Table of contents for Inside Your Brain in Inside Your Brain

4 weeks Brain development starts just three weeks after fertilisation. The first structure is the neural tube, which divides into regions that later become the forebrain, midbrain, hindbrain and spinal cord. 6 weeks The pattern of the brain and spinal cord is now laid out and is gradually refined, controlled by gradients of signalling molecules that assign different areas for different functions. 11 weeks As the embryo becomes larger, the brain continues to increase in size and neurons migrate and organise. The surface of the brain gradually begins to fold. At this point, a foetus only measures about five centimetres in length. Birth Before a baby is born, around half of the nerve cells in the brain are lost and connections are pruned, leaving only the most useful. This process…

“In a sense, the main function of the brain is in ordering information – interpreting the outside world and making sense of it”…

1 Boost your memory Look at this list of items for one minute, then cover the page and see how many you can remember: Difficult? Try again, but this time make up a story in your head, linking the objects together in a narrative. “Duck opened his front door to find his table upturned, there were teacups everywhere” …You get the idea. Make it as silly as you like; strange things are much more memorable than the mundane. 2 Slow brain ageing Learning a new language is one of the best ways to keep your brain active. Here are four new ways to say hello: • Polish: Czesc! (che-sh-ch) • Russian: Zdravstvuj (zdrah-stvooy) • Arabic: Marhaba (mar-ha-ba) • Swahili: Hujambo (hud-yambo)…

Where two neurons meet, a very small gap (synapse) exists between them. The electrical impulse travelling along the axon of the neuron must convert into a chemical signal to bridge this gap. The chemicals that do this are called neurotransmitters. These so-called chemical messengers are involved in our different responses to situations. Your emotions depend on fluctuating levels of neurotransmitters, which cause the activation of different parts of the brain responsible for different moods, or activate parts of the brain that trigger the stimulation of the autonomic nervous system. Adrenaline Released by the adrenal glands that sit on top of each kidney, adrenaline increases the flow of blood to our muscles, raises our heart rate and dilates our pupils. It is crucial in our fight-or-flight survival response. Oxytocin Also known…

As light reflects off objects, waves enter the eye through the pupil. They’re refracted by the lens and the cornea so that they reach the retina at the back of the eye. The retina is a sensory membrane made up of millions of light-sensitive nerve cells that fire electrical signals along the optic nerve to the brain when they’re stimulated by light waves. Because light travels in straight lines and enters the eye through a small, curved aperture, waves reflecting off objects above the eye hit the bottom of the retina and vice versa. This creates an inverted image of the world, but the brain processes these signals to produce a final image that matches the true orientation of the landscape. As members of a predator species, our eyes are…

Humans are highly social animals, relying on others for comfort, safety and happiness. We live in large groups and often have additional connections outside of our close circles, and we’re able to do this in part because we possess the ability to remember and identify faces. Faces of those who are important to us – whether for positive or negative reasons – are stored in our brains ready for the next time we encounter them. Even after years apart, old friends can recognise each other across the street, while the face of a stranger walking past fades from the memory almost instantly. A part of the brain called the fusiform gyrus is often closely associated with face and body recognition. It forms part of the ventral temporal cortex, which is…

The brain is a powerful learning machine; it has the ability to learn from previous experiences in order to ‘predict’ future events. This is known as anticipatory timing and it is what enables humans to successfully navigate the world that we live in and also plays a key role in helping us to concentrate. But how does the brain do this? Researchers think two different regions are responsible for its ability to ‘predict’ the future. These regions are known as the basal ganglia, a group of structures that are found deep within the cerebral hemisphere, and the cerebellum, which is located at the back of the brain. Both structures are associated with cognition and movement. The basal ganglia is associated with tasks that involve rhythm – such as singing along…

To demonstrate just how complex a subject consciousness is, let’s explore the vast range of definitions provided by authority figures. The Oxford English Dictionary gives not one but three definitions of consciousness: ‘The state of being aware of and responsive to one’s surroundings’, ‘a person’s awareness or perception of something’, and ‘the fact of awareness by the mind of itself and the world’. The English philosopher John Locke said, “Consciousness is the perception of what passes in a man’s own mind.” Dr Giulio Tononi, a neuroscientist, psychiatrist, and leading authority on the brain during sleep, defines consciousness as that which “corresponds to the capacity of a system to integrate information”. The famous philosopher Descartes stated, “I think therefore I am.” And the psychologist and philosopher William Davidson needed six pages…

On 7 July 2012, three renowned neuroscientists published the Cambridge Declaration on Consciousness. This declaration states, “The weight of evidence indicates that humans are not unique in possessing the neurological substrates that generate consciousness.” Essentially, three experts in the field told the world that animals are conscious. The declaration goes on to say that nonhuman animals have the biological features required for consciousness. For example, most – if not all – mammals have a claustrum; if this is the brain area that controls consciousness, then all mammals must be conscious. The size and complexity of the claustrum (and its equivalent structures in non-mammals) varies significantly between species, which could account for any differences in consciousness among animals. What’s more, many species, ranging from birds to apes, are able to recognise…

