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16923194 big-picture-on-thinking


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16923194 big-picture-on-thinking

  1. 1. BigPicture ISSUE 4 SEPTEMBER 2006 on THINKINGNow you see it...Optical illusions An invisible gorilla?such as this helpus understand howthe brain works. Brain power. Find out on page 3. The human brain may be the most complex structure in the universe. It is so powerful that it is has blossomed; and the genetic attempting to understand itself, revolution has allowed us to through research. probe the function of individual genes and proteins. The task is daunting. Some neuroscientists say that if the These techniques are shedding brain were simple enough to be light on the very essence of understood, we would not be human life – how we feel, how clever enough to understand it. we think and how we act. Even the most difficult question of all, Yet the nature of human the nature of consciousness, existence has fascinated us is beginning to be unravelled. for centuries. It used to be philosophers who held sway While exciting, these on the nature of human life, developments also raise unease. the mysteries of consciousness, Can we really see ourselves and other Big Questions. simply as ‘biological computers’? If we understand the basis of In the past 20 years, though, a our mental self-image, or identity, battery of new techniques has can we (and should we) seek to opened up new ways of exploring change ourselves into something the brain. Functional imaging else? And if our actions are just allows us to watch the brain in biology in action, how responsible action; our understanding of the can we be for what we do? biochemistry of nerve function FIND OUT MORE Vision, memory and how our eyes play tricks on us 2–3 Mood, emotions, personality and feelings 4–5 Consciousness and self-identity 6–7 Understanding other people (and ourselves) 8–9 How free is free? Controlling our actions 10–11 Real voices: Life with synthaesthesia and schizophrenia 12–13 New knowledge, new issues 14–15 The big picture 16
  2. 2. LOOKING AND FAST FACT The adult brain contains around oneLEARNING hundred billion neurons and even more support cells. Our brains are staggeringly clever things. They can take in incredible amounts of information, filter out what is not needed, store away information for future reference, recall past experience, and control what the rest of the body does. What’s more, they do all these things simultaneously, every waking second The brain at work of the day. The brain operates by division Motor cortex: Somatosensory of labour: different areas are Control of cortex: Touch We are just beginning to work out how movement specialised for different functions the brain manages these incredible Visual cortex: (see diagram). However, these feats, and how it is that single cells – Vision are not independent republics – mainly neurons – acting together can connections between them do so many wonderful things. are equally important. Cerebellum: Unconscious Hypothalamus: Auditory control, (e.g. Body physiology cortex: posture, balance) (e.g. temperature Hearing control)Amygdala:Emotion Hippocampus: Making memories Frontal cortex: Thinking Broca’s area: Speech Education editor: Rachel Thomas Editor: Ian Jones Writers: Lisa Melton, Julie Reza Many insights have come from Illustrator: Glen McBeth Advisory board: Richard Ashcroft, Nan Davies, people whose brain injuries have altered their behaviour. The TYPES OF MEMORY Ray Dolan, Michael Reiss, Tamara Russell, classic case is that of railway Irene Tracey worker Phineas Gage. In 1848 1 Procedural memory or ‘how to’ memories All images, unless otherwise indicated, are from (e.g. how to swim or ride a bicycle) are stored the Wellcome Trust’s Medical Photographic Library. an explosion blew a metal rod in the cerebellum and putamen. The Wellcome Trust is an independent biomedical through his skull, removing a research funding charity (registered charity no. 210183). The Trust’s mission is to foster and promote research large chunk of forebrain. Gage 2 Emotional memories such as those related to survived but his personality phobias and flashbacks are initially encoded with the aim of improving human and animal health. changed dramatically. Formerly a in the amygdala, which then influences other Reflecting the profound impact today’s research will have on society, the Wellcome Trust also seeks to raise reliable worker, after the accident memory-encoding regions. awareness of the medical, ethical and social implications he became a drunken drifter, of research and promote dialogue between scientists, the public and policy makers. aggressive and impulsive, his 3 Episodic memory is made up of the personal memories, our ‘filmic’ recollection of past © The Trustee of the Wellcome Trust, London, 2006. ability to control behaviour lost experiences. This is encoded by the hippocampus All rights reserved. Except as set out below, no part of this publication may be reproduced, stored in a with his prefrontal cortex. and stored in the cortex. retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission 4 Semantic memory is for facts. They are registered by the cortex and end up in the temporal lobe. of the Wellcome Trust. The Wellcome Trust consents to photocopies of all We also have an unconscious (or ‘implicit’) memory or part of this publication being made by educational institutions for non-profit, educational classroom use – we may unconsciously react to a stimulus provided that the above copyright notice and any differently if we have experienced it before, even credits attaching to images or text featured in the photocopy appear clearly in such a photocopy. if we are not aware that we have seen it before. MC-3580.p/20K/09–2006/SW2 | BIG PICTURE 4
  3. 3. Learning and memory The brain structures, neurons and even molecules and genes associated with memory are beginning to be identified. We are in many ways the sum of our experiences. How we act and behave depends not just on what is happeningThe mind’s eye to us now but also on what has happened to us in the past. We learnVision is our most crucial sense. We rely and we can make memories.on it for survival but just how reliable is it? Nearly all animals can learn. A simpleIt is tempting to think of our eyes as mini-cameras form of learning is association – someconstantly filming the outside world. In fact, vision is kind of sensory stimulus is ‘remembered’nothing like that. The seamless view of the world is and an animal’s behaviour changes thean illusion created by the brain after it has dismantled next time it encounters that stimulus.the input it receives from the eyes. The classic example is provided by When a nerve impulse (green) arrives at the endFor a start, we do not look at a scene in a steady Pavlov’s dogs, who were given food of a neuron, neurotransmitters ferry the signalway. Instead, our eyes constantly flicker back and every time a bell rang. Eventually, they across the synapse (pink), setting off a new began to salivate in response to the action potential (blue). Signals are also sentforth (involuntary movements known as saccades), back to the original neuron (yellow, top) so thatscanning scenes in detail. From this constantly bell on its own. the next time a nerve impulse arrives (bottom)shifting input, the brain builds up a coherent mental Human memory is more complex – the second neuron reads more strongly.picture corresponding