Posts tagged science

June 18, 2012

New pictures from the University of Iowa show what it looks like when a person runs out of patience and loses self-control.

This image shows brain activity when people exert self-control. Credit: University of Iowa

A study by University of Iowa neuroscientist and neuro-marketing expert William Hedgcock confirms previous studies that show self-control is a finite commodity that is depleted by use. Once the pool has dried up, we’re less likely to keep our cool the next time we’re faced with a situation that requires self-control.

But Hedgcock’s study is the first to actually show it happening in the brain using fMRI images that scan people as they perform self-control tasks. The images show the anterior cingulate cortex (ACC)—the part of the brain that recognizes a situation in which self-control is needed and says, “Heads up, there are multiple responses to this situation and some might not be good”—fires with equal intensity throughout the task.

However, the dorsolateral prefrontal cortex (DLPFC)—the part of the brain that manages self-control and says, “I really want to do the dumb thing, but I should overcome that impulse and do the smart thing”—fires with less intensity after prior exertion of self-control.

This image shows brain activity after people have been engaged in self-control tasks long enough that self-control resources have been depleted. Credit: University of Iowa

He said that loss of activity in the DLPFC might be the person’s self-control draining away. The stable activity in the ACC suggests people have no problem recognizing a temptation. Although they keep fighting, they have a harder and harder time not giving in.

Which would explain why someone who works very hard not to take seconds of lasagna at dinner winds up taking two pieces of cake at desert. The study could also modify previous thinking that considered self-control to be like a muscle. Hedgcock says his images seem to suggest that it’s like a pool that can be drained by use then replenished through time in a lower conflict environment, away from temptations that require its use.

The researchers gathered their images by placing subjects in an MRI scanner and then had them perform two self-control tasks—the first involved ignoring words that flashed on a computer screen, while the second involved choosing preferred options. The study found the subjects had a harder time exerting self-control on the second task, a phenomenon called “regulatory depletion.” Hedgcock says that the subjects’ DLPFCs were less active during the second self-control task, suggesting it was harder for the subjects to overcome their initial response.

Hedgcock says the study is an important step in trying to determine a clearer definition of self-control and to figure out why people do things they know aren’t good for them. One possible implication is crafting better programs to help people who are trying to break addictions to things like food, shopping, drugs, or alcohol. Some therapies now help people break addictions by focusing at the conflict recognition stage and encouraging the person to avoid situations where that conflict arises. For instance, an alcoholic should stay away from places where alcohol is served.

But Hedgcock says his study suggests new therapies might be designed by focusing on the implementation stage instead. For instance, he says dieters sometimes offer to pay a friend if they fail to implement control by eating too much food, or the wrong kind of food. That penalty adds a real consequence to their failure to implement control and increases their odds of choosing a healthier alternative.

The study might also help people who suffer from a loss of self-control due to birth defect or brain injury.

"If we know why people are losing self-control, it helps us design better interventions to help them maintain control," says Hedgcock, an assistant professor in the Tippie College of Business marketing department and the UI Graduate College’s Interdisciplinary Graduate Program in Neuroscience.

Provided by University of Iowa

Source: medicalxpress.com

June 18, 2012

Fear conditioning using sound and taste aversion, as applied to mice, have revealed interesting information on the basis of memory allocation.

Credit: Thinkstock

European ‘Cellular mechanisms underlying formation of the fear memory trace in the mouse amygdala’ (FEAR Memory TRACE) project is investigating memory allocation and the recruitment of certain neurons to encode a memory. By studying conditioned fear memory in response to an auditory stimulus, the researchers have delved into pathological emotional states and neural mechanisms involved in memory allocation, retrieval and extinction.

Prior research has revealed that the conditioned fear response in mice is located in a specific bundle of neurons in the amygdala. Memory allocation modulation is due to expression of the transcription factor, cyclic adenosine 3’, 5’-monophosphate response element binding protein (CREB) and possibly neuronal excitability.