Learning is no longer unique to living beings. Artificial intelligence (AI) is the ability of machines to perform tasks that would ordinarily require human intelligence, such as recognising faces or calculating sums. It has already proved invaluable for things like cybersecurity. Intelligence, artificial or natural, is formed through learning. Machines are taught in much the same way as dogs are taught new tricks: with punishment and reward. The computer is taught the concept of punishment and reward and then, instead of bone-shaped biscuits, it receives virtual rewards for correct responses. But if a system can understand the concept of punishment, then can it feel suffering? If a machine did not like what was being done to it, and had sufficient learning ability, could it break free and seek revenge? Would…

EEG recording As the sender watches the game, he decides to fire the cannon, generating a recognisable EEG signal. TMS Using transcranial magnetic stimulation, an electrical signal is delivered through the receiver’s scalp. Signal analysis The signal is sent to a computer, where it is compared with a known pattern. If it is a match, it is transferred. Wireless transmission There is no need for the two brains to be physically connected; the digital signal is transmitted over the internet. Push the button The artificial signals trigger the receiver to push the button. The key press is relayed back to the first computer, winning the game. Mind control In a groundbreaking experiment in 2013, researchers at the University of Washington successfully linked two human brains together and proved their principle…

In 2013, scientists at the Austrian Academy of Sciences achieved something incredible: they grew part of a human brain in a Petri dish. Using a combination of embryonic stem cells and stem cells taken from adult skin, the team recreated the neuroectoderm, the embryonic structure that goes on to form the brain and the spinal cord. The cells were put in three-dimensional scaffolds to give them something to grow around and then given nutrients and oxygen and allowed to develop. Amazingly, the structures organised themselves into something resembling the brain of a nine-week-old foetus. Some contained the pigmented cells of a retina, others developed a cortex, and some even had a hippocampus. These mini-brains were about the size of a pea and incapable of thought, but they provided a valuable…

Navigation systems This advanced computer system merges pre-operative CT and MRI scans with intra-operative information gathered from lasers and infrared. The result is a ‘map’, that surgeons can then follow in order to safely navigate to tumours located in hard-to-reach places. Burr-hole drill Although not used much any more in the Western world, a drill is used to evacuate blood clots that form around the brain following accidents. They are still used in some parts of the world. Haemostat A vital surgical tool, a haemostat is a scissor-shaped device used to control bleeding. They are locked in place via a series of interlocking teeth, which can be varied according to the amount of pressure needed.…

He was a workaholic Between 1918 and 1928 Cushing published six books alongside almost 100 scientific papers and reports. In order to achieve this, it’s estimated that he wrote more than 10,000 words per day. He was also a war doctor During World War I, Cushing travelled to France and spent over three months treating around 133 soldiers with brain injuries. He was an award-winning writer In 1926, Cushing won the prestigious literary Pulitzer Prize for the biography of Sir William Osler, a Canadian physician and one of the founding fathers of Johns Hopkins Hospital. He only had nine toes Suffering from Buerger’s disease, a blood clotting condition had left one of Cushing’s toes gangrenous. In 1935, he had the middle toe on his left foot amputated. He was connected…

1957 First cochlear implant The first cochlear implant converts sound waves into strong electrical impulses. They still bring improved hearing to many people around the globe today. 1990s CAT-CAM The widespread introduction of the modern fitting limb prosthesis – the contoured adducted trochanteric-controlled alignment method (CAT-CAM) – paves the way for the development of today’s sophisticated prostheses. 2002 Median nerve cybernetics A microelectrode array is implanted into a healthy volunteer’s median nerve located in the arm, which enables him to control hand functions. 2008 Monkeys Two monkeys learn to feed themselves marshmallows using a robotic arm controlled by a computer that’s linked to their brains. 2009 Modular prosthetic limb Developed by the US’s Defense Advanced Research Projects Agency (DARPA), this prosthesis offers 22 degrees of motion with independent movement of…

The brain’s tendency to prioritise visual input over tactile input makes it possible to manipulate the experience of pain. In a study conducted by researchers at Oxford University, participants suffering from chronic pain in their right arm were asked to move the limb while looking at it through a pair of binoculars. They were then asked to do the same again, but while looking through the other end of the binoculars. When presented with a magnified view of their arm, every participant reported experiencing an increase in pain, but when their arm looked smaller or further away, the pain, and even the swelling, increased significantly less. Exactly how this illusion works remains unclear. One theory is that magnifying the arm enhances the sense of touch, while another suggests that by…

