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Panel News 16 (Spring 2003)
- Or view: Panel News 16 as a PDF file
- Building Developments at the Unit
- Language Physiology Lab opened at the Cognition and Brain Sciences Unit
- Latest news from the panel office
- Ann Lickorish retires
- Feeling Sad in the Name of Science
- A Caring Side to the MRC-CBU
- Public Science Event
- Fear and loathing in the human brain
- The missing space
- Different brain areas 'know' different things about objects
- Struggling to understand: how the brain makes sense of distorted speech
- Can interruption be useful?
- Students at the CBU
- What is it like to hear with a bionic ear?
- A beginner's guide to neuroimaging
Building Developments at the Unit
Regular Panel Volunteers cannot have failed to notice the new building developments at the Unit. In the last edition of "Panel News" we reported on the change of name from "Applied Psychology Unit" to "Cognition and Brain Sciences Unit" to reflect the Unit's change of emphasis from applied cognitive psychology and practical technological systems to theory development and the integration of cognitive science with neuroscience. As part of this process of change and renewal, the Unit has undergone a major programme of remodelling and rebuilding. Along with the refurbishment of the Edwardian mansion that forms the old heart of the Unit, the centrepiece of these developments is the recently completed West Wing. This is a dramatic two-storey addition to the CBU facilities, which houses extensive laboratory space for testing on the ground floor and excellent lecture theatre and seminar room facilities on the first floor.
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We would like to thank all our Volunteers for putting up with the upheaval during the building works, when car-parking was a particular problem, with the builders compound taking over a large portion of the car park. We hope that you will agree that the comfortable testing rooms - and new waiting room - made the disruption worthwhile. Those of us working here certainly feel that the changes have provided a more pleasant and comfortable environment in which to carry out our research.
Language Physiology Lab opened at the Cognition and Brain Sciences Unit
At the end of year 2000, the CBUs methodological facilities were enriched by a 64-channel EEG (electroencephalography) laboratory. The laboratory was set up and is supervised by Friedemann Pulvermüller and assisted by Olaf Hauk and Yury Shtyrov, who are members of the Speech and Language group at the CBU. The focus of studies performed in the EEG lab so far has thus been on language related brain activity. In collaboration with Bob Carlyon and Christoph Micheyl from the Attention group, a psychoacoustic experiment was also performed recently.
EEG measures small changes in electrical activity on the scalp surface in the millisecond range. Only this technique (and the related MEG which measures magnetic fields) can monitor brain activity with such a high temporal resolution. However, the final goal is to make inferences on the brain processes generating the measured distribution of activity on the scalp. This requires sophisticated analysis methods. Several software packages and self-created software are therefore available in the laboratory.
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The main challenges of our research relate to the following questions:
At which point in time is word processing reflected in the EEG brain response? Is word-specific brain activity present already 1/10 of a second after the word is perceived?
Are aspects of the meaning of a word reflected in the EEG brain response? For example, do words referring to foot and mouth movements (walking vs. talking) activate brain regions in corresponding motor areas in the frontal cortex? Which brain waves reflect the processing of grammatical information? What is the role of attention in language processes? Are word meaning and grammar accessed automatically, i.e. without conscious control?
Which plastic changes in cortical activation follow lesions in the language centres of the brain? For example, do changes in the EEG brain response reflect recovery of language functions after stroke?
A typical experiment would involve watching a sequence of letter strings on a computer screen. Volunteers would have to decide by button press if these are real words or "pseudo-words". Such a "lexical decision" task is assumed to activate brain regions that store and process information about the word form, its spelling and pronunciation, and even about grammatical or meaning-related aspects, for example whether the word is a noun or verb, or refers to an animal or a tool.
In other experiments, volunteers are presented with sequences of the same spoken speech sounds via earphones. This sequence is occasionally interrupted by the presentation of a different speech sound, which may be a real word or not. While the speech stimuli are being presented, the volunteers can watch a silent movie of her or his own choice and should not attend to the somewhat boring language stimuli which are then processed pre-attentively by the brain. As our earlier studies show, the automatic brain response to a word differs from that of a pseudo-word. We are currently investigating which aspects of a word are reflected in the automatic brain response. Meaning-related as well as grammatical aspects are of interest here.
So, if you would like to watch a film from our movie selection and do not mind a few sounds in your ears, you are very welcome to come to the lab for two or three well-paid relaxing hours.
Although EEG is widely applied in basic research as well as in clinical environments, it is only sensitive to certain aspects of the processing taking place inside the brain. The biggest methodological challenge in current neuroscience is to combine information from different techniques to obtain consistent data about the temporal and spatial aspects of brain activation. For answering the question When does which area become active?, a second neurophysiological technique is available called magnetoencephalography or MEG. We are acquiring MEG data with one of the most advanced MEG systems at the Biomag laboratory at Helsinki University (306 channels). To monitor the spreading of activity from one brain area to others, we also perform studies combining EEG and Transcranial Magnetic Stimulation (TMS). TMS allows to briefly induce electrical activity within a well-defined brain area, and EEG monitors the spread of this activity within the following tens of milliseconds. Another intriguing approach is to run experiments both in the EEG lab and also in the functional Magnetic Resonance Imaging scanner at the Wolfson Brain Imaging Centre (WBIC), Addenbrookes Hospital. The intention is to use the superior spatial resolution of fMRI to optimise algorithms used in EEG analysis to estimate brain activity from the electrical scalp distribution. In combination, these methods can yield an accurate spatial-temporal image of brain activity.