FEAR Memory TRACE focused on the electrophysiological properties of neurons encoding the same memory. The project also aimed to ascertain the biophysical mechanisms in the plasticity changes recorded in the specific set of neurons in the fear memory trace.

Recording information on auditory fear conditioning and conditioned taste aversion, the scientists used intra-amygdala surgery using viral vectors and electrophysiological experiments to detect neuronal excitability.

Transfected by virus, CREB tagged with green fluorescent protein together with the gene for channelrhodopsin2 were used in neural control experiments. Combined, these two elements caused neuron firing in specific nerve cells. Molecular techniques included western blot for protein detection, genotyping and viral DNA preparation.

Behavioural tests on long- and short-term memory of mice involving fear conditioning and taste aversion showed increased memory performance at the three-hour point rather than the five-hour point. The intrinsic excitability of the mice receiving both shock and the tone was increased at three hours, not five, compared to mice that only received the tone.

As the project continues to its close in two years, the aim is to identify biophysical mechanisms involved in recruiting neurons that compete with each other for a specific memory. FEAR Memory TRACE will also develop computational models to assess the role of these mechanisms in memory performance.

Information on biochemical processes in neural mechanisms has wide application in many clinical situations including patients suffering memory loss, such as stroke victims. Fear response manipulation can be applied in treatment of neuroses and phobias.

Provided by CORDIS

Source: medicalxpress.com

June 17, 2012

A collaborative research team led by Professor Tadashi ISA from The National Institute for Physiological Sciences, The National Institutes of Natural Sciences and Fukushima Medical University and Kyoto University, developed a “double viral vector transfection technique” which can deliver genes to a specific neural circuit by combining two new kinds of gene transfer vectors. With this method, they found that “indirect pathways”, which were suspected to have been left behind when the direct connection from the brain to motor neurons (which control muscles) was established in the course of evolution, actually plays an important role in the highly developed dexterous hand movements. This study was supported by the Strategic Research Program for Brain Sciences by the MEXT of Japan. This research result will be published in Nature (June 17th, advance online publication).

It is said that the higher primates including human beings accomplished explosive evolution by having acquired the ability to move hands skillfully. It has been thought that this ability to move individual fingers is a result of the evolution of the direct connection from the cerebrocortical motor area to motor neurons of the spinal cord which control the muscles. On the other hand, in lower animals with clumsy hands, such as cats or rats, the cortical motor area is connected to the motor neurons, only through interneurons of the spinal cord. Such “indirect pathway”remains in us, primates, without us fully understanding its functions. Is this “phylogenetically old circuit” still in operation? Or maybe suppressed since it is obstructive? The conclusion was not attached to this argument.

The collaborative research team led by Professor Tadashi ISA, Project Assistant Professor Masaharu KINOSHITA from The National Institute for Physiological Sciences, The National Institutes of Natural Sciences and Fukushima Medical University and Kyoto University developed “the double viral vector transfection technique”which can deliver genes to a specific neural circuit by combining two new kinds of gene transfer vectors.

With this method, they succeeded in the selective and reversible suppression of the propriospinal neurons (spinal interneurons mediating the indirect connection from cortical motor area to spinal motor neurons)

The results revealed that “indirect pathways” play an important role in dexterous hand movements and finally a longtime debate has come to a close.

The key component of this discovery was”the double viral vector transfection technique”in which one vector is retrogradely transported from the terminal zone back to the neuronal cell bodies and the other is transfected at the location of their cell bodies. The expression of the target gene is regulated only in the cells with double transfection by the two vectors. Using this technique, they succeeded in the suppression of the propriospinal neuron selectively and reversibly.

Such an operation was possible in mice in which the inheritable genetic manipulation of germline cells were possible, but impossible in primates until now.

Using this method, further development of gene therapy targeted to a specific neural circuit can be expected.

Professor Tadashi ISA says “this newly developed double viral vector transfection technique can be applied to the gene therapy of the human central nervous system, as we are the same higher primates.

