We are more than our brains

Alan Jasanoff writes:

Brains are undoubtedly somewhat computer-like – computers, after all, were invented to perform brain-like functions – but brains are also much more than bundles of wiry neurons and the electrical impulses they are famous for propagating. The function of each neuroelectrical signal is to release a little flood of chemicals that helps to stimulate or suppress brain cells, in much the way that chemicals activate or suppress functions such as glucose production by liver cells or immune responses by white blood cells. Even the brain’s electrical signals themselves are the products of chemicals called ions that move in and out of cells, causing tiny ripples that can spread independently of neurons.

Also distinct from neurons are the relatively passive brain cells called glia (Greek for glue) that are roughly equal in number to the neurons but do not conduct electrical signals in the same way. Recent experiments in mice have shown that manipulating these uncharismatic cells can produce dramatic effects on behaviour. In one experiment, a research group in Japan showed that direct stimulation of glia in a brain region called the cerebellum could cause a behavioural response analogous to changes more commonly evoked by stimulation of neurons. Another remarkable study showed that transplantation of human glial cells into mouse brains boosted the animals’ performance in learning tests, again demonstrating the importance of glia in shaping brain function. Chemicals and glue are as integral to brain function as wiring and electricity. With these moist elements factored in, the brain seems much more like an organic part of the body than the idealised prosthetic many people imagine.

Stereotypes about brain complexity also contribute to the mystique of the brain and its distinction from the body. It has become a cliché to refer to the brain as ‘the most complex thing in the known Universe’. This saying is inspired by the finding that human brains contain something on the order of 100,000,000,000 neurons, each of which makes about 10,000 connections (synapses) to other neurons. The daunting nature of such numbers provides cover for people who argue that neuroscience will never decipher consciousness, or that free will lurks somehow among the billions and billions.

But the sheer number of cells in the human brain is unlikely to explain its extraordinary capabilities. Human livers have roughly the same number of cells as brains, but certainly don’t generate the same results. Brains themselves vary in size over a considerable range – by around 50 per cent in mass and likely number of brain cells. Radical removal of half of the brain is sometimes performed as a treatment for epilepsy in children. Commenting on a cohort of more than 50 patients who underwent this procedure, a team at Johns Hopkins in Baltimore wrote that they were ‘awed by the apparent retention of memory after removal of half of the brain, either half, and by the retention of the child’s personality and sense of humour’. Clearly not every brain cell is sacred.

If one looks out into the animal kingdom, vast ranges in brain size fail to correlate with apparent cognitive power at all. Some of the most perspicacious animals are the corvids – crows, ravens, and rooks – which have brains less than 1 per cent the size of a human brain, but still perform feats of cognition comparable to chimpanzees and gorillas. Behavioural studies have shown that these birds can make and use tools, and recognise people on the street, feats that even many primates are not known to achieve. Within individual orders, animals with similar characteristics also display huge differences in brain size. Among rodents, for instance, we can find the 80-gram capybara brain with 1.6 billion neurons and the 0.3-gram pygmy mouse brain with probably fewer than 60 million neurons. Despite a greater than 100-fold difference in brain size, these species live in similar habitats, display similarly social lifestyles, and do not display obvious differences in intelligence. Although neuroscience is only beginning to parse brain function even in small animals, such reference points show that it is mistaken to mystify the brain because of its sheer number of components.

Playing up the machine-like qualities of the brain or its unbelievable complexity distances it from the rest of the biological world in terms of its composition. But a related form of brain-body distinction exaggerates how the brain stands apart in terms of its autonomy from body and environment. This flavour of dualism contributes to the cerebral mystique by enhancing the brain’s reputation as a control centre, receptive to bodily and environmental input but still in charge.

Contrary to this idea, our brains themselves are perpetually influenced by torrents of sensory input. The environment shoots many megabytes of sensory data into the brain every second, enough information to disable many computers. The brain has no firewall against this onslaught. Brain-imaging studies show that even subtle sensory stimuli influence regions of the brain, ranging from low-level sensory regions where input enters the brain to parts of the frontal lobe, the high-level brain area that is expanded in humans compared with many other primates.

