Category Archives: Research

Psychology, Research, Science

Brain entropy

NEUROSCIENCE

Intro: A new research study helps to measure levels of consciousness

“OUR brains produce more entropy when we are awake than when we are asleep.” The finding from a research study could lead to better ways to measure the consciousness of people who appear to be in a coma.

Entropy is a measure of disorder, and in our universe, everything tends to move from less disorder to more over time. For instance, breaking a coffee cup increases entropy. While this breaking can happen in many ways, you never see a broken cup spontaneously reassemble itself and therefore decrease its entropy.

Electrical signals in our brains can also produce entropy as part of processing and transmitting information, such as the visual signals from our eyes. Researchers at the Paris-Saclay University in France wanted to determine whether our brains produce more entropy when we are awake or when we are asleep.

The scientists used functional magnetic resonance imaging (fMRI) to scan the brains of 15 people in different states of consciousness: while each person was awake and in three stages of sleep, from light to very deep.

To calculate entropy, the research team used a model that was previously developed from studying the pathways that electrical signals can follow inside of the brain. The different routes help reveal the different processes they can carry out, and each of those processes produces different amounts of entropy. From this, the researchers calculated entropy production for each person in each state of consciousness. The findings suggest that entropy decreases as people fall deeper into sleep. In the state of deepest sleep, people’s brains, on average, produced 25 per cent less entropy than when they were awake.

This now gives researchers and scientists a way to quantify consciousness. A person whose brain shows the same amount of entropy production in an fMRI study as someone who is deeply asleep is likely to have the same types of processes happening in their brain and to be at a similar level of consciousness.

This new method could potentially be used to quantify the consciousness of people in comas or eventually help to diagnose people with locked-in syndrome, who are conscious but unable to communicate with the external world.

Previous research has linked consciousness to entropy. Some fMRI studies, for example, have indicated that states of very altered consciousness, such as those induced by psychedelic substances like psilocybin, result in an increase in entropy of the brain itself – meaning that it is harder to predict its overall electrical state – and not just the entropy different signals produce.

Understanding the state of awareness of people that are minimally conscious has long been an area of scientific study. However, it isn’t yet clear that entropy production is an unambiguous mark of consciousness.

For example, dreams can happen in deep sleep – a time of low entropy – but they reflect a high level of consciousness. As such, dreams could actually increase entropy production in the brain, but the study carried out by researchers didn’t consider this.

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Environment, Research, Science

Migrating animals: How do they find their way?

ETHOLOGY

Intro: The ability by some animals to find their way when migrating over long distances intrigues and amazes us. The puzzle of how they do this is difficult to solve and we are only really just beginning to find answers

SOME of the migratory habits of animals are truly astonishing, not least because without our own navigational aids, our compasses and our GPS systems, we very easily get lost ourselves. Arctic terns leave their northern breeding grounds in and around the Arctic Circle towards the end of the summer to fly south all the way to the Antarctic coast, arriving in time for the onset of summer in the southern hemisphere, and then fly all the way back to the Arctic to breed the following spring. If the terns flew directly between their two destinations, this would involve journeys totalling over 32,000 km (20,000 miles), but they actually adopt much more convoluted routes, increasing the distances they cover by tens of thousands of miles. Yet after covering such enormous distances, the terns often return to the exact spot where they bred the previous year.

Atlantic salmon spend most of their adult lives in the ocean before returning to the same river where they were born, and usually to the same stretch of that river, to spawn. Some monarch butterflies are involved in a circular migration – which takes several generations to complete, travelling from southern Canada to overwintering sites in central Mexico while every year, millions of Christmas Island crabs travel from the forest in the interior of their Indian Ocean island to the coast to breed. Several species of frogs and toads engage in similar annual mass migrations, and sea turtles such as loggerheads and leatherbacks give the impression of being engaged in a lifelong migration, swimming for what can be thousands of kilometres between breeding grounds on beaches and feeding grounds in the distant ocean.

Navigating animals

These birds, fish, butterflies, crabs and turtles provide a few examples from among the thousands of species of animals that engage in migratory behaviour of one sort or another. Charles Darwin thought that animals, and to some extent humans as well, possessed an instinctive ability to orientate themselves in their surroundings, which they could use to navigate by dead reckoning, but he could not be any more specific about how this ability worked. Beginning in the 1910s, the Austrian animal behaviourist Karl von Frisch carried out experimental research on honeybees, which showed that their primary means of navigation involved using the position of the Sun to orientate themselves, but that they could also detect and follow the pattern of ultraviolet light in blue skies, which is caused by polarisation and is invisible to human eyes. On cloudy days, Frisch found that the bees could also make use of the Earth’s magnetic field to find their way when the Sun and polarised light were not visible. He would also be the first to describe the so-called waggle dance that the bees engaged in as a means of communicating the location of a source of nectar they had found to other bees in a hive.