to a scene. in fact, we have several different typesWe now know that neurons in our brain specialise of memory, involving many parts of STRANGE TIMESin recognising particular aspects of a scene, such the brain (see box, below left).as edges or dots or motion. Each neuron has a Making memories Some people with brain damage,‘receptive field’, an area around it that is sensitive But what exactly does a ‘memory’ or by a quirk of fate, lack a veryto its favoured stimulus (like a detector attached to look like in the brain? Again, it is specific mental function.a security light, which can detect movement within difficult to liken it to anything everyday Blindsighta particular area of ground). such as a photograph in an album. Remarkably, some patients haveThen, in a computational task of staggering Memories are hard to pin down, as no conscious vision but can stillcomplexity, the brain integrates all these signals to they involve a constellation of neurons point at a coloured dot on a screencreate a visual impression of the outside world. connecting together in different patterns. when forced to guess. This suggests Putting away the memory of Christmas that we can ‘see’ things withoutPay attention being consciously aware of them.Another key difference between the visual system day is produced by millions of neuraland a camera is the phenomenon of attention. brain patterns firing: some for the SynaesthesiaThere is so much going on in the world that the brain taste of Brussels sprouts, others for Some people don’t just hear soundshas to filter out unnecessary input. One way it does a favourite carol. The pattern remains – they see them too (see page 12).this is by focusing on (or ‘attending’) to a small area after the stimulus disappears and a memory is born. Prosopagnosiaat any one time. People with prosopagnosiaWe are not very aware of this, partly because our In terms of mechanisms, memory making are unable to recognise faces,peripheral vision is sensitive to movement, so if is thought to depend on neurons suggesting that there is a ‘module’something noteworthy happens there we are quick to strengthening their connections to one in the brain specifically dealingnotice. But it means we take in much less of a scene another – ‘remembering’ that they have with face recognition.than we might imagine. been in touch before (see figure above). Akiyoshi KitaokaA nice example is a study in which volunteers wereasked to watch a videotape of people playingbasketball. They were asked to count the passesmade by one of the teams. Afterwards they wereasked if they had noticed anything unusual.Fixated on counting, almost half failed to spot a womandressed in a gorilla suit who stopped to face thecamera, banged her chest and walked off.Filling inThe other big difference between the brain and acamera is that the brain guesses more. Whenpresented with incomplete information, it fills in thegaps, making assumptions about what should bethere given the rest of the visual input it is receiving. Optical quirk – This optical illusion illustrates how our perception can be tricked –This filling in can be useful. The visual system is in this case into believing something is moving. Optical illusionsoften trying to extract patterns. So when it finds one have told us much about how the brain interpretsbut with a bit missing, it fills in the missing space, so scenes, for more details (and illusions) see... ON THE WEBwe get a complete coherent picture. But it sometimesleaps to the wrong conclusion. Can we believe our Not always. SEPTEMBER 2006 | 3
  4. 4. WHY DO I THINKAND FEEL?We sometimes think of a brain as a powerful computer. But it is much more thanthat. Our brains are also home to our feelings, moods, personalities and character.Courage is not found in the heart but in our brain’s neural networks. Memories are made of this long-term behaviour and decision-Emotions As well as preferentially focusing on making. So our choices depend inWe are emotional creatures. emotional stimuli, we also remember part on our past feeling states.The brain is not just a logic them better. We tend to remember Highly illogicalmachine, but also handles not the mundane but the eventsemotions – some of the most that are emotionally charged – the good or the bad. Again, memory Emotion and reason are often thought of as enemies – a battle FASTpowerful drivers of humanbehaviour. enhancement seems to depend on between cold, hard logic and irrational, emotional decision-making. FACT Length of activity in the amygdala. myelinatedEmotion is important to how we In fact, though, emotional responses Sometimes, though, people do not nerve fibres inexperience life. Love, fear, anger, may enhance our decision-making brain = 150 000 want to be reminded of emotionallydisgust are central to human ability, for example by helping us to to 180 000 km charged experiences. People withexperience. This handful of raw make value judgements about people (enough to post-traumatic stress disorderemotions, in different combinations, based on their facial expressions or go round the (PTSD) suffer from unwantedadds spice to our existence, defines because of an awareness of our Earth about flashbacks and intrusive memories ofmany of our goals and influences current bodily state. four times) their trauma. Interestingly, creationour decisions. of traumatic memories depends onIn their crudest form, emotions help a particular neurotransmittersurvival. Fear and disgust drive usaway from possible sources of harm, (noradrenaline), and a drug that blocks its action – propanolol, more usually WHAT GOVERNSsuch as predators or rotten food;love helps us reproduce. They have used to slow the heart – can prevent traumatic memories being laid down. MOOD? There is interest in using this as a Our mood, or predominant emotion, is governed bya profound impact on us, affecting drug to treat, or even prevent, PTSD. several neurotransmitters produced in our bodies.almost all aspects of our behaviourand thinking. Serotonin enhances mood by reducing depression Feelings, nothing more than feelings and anxiety. Antidepressants that increase serotoninOne impact is on attention (see Neuroscientists see emotions as levels are now widely used to treat 3). We detect emotional stimuli well-described and consistent brain Interestingly, low serotonin levels have been found– faces with positive or negative responses. They translate into in suicide victims.expressions, or spiders and snakes– much quicker than neutral ones. subjective experiences we know as Dopamine, nicknamed ‘the pleasure chemical’, feelings. These derive in part from promotes a feeling of bliss. This explains theOddly, though, functional imaging the physiological changes created attraction of alcohol, nicotine, and drugs such as(see page 6) has shown that the brain by the emotional stimuli, which are cocaine, all of which increase dopamine levels.also reacts to emotional stimuli before registered by sensors of the body’sthe nature of stimuli has been explicitly Playing sports makes us feel better due to the internal state (internal organs,recognised, or even without any release of noradrenaline, another feel-good energy levels etc.).conscious recollection that we’ve chemical. Pleasure is also increased by endorphins,seen something scary (for instance). It is likely that the brain systems the body’s natural painkillers, which are also handling emotions are not the same released during exercise.The key brain region here is the as those responsible for feelings.amygdala, which receives visual Other chemicals, such as GABA and histamine, For example, some people withinput independent of the main vision may also influence mood. Our final mood is governed amygdala damage do not showprocessing areas of the brain. If it by complex interplay between all these chemicals, emotional responses but stilldetects frightening stimuli, it sends with each chemical’s level being modified by experience feelings.messages to other parts of the brain, factors such as heredity, environment, lifestyle –triggering a series of responses – Another distinction is that feelings and even diet.making us ‘frightened’. seem to have more influence over4 | BIG PICTURE 4