Olaf Hauk, Yury Shtyrov, Friedemann Pulvermüller
Latest news from the Panel Office
First, the Panel Office would like to thank our volunteers for all the assistance you have given us at the CBU, and, for those of you who have been helping us for a number of years, in our previous incarnation when we were called the APU. Without your help and generosity with your time much of the research carried out by our scientists would grind to a halt. We have a great variety of people on our panel. Some of you have only recently joined our Volunteer Research Panel, and others have been coming for many years. We have quite a large turnover among our student population, as every summer we have to say goodbye to a number of them, but we also have some Cambridge residents who have been very faithful to us over the years.
During the last few years our long-standing volunteers will have noticed a distinct change in the direction of our research. Many of our scientists now try to understand aspects of cognition (attention, emotion, memory, language, etc) by studying the ways in which these processes can be impaired in clinical populations, such as people with a progressive brain disease (like Alzheimer's disease) or who have suffered a stroke or a major depressive illness. In order to assess the extent of the impairment on various tests, we need to know how normal individuals perform on the very same tests: we call such scores "control" data. Because the patients are sometimes very impaired, the tests are often rather simple. So if you are asked to do tests that seem mundane or too easy for you: please be assured that your control results are extremely important and useful to us. Some of our other experiments may seem rather repetitive, some require a great deal of concentration, and some come under the heading 'fun computer games', but all are an important part of our various research interests. We also have a team of scientists studying the way the brain functions using Functional Magnetic Resonance Imaging (fMRI), which takes place at the Wolfson Brain Imaging Centre (WBIC), which is located on the Addenbrookes site. Whichever type of experiment you are asked to take part in, your data is highly valued, and will contribute significantly to the final results.
You will have noticed that we now ask you for many more signatures each time you come in to be tested. This is necessary in order that we comply with the latest Data Protection Act. First, we need you to sign to say that you have had the nature of the experiment explained to you, so that you know roughly what you are going to be asked to do. Then, although you know that any data collected from our experiments is likely to be used in publications and presentations, we now need your express permission each time to use your specific data. We will, of course, never present any data in a form where any of the participants can be identified. We also require your signature if you have had a scan, so other scientists can look at it, or if you have done some of our standard psychological tests, so that other scientists can decide whether you fit into a suitable subset of volunteers. Finally, we still require your signature acknowledging the receipt of your honorarium.
We hope that you find your visits to the CBU an interesting and worthwhile experience, and will continue to help us for many years to come. Please tell all your friends how enjoyable it can be, and encourage any who are not yet members of the Panel (minimum age 16, no upper limit!) to contact us so they too can participate.
Ann Lickorish and Jackie Harper
Ann Lickorish retires
Ann came to the APU in 1982 where she worked for 15 years with Pat Wright, one of our Senior Scientists. Although her background was in Mathematics, she was able to quickly grasp the fundamentals of the psychological work being carried out at the Unit, and became an invaluable member of the Unit. It was her considerable skill in programming that resulted in her being asked to take up the challenge of setting up the Patient Panel database in 1997, following Pat Wright's move away from the Unit. When Sue Allison, the Volunteer Panel Manager, retired in 1998 Ann became Panel Manager, in charge of both the Patient Panel and the Volunteer Panel and Jackie Harper was appointed as her assistant.
Ann herself has now decided to take early retirement so that she can spend a year in Australia, accompanying her husband on his sabbatical year from his post at the University of Cambridge. As well as being a wonderful opportunity to see the country, it also enables them both to see their daughter and her husband and grandchildren. We wish her health and happiness in her retirement.
Jackie Harper now follows in Ann's footsteps as Panel Manager and will no doubt keep things running smoothly and efficiently.
Feeling Sad in the Name of Science
Would you volunteer to be sad, given the choice? Well that's just what hundreds of members of the volunteer panel have done recently in an effort to help us gain a better understanding of depressed moods. Agreeing to try to make yourself depressed for an hour in the name of science may seem like a rather odd way to spend your time but the information that we can gain from these kinds of experiments is extremely valuable.
So what is the point of making people sad?
Asking healthy volunteers to take part in mood research allows us to find out more about how sad moods shape our everyday activities without running the risk of making depressed volunteers feel even more depressed. In one recent project, panel volunteers helped us to look at how sad moods can affect our ability to problem-solve. We know that when people get depressed, they have greater difficulty resolving problems, particularly social problems such as arguments with friends or work colleagues. This can intensify their feelings of depression and undermine their self-confidence. We wanted to find out more about why depressed moods lead to problem-solving difficulties. We asked for healthy volunteers who were willing to take part in mood inductions and randomly divided them into four groups. Two groups took part in sad mood inductions and for comparison, two groups were given neutral mood inductions. Before and after the mood inductions, our volunteers took part in a prob-lem-solving task. This involved them telling us the steps that they would take to solve tricky social situations, such as noticing your friends are avoiding you, or not getting along with your boss at work.