We can all find ourselves becoming sentimentally attached to objects, even when there is no obvious reason to value these so highly. The endowment effect describes a common situation where people place greater value in something they already own than something they are yet to acquire, due to an emotional bias. In psychological studies, such as that by Kahneman, Knetsch and Thaler in 1990, it has been regularly observed that participants will demand a far greater price for something they perceive as their property than the amount they are willing to pay for something of equivalent value. It has been suggested that this is a form of loss aversion – as a species we experience greater anxiety in losing something than we feel pleasure from gaining an equal reward, although…

While we like to believe that we are open-minded and observe all of the available information on a subject before drawing a conclusion, the reality is that this doesn’t always happen. Confirmation bias is a flaw in how we collect, process and recall information, which suffers from a tendency to favour that which confirms preexisting beliefs. Since decision-making falls back on experience and preconceived ideas, it can be uncomfortable for us to reject what we think we already know and accept a new truth. We therefore pay greater attention to data that reaffirms our beliefs and ignore facts that question them. This can have significant implications in areas such as the medical profession, where a doctor diagnosing a patient may recognise initial indicators of an illness and fail to seek,…

Gambling creates complex responses in humans. There is a clear emotional investment in the outcome of a bet, yet there are more deep-seated psychological processes at work. Gambler’s fallacy is the incorrect reasoning that after a series of repeated events, such as scoring a red on a roulette wheel, a different event becomes more likely – scoring a black, for example. This is opposite, yet related to, the hot hand fallacy, arising from a misperception about small sample sizes, where we assume shorter series of random occurrences yield similar results to longer sets. Where a winning or losing streak is encountered, we expect an inverse event to create balance. Tversky and Kahneman called this the representativeness heuristic – comparison to previous experiences of event sequences. In reality, where events are…

Narcolepsy is an uncommon, long-term brain disorder affecting roughly 30,000 people in the UK. It affects the brain’s ability to regulate sleep-wake cycles, causing sufferers to suddenly fall asleep. The body’s sleep-wake cycle is normally controlled by the hypothalamus (an almond-sized region found deep within the brain) that produces a chemical called hypocretin. This chemical normally helps to regulate wakefulness, but most narcoleptics do not seem to produce it in significant levels. Scientists think that the immune system mistakenly attacks the cells that produce hypocretin. However, this isn’t the cause for all cases of narcolepsy – some may be triggered by stress or an infection. Although there is no cure for narcolepsy, there are medicines that can control some of the symptoms. For some sufferers, lifestyle changes may also help.…

Motor neuron diseases (MND) is the name given to a group of conditions that destroy the body’s motor neurons – the specialised nerve cells that are responsible for controlling the movement of our muscles via the central and peripheral nervous systems. From gripping a glass and waving your hand to walking, breathing and swallowing, the motor system allows us to make the movements that we depend upon every day. MND are rare, progressive conditions that affect roughly two in every 100,000 people in the UK. There are two types of motor neurons: upper motor neurons (in the brain) and lower motor neurons (in the brain stem and spinal cord). Electrical messages are transmitted from the upper motor neurons to the muscles in the arms, legs, tongue, face, torso and more…

The folds and pockets of our brains are a biological rarity that we only share with a few other species, including dolphins, some primates and elephants. It’s a clever evolutionary adaptation that allows intelligent species to squash a huge amount of cortical tissue into a small space, allowing enormous brainpower to be crammed into our relatively small skulls. Folding starts during the second trimester of pregnancy, creating ridges (gyri) and fissures (sulci), but the biology behind the distinctive wrinkles is stranger than you might think. The organisation of the brain is determined by complex cascades of chemical signals, but the overall shape seems to be the result of simple physics. Grey matter sits on the outside of the brain, and during development its growth rapidly outpaces the growth of white…

It’s true that the different sides of the brain perform different tasks, but do these anatomical asymmetries really define our personalities? Some psychologists argue that creative, artistic individuals have a more developed right hemisphere, while analytical, logical people rely more heavily on the left side of the brain, but so far the evidence for this two-sided split has been lacking. A team at the University of Utah attempted to answer the question by dividing the brain up into 7,000 regions and analysing the fMRI scans of over 1,000 people in order to determine whether the networks on one side of the brain were stronger than the networks on the other. Despite the popularity of the left versus right brain myth, the team (who published their findings in the journal PLOS…

If nothing could cross the blood-brain barrier, your brain cells would quickly die. In fact, water and some gases pass through easily, and the cells are able to take up important molecules, such as sugars, and pass them across. Molecules that dissolve in fat can also slip through, allowing chemicals like nicotine and alcohol to easily pass into the brain. There is a problem though. Most medicines are too big or too highly charged to cross over, and if a patient has a neurological condition like depression or dementia, treating the brain directly is a real challenge. Researchers are working on ways to breach the barrier, including delivering treatments directly into the fluid around the brain, disrupting the barrier by making the blood vessels leaky, and even designing Trojan horse…