  5. 5. Probing personality Can personality be studied in a reliable way? FAST We all recognise that people are unique, with distinct FACT personalities. We also have an urge to categorise, and numerous approaches have been taken to analyse Total number personalities and draw out common themes. of neurons in cerebral Personality is sometimes broken down into a number of cortex = qualities. The most common tests focus on four or five 10–20 billion qualities – like the so-called Big Five: NUN BETTER: Is happiness actually good for us? A study of (about three nuns suggests it may be. The nuns had written autobiographies times the Openness to experience Agreeableness in their 20s. When these were scored for positive or negative emotions, those most positive lived on average ten years population Conscientiousness Neuroticism longer than those expressing the least positive feelings. of the Earth) Extraversion Subjects complete carefully constructed questionnairesHappiness and end up with scores for each of the categories. A variant of this method is the Myers–Briggs model:Research has tended to look at the dark side of life – anxiety, Extraversion vs Introversiondepression and so on. The flipside, happiness or contentment, Sensing vs INtuitionhas been neglected, but is now receiving more attention. Thinking vs FeelingMoney can’t buy me love, sang the Beatles, and it can’t buy much happiness Judging vs Perceivingeither. A little bit extra seems to help, but above a fairly low threshold more These tests seem to be fairly robust – if people do themoney does not add to our happiness (though around the world, a great many test on different days, their scores tend to be very similarpeople will be below this threshold). Relative wealth seems to be crucial – and they are not influenced much by there someone better off than us? As Samuel Johnson noted: “Life is aprogress from want to want, not from enjoyment to enjoyment.” Are these measures of value? They can be useful tools for self-awareness and help people understand andSimilarly, Ghana, Mexico, Sweden, the UK and the USA all share similar life interact with others. They may also help to identifysatisfaction scores even though average income varies ten-fold between the people susceptible to mental health problems. Forrichest and poorest countries. example, psychological measures provide a very goodIn 44 countries surveyed in way of picking out people likely to suffer from post-2002, family life provided the traumatic stress disorder after a traumatic incident.greatest source of satisfaction. One problem with such personality tests, though, is thatAnd it’s good for us too: individuals can end up being pigeon-holed into a certainmarried people live on average ‘type’ or behaving in ways they think are expected of them.three years longer and enjoygreater physical and psychological health than the unmarried. More generally,the extent of our social network is the best predictor of happiness.Other important factors include satisfaction with work and working conditionsand extent of choice and political freedom in the society in which we live.Can we do anything about our state of happiness? Good fortune can raise ourmood temporarily, but we gradually return to some kind of baseline, suggestingthat we may have some inbuilt happiness level. If we do want to be happy, it isbest to concentrate on social connections and fulfilling work rather thanthe pursuit of wealth – or you could move to Bhutan, where the King recentlyannounced that his nation’s objective would be gross national happiness.Trust me, I’m a scientistAlthough we do fall out occasionally, humansociety is notable for its degree of cooperation SEEING THINGS: The Rorschach inkblot test, one of the earliest personality tests. People look at inkblots and quickly say whatbetween individuals. they think they show. But analysis of the test is subjective too,Cooperation presents a difficulty for evolutionary as interpretation varies with the psychologist.theory, which at its simplest suggests that individualsshould just look out for themselves. More sophisticated Mental health – broadly speaking, three kinds of mental health disorder exist.analyses, though, show that helping others can bring • Mood disorders – Depression, bipolar disorder (manic depression).you benefits – the phenomenon of indirect reciprocity – Long-term disturbance to help somebody, somebody else helps you. • Anxiety disorders – Post-traumatic stress disorder, social phobia,This analysis can explain how factors such as reputation, phobias, obsessive–compulsive disorder. States of excessive anxietyperceived moral character and other aspects of social interfering significantly with daily life.communication can develop. • Personality disorders – Antisocial personality disorders, borderlineWe know a little about the brain systems responsible for personality disorder. Inflexible and problematic patterns of thoughtthese phenomena. Logical reasoning plays a part but is and behaviour. Less consensus on their medical nature.not the whole story. One interesting player is the hormone Find out more at ON THE WEBoxytocin, which encourages bonding. When given tosubjects playing a risky investment game, it makes them trusting of their (unidentified) partners. SEPTEMBER 2006 | 5
  6. 6. WHO AM I?We can usually tell when we have spoken and when we havelistened to others. Or whether we have moved our arm or someoneelse has moved it for us. Our brains can distinguish ‘us’ from ‘them’.More philosophically, we also have a perception ofourselves – our personality and character. That, more Times pastthan our physical form, is what we mean by ‘me’. The Greek physicianWe have a sense of ourselves occupying our body Hippocrates, who livedand can imagine an existence outside it. around 400 BCE, was the firstBecause these impressions are subjective – existing to emphasise the importancejust within our own heads – they are very difficult to study. of the body in generatingDo you feel pain in the same way as I do? Or experience functions such as memory,the colour red in the same way? thought and reason.We are beginning to discover how the brain creates He proposed a purely materialist What is consciousness?these internal impressions, including those of self and account of body and mind in which Philosophers have spent centuriesself-identity. our health and behaviour are debating the nature of consciousness. governed by four ‘humours’ – It remains a highly controversial WAYS OF SEEING blood, phlegm, bile and black bile. topic, with plenty of disagreement. Lower passions such as greed and PSYCHOLOGICAL STUDIES Consciousness encompasses feelings lust must reside in the liver and Assess people’s behaviour or responses and experience, many of which are guts, reason in the