'Strikingly similar' brains of man and fly may aid mental health research

A new study by scientists at King’s College London’s Institute of Psychiatry and the University of Arizona (UA) published in Science reveals the deep similarities in how the brain regulates behaviour in arthropods (such as flies and crabs) and vertebrates (such as fish, mice and humans).

The findings shed new light on the evolution of the brain and behaviour and may aid understanding of disease mechanisms underlying mental health problems.

Based on their own findings and available literature, Dr Frank Hirth (King’s) and Dr Nicholas Strausfeld (UA) compared the development and function of the central brain regions in arthropods (the ‘central complex’) and vertebrates (the ‘basal ganglia’).

Research suggests that both brain structures derive from embryonic stem cells at the base of the developing forebrain and that, despite the major differences between species, their respective constitutions and specifications derive from similar genetic programmes.

The authors describe that nerve cells in the central complex and the basal ganglia become inter-connected and communicate with each other in similar ways, facilitating the regulation of adaptive behaviours. In other words, the response of a fly or a mouse to internal stimuli such as hunger or sleep, and external stimuli such as light/dark or temperature, are regulated by similar neural mechanisms.

Dr Hirth from the Department of Neuroscience at King’s Institute of Psychiatry says: “Flies, crabs, mice, humans: all experience hunger, need sleep and have a preference for a comfortable temperature so we speculated there must be a similar mechanism regulating these behaviours. We were amazed to find just how deep the similarities go, despite the differences in size and appearance of these species and their brains.”

Dr Strausfeld, a Regents Professor in the UA’s Department of Neuroscience and the Director of the UA’s Center for Insect Science, says: “When you compare the two structures, you find that they are very similar in terms of how they’re organized. Their development is orchestrated by a whole suite of genes that are homologous between flies and mice, and the behavioral deficits resulting from disturbances in the two systems are remarkably similar as well.”

In humans, dysfunction of the basal ganglia can cause severe mental health problems ranging from autism, schizophrenia and psychosis, to neurodegeneration - as seen in Parkinson’s disease, motor neurone disease and dementia - as well as sleep disturbances, attention deficits and memory impairment. Similarly, when parts of the central complex are affected in fruit flies, they display similar impairments.

Dr Hirth (King’s) adds: “The deep similarities we see between how our brains and those of insects regulate behaviour suggest a common evolutionary origin. It means that prototype brain circuits, essential for behavioural choice, originated very early and have been maintained across animal species throughout evolutionary time. As surprising as it may seem, from insects’ dysfunctional brains, we can learn a great deal about how human brain disorders come about.”

The findings suggest that arthropod and vertebrate brain circuitries derive from a common ancestor already possessing a complex neural structure mediating the selection and maintenance of behavioural actions.

Although no fossil remains of the common ancestor exist, trace fossils, in the form of tracks criss-crossing the seafloor hundreds of millions of years ago, reveal purposeful changes in direction.

Dr Strausfeld (UA) says: “If you compare these tracks to the tracks left behind by a foraging fly larva on an agar plate or the tunnels made by a leaf-mining insect, they’re very similar. They all suggest that the animal chose to perform various different actions, and action selection is precisely what the central complex and the basal ganglia do.”

The trace fossils may thus support the early existence of brains complex enough to allow for action selection and a shared ancestry of neural structures between invertebrates and vertebrates.

Ability To ‘Think About Thinking’ Not Limited Only To Humans According to New Research

Humans’ closest animal relatives, chimpanzees, have the ability to “think about thinking” – what is called “metacognition,” according to new research by scientists at Georgia State University and the University at Buffalo.

Michael J. Beran and Bonnie M. Perdue of the Georgia State Language Research Center (LRC) and J. David Smith of the University at Buffalo conducted the research, published in the journal Psychological Science of the Association for Psychological Science.

“The demonstration of metacognition in nonhuman primates has important implications regarding the emergence of self-reflective mind during humans’ cognitive evolution,” the research team noted.