We feel our emotions, and not just in our head and heart – our bodily state changes to react to the chemical storm in our system. We might feel a tight knot in our stomach as we dread walking onto a stage to give a speech, or we might feel our cheeks flush red when we answer a question wrong. Researchers from Aalto University in Finland explored how humans physically feel their emotions by mapping the sensations topographically. Their findings were consistent across Western European and East Asian cultures, which suggests the way people feel during an emotional experience stems from a biological source rather than a cultural interpretation. The study also highlighted that emotions adjust our bodily state to either prepare ourselves physically to fight or flee or to…

No images are formed within the eyes themselves; they simply take in light waves and pass on information. When light waves hit the retina they activate certain cells, which fire electrical signals down the optic nerves. The optic nerves meet and cross at a point at the base of the hypothalamus known as the optic chiasm, so that each half of the brain can combine information from both eyes about one half of the visual field. Sorted into left and right, signals continue down the optic tracts until they terminate in the thalamus. From here they’re relayed to the occipital lobe, which contains visual cortexes able to process, interpret and recognise visual signals. Many neurons in the brain’s visual region respond to contrast and edges. Edges and overall shapes are…

Many social animals can distinguish kin from strangers, and, like us, they use this ability to maintain bonds with family members and remember enemies. For creatures like paper wasps, facial recognition is a crucial tool used alongside other features like pheromones to quickly identify an intruder. Dogs, descended from social wolves, can recognise each other and their owners, even identifying different emotions on human faces. Horses too can interpret how both their equine and human companions are feeling by looking at their expressions. Cats, on the other hand, don’t seem to distinguish between human faces; instead, they rely on other cues like scent and voice tone. Often thought of as possessing low intelligence, sheep were recently found to be able to recognise human faces. Shown a photograph of a person,…

In the professional sporting world, the speed and precision with which athletes make decisions can be the difference between success and failure. But it’s not just their bodies that are built for sport – it’s their brains too. Studies suggest that some areas of athletes’ brains are larger than those of their less-physically able counterparts. Researchers at the Chinese Academy of Sciences compared the brains of professional divers with those who did not participate in professional training. The researchers found that three regions – the left superior temporal sulcus, the right orbitofrontal cortex and the right parahippocampal gyrus – of the professional divers’ brains were significantly thicker than the non-athlete group. Another study revealed that professional cricket players were more able to accurately predict the trajectory of the ball significantly…

“The heart beats faster and the blood vessels constrict, boosting blood supply to the muscles and brain” The fight or flight response is all-consuming. Your heart beats faster, your breathing becomes quick and deep, your palms sweat, and your mouth goes dry. With fractions of seconds to react in the face of danger, this is what gets you out of harm’s way before you’ve even had time to think. It’s an ancient self-defence mechanism that’s hardwired into the nervous system – your body’s way of getting you ready for battle. The body’s panic button is a walnut-sized piece of brain tissue called the amygdala, and its job is to monitor incoming sensory signals for signs of threat. It is connected to a larger brain area called the thalamus, which acts…

Numerous mental health conditions are based on conscious and subconscious thoughts. For example, people with obsessive-compulsive disorder (OCD) – a broad condition involving repetitive behaviours and routines – may experience intrusive thoughts. These are negative or inappropriate thoughts that occupy their conscious mind. Thoughts like ‘Have I locked the front door?’ or ‘Did I leave the stove on?’ can overcome the person, meaning they are unable to think of anything else in that moment. Post-traumatic stress disorder (PTSD) and personality disorders can arise from people forcing certain distressing thoughts out of their consciousness. This results in unhealthy coping behaviours and leads to unpleasant experiences such as flash-backs, where the upsetting thoughts and images suddenly enter the person’s consciousness. Having a greater understanding of what conscious thoughts are and how they…

At the end of a long day, there’s nothing as inviting as a cosy bed. After little sleep the night before, a day packed with activity or hours of solid concentration, it can become a challenge just to keep your eyes open. Most people are lucky enough to sleep comfortably and safely, but becoming unconscious and paralysed put our ancestors at risk of attack from enemies and animals. The benefits must have outweighed the dangers, but why did humans evolve to spend so much of their lives asleep in the first place? The real answer is that no one’s completely sure. While we’ve moved on from Lucretius’ theory of ominous air particles attacking the spirit each night, many of the exact details about our time spent slumbering remain a mystery.…

Brains are complex, as is music, so teasing out the neurological response to melodies is something of a challenge, but researchers across the world have been working to demystify the baffling science behind it. The first components of music to be processed by the brain are the basic sounds – pitch, length and volume. From this, the brain then teases out melody and distinguishes between different instruments. This information is then compared to memories, establishing whether the incoming sound is familiar and revealing any linked emotions. All together, the processing leads to a response, whether that’s switching the song off or starting to dance. And if you move, that feeds back into your brain again, affecting the experience even further. Some of the complexities of the brain’s response to music…