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How did we induce the sad moods? There are various tried and tested methods. Mood induction experiments usually involve activities like listening to slow, depressing music, or watching tear-jerking film clips. Volunteers are always told that they can stop at any time if they get fed up with the tasks. In our study, we used two different kinds of sad mood induction, one where volunteers thought about sad personal memories (Group 1) and another where they focused on sad feelings and analysed what it meant to them to feel this way (Group 2). While doing this, they listened to depressing music. In the other two groups volunteers took part in neutral mood tasks. They either thought about how they were feeling at that moment in the experiment and thought about what it was like to feel that way (Group 3) or they recalled recent everyday events that were quite neutral, like the last time they went shopping for food (Group 4).
As you may imagine, mood inductions don't always work and sad mood inductions in particular have been known to make some people laugh! For these poor participants often the more they try to be sad, the funnier they find it. However, the majority of our volunteers kindly persevered with the tasks and the mood inductions had the desired effect. No change in happiness or sadness was found in the neutral groups before and after the induction. In the sad groups, volunteers were less happy and more despondent after the induction than they had been before. The intensity of the induced depressed mood was also similar in each of the sad groups.
How did we use the mood inductions to test problem-solving? We compared the groups' performance on the problem-solving task before and after they engaged in the mood inductions, measuring how effective the groups were in a number of different ways. If volunteers in the sad mood groups were less effective than volunteers in the neutral groups after the mood inductions, then we would know that feeling sad had a negative effect on problem-solving. If one sad group performed badly but the other sad group did not, it would suggest that only certain kinds of sad mood have a detrimental effect.
What did we find? As we'd measured the effectiveness of our volunteers problem-solving abilities before they took part in the mood inductions we had a baseline measurement of their performance; no differences were found between the four groups in this baseline measurement. After the mood inductions, only one of the sad mood groups performed poorly at the problem-solving task. This was the group who had focused on their sad feelings and analysed their feelings (Group 2). The sad group who had thought about unhappy memories (Group 1) were as good at the problem-solving task as the volunteers in the two neutral groups. The graph above shows how the effectiveness of Group 2 decreased from pre-induction to post-induction whereas the performance of the other three groups improved slightly.
So what does this tell us? It suggests that not all sad moods have a negative effect on problem-solving. The findings also suggest that it is not the negativity of the mood that impairs problem-solving, as both negative groups (1 & 2) were equally sad. Instead our results indicate that it is the action of thinking about our sad feelings and analysing why we feel depressed that reduces the effectiveness of our problem solving. Focusing on the specifics of the sad mood may make us feel unhappy but it is unlikely to interfere with our ability to find effective solutions.
How will these findings help depressed people? We hope that research like this will help us to build up our understanding of how depressed moods effect everyday activities like problem-solving. If we can improve our understanding then we use this knowledge to find ways of lifting people's depression and preventing it from returning.
This study was carried out as part of a PhD thesis. We would like to extend our grateful thanks to all of the members of the volunteer panel who took part in this research.
Jennifer Potts
A Caring Side to the MRC-CBU
As many of you probably know, either from reading previous issues of the Panel News or from being told this explicitly when you come to participate in experiments here, often you are contributing what we call "control" data. A great deal of our research at the MRC-CBU is concerned with the impairments in cognitive function that result from brain injury or disease. When we test neurological patients with such cognitive disorders, we need to be able to judge just how impaired their performance is on particular tests; thus we need to measure the performance of normal individuals, of similar age and educational level to the patients, on the same tests.
In the Memory & Knowledge research group at the CBU, we study many patients with neurodegenerative diseases. The best known of these progressive conditions is Alzheimer's disease (AD); but there is another condition - of much lower incidence than AD but the second most common cause of dementing illness in people under the age of 65 - which is called "frontotemporal dementia" (FTD). In contrast to AD, which has a rather widespread impact on brain function, FTD tends to affect either the frontal or temporal lobes of the brain much more selectively. We test patients with FTD longitudinally, and extensively. The results of this testing are often very sad, because the patients' performance deteriorates over time; but the results are also extremely informative in our goal of understanding how and where cognitive functions like memory and language are represented in the brain. Because our research group - particularly Professor John Hodges, Consultant Behavioural Neurologist in Cambridge - is now widely known for work on FTD, patients are often referred from far afield, and we currently have about 50 cases in our cohort.
These patients and their families contribute a great deal to our research by agreeing to participate in our studies. Unfortunately, at this stage of medical understanding of these conditions, there is very little in the way of effective treatment to halt or slow the disease process. Since we cannot make the patients better: what can we do for them and their families in return for their generous contributions to our work?
Our current answer to this perplexing issue is that, starting about three years ago and occurring every few months, we hold meetings at the CBU of a "Carers' Support Group" for carers of the patients with FTD in our studies. (We also study AD; but carers of AD patients are well supported by local branches of the national Alzheimer's Disease Society; there is nothing comparable in the case of FTD).
Even if you are lucky enough not to have experienced such problems personally, you can probably imagine the burdens and stresses and down-right bewilderment of looking after a partner or a parent with FTD in whom aspects of memory, language, judgement, personality, and ability to cope in the everyday world are becoming progressively more disrupted. These carers have many questions and issues on which they need advice and information. Members of our group give talks on relevant topics and spend time answering both group and individual questions. We also have invited speakers on topics outside our own expertise, such as legal and genetic aspects of FTD.
