulation could help patients, which requires studies with animal models not possible to conduct with humans.”

Professor Tim Griffiths, consultant neurologist at Newcastle University, also co-author of the study, added: “This discovery has already inspired new research underway with neurology and neurosurgery patients.”


Common fronto-temporal effective connectivity in humans and monkeys. Francesca Rocchi et al. Neuron. DOI: 10.1016/j.neuron.2020.12.026

Provided by Newcastle University

T Cells Linked to Myelin Implicated in MS-Like Disease in Monkeys (Neuroscience)

Some of the T cell epitopes targeting myelin in monkeys were the same as those found in humans with multiple sclerosis. Researchers say linking these specific cells opens the doors to developing antiviral therapies that could be useful to treat newly diagnosed cases of MS in humans.

Scientists have uncovered new clues implicating a type of herpes virus as the cause of a central nervous system disease in monkeys that’s similar to multiple sclerosis in people.

The findings, published in the Annals of Clinical and Translational Neurology, expand on previous work to understand the cause of the disease and potentially develop antiviral therapies. The work was led by scientists at Oregon Health & Science University.

“This gives us a better understanding of the model,” said Scott Wong, Ph.D., senior author of the study and a scientist at the OHSU Vaccine and Gene Therapy Institute and the Oregon National Primate Research Center. “It draws more parallels to MS in people.”

The new study reveals the presence of two kinds of T cells, a type of white blood cell that’s a critical part of the body’s immune system. In this case, scientists determined the T cells were associated with an immune response involving the loss of myelin, the protective sheath that covers nerve fibers.

Myelin and nerve fibers become damaged in multiple sclerosis, which slows or blocks electrical signals required for us to see, move our muscles, feel sensations and think.

“We found that some of the T cell epitopes targeting myelin in these animals are identical to those found in humans with MS,” Wong said.

By linking these specific T cells to the loss of myelin, scientists say the new study opens the possibility of developing an antiviral therapy that could be especially useful for newly diagnosed cases of multiple sclerosis.

“If we found a unique virus that we believed was causing MS, then you could in theory come up with a vaccine against that virus,” said co-author Dennis Bourdette, M.D., professor emeritus and former chair of neurology in the OHSU School of Medicine.

The work builds on a chance discovery in the colony of Japanese macaques at the primate center.

Myelin and nerve fibers become damaged in multiple sclerosis, which slows or blocks electrical signals required for us to see, move our muscles, feel sensations and think. Image is in the public domain

In 2011, scientists at OHSU published research identifying a group of monkeys at the primate center with a naturally occurring disease known as Japanese macaque encephalomyelitis. Since then, scientists have been working to understand the cause and progression of the disease in the macaques with an eye toward applying possible therapies in people.

The latest study points toward developing strategies to combat the disease leveraging the body’s immune response.

“If we can understand how it’s doing it, we may be able to test vaccine strategies,” Wong said. “I’m not sure we can prevent virus infection, but we may be able to prevent virus-associated disease.”

Funding: This research was supported by the U.S. Department of Defense award numbers W81XWH-09-1-0276 and W81XWH-17-1-0101; the National Institutes of Health, award numbers P51OD011092 and R24-NS104161; the Laura Fund for Multiple Sclerosis Research; and the Race to Erase MS.

Reference: Govindan, A.N., Fitzpatrick, K.S., Manoharan, M., Tagge, I., Kohama, S.G., Ferguson, B., Peterson, S.M., Wong, G.S., Rooney, W.D., Park, B., Axthelm, M.K., Bourdette, D.N., Sherman, L.S. and Wong, S.W. (2021), Myelin‐specific T cells in animals with Japanese macaque encephalomyelitis. Ann Clin Transl Neurol. https://doi.org/10.1002/acn3.51303 https://onlinelibrary.wiley.com/doi/10.1002/acn3.51303

Provided by Oregon Health and Science University

Monkey See Others, Monkey Do: How The Brain Allows Actions Based On Social Cues (Neuroscience)

Researchers at NIPS in Japan show that information flow between two regions in the front of the brain makes it possible for monkeys to correctly interpret social cues.

