Archive for November 2009
The human brain is bombarded with all kinds of information, from the memory of last night’s delicious dinner to the instructions from your boss at your morning meeting. But how do you “tune in” to just one thought or idea and ignore all the rest of what is going on around you, until it comes time to think of something else?
Researchers at the Kavli Institute for Systems Neuroscience and Centre for the Biology of Memory at the Norwegian University of Science and Technology (NTNU) have discovered a mechanism that the brain uses to filter out distracting thoughts to focus on a single bit of information. Their results are reported in 19 November issue of Nature.
Think of your brain like a radio: You’re turning the knob to find your favourite station, but the knob jams, and you’re stuck listening to something that’s in between stations. It’s a frustrating combination that makes it quite hard to get an update on swine flu while a Michael Jackson song wavers in and out. Staying on the right frequency is the only way to really hear what you’re after. In much the same way, the brain’s nerve cells are able to “tune in” to the right station to get exactly the information they need, says researcher Laura Colgin, who was the paper’s first author. “Just like radio stations play songs and news on different frequencies, the brain uses different frequencies of waves to send different kinds of information,” she says.
Gamma waves as information carriers
Colgin and her colleagues measured brain waves in rats, in three different parts of the hippocampus, which is a key memory center in the brain. While listening in on the rat brain wave transmissions, the researchers started to realize that there might be something more to a specific sub-set of brain waves, called gamma waves. Researchers have thought these waves are linked to the formation of consciousness, but no one really knew why their frequency differed so much from one region to another and from one moment to the next.
Information is carried on top of gamma waves, just like songs are carried by radio waves. These “carrier waves” transmit information from one brain region to another. “We found that there are slow gamma waves and fast gamma waves coming from different brain areas, just like radio stations transmit on different frequencies,” she says.
You really can “be on the same wavelength”
“You know how when you feel like you really connect with someone, you say you are on the same wavelength? When brain cells want to connect with each other, they synchronize their activity,” Colgin explains. “The cells literally tune into each other’s wavelength. We investigated how gamma waves in particular were involved in communication across cell groups in the hippocampus. What we found could be described as a radio-like system inside the brain. The lower frequencies are used to transmit memories of past experiences, and the higher frequencies are used to convey what is happening where you are right now.”
If you think of the example of the jammed radio, the way to hear what you want out of the messy signals would be to listen really hard for the latest news while trying to filter out the unwanted music. The hippocampus does this more efficiently. It simply tunes in to the right frequency to get the station it wants. As the cells tune into the station they’re after, they are actually able to filter out the other station at the same time, because its signal is being transmitted on a different frequency.
“The cells can rapidly switch their activity to tune in to the slow waves or the fast waves,” Colgin says, “but it seems as though they cannot listen to both at the exact same time. This is like when you are listening to your radio and you tune in to a frequency that is midway between two stations- you can’t understand anything- it’s just noise.” In this way, the brain cells can distinguish between an internal world of memories and a person’s current experiences. If the messages were carried on the same frequency, our perceptions of the world might be completely confused. “Your current perceptions of a place would get mixed up with your memories of how the place used to be,” Colgin says.
The cells that tune into different wavelengths work like a switch, or rather, like zapping between radio stations that are already programmed into your radio. The cells can switch back and forth between different channels several times per second. The switch allows the cells to attend to one piece at a time, sorting out what’s on your mind from what’s happening and where you are at any point in time. The researchers believe this is an underlying principle for how information is handled throughout the brain.
“This switch mechanism points to superfast routing as a general mode of information handling in the brain,” says Edvard Moser, Kavli Institute for Systems Neuroscience director. “The classical view has been that signaling inside the brain is hardwired, subject to changes caused by modification of connections between neurons. Our results suggest that the brain is a lot more flexible. Among the thousands of inputs to a given brain cell, the cell can choose to listen to some and ignore the rest and the selection of inputs is changing all the time. We believe that the gamma switch is a general principle of the brain, employed throughout the brain to enhance interregional communication.”
Can a switch malfunction explain schizophrenia?
People who are schizophrenic have problems keeping these brain signals straight. They cannot tell, for example, if they are listening to voices from people who are present or if the voices are from the memory of a movie they have seen. “We cannot tell for sure if it is this switch that is malfunctioning, but we do know that gamma waves are abnormal in schizophrenic patients,” Colgin says. “Schizophrenics’ perceptions of the world around them are mixed up, like a radio stuck between stations.”