Although we hope never to see any member of the Subject Panel at these meetings, we thought that you might like to know about this aspect of our work: a glimpse of the caring face of the MRC-CBU.
Karalyn Patterson, John Hodges, Kim Graham
Public Science Event
Would you like to learn more about how the human brain makes sense of spoken language? Or how our brains deal with emotions such as fear or disgust? Or how scientists can help those with memory problems?
The CBU participates in National Science Week each year, when topics such as these are discussed during an afternoon of short talks, experiments and informative posters. If you would like information on the next Science Week event, please contact Sian Miller (email: sian.miller@mrc-cbu.cam.ac.uk).
Fear and loathing in the human brain
An area of research carried out at the CBU involves face and emotion processing. The face is very important in guiding our behaviour. When we encounter someone we recognise, we react differently to them than to a stranger. Similarly, the expression on another person's face can influence our subsequent behaviour. For example, a smile generally indicates that a person is happy about something and often induces other people to smile, too. In contrast, seeing someone looking frightened makes us anxious to know the cause of their concern - after all, the chances are that what frightens others will also frighten ourselves.
A good deal of psychological research has shown that recognising what emotion someone is feeling from looking at their face involves different processes in the brain and mind from recognising who they are (their identity). However, it is only in recent years that research has begun to show that the recognition of emotion from the face is not based on just one system. For example, studies, including those done at the CBU, have shown that recognition of facial and vocal expressions of fear and, to some extent anger, are particularly affected in people with bilateral damage to the amygdala, a small almond-shaped structure buried deep in the medial temporal lobe of the brain. This finding has been supported by functional neuroimaging studies of healthy volunteers which demonstrate that viewing fearful facial expressions produces an increased signal in the amygdala.
In an effort to determine whether individual emotions are processed in different areas of the brain, similar brain imaging studies have shown that facial expressions of disgust produced increased signals in different parts of the brain - the insula and basal ganglia. In line with these findings, it is of interest that the insula has been activated in functional imaging studies of taste and smell, whereas electrical stimulation of the insula of conscious human patients undergoing surgery for epilepsy brought about feelings of nausea, unpleasant tastes, and sensations in the stomach.
In order to try to understand the function of these brain areas in recognising disgust, we recently studied a person (whom we refer to as NK) with selective damage to the insula and basal ganglia. On tests examining the recognition of disgust from both the face and the voice, NK was impaired compared with the performance of neurologically normal volunteers from the CBU panel. In contrast, recognition of emotional signals of other emotions (happiness, sadness, anger, fear, and surprise) was normal. In order to investigate whether a deficit in processing an emotion from the face and the voice also extended to domains other than human signals, we developed further tests of emotion recognition, such as pictures of scenes which illustrate various emotions (e.g., a filthy toilet for disgust, a beautiful sunset for happiness). NK had no difficulty identifying the emotions depicted in these situations, including disgust, which suggests that the difficulty in recognising facial and vocal expressions of disgust does not arise from a lack of understanding of the concept of disgust. However, on a questionnaire measuring experience of disgust, NK demonstrated an abnormal reaction to disgust-provoking scenarios (i.e. he was generally not disgusted by situations which would normally provoke disgust), whereas his scores on questionnaires measuring his experience of fear and anger were well within the normal limits. Overall, the results of this study provide evidence that the insula and basal ganglia may be instrumental in recognising signals of disgust from both the face and the voice. In addition, this study indicates that these brain areas are also involved in the experience of this emotion.
By undertaking the various tests of emotion recognition that we use in our research, members of the CBU volunteer panel have helped us to gather valuable "control" data which we can use as a comparison against the performance of people with certain types of brain injury and gradually build up a picture of how and where the brain is processing emotion.
Andy Calder and Jill Keane
The missing space
Jumping up, his chair tips backwards, and Benjamin yells excitedly at the top of his voice, what he knows about the rise and fall of Pompeii. But it is not his turn to speak. Told off by his teacher, he stumbles over his belongings as he returns to his place, only to start arguing with his classmate over a lost pencil. By the end of the lesson Benjamin has produced few squiggly sentences in his book - not nearly half the work he was supposed to complete.
I met Benjamin when he was 7 years old - a very intelligent child, yet incapable of engaging in any activity for more than a few moments. Sadly I witnessed him struggle with his own restlessness, which not only prevents completion of his schoolwork but also inhibits the development of friendships and challenges both, teachers and parents.
Benjamin suffers from Attention Deficit Hyperactivity Disorder (ADHD) - a disorder characterised by inattention and impulsive behaviour, predisposing to underachievement, to social- and psychiatric problems in later life.
Roughly 1-3% of children in the UK suffer from ADHD. Although ADHD has become a topical issue for teachers, psychologists and doctors alike, relatively little is known about what really underlies or causes the disorder. Whether a child is labelled 'ADHD', rests largely on the subjective judgement of the doctor handling the child.
However, there are many possible reasons why a child may behave in an inattentive or overactive manner. Most parents will recognise times when children have 'played up', when it became impossible to stop them shouting and running around in a state of high excitement. But some children do this more often than others - and then it may become a problem. Learning-difficulties or complex social circumstances may contribute to behaviour that is difficult to control. The border between a frustrated or socially disturbed child and a child that suffers ADHD is often difficult to define. What distinguishes ADHD? If we could only assess the core of inattentive behaviour more objectively, it would help to disentangle this disorder from other problems a child might experience, and possibly facilitate development of appropriate support for those suffering with ADHD, along their challenging pathways.