In baseball, a batter’s reaction when he swings and misses can differ depending on whether they were totally fooled by the pitch or simply missed the change-up they expected. Interpreting these reactions is critical when a pitcher is deciding what the next pitch should be. This type of socially interactive decision-making is the topic of a recent brain study led by Masaki Isoda at the National Institute for Physiological Sciences (NIPS) in Japan. They found that this ability requires a specific connection between two regions in the front of the brain, and that without it, monkeys default to making decisions as if they were playing against an inanimate object.

Information flow from PMv to MPFC is vital for making decisions based on social cues provided by other monkeys (left); when this neuronal pathway is silenced, monkeys cannot catch the social cues (right). ©Taihei Ninomiya.

Two regions in the front of the brain–the PMv and the mPFC–contain “self”, “partner”, and “mirror” neurons that signal self-actions, other-actions, or both, respectively. Scientists believe that these types of neurons are what make social qualities such as empathy possible. However, despite years of research, not much is known about how these brain regions work together. The NIPS team set out to find some answers.

They trained monkeys to play a game with a partner in which they pressed buttons to obtain rewards. Sometimes, the rules of the game changed, and the monkeys made mistakes. Sometimes monkeys made mistakes simply because they were careless. “Monkeys continued using the same rule if they thought the other monkey’s mistakes were accidental,” says Masaki Isoda. “But, if they thought the mistakes were because the rules had changed, the monkeys adjusted their thinking and switched rules.” The researchers included three types of partners: real monkeys, recorded monkeys, and inanimate objects.

They found that the proportion of partner cells was much higher in the mPFC than in the PMv, indicating it could be particularly important for understanding what others are thinking. Partner cells in the mPFC were most active and most affected by the PMv when partners were real and least active and least affected when they were inanimate objects. Thus, it seemed possible that the ability of a monkey to recognize social cues depends on mPFC cells getting social information from the PMv.

To test this hypothesis, the researchers used viral vector technology to temporally silence only neurons in the PMv that connect to the mPFC. In this situation, monkeys made many more mistakes after their partners made careless errors, behaving as if every error was because the rules had changed. “This behavior was reminiscent of an autistic monkey who played the same game,” says Taihei Ninomiya. “As difficulty understanding social cues is a hallmark of autism, understanding the role of the PMv-mPFC pathway provides a good direction for future research into autism spectrum disorders.”

References: Ninomiya, T., Noritake, A., Kobayashi, K. et al. A causal role for frontal cortico-cortical coordination in social action monitoring. Nat Commun 11, 5233 (2020). https://doi.org/10.1038/s41467-020-19026-y link: http://dx.doi.org/10.1038/s41467-020-19026-y

Provided by National Institute of Natural Sciences

How Do Basal Ganglia Neurons Convey Information For The Control Of Voluntary Movements? (Neuroscience)

It is common that neurons transmit information to another group of neurons by increasing or decreasing their activity, i.e. “firing rate changes”. In addition to firing rate changes, synchronized activity of a certain group of neurons, i.e. “correlated activity”, has been suggested to play an important role in conveying information. This study revealed that, in the basal ganglia, information for the movement control is conveyed primarily by firing rate changes and correlated activity play only minor role in healthy conditions (Figure).

Summary of findings. Activity of multiple neurons located in the arm regions of the basal ganglia was recorded while monkeys performed a motor task that required their arm movements. Most neurons in the basal ganglia exhibited non-correlated activity, although they showed firing rate changes during the task. © Atsushi Nambu.

The research team consists of Dr. Woranan Wongmassang, Professor Atsushi Nambu, and their colleagues recorded neuronal activity of multiple neurons simultaneously in the basal ganglia while monkeys performed a motor task that required their arm movements. They found that most neurons located in the arm regions of the basal ganglia showed firing rate changes in relation to arm movements. On the other hand, the percentage of neurons that showed correlated activity during the task was very small.

Professor Nambu claims, “Unlike in healthy conditions, a large proportion of neurons in the basal ganglia show strong synchronized activity in Parkinson’s disease. So, it is possible that symptoms could be improved by decreasing abnormally increased correlated activity in the basal ganglia. The findings provide important clues to develop effective treatment for Parkinson’s disease.”

References: Wongmassang, W, Hasegawa, T, Chiken, S, Nambu, A. Weakly correlated activity of pallidal neurons in behaving monkeys. Eur J Neurosci. 2020; 00: 1– 14. https://doi.org/10.1111/ejn.14903 link: https://onlinelibrary.wiley.com/doi/full/10.1111/ejn.14903

Provided by National Institutes Of Natural Sciences

Primates Aren’t Quite Frogs (Neuroscience)

Spinal modules in macaques can independently control forelimb force direction and magnitude.