Nature 462, 353-357 (19 November 2009) | doi:10.1038/nature08573; Received 10 July 2009; Accepted 9 October 2009
Frequency of gamma oscillations routes flow of information in the hippocampus.
Laura Lee Colgin1, Tobias Denninger1,3, Marianne Fyhn1,3, Torkel Hafting1,3, Tora Bonnevie1, Ole Jensen2, May-Britt Moser1 & Edvard I. Moser1
1. Kavli Institute for Systems Neuroscience and Centre for the Biology of Memory, MTFS, Olav Kyrres gate 9, Norwegian University of Science and Technology, NO-7489 Trondheim, Norway
2. Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, P.O. Box 9101, Nijmegen NL-6500 HB, The Netherlands
3. Present addresses: Massachusetts Institute of Technology, The Picower Institute for Learning and Memory, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA (T.D.); University of California San Francisco, Department of Physiology, 513 Parnassus Avenue, San Francisco, California 94143, USA (M.F. and T.H.).
Correspondence to: Laura Lee Colgin1Edvard I. Moser1 Correspondence and requests for materials should be addressed to L.L.C. (Email: firstname.lastname@example.org) or E.I.M. (Email: email@example.com).
Gamma oscillations are thought to transiently link distributed cell assemblies that are processing related information, a function that is probably important for network processes such as perception attentional selection and memory. This ‘binding’ mechanism requires that spatially distributed cells fire together with millisecond range precision; however, it is not clear how such coordinated timing is achieved given that the frequency of gamma oscillations varies substantially across space and time, from approx 25 to almost 150 Hz. Here we show that gamma oscillations in the CA1 area of the hippocampus split into distinct fast and slow frequency components that differentially couple CA1 to inputs from the medial entorhinal cortex, an area that provides information about the animal’s current position, and CA3, a hippocampal subfield essential for storage of such information. Fast gamma oscillations in CA1 were synchronized with fast gamma in medial entorhinal cortex, and slow gamma oscillations in CA1 were coherent with slow gamma in CA3. Significant proportions of cells in medial entorhinal cortex and CA3 were phase-locked to fast and slow CA1 gamma waves, respectively. The two types of gamma occurred at different phases of the CA1 theta rhythm and mostly on different theta cycles. These results point to routeing of information as a possible function of gamma frequency variations in the brain and provide a mechanism for temporal segregation of potentially interfering information from different sources.
Research by the University of Warwick and the University of Manchester finds that psychological therapy could be 32 times more cost effective at making you happy than simply obtaining more money. The research has obvious implications for large compensation awards in law courts but also has wider implications for general public health.
Chris Boyce of the University of Warwick and Alex Wood of the University of Manchester compared large data sets where 1000s of people had reported on their well-being. They then looked at how well-being changed due to therapy compared to getting sudden increases in income, such as through lottery wins or pay rises. They found that a 4 month course of psychological therapy had a large effect on well-being. They then showed that the increase in well-being from an £800 course of therapy was so large that it would take a pay rise of over £25,000 to achieve an equivalent increase in well-being. The research therefore demonstrates that psychological therapy could be 32 times more cost effective at making you happy than simply obtaining more money.
Governments pursue economic growth in the belief that it will raise the well-being of its citizens. However, the research suggests that more money only leads to tiny increases in happiness and is an inefficient way to increase the happiness of a population. This research suggests that if policy makers were concerned about improving well-being they would be better off increasing the access and availability of mental health care as opposed to increasing economic growth.
This research helps to highlight how relatively ineffective extra income is at raising well-being. The researchers further draw on two striking pieces of independent evidence to illustrate their point — over the last 50 years developed countries have not seen any increases to national happiness in spite of huge economic gains. Mental health on the other hand appears to be deteriorating worldwide. The researchers argue that resources should be directed towards the things that have the best chance of improving the health and happiness of our nations — investment in mental health care by increasing the access and availability of psychological therapy could be a more effective way of improving national well-being than the pursuit of income growth.
The research also has important implications for the way in which “pain and suffering” is compensated in courts of law. Currently the default way in which individuals are compensated is with financial compensation. The research suggests that this is an inefficient way at repairing psychological harm following traumatic life events and that a more effective remedy would be to offer psychological therapy.
University of Warwick researcher Chris Boyce said: “We have shown that psychological therapy could be much more cost effective than financial compensation at alleviating psychological distress. This is not only important in courts of law, where huge financial awards are the default way in which pain and suffering are compensated, but has wider implications for public health and well-being.”