Made up of two halves (hemispheres) our brain controls much of our behaviour. Language, memories, feelings are encoded in a network composed of billions of cells called neurons, inter-linked via delicate communication networks of fibres (axons and dendrites). Moving, talking, or the experience of emotions, all appears to be associated with increases or decreases of activity in certain networks of cells and fibres within the brain. While communicating with each other, the two halves of the brain play very different roles in these processes.
Kenneth Heilmann (1979) was one of the first to suggest that the right half of the brain plays an important part in controlling our ability to concentrate. He realised that patients with damage to the right part of the brain became unable to concentrate and quite often impulsive in their behaviour. Furthermore, despite full visual capability, they were unable to direct the focus of their attention towards their left-hand side. They now ignored the left half of a page when reading, for instance, or did not respond to a person approaching from the left.
The similarity between the distraction of these patients and the behaviour of children like Benjamin seemed striking. Could it be possible that at least some children with ADHD encounter similar difficulties in directing attention to their left-hand side?
I have spent many hours since with Benjamin, examining his attentiveness to events on either side of his body-midline. The results were astonishing. Benjamin largely ignored anything to his left. He was lacking awareness of the space to his left-hand side. Some of his schoolwork then appeared in a different light. For example, his strange preference for drawing on the right half of the paper, usually seen as defiant refusal to follow instructions of the teacher, may well be part of his disability.
Benjamin has no obvious brain damage, suggesting that possibly quite subtle changes within the organisation of right-sided brain-networks may be at the core of his problem.
It now seems Benjamin is not alone. We have started to look at larger groups of children with- and without attention problems, aiming to establish further whether there is a link between inattention and the ability to process information in space. We intend to develop means and measures to distinguish these children from those, whose inattention is due to other reasons. At the same time we are working on methods to improve concentration.
As these investigations create new insight into disorders of attention, it is our hope to build a bridge between scientists and clinicians. A careful dialogue between these disciplines will help to transform theoretical work into clinical practice.
Veronica Dobler
Different brain areas 'know' different things about objects
When we recognise an object and believe we 'know' what it is, we are not usually aware of the many different types of information we know about it. For example, we may know how, why and where an object is used, as well as what it looks, sounds, tastes and feels like. Different aspects of information are more or less relevant to different objects.
Imagine what you know about a fire engine: it is a vehicle, is used for emergencies, is used to put out fires, it has hoses and ladders on it, is large, is red, and makes a noise. In contrast , imagine what you know about an aspirin: it is a medicine, is bought at the pharmacy or supermarket, is taken with water, is held in the hand, is small, is white, and perhaps also has a particular texture and taste associated with it, but does not make a sound. All these aspects of object knowledge come together to form our stable concept of what an object is. What it is not clear, however, is whether all aspects 'reside' in the same area of the brain or whether different types of knowledge are stored in specialised regions of the brain. In fact, patients with damage to the brain can sometimes demonstrate impaired knowledge of quite specific aspects of object concepts (for example, whether objects make sounds or not) while other types of information (visual knowledge, for example) remain pretty much intact. This suggests that these different types of knowledge are stored in distinct brain areas. One current theory regarding the way in which object knowledge may be organised in the brain is that each type of information might be stored in a brain region which is in or near to the area which is specialised for processing similar information when it is learnt and experienced. So, for example, knowledge about the visual appearance of objects might be stored in or near to brain areas involved in the perception of visual object properties, while information about the sound an object makes might be stored near to the brain regions specialised for processing incoming sounds.
We recently investigated this theory using a brain scanning technique called positron emission tomography (PET) which is performed at the Wolfson Brain Imaging Centre, Addenbrooke's Hospital. This technique involves a very low dose of radioactivity which allows the measurement of how much blood is flowing to different areas of the brain. This, in turn, provides a measure of how active various brain structures are. Different tasks are performed during each scan, so we can compare levels of activation of particular brain areas in response to different tasks.
We asked volunteers to make judgements either about the visual attributes (colour: 'Is it coloured?' fire engine - 'yes', aspirin — 'no', or size: 'Is it small?': aspirin — 'yes', fire engine — 'no') or sounds ('Does it make a noise?': fire engine — 'yes', aspirin — 'no') typically associated with objects. By comparing the scans acquired during these tasks we could then examine which parts of the brain are uniquely involved in retrieving visual and auditory aspects of object knowledge.
The results from the study support the theory that k n o w l e d g e about different aspects of objects is stored near the brain areas specialised for the perception of similar information. Retrieval of visual aspects of object knowledge (colour and size) activated a region of the temporal lobe near the rear of the brain in the right hemisphere which is associated with the perceptual processing of visual object properties such as colour (circled on the right-hand side of the picture below). This area was not activated when knowledge about object sound was retrieved. In contrast, judgements about the sounds that objects make activated an area at the junction of the temporal and parietal lobes in the left hemisphere of the brain adjacent to regions specialised for the perception and processing of sound information (circled on the left-hand side of the picture below). This area was not activated when visual object information was accessed. It can also be seen in the picture that more brain regions than those just mentioned were activated by each of the tasks, but these findings can be accounted for by other factors and are not relevant to the particular question described here. The brain is complex and probably never does just one thing!