head. These under controlled experimental purely subjective (the sensation of ideas persist – we still speak of circumstances. taste for example, or ‘the redness making decisions according to our of red’). These are known as qualia. Example: Experiments exploring our heart or our head. A major problem for science is to approach to risk. The philosopher Plato, who lived understand how these experiences FUNCTIONAL IMAGING during the same period, rejected can arise from the brain’s raw (e.g. functional magnetic resonance this idea. He believed in the soul. material – the neurons, other types imaging, fMRI) These competing theories prevailed of cells and surrounding fluids and Measures brain activity during until the 17th century, when French intercellular ‘glue’ inside our skulls. particular tasks. philosopher René Descartes (above) Scientists often talk in terms of an Example: Reveals which areas are active conceived the idea that there is a ‘emergent property’ – something when we read and comprehend language. total split between the conscious that happens collectively that would mind and the body – the dualist not have been predicted on the EEG (electroencephalography) concept. He believed that voluntary basis of what is known of the Recording of brain waves through the thought and movement are the individual units. scalp; gives clues to timing, locality and type of brain function. properties of an immortal soul. Some neuroscientists call the Example: Monitoring brain activity The dualist concept has endured for subjective element the ‘hard’ problem during sleep. centuries. Its success is probably of consciousness. Because it is because, intuitively, we find it hard ‘private’ to an individual, some argue NEUROPSYCHIATRY to accept the idea that ‘mere’ brain that it is not something that we will Assessing impact of damage to specific tissue can produce feelings and ever be able to explain meaningfully. parts of the brain. experiences like love, imagination, Example: Damage to Broca’s area More conveniently, consciousness dreams and passion. removes ability to speak. can be likened to awareness – For ages, scientists were reluctant of one’s self and surroundings. It is ELECTROPHYSIOLOGY to tackle the issue of mind and sometimes divided into phenomenal Studying the firing patterns of neurons consciousness because it was consciousness (P-consciousness), and their response to different chemicals. either too philosophical or just too an awareness of what is going on Examples: Understanding role of elusive to study experimentally. now, and access consciousness neurotransmitters in memory. What actually is ‘consciousness’? (A-consciousness), reflecting internally, ANIMAL STUDIES How can you measure it? drawing on past experience Links between genes, neurons, brain and and memory. behaviour can be studied in animals that can be genetically engineered. Example: Neuron function in the sea slug; neural pathways controlling sexuality in ABNORMAL VERSUS NORMAL the fruit fly. Neuroscience research has tended to focus on abnormal function – such as Phineas Gage (see page 2), ‘memory men’, or people with MODELLING aphasia. While this is still an important element of research, greater Using computers to model the behaviour attention is now given to studies of the ‘normal’ – what is going on of neurons acting together. inside the heads of people who are not judged to have any clinical Examples: Neural networks mimicking problem. This is shedding light on brain function, but also helps us brain activity leading to epileptic seizures. to judge when something should be classified as ‘abnormal’.6 | BIG PICTURE 4
  7. 7. The science of Unconscious visionconsciousness Vision is so important to us that it tends to dominate research on consciousness. To get at the heart of a conscious experience, we need toConsciousness is one of the last great mysteries compare the brain’s response to consciously and unconsciously perceivedof modern science. stimuli. But how do you have an unconscious visual experience?Zoom into the brain, and you see a dense network of The usual trick is to apply backward masking – a visual stimulus is showncells. The vivid quality of our conscious experience, our to a subject very briefly and is then replaced by a strong second stimulus.emotions, imagination, dreams and mystical experiences, This dominates the conscious visual response, ‘masking’ the original stimulus.are all underpinned by a flurry of electrical activity, neurons Subjects cannot say, or even guess, what it is they were shown.firing and interacting in different sets of patterns. Everyaspect of the mind, most neuroscientists now believe, However, psychological tests and brain imaging shows that they havecan be explained in mechanistic terms. registered the image. If it was an angry face, they react much more strongly when shown it again than if they are seeing it for the first time – even thoughFrancis Crick was one of the first to propose that they do not ‘know’ they have seen it before.consciousness or awareness is underpinned by brainactivity alone – what he called his ‘astonishing hypothesis’.In the 1960s, he argued that neuroscientists must searchout the neurons that fire specifically during consciousmoments – the so-called neural correlates ofconsciousness.Of course, many neurons are active when we are consciousbut that doesn’t mean they are necessarily contributingto a conscious experience. One way to narrow thesearch is to compare a sensory system operating withor without conscious awareness (e.g. by using backwardmasking; see right). An alternative is to examine the impactof different types and doses of anaesthetics, which canselectively remove aspects of conscious experience.Although not certain, there is a growing consensus thatconsciousness is not located in one specific part of thebrain but is distributed around the brain in a kind ofnetwork. Some liken it to a virtual ‘workspace’ thatdraws upon unconscious neural activity all around thebrain, assimilating our conscious view of the world.This view is a little like a security guard using securitycameras to monitor what is going on around a building.This is curiously similar to an early metaphor for Sleep and consciousnessconsciousness, in which a tiny man – the homunculus – During sleep, our brain slips into autopilot. The key change,sat in the brain absorbing information from the outside it seems, is the loss of communication between different areasworld and deciding what the body should do. of the brain. Each day, when we fall asleep, we depart consciousness. The sleeping brain has long puzzled scientists, who have noticed that even though consciousness fades the brain remains active. Vivid dreams are similar to a ‘virtual reality’ experience. Intensely visual dreams light up the visual cortex, nightmares trigger activity in the amygdala, and the hippocampus flares up from time to time to replay recent events. The pathways that carry signals from the auditory cortex are also active, as are the motor areas. But despite this symphony of brain activity, people still have no conscious experience. Scientists now believe they can explain why. With the onset of sleep, the connections between brain areas weaken and the information, though present, is not integrated. So, when a powerful magnet is used to stimulate the brain specifically in the premotor area, activity spreads to the rest of the brain when people are awake but remains locally confined when they are asleep. A similar uncoupling could explain how anaesthetics work. Recent studies suggest that neural activity does not stop, but the brain no longer integrates information from different areas of the brain. Sleep yourself better – Want to improve your dance moves? Finish a crossword? Then take to your bed. Far from shutting off, the brain uses sleep as a time to lay down memories and replay the day’s activities. We may not know it, but we wake up better prepared for the world than when we went to sleep. Find out more at DIVISION OF LABOUR: A 1930s view of the body. ON THE WEB The technology may look antiquated, but the idea of ‘division of labour’ in the brain is still valid. SEPTEMBER 2006 | 7