Metacognition is the ability to recognize one’s own cognitive states. For example, a game show contestant must make the decision to “phone a friend” or risk it all, dependent on how confident he or she is in knowing the answer.

“There has been an intense debate in the scientific literature in recent years over whether metacognition is unique to humans,” Beran said.

Chimpanzees at Georgia State’s LRC have been trained to use a language-like system of symbols to name things, giving researchers a unique way to query animals about their states of knowing or not knowing.

In the experiment, researchers tested the chimpanzees on a task that required them to use symbols to name what food was hidden in a location. If a piece of banana was hidden, the chimpanzees would report that fact and gain the food by touching the symbol for banana on their symbol keyboards.

But then, the researchers provided chimpanzees either with complete or incomplete information about the identity of the food rewards.

In some cases, the chimpanzees had already seen what item was available in the hidden location and could immediately name it by touching the correct symbol without going to look at the item in the hidden location to see what it was.

In other cases, the chimpanzees could not know what food item was in the hidden location, because either they had not seen any food yet on that trial, or because even if they had seen a food item, it may not have been the one moved to the hidden location.

In those cases, they should have first gone to look in the hidden location before trying to name any food.

In the end, chimpanzees named items immediately and directly when they knew what was there, but they sought out more information before naming when they did not already know.

The research team said, “This pattern of behavior reflects a controlled information-seeking capacity that serves to support intelligent responding, and it strongly suggests that our closest living relative has metacognitive abilities closely related to those of humans.”

Anything you can do I can do better: Neuromolecular foundations of the superiority illusion

The existential psychologist Rollo May wrote that “depression is the inability to construct a future” while Lionel Tiger stated that “optimism has been central to the process of human evolution”. These deceptively simple phrases are remarkable in their depth and the connections they form between philosophy, psychology and neuroscience. Both capture the essence of human nature by articulating their insight that our ability to imagine and plan for the future is not only one of the most striking aspects of our species, but also that the inability to exercise this faculty is profoundly damaging to our happiness and sense of self. Two concepts related to these observations are depressive realism – the assertion that people with depression actually have a more accurate perception of reality, and moreover are less affected by its counterpoint, the superiority illusion. The superiority illusion is a cognitive bias by which individuals, relative to others, overestimate their positive qualities and abilities (such as intelligence, cognitive ability, and desirable traits) and underestimate their negative qualities. (Other cognitive biases include optimism bias and illusion of control.) While mathematically flawed – given a normal population distribution, most people are not above average – the superiority illusion is a positive belief that promotes mental health. Recently, scientists at the National Institute of Radiological Sciences (Chiba, Japan), the Japan Science and Technology Agency (Saitama), and Stanford University School of Medicine used resting-state functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) to study the default states of neural and molecular systems that generate the superiority illusion. They showed that resting-state functional connectivity between the frontal cortex and striatum regulated by inhibitory dopaminergic neurotransmission determines individual levels of the superiority illusion. The scientists state that their findings help clarify how the superiority illusion is biologically determined and identify potential molecular and neural targets for treating depressive realism.

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Bulging Eyes Of The Tarsier Provide Insight Into Evolution Of Human Vision

A new study, led by Dartmouth College, suggests that primates developed highly accurate, three-color vision that allowed them to shift to daytime living after eons of wandering in the dark.

The findings, published in the journal Proceedings of the Royal Society B: Biological Sciences, challenge the prevailing theory that trichromatic color vision, a hallmark event in primate evolution, evolved only after primates became diurnal. Learning to rise with the sun was an evolutionary shift that gave rise to anthropoid (higher) primates, which led to the human lineage.

Dr. Amanda D. Melin, a postdoctoral research associate in the Department of Anthropology at Dartmouth, led the team of scientists who based their findings on a genetic study of tarsiers, the enigmatic elfin primate that branched off early on from monkeys, apes and humans. These tiny animals, which measure between 3.3 and 6.5 inches in height, have a number of unusual traits – from communicating in pure ultrasound to their bulging eyes. Sensory specializations such as these have long fueled debate on the adaptive origins of anthropoid primates.