1700 BCE An Egyptian surgeon records details of his patients, producing the first written example of the word ‘brain’. 130-200 CE Greek surgeon Galen suggests the brain is responsible for sensory perception and the control of movement. 1837 Czech Johannes Purkinje describes a nerve cell for the first time; the large, branching neurons of the cerebellum. 1861 Pierre Paul Broca identifies the region of the brain responsible for speech, now known as ‘Broca’s area’. 1906 Camillo Golgi and Santiago Ramón Y Cajal share the Nobel Prize for demonstrating that the brain is a network of neurons.…

First described in a paper in 1912 entitled The Pituitary Body and its Disorders, Cushing outlined the science behind what would later be known as Cushing’s disease. Becoming a common acquiesce with the human pituitary gland, Cushing uncovered its effect on the debilitating condition. Displaying symptoms of excess inflammation, Cushing’s disease is the result of the pituitary gland’s overproduction of adrenocorticotropic hormone (ACTH). In turn, this hormone triggers the release of another steroid hormone called cortisol. At normal levels, cortisol controls blood sugar levels and metabolism, for example, but during overproduction it can be damaging to the body. Cushing discovered that a tumour growing on the pituitary gland can expedite the production of cortisol in the body, deploying more ACTH, which can lead to damaging effects.…

If an LCD screen is filmed with a video camera, the screen often appears to flicker. This is because the screen is actually flickering in real life, and it’s our eyes that are being fooled into seeing a continuous image. When a camera captures a scene, it takes a series of rapid shots and stitches them together to create a moving image. Therefore, if its frame rate does not match that of the screen it is filming, it picks up the flickering. Our eyes, on the other hand, are constantly sending information to our brains, and so hang onto an afterimage of the light from the screen in order to fill in the gaps caused by the flickering.…

“The brain prioritises visual feedback over tactile feedback”…

The placebo effect is all in the mind, and it’s controlled by the parts of the brain that are responsible for managing anxiety, reward and pain. The cerebral cortex controls the highest brain processes, like consciousness and intelligence. The region at the front, known as the prefrontal cortex, handles complex behaviour, including our response to a placebo. When we take a sugar pill believing it will help with pain, the prefrontal cortex passes messages to pain control neurons called the periaqueductal gray. These send natural, morphine-like painkillers into the brainstem, triggering the release of serotonin. More painkillers, known as enkephalins, then flood the spinal cord, where they block pain signals before they are able to reach the brain. At the same time dopamine streams into the brain’s reward system, helping…

“Our brains take shortcuts to enable rapid judgements – known as heuristics – whereby we prioritise certain parts of larger problems” As humans living in an ever-changing world, we have rather a lot to think about. We make hundreds of decisions everyday, from simple choices like what to eat for breakfast to devising complex business strategies at work. As we are bombarded by sensory inputs, each providing new information to process, we must draw on previous experiences to recognise, understand and act on our perception of the world. To do this our brains take shortcuts to enable rapid judgements – known as heuristics – whereby we prioritise certain parts of larger problems over others. While this is a critical coping mechanism to compensate for the limited processing amplitude of the…

Willpower plays an important part in society and is often seen as a measure of strength of character by our peers. However, the choice to accept a smaller reward sooner rather than a larger return in the future is a far more complex behaviour than may be immediately obvious. There is a tendency among humans to perceive future rewards as less attractive, attributing less value the more temporally distant this becomes. We make inconsistent choices over time, even when presented with the same information. In evolutionary terms this can be explained by the choices early humans would have experienced – with immediate risk, such as starving to death, it made more sense to select instant solutions. Today, however, where we need to think longer term, such as saving for a…

Memory recall is a critical brain function, yet we experience so much sensory input that we rely on mental shortcuts to identify familiar stimuli. The availability heuristic, first described by Amos Tversky and Daniel Kahneman, is the process of unconsciously prioritising most recently acquired information, biasing assessments of a situation on that which is most easily recalled. Research has shown how participants overestimate the relevance of information that they are able to easily remember, even if this is a first impression of the broader situation. The likely thought process is that we assume if information is readily available to recall it must be more important than that which does not quickly come to mind. While cognitively useful, the implications for judicial decisions, education-curriculum design and learning performance are significant, where…

Every decision we make is a process of weighing up costs and benefits. Where we deem the potential costs too high to justify an action we may decide not to engage in that behaviour. Risk compensation is a hypothesised mental adjustment whereby we take greater risks when perceived safety is increased, thereby nullifying those safety measures. Closely associated with this theory is Professor Sam Pelzman, who suggested that road safety strategies are useless, since with increased protection comes increased risk taking by drivers. This became known as the Peltzman Effect. While this has been widely disputed, another study by Gerald J S Wilde noted decreased traffic deaths in Sweden after a change in driving side. Once drivers became accustomed to right-hand driving, fatality rates increased once more, an effect termed…