“Often the importance of money for improving our well-being and bringing greater happiness is vastly over-valued in our societies. The benefits of having good mental health, on the other hand, are often not fully appreciated and people do not realise the powerful effect that psychological therapy, such as non-directive counselling, can have on improving our well-being.”
Health Economics, Policy and Law doi:10.1017/S1744133109990326
Money or mental health: the cost of alleviating psychological distress with monetary compensation versus psychological therapy
Christopher J. Boycea1 c1 and Alex M. Wooda2
a1 Department of Psychology, University of Warwick, Coventry, UK
a2 School of Psychological Sciences, University of Manchester, Manchester, UK
Abstract Money is the default way in which intangible losses, such as pain and suffering, are currently valued and compensated in law courts. Economists have suggested that subjective well-being regressions can be used to guide compensation payouts for psychological distress following traumatic life events. We bring together studies from law, economic, psychology and medical journals to show that alleviating psychological distress through psychological therapy could be at least 32 times more cost effective than financial compensation. This result is not only important for law courts but has important implications for public health. Mental health is deteriorating across the world – improvements to mental health care might be a more efficient way to increase the health and happiness of our nations than pure income growth.
Correspondence: c1 Correspondence to: Christopher J. Boyce, Department of Psychology, University of Warwick, Coventry CV4 7AL, UK. Email: firstname.lastname@example.org
A study by researchers at the University of Bergen, Norway, and the Institute of Psychiatry (IoP) at King’s College London has found that depression is as much of a risk factor for mortality as smoking.
Utilising a unique link between a survey of over 60,000 people and a comprehensive mortality database, the researchers found that over the four years following the survey, the mortality risk was increased to a similar extent in people who were depressed as in people who were smokers.
Dr Robert Stewart, who led the research team at the IoP, explains the possible reasons that may underlie these surprising findings: ‘Unlike smoking, we don’t know how causal the association with depression is but it does suggest that more attention should be paid to this link because the association persisted after adjusting for many other factors.’
The study also shows that patients with depression face an overall increased risk of mortality, while a combination of depression and anxiety in patients lowers mortality compared with depression alone. Dr Stewart explains: ‘One of the main messages from this research is that ‘a little anxiety may be good for you’.
‘It appears that we’re talking about two risk groups here. People with very high levels of anxiety symptoms may be naturally more vulnerable due to stress, for example through the effects stress has on cardiovascular outcomes. On the other hand, people who score very low on anxiety measures, i.e. those who deny any symptoms at all, may be people who also tend not to seek help for physical conditions, or they may be people who tend to take risks. This would explain the higher mortality.’
In terms of the relationship between mortality and anxiety with depression as a risk factor, the research suggests that help-seeking behaviour may explain the pattern of outcomes. People with depression may not seek help or may fail to receive help when they do seek it, whereas the opposite may be true for people with anxiety.
Dr Stewart comments: ‘It would certainly not surprise me at all to find that doctors are less likely to investigate physical symptoms in people with depression because they think that depression is the explanation, but may be more likely to investigate if someone is anxious because they think it will reassure them. These are conjectures but they would fit with the data.’
The researchers point out that the results should be considered in conjunction with other evidence suggesting a variety of adverse physical health outcomes and poor health associated with mental disorders such as depression and psychotic disorders.
In light of the findings, Dr Stewart makes suggestions on the focus of future developments in the treatment of depression and anxiety: ‘The physical health of people with current or previous mental disorder needs a lot more attention than it gets at the moment.
‘This applies to primary care, secondary mental health care and general hospital care in the sense that there should be more active screening for physical disorders and risk factors, such as blood pressure, cholesterol, adverse diet, smoking, lack of exercise, in people with mental disorders. This should be done in addition to more active treatment of disorders when present, and more effective general health promotion.’
The British Journal of Psychiatry (2009) 195: 118-125. doi: 10.1192/bjp.bp.108.054866
Levels of anxiety and depression as predictors of mortality: the HUNT study,
Arnstein Mykletun, Ottar Bjerkeset, Simon Øverland, Martin Prince, Michael Dewey and Robert Stewart
Background Depression is reported to be associated with increased mortality, although underlying mechanisms are uncertain. Associations between anxiety and mortality are also uncertain.
Aims To investigate associations between individual and combined anxiety/depression symptom loads (using the Hospital Anxiety and Depression Scale (HADS)) and mortality over a 3–6 year period.