The findings from this functional neuroimaging study show that all types of object knowledge are not stored in a single long-term memory brain area, but rather each type of knowledge is stored in a specific brain region which takes advantage of the specialised processing properties of various brain structures. Understanding how the storage of these types of long-term knowledge is organised in the normal brain provides an important step towards comprehending what may have gone wrong in patients with diseases or brain damage which affect these knowledge systems, and developing suitable tests and strategies to investigate disruptions of these systems more effectively. We would like to thank the members of the Volunteer Panel who took part in this PET study and enabled us to acquire these valuable and exciting results.
Marion Kellenbach, Matthew Brett and Karalyn Patterson
Struggling to understand: how the brain makes sense of distorted speech
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In everyday life, it is not always easy to understand what people are saying. Sometimes it can be difficult to carry on a conversation because of background noise such as the buzz of conversation in a busy pub, or sudden interruptions from coughs and sneezes. Even if we can hear the speaker clearly, an unfamiliar accent may cause problems in understanding. In each of these situations, we may be aware that we are struggling to understand what is being said to us. A recent project led by Ingrid Johnsrude and Matt Davis of the Language Group investigated the brain processes that are engaged when we are trying to make sense of speech in difficult situations such as these.
For this study we used three types of artificial distortion, analogous to real situations in which speech can be difficult to understand. For instance, speech presented over a continuous background noise is similar to having a conversation in a noisy environment. Sentences interrupted by occasional bursts of noise are equivalent to the effect of coughs or other loud interruptions. To simulate the effect of hearing an unfamiliar accent, sentences were processed by computer to create speech that sounded like a harsh, robotic whisper. For each of these three types of distortion, a range of parameters were used to make sentences that were progressively more difficult to understand - for instance by increasing the amount of background noise, the number of interruptions, or by increasing the amount of computerised distortion.
Working with two undergraduate students from Cambridge University, Iain Turnbull and Philip Dilks, we tested how many words people could repeat from regular sentences that had been distorted in one of these three ways and to different degrees. For each type of distortion we observed a continuum of responses. With the lightest distortions, people could repeat most of the words in each sentence correctly. As the sentences became more severely distorted people could repeat fewer of the words, until, for the most severe distortions, people could repeat very few words, making these sentences impossible to understand.
Having tested these sentences and distortions, we then used functional Magnetic Resonance Imaging (fMRI) to investigate which regions of the brain were most active when people listened to sentences that had been distorted in different ways and to different degrees. The fMRI scans carried out at the Wolfson Brain Imaging Centre at Addenbrokes Hospital provide a measure of blood flow throughout the brain. Since blood flow increases to the parts of the brain that are working harder, we can use fMRI to discover which brain areas are involved when hearing clear speech, and also how these areas react as speech becomes increasingly difficult to understand.
We observed several areas in the frontal and temporal lobe of the left hemisphere in which blood flow changed in response to these different kinds of sentences. The coloured areas shown in the figure on the left indicate areas in which blood flow increased for more comprehensible sentences, this correlation suggested that these areas play an important role in understanding speech. We can use the response to different forms of distortion to tell us what role each of these areas plays in the comprehension process. For instance, we see an area (coloured red in the figure) which responds more strongly to some forms of distortion than others. We think that this area is involved in processing the sound of speech, and responds differently because the three distortions sound different. Conversely areas which responded equally to the three forms of distortion (coloured blue in the figure) may play a higher level role in comprehension, and may be involved in processing the words and meanings of speech. Finally we saw regions in the frontal lobe which responded more strongly to distorted speech than to clear speech. One interpretation of this finding is that these brain areas are involved when people are working harder to understand distorted speech.
Matt Davis
Can interruption be useful?
Brian was a well-educated man in his mid 40's. In 1995 he suffered a serious head injury in a road accident that left him in coma for 3 days. In many ways his recovery was remarkable. Over two years his performance on tests of reasoning and memory returned to above average levels. Unfortunately, it was only when Brian returned to work that his remaining deficits became apparent. His job required a great deal of flexibility. In order to achieve goals and meet deadlines he would need to keep track of a changing situation, re-prioritise, and switch between one activity and another. Despite his many intact cognitive abilities, and in common with many people who have suffered damage to the frontal areas of the brain, it was precisely this level of organisation that Brian now found so difficult.
A great deal of psychological research, particularly work carried out at this Unit, has focused on the down side of interruption or distraction. When we are trying to focus on a difficult activity and other events compete for our attention, performance usually suffers. Measuring these effects has been very important in characterising 'limited capacities' like working memory and attention. In thinking about cases like Brian's, however, we wondered whether interruption might have some advantages. One problem shared by Brian and other patients is a tendency to get so caught up in one activity that they neglect their overall goal. For example, Brian might get so engrossed in writing a report that he would fail to prepare for, or even miss, an appointment with a client. Would deliberately contriving interruptions to current activity help Brian in keeping track of his main aims?