Around one in 100 people have epilepsy, making it one of the most common neurological conditions in the UK. Epilepsy is one of the world’s earliest recognised conditions – written records date back to 4000 BCE – and the Greek philosopher Hippocrates was the first person to propose the idea that epilepsy originates in the brain. A seizure occurs when neurons fire too many electrical signals, causing the brain to mix up the messages, which temporarily disrupts the way that it functions. There are over 40 different types of seizure, each of which affect people with epilepsy in different ways depending on which part and how much of the brain has been affected. Some people remain completely conscious and experience twitching limbs. Others may lose consciousness, fall to the ground…

Within weeks of fertilisation, neural progenitors start to form; these stem cells will go on to become all of the cells of the central nervous system. They organise into a neural tube when the embryo is barely the size of a pen tip, and then patterning begins, laying out the structural organisation of the brain and spinal cord. At its peak growth rate, the developing brain can generate 250,000 new neurons every minute. By the time a baby is born, the process still isn’t complete. But, by the age of two, the brain is 80 per cent of its adult size. 20 watts Your brain is incredibly efficient, using less energy than a standard light bulb.…

The left versus right brain myth is actually based on Nobel Prize-winning science. In the 1940s, a radical treatment for epilepsy was trialled; doctors severed the corpus callosum of a small number of patients, effectively splitting their brains in two. If a patient was shown an object in their right field of view, they had no difficulty naming it, but if they were shown the same object from the left, they couldn’t describe it. Speech and language are processed on the left side of the brain, but the information from the left eye is processed on the right. The patients were unable to say what they saw, but they could draw it. Psychologists wondered whether the differences between the two hemispheres could create two distinctive personality types: left-brained and right-brained.…

How are you feeling right now? Are you relaxed laying on your sofa and listening to the gentle sounds of the dawn chorus outside your window? Or maybe you are tense with your shoulders hunched up around yourself as you try to get five minutes peace in a busy office? You would think that it is easy to work out if we are happy or sad, angry or calm, but humans cycle through such a vast array of emotions throughout their lives it can be difficult to distinguish them from one another. Emotions are not a simple experience. Every time you feel something your body initiates a physiological change, a chemical release and a behavioural response. This process involves multiple processes working together, including your major organs, neurotransmitters and limbic…

Memories are formed in our brains through electronic pulses passing between neurons. As neurons fire more than once, the pathway and link between the neurons strengthens; if the first neuron is triggered in the future, it is more likely that the others will too. Memories are stored in different areas of the brain, depending on what they are and what they are used for. Input The stimulus for a memory can be nearly anything. It can be related or unrelated. For example, if you see a letterbox, you may remember you had a letter to post, therefore stimulating a memory through a related input. However, some people use unrelated stimuli, like a piece of string tied to their finger, which they have formed an unrelated link to something else with.…

The brain filters out a lot of visual information in order to conserve energy and enable us to focus on important objects and movements, but it also fills in the gaps to help us make sense of the world. A dog standing behind a picket fence is still recognisable as a whole dog rather than small segments of a dog, even though parts are hidden, for example. This phenomenon, known as visual pattern completion, relies on the brain’s ability to make connections and find patterns. When an apparently incomplete image is processed by the brain’s visual region, it searches for a pattern to work out what’s missing and delves into its stores of long-term memories. Using memories that match, it pieces together a satisfactorily likely image. While visual pattern recognition…

We make hundreds of decisions every day; some are trivial, like deciding what to eat for breakfast, others are more complicated – and have consequences – such as deciding whether or not to apply for that job. Making a decision is one of the most essential human behaviours, but just how does the brain make a decision? Decision-making is a complex process, and although it has been studied for years, it is a process that we only partially understand. What we do know is that there’s not one single decision-making region of the brain but rather various brain regions – including the anterior cingulate cortex, orbitofrontal cortex (a region in the prefrontal cortex) and ventromedial prefrontal cortex – that work together to make a decision. Scientists think that the ability…

The fight or flight response evolved to get us out of sticky situations fast. But it’s only supposed to work on short timescales. To boost muscle power in a time of crisis, the body has to borrow resources from other areas; when the crisis is over, those areas need their blood supply back. But what happens when the threat doesn’t go away? The fight or flight response gives way to the stress response. The sympathetic nervous system calms down and adrenaline production stops, allowing heart rate and blood flow to return to normal. In its place, cortisol kicks in. Known as the stress hormone, cortisol can talk to almost every cell in the body. Its main job is to change metabolism and dampen lower-priority activities like growth, reproduction and immunity.…