Many of these stimuli seem to take direct control of us. For instance, when we view illustrations, visual features often seem to grab our eyes and steer our gaze around in spatial patterns that are largely reproducible from person to person. If we see a face, our focus darts reflexively among eyes, nose and mouth, subconsciously taking in key features. When we walk down the street, our minds are similarly manipulated by stimuli in the surroundings – the honk of a car’s horn, the flashing of a neon light, the smell of pizza – each of which guides our thoughts and actions even if we don’t realise that anything has happened.

Even further below our radar are environmental features that act on a slower timescale to influence our mood and emotions. Seasonal low light levels are famous for their correlation with depression, a phenomenon first described by the South African physician Norman Rosenthal soon after he moved from sunny Johannesburg to the grey northeastern United States in the 1970s. Colours in our surroundings also affect us. Although the idea that colours have psychic power evokes New Age mysticism, careful experiments have repeatedly linked cold colours such as blue and green to positive emotional responses, and hot red hues to negative responses. In one example, researchers showed that participants performed worse on IQ tests labelled with red marks than on tests labelled with green or grey; another study found that subjects performed better on computerised creativity tests delivered on a blue background than on a red background.

Signals from within the body influence behaviour just as powerfully as influences from the environment, again usurping the brain’s command and challenging idealised conceptions of its supremacy. [Continue reading…]

A watery lake is detected on Mars, raising the potential for alien life

The New York Times reports:

For the first time, scientists have found a large, watery lake beneath an ice cap on Mars. Because water is essential to life, the discovery offers an exciting new place to search for life forms beyond Earth.

Italian scientists working on the European Space Agency’s Mars Express mission announced on Wednesday that a 12-mile wide underground liquid pool — not just the momentary damp spots seen in the past — had been detected by radar measurements near the Martian south pole.

“Water is there,” Enrico Flamini, the former chief scientist of the Italian Space Agency who oversaw the research, said during a news conference.

“It is liquid, and it’s salty, and it’s in contact with rocks,” he added. “There are all the ingredients for thinking that life can be there, or can be maintained there if life once existed on Mars.”

The body of water appears similar to underground lakes found on Earth in Greenland and Antarctica. On Earth, microbial life persists down in the dark, frigid waters of one such lake. The ice on Mars would also shield the Martian lake from the damaging radiation that bombards the planet’s surface. [Continue reading…]

Owls see the world much like we do

The New York Times reports:

Owl eyes are round, but not spherical. These immobile, tubular structures sit on the front of an owl’s face like a pair of built-in binoculars. They allow the birds to focus in on prey and see in three dimensions, kind of like humans — except we don’t have to turn our whole heads to spot a slice of pizza beside us.

Although owls and humans both have binocular vision, it has been unclear whether these birds of prey process information they collect from their environments like humans, because their brains aren’t as complex. But in a study published in the Journal of Neuroscience on Monday, scientists tested the ability of barn owls to find a moving target among various shifting backgrounds, a visual processing task earlier tested only in primates.

The research suggests that barn owls, with far simpler brains than humans and other primates, also group together different elements as they move in the same direction, to make sense of the world around them.

“Humans are not so different from birds as you may think,” said Yoram Gutfreund, a neuroscientist at Technion Israel Institute of Technology who led the study with colleagues from his university and RWTH Aachen University in Germany.

A critical part of perception is being able to distinguish an object from its background. One way humans do this is by grouping elements of a scene together to perceive each part as a whole. In some cases, that means combining objects that move similarly, like birds flying in a flock, or the single bird that breaks away from it.

Scientists have generally considered this type of visual processing as a higher level task that requires complex brain structures. As such, they’ve only studied it in humans and primates. [Continue reading…]

Space is full of dirty, toxic grease, scientists reveal

The Guardian reports:

It looks cold, dark and empty, but astronomers have revealed that interstellar space is permeated with a fine mist of grease-like molecules.

The study provides the most precise estimate yet of the amount of “space grease” in the Milky Way, by recreating the carbon-based compounds in the laboratory. The Australian-Turkish team discovered more than expected: 10 billion trillion trillion tonnes of gloop, or enough for 40 trillion trillion trillion packs of butter.

Prof Tim Schmidt, a chemist at the University of New South Wales, Sydney and co-author of the study, said that the windscreen of a future spaceship travelling through interstellar space might be expected to get a sticky coating.