In collaboration with the Oliver Zangwill Centre for Neuropsychological Rehabilitation at Ely, we asked 10 head injured patients to complete a test under two conditions. In the 'Hotel' test, the patients were asked to tackle five activities that might be necessary in running a hotel (making up customers' bills, sorting conference labels alphabetically, and so on). The crucial aspect of the test was that completing any of these component tasks would take longer than the 15 minutes available for the whole test. As the patients were instructed to try each of the activities - and to spend as long on each as possible - we were trying to assess their ability to keep track of the time, and not get so caught up in one part of the test that they neglected the main aspect of the task. In one condition a loud, distracting 'bleep' was presented every so often and we simply asked patients to use this as a reminder to think about what they were doing.
Compared with volunteers from the panel, the patients performed poorly on the basic Hotel Test. They attempted significantly fewer of the tasks and were poor at allocating time to the different components exactly reflecting aspects of their difficulties in daily life. With the introduction of the interruptions, however, their performance significantly improved and was no longer any different from that of the control group.
There are many reasons why a person could do badly on this test. They could, for example, fail to remember the instructions or have misunderstood them in the first place. The fact that patients improved with the presentation of the uninformative tone is very useful in ruling out some of these other factors. Most importantly it suggests that using environmental manipulations can help such patients in organising their remaining abilities in order to achieve useful goals. Increasingly we all have access to devices such as pagers, organisers and mobile phones that allow us to cue ourselves at some point in the future to perform a particular activity. We are now actively exploring whether these devices can be used to help head injured patients to be more effective in planning and reflecting on progress.
Tom Manly
(This work was carried out by Tom Manly, Kari Hawkins, Jon Evans, Karina Woldt and Ian Robertson.)
Students at the CBU
The CBU houses up to 18 or so PhD students, registered at the University of Cambridge, who are at varying stages of completing their PhD studies. The help given to their research by members of the Volunteer Panel is invaluable. Here is just a small sample of the work that they are engaged in.
Apraxia - the inability to move on command
Apraxia is a movement disorder with symptoms that are easily overlooked, if help is not expressly sought, because it is seldom noticed by the patient or relatives. Why is this so?
A patient with Apraxia for example might be asked to gesture waving goodbye on command and fail to do so. Yet when leaving the testing room the same patient waves goodbye. Similarly, when being asked to blow out a candle, a patient with apraxia might not be able to do so. As soon as a candle is put in front of the patient though, he or she will be able to blow it out. So in everyday life necessary movements can be made and a person with apraxia might not suffer from any obvious motor or sensory deficits and be able to use his or her limbs normally.
Yet it deserves attention, because it provides clues to the way action planning is organized in the brain. Plans of motor actions seem to be present in the brain of apraxic patient but they can't access them.
We are interested where in the brain motor plans for movements are stored in healthy individuals. Further we are investigating whether a movement that is highly learned and automatic is processed differently and in a different location in the brain, compared to newly learned movement. We are using functional Magnetic Resonance Imaging to make brain activation associated with movements visible.
The participation of research panel members is allowing us to find out more about the motor systems that might be damaged in patients with apraxia. Thank you!
Katja Osswald (supervisor: Matthew Brett)
Helping people with depression
Major depression is a serious health problem carrying substantial personal and social costs. After one recovers from depression, there is a significant risk of depression coming back again. Previous research has shown that, for many people, when they are depressed, they tend to be extremely self-critical, pessimistic and ruminative in their thinking. When one recovers from depression, these ways of thinking may seem to have disappeared but they can easily be reactivated in certain circumstances such as a lowering of mood. It is therefore important to find a way to help people who have recovered from depression to learn skills to deal with their thinking and mood so as to stay well. A few years ago, this unit did a pioneer study on an innovative cost-effective psychological group training programme which has been designed to prevent relapse in recovered depressed patients. This eight-week programme draws on the research findings about the interaction of mood and thinking and the long tradition of mindfulness training. It showed that patients with three or more previous episodes of depression who received the training had significantly lower relapse rate in the twelve-month follow-up period. My study aims to further investigate the effectiveness of this programme and to assess its impact on the way people think and see themselves and their environment. In addition to the 75 people who have recovered from depression, I have also had the assistance of 50 panel members who have never been depressed before to participate in this study. Information from the panel members has helped me to examine their ways of thinking and perception in contrast with the recovered depressed people before and after the programme. A deeper understanding of what brings about the changes in people's ability to handle their thoughts and feelings and 'nip in the bud' the downward depressive spiral will have significant contribution to further improve the preventative treatments for depression.
Helen Ma (supervisor: John Teasdale)
Understanding why some people only see half the world
My research examines how good we are at focussing on or attending to the things that are important in guiding our behaviour in the visual world. Following brain injury, some patients are unable to attend to things on one side of space and so they have problems 'seeing' things on that side. This disability can lead them, for example, only to eat half the food on their plate and bump into things on their poor side. My research has required me to use both healthy individuals from the Volunteer Panel and patients to try to understand how we normally manage to attend to things in the visual world and what goes wrong following brain injury. We have carried out a series of studies with the same group of participants in each, to see whether we can examine the characteristic problems patients have following damage to particular regions of the brain. We have found that people with the spatial problems I have described, also have other difficulties which may exacerbate their problems. These include a slowing in the speed at which they can identify objects and a reduction in the number of objects they can focus on at any one time. We hope that this research will help to better understand the scope of the problems patients may have following damage to specific regions of the brain. This may help us to get a better idea of how the brain solves the complex puzzle of deciding what we should attend to. In addition, by seeing what happens when the brain is damaged we can find out which regions of the brain are particularly important in solving this puzzle. Finally, this work will hopefully help to better characterise the multiple problems patients have following damage to a particular region of the brain and thus we may be able to develop rehabilitation strategies for patients which address all their difficulties and help them to overcome them.