Scientists aim to measure consciousness using specialist equipment like brain scanners. These record a person’s brain activity while they are thinking about different things or receiving different stimuli. Scientists can then analyse this activity to look for patterns that can explain certain behaviours. Most neuroscientists agree that consciousness involves combining information from different parts of the brain. There is growing evidence to suggest that an area called the claustrum is where this information is combined. Neurons in the claustrum connect to most other brain areas, especially the cortex. The cortex is the outer part of the mammalian brain and is responsible for lots of tasks, such as receiving and interpreting sensory information (i.e. sound and vision). The claustrum could link all these processing areas and combine their products to produce…

All animals sleep, and most also dream while they’re asleep. Live brain scans of humans dreaming show activity mainly in the parts of the brain controlling vision, memory, movement and emotion. Scientists have proved that dreaming is not just a by-product of sleep but actually has multiple purposes. One function is to cement memories in the brain by re-living them. Interestingly, these memories are replayed without the presence of the anxiety hormone, noradrenaline. This means the emotional impact of memories is removed, so they can be remembered without triggering a negative emotional response. Therefore, dreaming serves to help our mental health by making our memories less painful. Dreaming also recalibrates the brain. Resetting the processing centres to default allows for more precise functioning the next day in tasks like facial…

Training images The program is trained using a series of images, alongside their corresponding fMRI patterns. fMRI scan Functional magnetic resonance imaging is used to identify the parts of the brain activated by different visual stimulation. Voxel pattern The fMRI data is stored as voxel patterns, three-dimensional grids of information. Test image When the subject is shown a new image, the program searches through its training database to find the nearest match. Identification If the program cannot find an exact match, it will use its training data to find a best estimate. A machine that can read your mind Have you ever wished someone else could see what you can see? A team at the University of California, Berkley, have developed a program that can tell what film you are…

There is still so much we don’t know about the human brain. However, if something goes wrong and it needs an operation, you will find yourself in need of a neurosurgeon. These guys can operate on the vast number of structures within the brain and spinal cord and have a full arsenal of techniques and – literally – cutting-edge technologies to hand. A neurosurgeon’s workload comes in two main forms. The emergency work is often a result of road traffic accidents or fights and often affects young men with head injuries. These patients may have bleeding within the skull, which is exerting pressure on the brain – the neurosurgeon must relieve that pressure. There is also the planned work, where neurosurgeons try to remove tumours without causing any damage to…

Removing brain tumours is all in the planning. Actually taking them out is easy – leaving in what’s important is what’s hard. Knowing precisely where to cut is the difference between a good and a bad functional outcome for the patient. Especially in young people, having good physical skills and memories is just as important as staying alive. CT scans use multiple X-rays to build up pictures and are good at looking for bleeding. MRI scans use magnets and change the directions of the atoms within cells; these are best at looking for tumours. The latest technology fuses MRI with high-powered computers to build up 3D models of individual nerve fibres based upon the direction of movement of water within these fibres – diffusion MRI.…

1869 Born on 8 April to Bessie Williams and Kirke Cushing, Harvey Cushing was the youngest of ten children. 1891 Cushing graduates from Yale University in Connecticut, US, with a bachelor’s degree. 1985 Beginning his career in medicine, Cushing graduates from Harvard Medical School. 1896 He moves to Johns Hopkins Hospital to train as a surgeon under the respected William S Halsted. 1902 Cushing defines the body’s response to intracranial pressure caused by injury to the brain. 1912 Having identified the connection between the pituitary gland and cortisol production, Cushing’s disease is discovered. 1913 Cushing begins his role of Chief of Surgery at the Peter Bent Brigham Hospital. 1931 Reaching a medical milestone, Cushing completes his 2,000th verified tumour operation. 1932 Cushing retires as chief of surgery at the Peter…

Scientists are exploiting ways to connect the human brain to modern prostheses (such as artificial limbs) or via computers to expand our functionality. It’s hoped patients will be the ones to benefit, particularly those who have lost limbs. Motor prostheses interpret the natural signals sent from the brain. The electrical signals sent are detected using microelectrodes, which can be implanted underneath the skin or even buried into nerves. The brain signals for each particular movement are unique and slightly different, and the aim is to detect these individually to allow patients the ability to perform fine movements. However, the science is still developing to more accurately recognise these signals, and the perfect prosthesis does not yet exist. The initial technology was developed with monkeys and has come a long way…

Your eyeballs are your window to the world, enabling your brain to create colourful three-dimensional moving images of your surroundings in amazing detail. They work a bit like a camera, allowing light to enter through a lens, which then focuses it onto a kind of sensor called the retina. Your eyes can even zoom like a camera, as muscles help to flatten the lens to see distant objects, or thicken it to see things close-up. Once the light hits the retina, it is detected by light-sensitive cells called rods and cones. Rods are responsible for our sight in dark conditions, allowing us to see in monochrome, while cones allow us to see colour and detail in brighter conditions. When the light hits them, chemicals in the rods and cones change,…