“Amongst other stuff it’ll run into is interstellar dust, which is partly grease, partly soot and partly silicates like sand,” he said, adding that the grease is swept away within our own solar system by the solar wind.

The findings bring scientists closer to figuring out the total amount of carbon in interstellar space, which fuels the formation of stars, planets and is essential for life. [Continue reading…]

How spiders fly

James Gorman writes:

Sometimes spiders ride the wind. They spin out lines of silk that are caught by the breeze and carry them aloft. They have been reported to rise a mile or two above the earth, and perhaps even to cross oceans.

It’s called ballooning.

Moonsung Cho, an aeronautical engineer, was in Denmark the first time he saw the flight of a spider. It was autumn, when baby spiders often balloon en masse and spread to new areas.

He was completely taken by the phenomenon and made it the subject of his studies toward a doctorate at the Technical University of Berlin.
The flights of spiders are well known, but not their physics, so Mr. Cho tested crab spiders both in nature and in a wind tunnel, and discovered, among other things, what holds the spiders up in the air. [Continue reading…]

There is no biological difference between male and female brains

Taylor Lorenz writes:

Pop neuroscience has long been fascinated with uncovering secret biological differences between male and female brains. Just last year, the Google engineer James Damore caused an uproar after publishing a manifesto detailing the various ways women were biologically different from men.

But according to Lise Eliot, a professor of neuroscience at the Chicago Medical School and the author of Pink Brain, Blue Brain, anyone who goes searching for innate differences between the sexes won’t find them.

“People say men are from Mars and women are from Venus, but the brain is a unisex organ. We have the exact same structures,” she said onstage Monday at the Aspen Ideas Festival, which is co-hosted by the Aspen Institute and The Atlantic. “There is absolutely no difference between male and female brains.”

Eliot said neuroscientists have yet to find a single circuit that’s wired differently between men and women, and that differences between sexes are best explained by nurture, not nature. [Continue reading…]

‘Shocking’ die-off of Africa’s oldest baobabs

AFP reports:

Some of Africa’s oldest and biggest baobab trees — a few dating all the way back to the ancient Greeks — have abruptly died, wholly or in part, in the past decade, researchers said Monday.

The trees, aged between 1,100 and 2,500 years and some as wide as a bus is long, may have fallen victim to climate change, the team speculated.

“We report that nine of the 13 oldest… individuals have died, or at least their oldest parts/stems have collapsed and died, over the past 12 years,” they wrote in the scientific journal Nature Plants, describing “an event of an unprecedented magnitude.”

“It is definitely shocking and dramatic to experience during our lifetime the demise of so many trees with millennial ages,” said the study’s co-author Adrian Patrut of the Babes-Bolyai University in Romania.

Among the nine were four of the largest African baobabs.

While the cause of the die-off remains unclear, the researchers “suspect that the demise of monumental baobabs may be associated at least in part with significant modifications of climate conditions that affect southern Africa in particular.” [Continue reading…]

Bees may understand zero, a concept that took humans millennia to grasp

Kate Keller writes:

As a mathematical concept, the idea of zero is relatively new in human society—and indisputably revolutionary. It’s allowed humans to develop algebra, calculus and Cartesian coordinates; questions about its properties continue to incite mathematical debate today. So it may sound unlikely that bees—complex and community-based insects to be sure, but insects nonetheless—seem to have mastered their own numerical concept of nothingness.

Despite their sesame-seed-sized brains, honey bees have proven themselves the prodigies of the insect world. Researcher has found that they can count up to about four, distinguish abstract patterns, and communicate locations with other bees. Now, Australian scientists have found what may be their most impressive cognitive ability yet: “zero processing,” or the ability to conceptualize nothingness as a numerical value that can be compared with more tangible quantities like one and two.

While seemingly intuitive, the ability to understand zero is actually quite rare across species—and unheard of in invertebrates. In a press release, the authors of a paper published June 8 in the journal Science called species with this ability an “elite club” that consists of species we generally consider quite intelligent, including primates, dolphins and parrots. Even humans haven’t always been in that club: The concept of zero first appeared in India around 458 A.D, and didn’t enter the West until 1200, when Italian mathematician Fibonacci brought it and a host of other Arabic numerals over with him.