Previous research by this same team discovered the tarsiers’ ultrasound vocalizations last year. The new study sheds light on why the nocturnal animal’s ancestors had enhanced color vision better suited for daytime living conditions, like their anthropoid cousins.

The team analyzed the genes that encode photopigments in the eye. This analysis revealed that the last common ancestor of living tarsiers had highly acute, three-color vision much like modern monkeys and apes. Normally, such findings would indicate a daytime lifestyle. The tarsier fossil record, however, shows enlarged eyes that suggest they were active mainly at night.

Because of these contradictory lines of evidence, the researchers suggest that early tarsiers were instead adapted to dim light levels, like bright moonlight or twilight. Such conditions are dark enough to favor large eyes, but still bright enough to support trichromatic color vision.

Keen-sightedness such as this might have helped higher primates to carve out a fully daytime niche, the authors suggest, allowing them to better see prey, predators and fellow primates. They would also be able to expand their territory in a life no longer limited to the shadows.

Brain Size Didn’t Drive Evolution, Research Suggests

Brain organization, not overall size, may be the key evolutionary difference between primate brains, and the key to what gives humans their smarts, new research suggests.

In the study, researchers looked at 17 species that span 40 million years of evolutionary time, finding changes in the relative size of specific brain regions, rather than changes in brain size, accounted for three-quarters of brain evolution over that time. The study, published today (March 26) in the Proceedings of the Royal Society B, also revealed that massive increases in the brain’s prefrontal cortex played a critical role in great ape evolution.

"For the first time, we can really identify what is so special about great ape brain organization," said study co-author Jeroen Smaers, an evolutionary biologist at the University College London.

Is bigger better?

Traditionally, scientists have thought humans’ superior intelligence derived mostly from the fact that our brains are three times bigger than our nearest living relatives, chimpanzees.

But bigger isn’t always better. Bigger brains take much more energy to power, so scientists have hypothesized that brain reorganization could be a smarter strategy to evolve mental abilities.

To see how brain organization evolved throughout primates, Smaers and his colleague Christophe Soligo analyzed post-mortem slices of brains from 17 different primates, then mapped changes in brain size onto an evolutionary tree.

Over evolutionary time, several key brain regions increased in size relative to other regions. Great apes (especially humans) saw a rise in white matter in the prefrontal cortex, which contributes to social cognition, moral judgments, introspection and goal-directed planning.

"The prefrontal cortex is a little bit like the CEO of the brain," Smaers told LiveScience. "It takes information from other brain areas and it synthesizes them."

When great apes diverged from old-world monkeys about 20 million years ago, brain regions tied to motor planning also increased in relative size. That could have helped them orchestrate the complex movements needed to manipulate tools — possibly to get at different food sources, Smaers said.

Gibbons and howler monkeys showed a different pattern. Even though their bodies and their brains got smaller over time, the hippocampus, which plays a role in spatial tasks, tended to increase in size in relation to the rest of the brain. That may have allowed these monkeys to be spatially adept and inhabit a more diverse range of environments.

Prefrontal cortex

The study shows that specific parts of the brain can selectively scale up to meet the demands of new environments, said Chet Sherwood, an anthropologist at George Washington University, who was not involved in the study.

The finding also drives home the importance of the prefrontal cortex, he said.

"It’s very suggestive that connectivity of prefrontal cortex has been a particularly strong driving force in ape and human brains," Sherwood told LiveScience.

Origins of teamwork found in our nearest relative the chimpanzee

Teamwork has been fundamental in humanity’s greatest achievements but scientists have found that working together has its evolutionary roots in our nearest primate relatives – chimpanzees.

A series of trials by scientists found that chimpanzees not only coordinate actions with each other but also understand the need to help a partner perform their role to achieve a common goal.

Pairs of chimpanzees were given tools to get grapes out of a box. They had to work together with a tool each to get the food out. Scientists found that the chimpanzees would solve the problem together, even swapping tools, to pull the food out.