As well as altering how we perceive an object’s size, context can also affect how we perceive its colour. In this image, all of the green squares are exactly the same shade, but the ones on the left appear darker than those on the right. This is because the green squares on the left are on a lighter background, creating more contrast and so making them appear darker in comparison to their surroundings. This simultaneous contrast illusion is believed to be caused by the way the retina’s light-sensitive cells process two different colours next to each other. When the light reflected from a brighter background hits one of these cells, any adjacent cells are inhibited from firing off signals. This causes the light reflected from the green squares on the…

The ability to fool the brain into experiencing ownership of a fake body part is proving useful for helping patients with phantom limb pain – the feeling of pain in an amputated or paralysed limb. By placing the affected limb behind a mirror and then moving the opposite, unaffected limb in front of the mirror, the brain can be tricked into thinking the reflection is a real moving body part. This enables the patient to mentally move their phantom limb, perhaps unclenching it from a painful position to provide relief. The illusion works because the brain prioritises visual feedback over tactile feedback and so the observation of movement still manages to stimulate the processes in the brain involved in real movement.…

Sugar pills ease depression, colourful creams numb the skin and saline injections make pain melt away. The placebo effect is a powerful healer, but how does it actually work? In the 1890s, Ivan Pavlov discovered classical conditioning. His famous experiments taught dogs to associate the sound of a bell with the arrival of food. When they heard the noise, they started to dribble in anticipation. The same thing can happen to us with medicine. We make associations based on our experiences. If people take aspirin for a headache, they start to associate the shape and taste of the tablets with pain relief. Replace the pills with a placebo and the pain will still be lessened. Placebos, also known as ‘dummy’ or ‘inactive’ treatments, are made from inert substances like saline,…

The nocebo effect is like the placebo effect but in reverse. If we think that sugar pills are the real thing then they can cause side-effects just like real medicines. It’s hard to study the nocebo effect, but in 2014 Sara Planès and her colleagues at the Grenoble University Hospital in southeastern France gathered 86 studies together and reviewed the evidence. They found that symptoms of the nocebo effect tend to be non-specific, like nausea, dizziness and headache. They also discovered that it affects women more than men, and people with depression and anxiety are particularly vulnerable. The team were also able to confirm that, just as with the placebo effect itself, the nocebo effect is partly psychological and partly neurobiological. Conditioning can make us expect side-effects, and while chemical…

It can be a challenge to consider information that is not observable in our assessment of a situation. Where a person or object is not present, humans will naturally focus on those that we can see and form an opinion based solely on that condition. Survivorship bias refers to situations where we make assumptions based on the apparent success of a group of objects or people but fail to recognise that our sample is not representative of subjects that have been excluded. Looking at data of injuries sustained by car crash survivors, we may conclude that the worst injuries occur when sitting in the front seats, when in fact this data does not include people who were sat in rear seats and were killed in the accidents. To say better…

Stereotyping is one of the most recognised cognitive biases and carries with it many negative connotations. The stereotyping of people often results in the feeling of judgement within the subject group, and there are sinister implications for unreasonably assuming all members of that group are the same. However, as with many biases, there is a heuristic component, that allows rapid identification of people, places and objects. You might find yourself instinctively asking a person in an airline’s uniform for help with flight information, for example, assuming they will be an expert. This stereotype provides a rapid solution to a potentially complex real-world problem. With such social categorisation we learn to identify people less as individuals and more as part of a social group. We may be aware of this or…

As other cognitive bias examples have demonstrated, humans rely heavily on impressions of a situation to quickly make assessments. However, anchoring is another shortcut that can prove inefficient in the modern world. With this bias, we fix on the first piece of information we receive and use this as a basis for judging all subsequent facts. The common example is being given a lower-than-expected price for a product and immediately accepting this while missing out on potential better deals elsewhere. Another Tversky and Kahneman investigation suggested that we often incorrectly adjust expectations from the anchor, affecting our judgement. Even with experience and when armed with awareness of anchoring in action, it can prove difficult to avoid, influencing multiple decisions of a financial, social or professional nature. While it is possible…

Alzheimer’s disease is the most common form of dementia (a name given to symptoms that affect memory, thinking and communication) in the UK. The brain tends to shrink as we age, but we do not naturally lose neurons in appreciable numbers. However, in Alzheimer’s disease abnormal protein plaques build up in and around brain cells, leading to the loss of neurons and synapses. Most often, the brain structures associated with memory (such as the hippocampus) are damaged first. As the disease progresses, language, behaviour and speech are affected too. The death of neurons in the cortex (the outer layer of the brain) leads to the loss of long-term memories. Interestingly, a person’s ability to sing or play a musical instrument are stored deep within the brain, and these connections appear…