Polly Peers (supervisor: John Duncan)
Rhythm and motion: beat matters.....
Rhythm is a ubiquitous part of our lives. We walk and talk in a certain rhythm, and we listen to and perform rhythmic music. What's the relationship between the perception and production of rhythm? What effect does musical training have on rhythmic abilities? What parts of the brain process rhythm? These are some of the research questions in which I am interested.
My research looks at processing of rhythms that have a beat, and irregular rhythms that have no beat. I have found so far that people reproduce rhythms with a beat more easily and accurately than irregular rhythms, even when they are short. They are better able to detect changes in beat-based rhythms than in irregular rhythms. Watching rhythms instead of listening to them results in much worse performance for most people, but a few people's performance is enhanced. Whilst musicians are often better overall at these rhythm tasks, many non-musicians also perform at the top level, so training cannot underlie all rhythmic abilities.
In addition, I am curious about what areas of the brain are involved in processing rhythm, and if those areas are different when the rhythm has a beat versus when it is irregular. In order to look at this, I will conduct a brain-scanning study, looking at brain activity when people are listening to beat-based rhythms and irregular rhythms. There is reason to believe that beat-based rhythms are processed in part by the motor system (this would explain why we often move in response to rhythm, sometimes without even realizing it). Certain types of brain damage seem to interfere specifically with the ability to make periodic, predictable movements, not unlike those made when walking or producing a beat-based rhythm. Do these people hear rhythm the same way as others? This is another question I would like to address in future, by looking at their performance on rhythm listening and reproduction tasks.
Jessica Grahn (supervisor: Matthew Brett)
What is it like to hear with a bionic ear?
Drs. Christopher Long and Bob Carlyon are studying how people hear with a "bionic ear" known as a cochlear implant. This device provides a sense of hearing to patients whose hearing loss is so great that they receive little or no benefit from traditional hearing aids. Sound is picked up by a microphone worn behind the ear, digitally processed, and transmitted to a device beneath the skin, which then stimulates an array of electrodes that has been surgically implanted in the inner ear. These electrodes then directly stimulate the auditory nerve.
Although many cochlear implant users communicate well in quiet, they still report great difficulty understanding speech in noisy situations. Our overall goal is to understand how one could overcome this problem. As well as performing experiments with implant users, we have developed acoustic simulations which, we think, produce a pattern of activation in the auditory nerves of normal-hearing subjects that is similar to that produced by a cochlear implant in a deaf patient. These simulations allow us to examine fundamental issues of perception relevant to hearing with a cochlear implant and to rapidly explore a variety of different speech processing strategies — with normal-hearing subjects. Our experiments have shown that both cochlear implant users and normal hearing subjects listening to special stimuli are affected by the presence of an interfering sound in the same way. This helps confirm the ability of our simulations to provide insight into hearing with cochlear implants. Additional experiments will examine if we can allow cochlear implant users to use the "tricks" that normal hearing listeners use when listening to one voice when there are competing voices present — such as in a crowded room. The most successful of the speech processing strategies determined in the acoustic simulations, could later be implemented and tested in a cochlear implant and may help users to separate the speech of one speaker from competing sounds.
Christopher Long & Bob Carlyon
A beginner's guide to neuroimaging
We carry out our neuroimaging at the Wolfson Brain Imaging Centre, at Addenbrooke's Hospital. The centre has two scanners: one uses Positron Emission Tomography (or PET), and the other uses functional Magnetic Resonance Imaging (or fMRI). Both rely on 20th century advances in physics to capture 3D images of brain activity. As an example, say you are seeing a set of faces while in the scanner, the area of the brain used for processing facial information (in the temporal lobes) will increase in blood flow (picked up by the PET scanner) or will use more energy, in the form of taking oxygen from the blood (picked up by the fMRI scanner). Using this simple principle of linking increases in brain activity to specific psychological processes, we can learn vital details about the functional mapping of the brain.
At the Unit, neuroimaging has become one of the most prevalent and important means by which we can improve understanding in our various fields. In every area, from our emotions and memories, to language and learning, we are applying brain-scanning techniques to discover which parts of the brain support these processes.
While such work undoubtedly helps us learn about how the normal brain carries out all the mental tasks it does, the unit has a strong history in working with patients. So how does neuroimaging help us understand what can go wrong with the brain to lead to these debilitating illnesses? Well, we are actually scanning many patient groups, such as those with depression, anxiety, Parkinson's Disease, etc. to find out exactly how their brain activity differs from non-clinical populations, and how the drugs they are prescribed influences their neural functioning. We can even use neuroimaging techniques on those in a coma, to discover what residual function they may have - and possibly make predictions about their recovery.
Without your help, we could not continue making discoveries about how the brain works, and what goes wrong when mental illness occurs. It is very greatly appreciated.