The study, published in Biology Letters, by scientists from Warwick Business School, UK, and the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, sought to find out if there were any evolutionary roots to humans’ ability to cooperate and coordinate actions.

Dr Alicia Melis, Assistant Professor of Behavioural Science at Warwick Business School, said: “We want to find out where humans’ ability to cooperate and work together has come from and whether it is unique to us.

“Many animal species cooperate to achieve mutually beneficial goals like defending their territories or hunting prey. However, the level of intentional coordination underlying these group actions is often unclear, and success could be due to independent but simultaneous actions towards the same goal.

“This study provides the first evidence that one of our closest primate relatives, the chimpanzees, not only intentionally coordinate actions with each other but that they even understand the necessity to help a partner performing her role in order to achieve the common goal.

“These are skills shared by both chimpanzees and humans, so such skills may have been present in their common ancestor before humans evolved their own complex forms of collaboration”

Skulls of early humans carry telltale signs of inbreeding

Buried for 100,000 years at Xujiayao in the Nihewan Basin of northern China, the recovered skull pieces of an early human exhibit a now-rare congenital deformation that indicates inbreeding might well have been common among our ancestors, new research from the Chinese Academy of Sciences and Washington University in St. Louis suggests.

The skull, known as Xujiayao 11, has an unusual perforation through the top of the brain case — an enlarged parietal foramen (EPF) or “hole in the skull” — that is consistent with modern humans diagnosed with a rare genetic mutation in the homeobox genes ALX4 on chromosome 11 and MSX2 on chromosome 5.

These specific genetic mutations interfere with bone formation and prevent the closure of small holes in the back of the prenatal braincase, a process that is normally completed within the first five months of fetal development. It occurs in about one out of every 25,000 modern human births.

Although this genetic abnormality is sometimes associated with cognitive deficits, the older adult age of Xujiayao 11 suggests that any such deficits in this individual were minor.

Traces of genetic abnormalities, such as EPF, are seen unusually often in the skulls of Pleistocene humans, from early Homo erectus to the end of the Paleolithic.

"The probability of finding one of these abnormalities in the small available sample of human fossils is very low, and the cumulative probability of finding so many is exceedingly small," suggests study co-author Erik Trinkaus, the Mary Tileston Hemenway Professor of Anthropology in Arts & Sciences at Washington University in St. Louis.

"The presence of the Xujiayao and other Pleistocene human abnormalities therefore suggests unusual population dynamics, most likely from high levels of inbreeding and local population instability." It therefore provides a background for understanding populational and cultural dynamics through much of human evolution.

Neanderthal brains focussed on vision and movement

Neanderthal brains were adapted to allow them to see better and maintain larger bodies, according to new research by the University of Oxford and the Natural History Museum, London.

Although Neanderthals’ brains were similar in size to their contemporary modern human counterparts, fresh analysis of fossil data suggests that their brain structure was rather different. Results imply that larger areas of the Neanderthal brain, compared to the modern human brain, were given over to vision and movement and this left less room for the higher level thinking required to form large social groups.

The analysis was conducted by Eiluned Pearce and Professor Robin Dunbar at the University of Oxford and Professor Chris Stringer at the Natural History Museum, London, and is published in the online version of the journal, Proceedings of the Royal Society B.

Looking at data from 27,000–75,000-year-old fossils, mostly from Europe and the Near East, they compared the skulls of 32 anatomically modern humans and 13 Neanderthals to examine brain size and organisation. In a subset of these fossils, they found that Neanderthals had significantly larger eye sockets, and therefore eyes, than modern humans.

The researchers calculated the standard size of fossil brains for body mass and visual processing requirements. Once the differences in body and visual system size are taken into account, the researchers were able to compare how much of the brain was left over for other cognitive functions.