  8. 8. WHO ARE YOU?As social animals, we interact with other people,cooperating, negotiating and occasionally confronting.Our success as a species owes alot to our ability to work together – Face the factsfossil evidence suggests that early We draw important information from in children; it improves as children get older,humans were a tasty treat for people’s faces and facial expressions. dipping slightly at adolescence. Younger childrenpredators. As a collaborating pack, are generally less able to pick up subtle facialwe were safer and could become It is said that the route to a person’s soul is cues, one reason why their behaviour is lesshunters rather than hunted. through their eyes. There is much truth in that, influenced by others.) as we extract considerable information aboutCollective action depends on people’s moods and feelings from their faces, There are some suggestions that, as well aseffective communication. Although particularly the eyes. the stereotyped major expressions, there arewe have developed language, we many ‘micro-expressions’ that convey meaning.also draw important non-verbal We seem to have specific face-recognition The brain picks these up subconsciously.information from others – reading modules in the brain, emphasising theirfacial expressions, for example – importance to us. So when we recognise CHARLES DARWIN PROPOSEDand draw inferences about people’s someone it is usually through their faces and THAT FACIAL EXPRESSIONS WEREintentions and motivations. not, for example, their body posture. Further evidence comes from people with COMMON TO ALL HUMANITYIf we have problems with these prosopagnosia (see page 3) who specificallyforms of social communication, we cannot recognise faces. Even sheep seem to Expressions give away information about us,can have great difficulty functioning recognise other sheep by their faces. but so does the basic structure of our part of society. Sex, age and ethnicity can all be assessed The presence of a face-recognition module from faces. A masculine face is very different could also explain why we tend to ‘see’ faces from a feminine one. Even our sense of beauty is MIRROR, MIRROR in, for example, toast or on the moon – the strongly linked to facial features – a symmetrical brain interprets a face-like pattern of light and face is usually seen as more attractive. The discovery of mirror systems shade as a genuine face. has helped us understand the Through the ages, people have tried to take Charles Darwin proposed that facial this further and infer character from faces. planning and imagining of actions. expressions were common to all humanity – Was there a ‘criminal face’ that could be When we move to strike a tennis even remote populations laugh the same way used to identify possible miscreants? Despite ball, for example, our actions we do. We can all tell when someone is happy a huge amount of work, no convincing links are guided by the brain’s motor or sad or angry from the expression on their have ever been found. control systems. face. (Although this ability is not well developed Recently, it has become clear that these same systems are also active when we imagine making an action in our head (reliving a perfect cross-court volley, for example). And, remarkably, they also light up when we watch someone performing an action. The key difference is that the levels of activity are lower than when we actually perform the action – so muscular contraction is not actually triggered. Because the systems reflect the ‘real’ activity, they are known as mirror systems. The system is extraordinarily specific. Mirror systems fire when someone sees a person making an arm movement, for example, but not when they see a robotic arm move. It is possible that this activity allows us to put ourselves in others’ positions, experiencing (but to MR EXPRESSIVE HEAD: a lesser degree) what they are We draw much information about people’s state of mind experiencing. They may therefore from their facial expressions help us to infer the intentions and how a small change of others. can make a big difference – see back page.8 | BIG PICTURE 4
  9. 9. You or me?If our grasp of ‘us and them’ goes wrong, MIND THE GAPwe can have considerable problems in life. Humans have an uncanny ability to put themselves in the position of others.Most of us take for granted that we can tell the differencebetween an action we have generated ourselves and Young children can be horribly selfish. They want things for themselvesone forced on us by another. And most of our social and are not interested in sharing. Partly this is because they lack theinteractions with other people are not consciously ability to appreciate what other individuals are thinking and feeling.thought about. But if our brains are not adept at these This develops gradually during childhood.activities, life can be very challenging. Being able to understand the feelings and motivations of others, beingPeople with schizophrenia, for example, show several able to put yourself in other people’s shoes, is known as theory ofdistorted ways of thinking during psychotic episodes. mind. It is the basis of what we know as empathy – appreciating whatA common symptom is to believe that one’s actions are others are feeling and how our own behaviour may impact on them.being controlled by external forces. In brain scans, this is It is likely that people’s capacity for empathy varies. We can probablyapparent as activity patterns characteristic of externally identify people whom we feel are particularly empathic (or seem to lack it).applied (rather than internally generated) movements.(An odd consequence of this is that, during a psychotic In some conditions, theory of mind seems to be very badly affected.episode, people with schizophrenia can tickle themselves: A common feature of autism, for example, is an inability to appreciatethey do not perceive the hand doing the tickling as what others are thinking and feeling, or to appreciate the impact oftheir own.) one’s actions on others. As a result, people with autism generally lack social skills, and have to be taught how to behave in social situationsSimilarly, people with schizophrenia will sometimes hear where most of us would behave naturally, relying on unconsciousinternal voices, urging them to do things. Brain imaging social skills.again shows brain activity corresponding to externalsounds, not internal dialogue.A third common symptom in people with schizophreniais paranoia, a belief that people are following you orlooking at you all the time. This appears to be an error Body talkin processing information from others – a casual glance When people scratch their nose, does it mean they are lying?ignored by most is interpreted as evidence of a deep Popular psychology is full of accounts of ‘body