Researchers in Japan demonstrated for the first time the ‘spinal motor module hypothesis’ in the primate arm, opening a new pathway for recovery after disease or injury.

An experiment nearly 40 years ago in frogs showed that their leg muscles were controlled by simultaneously recruitment of two modules of neurons. It’s a bit more complex in macaques (The National Center of Neurology and Psychiatry).

The human hand has 27 muscles and 18 joints, which our nervous system is able to coordinate for complex movements. However, the number of combinations — or degrees of freedom — is so large that attempting to artificially replicate this control and adjustment of muscle activity in real time taxes even a modern supercomputer. While the method used by the central nervous system to reduce this complexity is still being intensely studied, the “motor module” hypothesis is one possibility.

Under the motor module hypothesis, the brain recruits interneuronal modules in the spinal cord rather than individual muscles to create movement; wherein different modules can be combined to create specific movements. Nearly 40 years ago, research in frogs showed that simultaneously recruiting two modules of neurons controlling leg muscles created the same pattern of motor activity that represents a “linear summation” of the two component patterns.

An international team of researchers, led by Kazuhiko Seki at the National Center of Neurology and Psychiatry’s Department of Neurophysiology, in collaboration with David Kowalski of Drexel University and Tomohiko Takei of Kyoto University’s Hakubi Center for Advanced Research, attempted to determine if this motor control method is also present in the primate spinal cord. If validated, it would provide new insight into the importance of spinal interneurons in motor activity and lead to new ideas in movement disorder treatments and perhaps even a method to “reanimate” a limb post-spinal injury.

The team implanted a small array of electrodes into the cervical spinal cord in three macaques. Under anesthesia, different groups of interneurons were recruited individually using a technique called intraspinal microstimulation, or ISMS. The team found that, as in the frog leg, the force direction of the arm at the wrist during dual-site simulation was equal to the linear summation of the individually recruited outputs. However, unlike the frog leg, the force magnitude output could be many times higher than that expected from a simple linear summation of the individual outputs. When the team examined the muscle activity, they found that this supralinear summation was in a majority of the muscles, particularly in the elbow, wrist, and finger.

“This is a very interesting finding for two reasons,” explains Seki. “First, it demonstrates a particular trait of the primate spinal cord related to the increased variety of finger movements. Second, we now have direct evidence primates can use motor modules in the spinal cord to control arm movement direction and force magnitude both efficiently and independently.”

In effect, using paired stimulation in the primate spinal cord not only directly activate two groups of interneurons, INa and INb, which recruit their target muscle synergies, Syn-a and Syn-b, to set the arm trajectory, but can also activate a third set of interneurnons that can adapt the motor activity at the spinal level to change the force of the movement, group INc. This would let the brain plan the path the arm should take while the spinal cord adapts the muscle activity to make sure that path happens.

One example of this “plan and adapt” approach to motor control is the deceptively simple act of drinking from a can of soda. The brain can predetermine the best way to lift the can to your mouth for a sip, but the actual amount of soda in the can — and therefore the can’s weight — is perhaps unknown. Once your brain has determined the trajectory the can should take — in this case INa and INb — the amount of force needed to complete that action can be modulated separately in INc, rather than redetermining which sets of muscles will be needed.

This study experimentally proves for the first time that primate arm movements may be efficiently controlled by motor modules present in the spinal cord. Based on the results of this research, it is expected that the analysis and interpretation of human limb movements based on the motor module hypothesis will further advance in the future.

In the field of robotics, this control theory may lead to more efficient methods to create complex limb movements, while in the field of clinical medicine, it is expected that new diagnostic and therapeutic methods will be created by analyzing movement disorders caused by neurodegenerative diseases and strokes.

References: Amit Yaron, David Kowalski, Hiroaki Yaguchi, Tomohiko Takei, and Kazuhiko Seki, “Forelimb force direction and magnitude independently controlled by spinal modules in the macaque”, Proceedings of the National Academy of Sciences of the United States of America, 2020. DOI】https://doi.org/10.1073/pnas.1919253117

Provided by Kyoto University