Method We utilised a unique link between a large population survey (HUNT–2, n = 61 349) and a comprehensive mortality database.
Results Case-level depression was associated with increased mortality (hazard ratio (HR) = 1.52, 95% CI 1.35–1.72) comparable with that of smoking (HR = 1.59, 95% CI 1.44–1.75), and which was only partly explained by somatic symptoms/conditions. Anxiety comorbid with depression lowered mortality compared with depression alone (anxiety depression interaction P = 0.017). The association between anxiety symptom load and mortality was U-shaped.
Conclusions Depression as a risk factor for mortality was comparable in strength to smoking. Comorbid anxiety reduced mortality compared with depression alone. The relationship between anxiety symptoms and mortality was more complex with a U-shape and highest mortality in those with the lowest anxiety symptom loads.
Learning to talk also changes the way speech sounds are heard, according to a new study published in Proceedings of the National Academy of Sciences by scientists at Haskins Laboratories, a Yale-affiliated research laboratory. The findings could have a major impact on improving speech disorders.
“We’ve found that learning is a two-way street; motor function affects sensory processing and vice-versa,” said David J. Ostry, a senior scientist at Haskins Laboratories and professor of psychology at McGill University. “Our results suggest that learning to talk makes it easier to understand the speech of others.”
As a child learns to talk, or an adult learns a new language, Ostry explained, a growing mastery of oral fluency is matched by an increase in the ability to distinguish different speech sounds. While these abilities may develop in isolation, it is possible that learning to talk also changes the way we hear speech sounds.
Ostry and co-author Sazzad M. Nasir tested the notion that speech motor learning alters auditory perceptual processing by evaluating how speakers hear speech sounds following motor learning. They simulated speech learning by using a robotic device, which introduced a subtle change in the movement path of the jaw during speech.
To assess speech perception, the participants listened to words one at a time that were taken from a computer-produced continuum between the words “had” and “head.” In the speech learning phase of the study, the robot caused the jaw to move in a slightly unusual fashion. The learning is measured by assessing the extent to which participants correct for the unusual movement.
“Its like being handed a two-pound weight for the first time and being asked to make a movement, it’s uncomfortable at first, but after a while, the movement becomes natural,” said Ostry. “In growing children, the nervous system has to adjust to moving vocal tract structures that are changing in size and weight in order to produce the same words. Participants in our study are learning to return the movement to normal in spite of these changes. Eventually our work could have an impact on deviations to speech caused by disorders such as stroke and Parkinson’s disease.”
“Our study showed that speech motor learning altered the perception of these speech sounds. After motor learning, the participants heard the words differently than those in the control group,” said Ostry. “One of the striking findings is that the more motor learning we observed, the more their speech perceptual function changed.”
Ostry said that future research will focus on the notion that sensory remediation may be a way to jumpstart the motor system.
The team previously found that the movement of facial muscles around the mouth plays an important role not only in the way the sounds of speech are made, but also in the way they are heard.
Haskins Laboratories was founded in 1935 by the late Dr. Caryl P. Haskins. This independent research institute has been in New Haven, Connecticut since 1970 when it formalized affiliations with Yale University and the University of Connecticut. The Laboratories’ primary research focus is on the science of the spoken and written word.
PNAS published online before print November 2, 2009, doi:10.1073/pnas.0907032106
Auditory plasticity and speech motor learning
* Sazzad M. Nasir
* and David J. Ostry
Abstract Is plasticity in sensory and motor systems linked? Here, in the context of speech motor learning and perception, we test the idea sensory function is modified by motor learning and, in particular, that speech motor learning affects a speaker’s auditory map. We assessed speech motor learning by using a robotic device that displaced the jaw and selectively altered somatosensory feedback during speech. We found that with practice speakers progressively corrected for the mechanical perturbation and after motor learning they also showed systematic changes in their perceptual classification of speech sounds. The perceptual shift was tied to motor learning. Individuals that displayed greater amounts of learning also showed greater perceptual change. Perceptual change was not observed in control subjects that produced the same movements, but in the absence of a force field, nor in subjects that experienced the force field but failed to adapt to the mechanical load. The perceptual effects observed here indicate the involvement of the somatosensory system in the neural processing of speech sounds and suggest that speech motor learning results in changes to auditory perceptual function.
In her weekly podcast, Merkel called the invitation a “great honour” and said she would use the occasion to thank the United States for backing German unification in 1990 — 11 months after the Wall’s fall — with “great enthusiasm and fondness”.