language’. If I cross my arms,interest and desire to cause harm. I’m being defensive; if I pull my ear, I’m likely to be lying; if I avoid your gaze,It is possible that impaired pick-up of social cues also I’ve got something to hide.underpins other forms of behaviour disorder. People with The basis of body language was in animal communication. Without language,antisocial personality disorder (psychopathy) seem less animals need ways to convey information to one another – and use parts ofable to identify fearful expressions, so will be less able to their bodies in imaginative ways to do so. Faces are again important, but sotell that their behaviour is having a negative impact on too are, for example, gestures of submission. Mating relies heavily on signalspeople. Some symptoms of autism, too, seem to be linked of intent, receptivity or rejection, often leading to elaborate defective recognition of social cues (see above right). The popularity of studying body language in humans owes much to Desmond Morris. He argued that information from animals could be extrapolated to humans. The scientific value of this area, social anthropology, has been questioned by many neuroscientists. The neuroscience of body language has been studied much less well than responses to faces. But it does appear that the brain can recognise particular body postures and that recognition occurs early during processing of a scene (as is also true of face recognition). There could be brain modules specifically for body perception. The body language responses studied to date seem to be closely linked to SPL the brain’s emotional responses. So seeing someone showing signs of SCHIZOPHRENIA: Coloured positron emission tomography distress fires up our amygdala. This cues behaviour needed to escape from (PET) scans of sections through a healthy brain (left) and a threatening stimuli (such as the need to run away very fast). schizophrenic brain (right). The colours show different levels of activity within the brain during an attention test. Red shows high We also seem to be particularly sensitive to bodies in motion – though as activity, through yellow and green to black (very low activity). The schizophrenic brain shows much lower activity in the frontal lobes. artists through the century have proved, our emotional responses to still images of bodies in peril are powerful and quick to appear.BODY LANGUAGE:Faces reveal muchabout someone’sinner thoughts andfeelings. We alsosubconsciously drawsome informationfrom body posture.What might thesepeople be thinkingor feeling? SEPTEMBER 2006 | 9
  10. 10. WHY DO I DO We usually like to believeWHAT I DO?Where naughty treats are concerned,though, we find it convenient to think that we are free agents, capable of informed choice about what we do.we are driven by powers beyondour control.Both points of view are correct, butit is not always obvious how muchconscious control we actually have.Even when we think we have madea conscious choice, this may actuallybe an illusion… THE CYCLE OF ADDICTION Eating and taking part in sexual activity are essential for life and for species survival, so are rewarded with a good feeling produced in the brain. Repeating the tasks leads to a cycle of reward. Dopamine, a feel-good chemical messenger (neurotransmitter), Wired is central to this cycle. Alcohol, How much of our behaviour is fixed, There is bound to be interplay between nicotine, and drugs such as embedded in the neural networks of these factors. We may be born with a genetic cocaine and heroin all increase our brain? Is it ‘hard-wired’ – set for predisposition to alcoholism but lucky enough dopamine levels. life – or more flexibly arranged? in our family and social life that we never get tipped over the edge into dependency. But why do some substances just Behaviour is complex. No single gene encodes produce pleasure while others for it, nor does any single event or experience Also, the brain itself is not set in stone. are addictive? The likely answer control it. Although we can control some It develops through childhood, goes through is that in addiction, substances aspects with our own willpower or volition, massive change at adolescence, and reaches trigger permanent changes to the in the end our behaviour arises from an maturity in our early 20s. Even then the dopamine/reward pathways, which intricate interplay between our environment, brain retains significant plasticity – it learns lead to cravings. In effect, drug our genes and us. and adapts. So if we practise tennis we intake goes from being a voluntary get better at it. activity, under conscious control, to OUR GENES EVEN HAVE SOME So exactly how much of our behaviour can an unconsciously driven desire, with CONTROL OVER BEHAVIOURS THAT be modified, and how much is inborn or different brain areas taking over. fixed by our upbringing? It is hard to say. WE ARE UNAWARE OF. Pinpointing exactly how each With humans such a debate is risky, as substance works can help identify Science has shown that many patterns of the notion of ‘hard-wiring’ can be used to ways to block the addiction cycle. behaviour, including alcoholism, criminality support racist or sexist views or other forms and homosexuality, have some genetic of bigotry. On the other hand, in Steven influence. Our genes even have some control Pinker’s famous phrase, we are clearly not over behaviours that we are unaware of – ‘blank slates’ either. such as hand clasping (people tend to intertwine clasped hands with either the right or the left side uppermost). FAST In the case of alcoholism, genes may FACT Our brains code for certain receptors that bind form a chemical messengers in the brain, or for million new enzymes involved in breaking down alcohol. connections Our social and cultural upbringing every second may also affect our alcohol consumption – of our lives our parents may be teetotal, for example.10 | BIG PICTURE 4
  11. 11. A BRIEF Morality talesHISTORY Morality is a social sense of what is right or wrong. One of the most hotly contested Functional imaging has shown that the superior temporal sulcus, as well as theOF MENTAL questions is whether our brains come with prefrontal cortex, is involved in making moralILLNESS some sense of morality already built in or whether it is something we have to learn. judgements. Psychological tests can also be used to see how people respond to moral dilemmas, or questionnaires examining theirPre-history (e.g. Stone Age) Our morals differ according to our sex, moral reasoning (i.e. how they would respondTrepanning (drilling holes in the skull) religion and culture. They also change with in different situations). These again show thatis used to get rid of evil spirits. age. Very young children can’t tell right from people with personality disorders are less wrong. In toddlers, morality is based aroundApprox. 