But animal cognition researchers at the RMIT University of Melbourne, Monash University in Clayton, Australia and Toulouse University in France had a hunch that honey bees might just be one of the few species able to grasp the concept. Despite the fact that they have fewer than one million neurons in their brain—compared to 86,000 million in a human brain—the team recognized their cognitive potential. [Continue reading…]

What enabled animal life to get more complex and diverse during the Cambrian explosion?

Jordana Cepelewicz writes:

When Emma Hammarlund of Lund University in Sweden first reached out to her colleague Sven Påhlman for help with her research, he was skeptical he’d have much insight to offer. He was a tumor biologist, after all, and she was a geobiologist, someone who studied the interplay between living organisms and their environment. Påhlman didn’t see how his work could possibly inform her search for answers about the rapid proliferation and diversification of animal life that, half a billion years ago, forever changed Earth’s evolutionary landscape.

In spite of Påhlman’s initial reservations, however, the pair has collaborated over the past four years to put forth a new interdisciplinary hypothesis, published in Nature Ecology & Evolution earlier this year, explaining why it took so long for animals to burst onto the scene.

For most of its 4.5-billion-year history, Earth has sustained life — but that life was largely limited to microbial organisms: bacteria, plankton, algae. Not until about 540 million years ago did larger, more complex species begin to dominate the oceans, but within just a few tens of millions of years (a blip on the evolutionary timescale), the planet had filled up with all kinds of animals. The fossil record from that period shows the beginnings of almost all modern animal lineages: animals with shells and animals with spines, animals that swam and animals that burrowed, animals that could hunt and animals that could defend themselves from predators.

Like many biologists, Hammarlund wondered why it took so long for complex animals to emerge — and why, when they finally did, it happened so suddenly. One of the leading theories about this hotly debated question holds that a skyrocketing rise in atmospheric oxygen around that time triggered what’s known as the Cambrian explosion. Earlier, when oxygen was scarce, the simple animals in the seas had anaerobic metabolisms that did not depend on it, and they even found oxygen problematic if not toxic. By shifting to aerobic respiration, however, animals gained an enormous metabolic advantage because the amount of energy that cells could produce per respiration cycle increased nearly twentyfold. That extra energy may have been what powered the greater complexity witnessed during the Cambrian period: increased biomass, improvements in their cellular systems, more complex body structures, and the capacity for energy-intensive movement and predation. [Continue reading…]

Theory of predictive brain as important as evolution — an interview with Lars Muckli

Our brains make sense of the world by predicting what we will see and then updating these predictions as the situation demands, according to Lars Muckli, professor of neuroscience at the Centre for Cognitive Neuroimaging in Glasgow, Scotland. He says that this predictive processing framework theory is as important to brain science as evolution is to biology.

Horizon magazine: You have used advanced brain imaging techniques to come up with a model of how the brain processes vision – and it says that instead of just sorting through what we see, our brains actually anticipate what we will see next. Could you tell us a bit more?

Lars Muckli: ‘We are interested to understand how the brain supports vision. A classical view had been that the brain is responding to visual information in a cascade of hierarchical visual areas with increasing complexity, but a more modern way is to realise that, actually, the brain is not meeting every situation with a clean sheet, but with lots of predictions.’

How does that work?

‘The main purpose of the brain, as we understand it today, is it is basically a prediction machine that is optimising its own predictions of the environment it is navigating through. So, vision starts with an expectation of what is around the corner. Once you turn around the corner, you are then negotiating potential inputs to your predictions – and then responding differently to surprise and to fulfilment of expectations.

‘So that’s what’s called the predictive processing framework, and it’s a proposed unifying theory of the brain. It’s basically creating an internal model of what’s going to happen next.’

Why does this happen?

‘First of all, the outside world is not in our brain so somehow we need to get something into our brain that is a useful description of what’s happening – and that’s a challenge.

‘We become painfully aware of this challenge if we try to simulate this in a computer model – how do we get information about the outside world into a computer model? The brain does that in an unsupervised way. It segments the visual input into object, background, foreground, context, people and so on, and no one ever gives the brain any kind of supervision to do so.

‘To have meaningful models of the world, you need to have something like a supervisor in your brain that says: “This is Object A. This is another object, and you need to find a name for this.” We don’t have a supervisor, but we have something – and that’s the currency of surprise. (The need) to minimise surprise is used as a supervisor.’

[Read more…]