Previous research by the Oxford scientists shows that modern humans living at higher latitudes evolved bigger vision areas in the brain to cope with the low light levels. This latest study builds on that research, suggesting that Neanderthals probably had larger eyes than contemporary humans because they evolved in Europe, whereas contemporary humans had only recently emerged from lower latitude Africa.

'Since Neanderthals evolved at higher latitudes and also have bigger bodies than modern humans, more of the Neanderthal brain would have been dedicated to vision and body control, leaving less brain to deal with other functions like social networking,' explains lead author Eiluned Pearce from the  Institute of Cognitive and Evolutionary Anthropology at the University of Oxford.

‘Smaller social groups might have made Neanderthals less able to cope with the difficulties of their harsh Eurasian environments because they would have had fewer friends to help them out in times of need. Overall, differences in brain organisation and social cognition may go a long way towards explaining why Neanderthals went extinct whereas modern humans survived.’

'The large brains of Neanderthals have been a source of debate from the time of the first fossil discoveries of this group, but getting any real idea of the “quality” of their brains has been very problematic,' says Professor Chris Stringer, Research Leader in Human Origins at the Natural History Museum and co-author on the paper. 'Hence discussion has centred on their material culture and supposed way of life as indirect signs of the level of complexity of their brains in comparison with ours.

'Our study provides a more direct approach by estimating how much of their brain was allocated to cognitive functions, including the regulation of social group size; a smaller size for the latter would have had implications for their level of social complexity and their ability to create, conserve and build on innovations.'

Professor Robin Dunbar observes: ‘Having less brain available to manage the social world has profound implications for the Neanderthals’ ability to maintain extended trading networks, and are likely also to have resulted in less well developed material culture – which, between them, may have left them more exposed than modern humans when facing the ecological challenges of the Ice Ages.’

The relationship between absolute brain size and higher cognitive abilities has long been controversial, and this new study could explain why Neanderthal culture appears less developed than that of early modern humans, for example in relation to symbolism, ornamentation and art.

You’re such a jerk

If that headline makes you feel bad, an expert says it’s because we’re genetically wired to take offense.

Insults are painful because we have certain social needs. We seek to be among other people, and once among them, we seek to form relationships with them and to improve our position on the social hierarchy. They are also painful because we have a need to project our self-image and to have other people not only accept this image, but support it. If we didn’t have these needs, being insulted wouldn’t feel bad. Furthermore, although different people experience different amounts of pain on being insulted, almost everyone will experience some pain. Indeed, we would search long and hard to find a person who is never pained by insults—or who himself never feels the need to insult others.

These observations raise a question: why do we have the social needs we do? According to evolutionary psychologists, our social needs—and, more generally, our psychological propensities—are the result of nature rather than nurture. More precisely, they are a consequence of our evolutionary past. The views of evolutionary psychologists are of interest in this, a study of insults, for the simple reason that they allow us to gain a deeper understanding of why it is painful when others insult us and why we go out of our way to cause others pain by insulting them.

We humans find some things to be pleasant and other things to be unpleasant. We find it pleasant, for example, to eat sweet, fattening foods or to have sex, and we find it unpleasant to be thirsty, swallow bitter substances, or get burned. Notice that we don’t choose for these things to be pleasant or unpleasant. It is true that we can, if we are strong-willed, voluntarily do things that are unpleasant, such as put our finger in a candle flame. We can also refuse to do things that are pleasant: we might, for example, forgo opportunities to have sex. But this doesn’t alter the basic biological fact that getting burned is painful and having sex is pleasurable. Whether or not an activity is pleasant is determined, after all, by our wiring, and we do not have it in our power—not yet, at any rate—to alter this wiring.

Why are we wired to be able to experience pleasure and pain? Why aren’t we wired to be immune to pain while retaining our ability to experience pleasure? And given that we possess the ability to experience both pleasure and pain, why do we find a particular activity to be pleasant rather than painful? Why, for example, do we find it pleasant to have sex but unpleasant to get burned? Why not the other way around? I have given the long answer to these questions elsewhere. For our present purposes—namely, to explain why we have the social needs we do—the short answer will suffice.