400 BCE able to identify the morally most appropriateHippocrates treats mental illness themselves. With age, morality shifts towards courses of a problem of the body rather than peer-group values and eventually movesa punishment sent by the Gods. towards consideration of the wider social group.1377 Morality is, of course, deeply rooted in theOpening of The Bethlem values held collectively by society. PhilosophersRoyal Hospital in London, and theologians have debated for centuriesalso known as Bedlam. whether absolute moral values exist, or1600s whether they are reflections of what is sociallyChains, shackles and imprisonment acceptable. What was morally acceptable toare largely used to restrain and control the ancient Greeks – slavery, for example –the mentally ill. may not be seen as OK today.1850s Neuroscience is helping us to understandAsylums built. the biological basis of human morality.1870s Examination of people with brain lesions A classic morality study is the ‘trolley problem’.Normal ovaries are removed to treat (damage) shows that people with early You are presented with a dilemma: a runaway trolley‘mental madness’ and ‘hysterical damage to the prefrontal cortex do not is about to kill five people. Should you throw a switch to divert the trolley onto a spur on which it will kill onevomiting’ in some women. develop normal moral responses. They lie person and allow the five to survive? You are thenEarly 1900s and cheat without feeling guilt or regret. given the same scenario, without the spur but withPsychoanalysis inspired Brain scans of people with antisocial the option to throw a man on the track to save the five. Should you throw him? People usually say ‘yes’ to theby Sigmund Freud, personality disorders show that psychopaths first dilemma, and ‘no’ to the second. Interestingly,Carl Jung and others. have less grey matter in the prefrontal cortex fMRI studies show that different parts of the brain are than normal people. active as the subject considers the two scenarios.1911Swiss psychiatrist Eugen Bleuler firstuses the term ‘schizophrenia’. Strange behaviour WWI Patients with shell shock are Many conditions with a genetic link affect the brain or behaviour – including autism, schizophrenia counselled – the precursor of and bipolar disorder (manic depression). There are a wide range of disorders, however, showing modern treatment for post- distinctive alterations in behaviour (including the examples below). Studies of people with these traumatic stress disorder. disorders can shed light on brain function.1936Lobotomy (surgical removalof part of the brain).1938Electro-shock therapy forschizophrenia and manic depression.1949Lithium for psychosis andmanic depression (nowcalled bipolar disorder).1952 REFLEX: Tim Howard, goalkeeper for Manchester FRIENDLY FACE: A young girl with the typicalThe first anti-psychotic drug, United and the USA, has Tourette syndrome. appearance of Williams–Beuren syndrome.Thorazine, for psychosis. Rex Features The University of Utah, Genetic Science Learning CenterMid-1950sBehaviour therapy for phobias. Tourette syndrome Williams–Beuren syndrome • People with Tourette have characteristic, (Williams syndrome)1960–63 semi-involuntary tics such as sudden, • Children with Williams–Beuren syndromeLibrium and Valiumfor nonpsychotic anxiety. rapid movements (e.g. blinking or sniffing) have a characteristic elfin-like face, and and verbal tics (e.g. shouting or swearing). tend to have a degree of developmental1970s–1980s delays and some learning disorders.A move away from asylums, • People seem unable to suppressmental institutions and hospitals unconscious thoughts or reflex-driven • They frequently have a love of music andto community-based healthcare. movement, possibly due to disrupted are polite and friendly by nature, often communication between the prefrontal being overly trusting of strangers.1980s‘Selective serotonin re-uptake cortex and other areas of the brain. • Recent research suggests the syndromeinhibitors’ for depression. • Recent research has shown that a gene is caused by loss of a chunk of1990s called SLITRK1 that is involved in brain chromosome 7, which typically removesNew generation of anti-psychotic development is disrupted in a small 28 genes.drugs for schizophrenia. number of cases. SEPTEMBER 2006 | 11
  12. 12. REAL VOICESThe brain works in mysterious ways. Some people experience life in very differentways because of quirks in the way their brain operates. We spoke to two such peopleabout the impact of unusual brain function – synaesthesia and schizophrenia –on their lives. SYNAESTHESIA is an unusual condition SCHIZOPHRENIA is typified by unusual affecting the senses. Typically two senses ways of thinking; common symptoms include become mixed – for example, sounds give hallucinations or internal voices, delusions and rise to a visual experience, or sight is linked to paranoia. Symptoms vary significantly, however, touch sensations (someone with vision–touch and the condition overlaps with bipolar disorder synaesthesia feels a touch if they see someone (manic depression). It tends to emerge in late else being touched). Its causes are unknown, adolescence. Its origins are uncertain; genetic but a genetic contribution is possible. The and environmental risk factors (e.g. poor maternal symptoms may stem from cross-wiring in the nutrition) have been identified. Roughly translated, brain, so that nerve impulses triggered by one schizophrenia means ‘shattered mind’; contrary sense activate brain areas responsible for a to popular perceptions, however, it is not different sense. associated with multiple personalities. WHAT ROLE DO YOU THINK YOUR Julie Roxburgh is a retired music BRAIN HAS IN YOUR CONDITION? teacher. When she hears sounds she sees them as colours: a condition known JR It could have something to as sound-to-colour synaesthesia. do with the connections in your brain – the wiring as you What are the most significant might call it. I know I certainly features of your synaesthesia? don’t have any control over it. JR It is very hard to describe. It’s as if I have a big screen in front of me, and when I hear sounds they appear on the screen as colours and shapes. Sometimes they are moving and they appear in Do you consider your condition different areas of the screen every time. I am a trained musician and I used to teach oboe and an illness or a disability? clarinet, so I know what colour to expect when JR I don’t think it could be called a disability I hear different instruments. The low notes on a compared to the dreadful problems that other clarinet, for example, are a blue-black colour and people have. However, it does create difficulties. the high notes are a murky white. Other sounds, Society is not designed for synaesthetes. I can’t such as traffic, can appear differently every time. go to places where there is a lot of noise. Music in shops is so distracting. How does it affect your life? JR I can’t always differentiate between my senses How do people react when you – whether I am hearing something or seeing it. tell them about your condition? When my alarm clock rings, I see brass-coloured JR Most people find it hard to understand. bubbles and white lines. It’s quite disturbing first Describing it is like trying to explain colour to thing in the morning when you are waking up. someone who has been blind from birth. Equally, Seeing colours and shapes all the time muddles up I can’t think what it would be like not to be my thought process, especially when I am tired. synaesthetic. My husband is a composer and I can’t imagine how he hears in his head the sounds he wants to write down, yet doesn’t see them.RIGHTOne person’s viewof numbers, which What do you think the originsare associated with of your condition are?particular colours. JR My brother, my mother and my son are all synaesthetic and I think my granddaughter might be. So there could be a genetic link.12 | BIG PICTURE 4