Since Frisch’s work, which earned him a Nobel Prize in 1973, other animals, such as sea turtles, have also been found to be able to detect the Earth’s magnetic field. Homing pigeons, which can return to their own lofts after being released hundreds of kilometres away, appear to use the magnetic field as one of a range of navigation techniques. Attempts have been made to discover how pigeons detect the magnetic field, which is actually very weak, and while we do not know for certain, one theory suggests they somehow make use of particles of magnetite, a highly magnetic mineral of iron oxide found in the upper part of their beaks. Even so, it remains a mystery how the navigational information that may be gained in this way is passed to the brain and processed.

Homing pigeons can switch between different methods of navigation as circumstances dictate, sometimes following known landmarks, such as coastlines, rivers and roads, while at others navigating by the Sun and stars. When it is too dark or cloudy for them to see the sky, they can fall back on finding their way by following the magnetic field. Researchers at the University of Texas who monitored the brain activity of pigeons while they were subjected to a moving magnetic field came to the conclusion that, as well as having compasses in their heads, the pigeons somehow constructed maps in their brains as they went along, so when they ended up in a place they had never been before they could head straight for home. We may like to think of ourselves as rather more intelligent than pigeons, but, for all our superior brainpower, we can’t do that.

Alternative theories

Research into the ability of European robins to use the Earth’s magnetic field to navigate suggests that the mechanism involved may work at a subatomic, or quantum, level. If this proves to be the case, then it would go some way to explaining how animals can detect and make use of the natural magnetic field, which is far too weak to provide enough energy to power any molecular chemical reactions. Magnetoreception, as this ability is known, appears to function through the eyes of the robin, so it is possible that light provides the energy required to activate so-called radical pairs, subatomic charged particles that are small enough to be influenced by the low levels of magnetism and may create some form of navigational signal that is then passed to the robin’s brain via the optic nerve.

See also:

. Book Review – ‘Greenery: Journeys In Springtime’

. Science Book

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Psychology, Research, Science

Are male and female brains wired differently? 

GENDER BRAINS

Intro: It is often pointed where we differ, but when it comes to our brains, research shows that there are far more similarities than differences

WE are told that men and women are so different, it’s as if they came from separate planets. Martian men are stereotypically target-focused, assertive, and good at navigating; women born on Venus are more empathetic, caring, and expert multitaskers. We are all fascinated by what makes the other sex tick, but back on Earth, when it comes to brains, much of what’s been written about the sex divide is more science fiction than scientific fact.

Websites and news outlets have seeped scientific-sounding theories into common wisdom, such as the idea that women listen with both sides of their brain, whereas men use only one side; or that men and women navigate using “entirely different” brain regions. Some even claim that there is a “male brain” and a “female brain”.

These ideas often have their roots in scientific research, but much of it is based on early experiments in our brains which were either found later to be insignificant, or their results were misinterpreted or misreported.

Scientists are suckers for wanting to tell a story that will be the talk of the town – and the media are willing accomplices. Less headline-grabbing experiments that show little or no difference can get stuffed in the drawer, never to see the light of day.

So, what does the science really say? From the eighth week in the womb, little boys’ and girls’ brains do start to develop slightly differently. Throughout our lives, the sex hormones testosterone, oestrogen, and progesterone mould our individual physical and emotional development. Hormone level differences tweak the dial on characteristics such as aggression, pain threshold, stress response, and parent-child bonding, but each person is so unique that there is often more variation within each sex than there is between them.

Male and female brains don’t differ significantly in size, either. Men’s brains are slightly larger as a consequence of their larger bodies, and thanks to detailed scanning we know that some brain parts differ in proportion between the sexes, but the differences are too small to claim that there is such a thing as a “male brain” or a “female brain”.

Most areas of mental functioning, behaviour and personality are the same in both sexes. What differences there are, such as in aggression levels, are usually driven by the differences in sex hormones such as testosterone after puberty.

Nature or nurture?

Recent research points to the historic sex divide actually being down to society, not science. When the magnifying glass of science reveals the workings of the brain, the accepted male and female stereotypes mostly vanish.

Some scientists now think that what differences there are between male and female brains – such as, say, in map reading – are the result not of biology, but of thousands of years of brain-training. The good news, however, is the brain is brilliant at learning new things – you can adapt and learn many new skills within a lifetime.

So it is logical that, if given the opportunity, men and women can learn skills stereotypical of the other sex very easily. For example, children who are given Lego to play with are likely to mature and have brains which have larger spatial cortexes, regardless of whether they are male or female.

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