We have the ability to experience pleasure and pain because our evolutionary ancestors who had this ability were more likely to survive and reproduce than those who didn’t. Creatures with this ability could, after all, be rewarded (with pleasurable feelings) for engaging in certain activities and punished (with unpleasant feelings) for engaging in others. More precisely, they could be rewarded for doing things (such as having sex) that would increase their chances of surviving and reproducing, and be punished for doing things (such as burning themselves) that would lessen their chances.

This makes it sound as if a designer was responsible for our wiring, but evolutionary psychologists would reject this notion. Evolution, they would remind us, has no designer and no goal. To the contrary, species evolve because some of their members, thanks to the genetic luck-of-the-draw, have a makeup that increases their chances of surviving and reproducing. As a result, they (probably) have more descendants than genetically less fortunate members of their species. And because they spread their genes more effectively, they have a disproportionate influence on the genetic makeup of future members of their species.

Evolutionary psychologists would go on to remind us that if our evolutionary ancestors had found themselves in a different environment, we would be wired differently and as a result would find different things to be pleasant and unpleasant. Suppose that getting burned, rather than being detrimental to our evolutionary ancestors, had somehow increased their chances of surviving and reproducing. Under these circumstances, those individuals who were wired so that it felt good to get burned would have been more effective at spreading their genes than those who were wired so that it felt bad. And as a result we, their descendants, would also be wired so that it felt good to get burned.

Evolutionary psychologists would also remind us that the evolutionary process is imperfect. For one thing, although the wiring we inherited from our ancestors might have allowed them to flourish on the savannahs of Africa, it isn’t optimal for the rather different environment in which we today find ourselves. Our ancestors who had a penchant for consuming sweet, fattening foods, for example, were less likely to starve than those who didn’t. The problem is that we who have inherited that penchant live in an environment in which sweet, fattening foods are abundant. In this environment, being wired so that it is pleasant to consume, say, ice cream, increases our chance of getting heart disease and other illnesses, and thereby arguably lessens our chance of surviving.

Stressed-Out Tadpoles Grow Larger Tails to Escape Predators

When people or animals are thrust into threatening situations such as combat or attack by a predator, stress hormones are released to help prepare the organism to defend itself or to rapidly escape from danger—the so-called fight-or-flight response.

Now University of Michigan researchers have demonstrated for the first time that stress hormones are also responsible for altering the body shape of developing animals, in this case the humble tadpole, so they are better equipped to survive predator attacks.

Through a series of experiments conducted at field sites and in the laboratory, U-M researchers demonstrated that prolonged exposure to a stress hormone enabled tadpoles to increase the size of their tails, which improved their ability to avoid lethal predator attacks.

"This is the first clear demonstration that a stress hormone produced by the animal can actually cause a morphological change, a change in body shape, that improves their survival in the presence of lethal predators. It’s a survival response," said Robert Denver, a professor of molecular, cellular and developmental biology and of ecology and evolutionary biology.

The team’s surprising findings are detailed in a paper to be published online March 5 in the journal Proceedings of the Royal Society B. First author of the paper is Jessica Middlemis Maher, a former U-M doctoral student, now at Michigan State University, who conducted the work for her dissertation.

Scientists have long known that environmental changes can prompt animals and plants to alter their morphology and physiology, as well as the timing of developmental events. For example, tadpoles can accelerate metamorphosis into frogs in response to a drying pond, a high density of predators or a lack of food.

The term “phenotypic plasticity” is used to describe modifications by animals and plants in response to a changing environment.

"There’s been a lot of interest in phenotypic plasticity among developmental biologists and evolutionary ecologists for more than 70 years, but there’s been relatively little focus on the mechanisms by which the environmental signal is translated into a functional response," Denver said.

"We’ve known, for example, that tadpoles can change their body shape in response to predation risk. But until now, nobody knew the basic physiological mechanisms mediating that response. That’s what’s novel about this study."

(Image: Wikimedia Commons)