  13. 13. WHAT ROLE DO YOU THINK YOUR BRAIN HAS IN YOUR CONDITION? EJ There seems to be a tendency to release too much or not enough DO YOU FEEL COMFORTABLE TELLING of certain chemicals from time to PEOPLE ABOUT YOUR CONDITION? time. You start feeling anxious and EJ Yes, and I believe it is important get very powerful emotional charges. to speak out. There are many people As time goes by you begin to suffering in silence because of ignorance recognise the occasions when you and prejudice. More people like myself need to do something about it, such need to tell others what it’s like. as talk to your psychotherapist. ABOVE: Composite artworkEdward Jones, 58, is a volunteer What treatment have you had? (by Chris Nurse)with the mental health charity Rethink. EJ The psychiatrist I saw after I was first diagnosed in two halves saved my life. He was able to gain my trust and I felt illustrating theHe was diagnosed with schizophrenia able to tell him exactly how I was feeling. Now I see decline into mentalat the age of 21. a psychotherapist whenever I feel the need to talk illness and the shattering of to someone. normal perception.What are the most significantfeatures of your condition? How do you feel people withEdward Jones Anxiety, paranoia and depression schizophrenia are portrayed inare features. But on a day-to-day basis delusions are the media?the biggest problem I have to deal with. My condition EJ When a person with schizophrenia commits a violentdistorts perception so I make sure to keep talking to crime the media tends to give it so much attention.people and asking them what’s real and what’s not. But as far as I know, the statistics show that fewerIn very severe cases of schizophrenia you can’t people with schizophrenia commit crime than ordinaryactually make the distinction. people. In a way, I don’t really blame the media for this because a lot of people like me aren’t speaking out.How does it affect your life?EJ I sometimes feel anxious and depressed. I go What do you think the originsover and over what people have said to me and put of your condition are?a negative interpretation on it. However, experience EJ I’d say the causes are genetic. My motherhas shown me that these feelings won’t last forever had schizophrenia. She twisted everything youand that I just have to wait for them to pass. said to make it seem hostile. She became angry very quickly and thought she heard voices.Are you responsible? ONLINE ACTIVITYIt was a high-profile murder case… What do you think? The activity is supported by backgroundThe accused had brutally slain In this activity, students are encouraged material, including the two podcasts – to think about the brain works, how it which can be listened to on the websitea colleague… controls behaviour and whether we are or downloaded onto an MP3 player –His defence? He’d been suffering always fully responsible for our actions. plus support notes for pupils and teachers.from a brain tumour at the time, Using specially commissioned podcasts,the physical changes in his brain students can also consider how science Full details can be found atcausing him to become more is reported in the media. and impulsive, makinghim less responsible for his actions.The press had a field day…This issue’s classroom activity is basedaround two podcasts. They are newsreports of the court case – produced incompletely different styles. | 13
  14. 14. WHAT DOESIT ALL MEAN?We are rapidly gaining a much better understanding of the brain and how it operates. We arebeginning to see how our thought processes and actions are shaped by activity in the brain.This new knowledge is exciting, but presents us with many challenges. And toolsand therapies for use in medicine or research could equally well be applied sociallyfor other uses. How are we going to manage these ethical quandaries?Responsible adults?If a lot of our behaviour is outside our consciouscontrol (or feels as if it is), can we always be heldresponsible for our actions?Our legal system (and many other aspects of society) arebased on the idea that we are ‘free agents’, able to decidefor ourselves how we behave.But how much freedom do we actually have to control ourbehaviour? Some brain responses are not under consciouscontrol. Sometimes, even when we think we are making a YOU ARE THE JUDGconscious decision, our brain has already made an Eunconscious one. Or our conscious and unconsciouswrestle for control of our actions.Our genetic inheritance will affect our brain and behaviour,as will the environment we experience in the womb, and the CASE STUDY 1 CASE STUDY 2way we are brought up. By the time we are adults, our scope Defendant X Defendant Yto behave in any way we choose is significantly reduced. • Impulsive behaviour runs in • She was brought up on a his family. deprived inner city estate.On the other hand, genetic or neuroscientific determinism– that we are ‘born’ or ‘hard-wired’ to behave in a particular • He has a variant in a • She was physically abusedway – can become a self-fulfilling prophecy. The prefrontal neurotransmitter receptor gene as a child.cortex, the ‘thinking brain’, still has plenty of scope to shape that may influence behaviour. • She stole a mobile phone toour actions. • He hit a bouncer at a nightclub, give to her boyfriend.Legally, courts are more lenient if a defendant can prove causing actual bodily harm. Do any of the factors influence‘diminished responsibility’. Sentencing will also depend Do any of the factors influence whether she is found guilty orto some extent on an assessment of a defendant’s mental whether he is found guilty or not? not? Should any influence thehealth. So far, there has been little evidence that judges are Should any influence the punishment if she is found guilty?willing to consider biological susceptibilities as a justifiable punishment if he is found guilty?defence. As we discover more about the links between brain Should any biological factor everand behaviour, it is likely that this will become a more be considered?common issue. HAVEHands off my brain YOURShould the contents of the brain be prejudice? And there is considerable interest in using such SAY...‘private property’? tools to spot when people are lying. There are characteristic On the Big patterns of brain activity that light up when people are not Picture websiteWe sometimes go to extreme lengths to prevent people telling the truth (though brain scanners are not 100 per cent you can castknowing what we are thinking. The most successful poker your vote and accurate as lie detectors at the moment).players have deadpan faces, so other players do not know see how yourwhat kind of hand they have. Or, in everyday life, we might This may be seen as intrusive. In the USA, the Center for answerstell the odd little white lie, or not tell someone what we Cognitive Liberty and Ethics argues: “What and how you compare toreally think about them if we want them to help us. think should be private unless you choose to share it.” everyone else’s.But suppose our real, inner thoughts could be laid bare. Supporters say that brain scanning could have great use –Functional imaging provides a powerful view of our inner identifying potential paedophiles seeking to work in schools,thought processes, revealing things that our outer or helping the police solve crimes. On the other hand, even ifexpression may be hiding. they were infallible (and they are not) the meaning of scanning results is open to interpretation. We have instinctive responsesIt has revealed that people respond differently to black faces but that does not mean we always act on them.than they do to white faces – evidence of hidden racial14 | BIG PICTURE 4