Blessed are the poor in spirit: for theirs is the kingdom of heaven. How stupid does the chancellor believe Germans to be? Isn’t delivering enthusiastic and fond speeches in Washington dulling people’s mind, rather than being an honour? How about fondness and enthusiasm in Khabul for a change?
of some things that are diamond shaped, and others that are just square…
see also: Rory Sutherland on advertising and intangible added value
No pain, no gain applies to happiness, too, according to new research published online in the Journal of Happiness Studies. People who work hard at improving a skill or ability, such as mastering a math problem or learning to drive, may experience stress in the moment, but experience greater happiness on a daily basis and longer term, the study suggests.
“No pain, no gain is the rule when it comes to gaining happiness from increasing our competence at something,” said Ryan Howell, assistant professor of psychology at San Francisco State University. “People often give up their goals because they are stressful, but we found that there is benefit at the end of the day from learning to do something well. And what’s striking is that you don’t have to reach your goal to see the benefits to your happiness and well-being.”
Contrary to previous research, the study found that people who engage in behaviors that increase competency, for example at work, school or the gym, experience decreased happiness in the moment, lower levels of enjoyment and higher levels of momentary stress. Despite the negative effects felt on an hourly basis, participants reported that these same activities made them feel happy and satisfied when they looked back on their day as a whole. This surprising find suggests that in the process of becoming proficient at something, individuals may need to endure temporary stress to reap the happiness benefits associated with increased competency.
The study examined whether people who spend time on activities that fulfill certain psychological needs, believed to be necessary for growth and well-being, experience greater happiness. In addition to the need to be competent, the study focused on the need to feel connected to others and to be autonomous or self-directed, and it examined how fulfilling these three needs affects a person’s happiness moment by moment within a day.
For two days, participants reported how they spent each hour, the enjoyment and stress experienced in that hour, and whether the activity met their need for competency, connectedness to others or autonomy. A second group of participants completed a similar survey, but reported on the day as a whole.
While behaviors that increase competency were associated with decreased happiness in the moment, people who spent time on activities that met the need for autonomy or feeling connected to others experienced increased happiness both an hourly and daily basis. The greatest increase in momentary happiness was experienced by participants who engaged in something that met their need for autonomy — any behavior that a person feels they have chosen, rather than ought to do, and that helps them further their interests and goals.
The authors suggest that shifting the balance of needs met in a day could help people find ways to cope with short term stress in the workplace. “Our results suggest that you can decrease the momentary stress associated with improving your skill or ability by ensuring you are also meeting the need for autonomy and connectedness, for example performing the activity alongside other people or making sure it is something you have chosen to do and is true to who you are,” Howell said.
Relating these momentary gains in happiness to people’s long term life satisfaction, the study found that those who are already satisfied with their life in the long term stand to gain most from the momentary happiness that is derived from feeling connected to others and a sense of autonomy.
“Like a wine connoisseur whose experience means they can appreciate a fine wine more than a novice, people who are already satisfied with their life may have learned how to glean the satisfaction of these needs from their daily activities,” Howell said.
Journal of Happiness Studies
Momentary Happiness: The Role of Psychological Need Satisfaction.
Ryan T. Howell 1, David Chenot 2, Graham Hill1 and Colleen J. Howell 3
(1) Department of Psychology, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
(2) Department of Social Work, California State University, Fullerton, CA, USA
(3) Department of Environmental Science, University of California, Riverside, CA, USA
Abstract Psychological well-being correlates positively with psychological need satisfaction—primarily the needs of autonomy, competence, and relatedness. The current study explores momentary happiness (defined as experienced enjoyment minus experienced stress over the course of an hour) as a function of momentary psychological need satisfaction. Results demonstrate that hour-by-hour ratings of psychological need satisfaction were correlated with momentary happiness, with individual differences in life satisfaction moderating this relationship. Ratings of autonomy and relatedness correlated positively with momentary happiness, while competence was negatively correlated with momentary happiness. Thus, engagement in competence-promoting behaviors may come at an affective cost, at least in the moment. When autonomy and relatedness needs were met, individuals with high levels of life satisfaction experienced greater increases in happiness than individuals with low levels of life satisfaction. This finding supports a sensitization model of well-being. Results are discussed with respect to their implications for self-determination theory (SDT).
Keywords Subjective well-being – Happiness – Self-determination theory – Psychological needs