And this is the discovery which reverses the general idea that the spinal cord is only a reflex pathway, but also plays a pivotal role in integrating the complex neural signals which enable dexterous movements.”

Provided by National Institute for Physiological Sciences

Source: medicalxpress.com

ScienceDaily (June 16, 2012) — A link between unconscious conflicts and conscious anxiety disorder symptoms have been shown, lending empirical support to psychoanalysis.

Data from the experiment showing that subliminal exposure to words related to a person’s unconscious conflict, followed by supraliminal exposure to words related to their anxiety symptoms, led to different alpha wave patterns compared with other scenarios. (Credit: Image courtesy of University of Michigan Health System)

An experiment that Sigmund Freud could never have imagined 100 years ago may help lend scientific support for one of his key theories, and help connect it with current neuroscience.

June 16 at the 101st Annual Meeting of the American Psychoanalytic Association, a University of Michigan professor who has spent decades applying scientific methods to the study of psychoanalysis will present new data supporting a causal link between the psychoanalytic concept known as unconscious conflict, and the conscious symptoms experienced by people with anxiety disorders such as phobias.

Howard Shevrin, Ph.D., emeritus professor of psychology in the U-M Medical School’s Department of Psychiatry, will present data from experiments performed in U-M’s Ormond and Hazel Hunt Laboratory.

The research involved 11 people with anxiety disorders who each received a series of psychoanalytically oriented diagnostic sessions conducted by a psychoanalyst.

From these interviews the psychoanalysts inferred what underlying unconscious conflict might be causing the person’s anxiety disorder. Words capturing the nature of the unconscious conflict were then selected from the interviews and used as stimuli in the laboratory. They also selected words related to each patient’s experience of anxiety disorder symptoms. Although these words differed from patient to patient, results showed that they functioned in the same way.

These verbal stimuli were presented subliminally at one thousandth of a second, and supraliminally at 30 milliseconds. A control category of stimuli was added that had no relationship to the unconscious conflict or anxiety symptom. While the stimuli were presented to the patients, scalp electrodes record the brain responses to them.

In a previous experiment Shevrin had demonstrated that time-frequency features, a type of brain activity, showed that patients grouped the unconscious conflict stimuli together only when they were presented subliminally. But the conscious symptom-related stimuli showed the reverse pattern — brain activity was better grouped together when patients viewed those words supraliminally.

"Only when the unconscious conflict words were presented unconsciously could the brain see them as connected," Shevrin notes. "What the analysts put together from the interview session made sense to the brain only unconsciously."

However, the experimental design in this first experiment did not allow for directly comparing the effect of the unconscious conflict stimuli on the conscious symptom stimuli.

To obtain evidence for that next level, the unconscious conflict stimuli were presented immediately prior to the conscious symptom stimuli and a new measurement was made, of the brain’s own alpha wave frequency, at 8-13 cycles per second, that had been shown to inhibit various cognitive functions.

Highly significant correlations, suggesting an inhibitory effect, were obtained when the amount of alpha generated by the unconscious conflict stimuli were correlated with the amount of alpha associated with the conscious symptom alpha — but only when the unconscious conflict stimuli were presented subliminally. No results were obtained when control stimuli replaced the symptom words. The fact that these findings are a function of inhibition suggests that from a psychoanalytic standpoint that repression might be involved.

"These results create a compelling case that unconscious conflicts cause or contribute to the anxiety symptoms the patient is experiencing," says Shevrin, who also holds an emeritus position in the Department of Psychology in U-M’s College of Literature, Science and the Arts. "These findings and the interdisciplinary methods used — which draw on psychoanalysis, cognitive psychology, and neuroscience — demonstrate that it is possible to develop an interdisciplinary science drawing upon psychoanalytic theory."

He notes that a prominent critic of psychoanalysis and Freudian theory, Adolf Grunbaum, Ph.D., professor of the philosophy of science at the University of Pittsburgh, has expressed satisfaction that the new results, when added to previous evidence, show that fundamental psychoanalytic concepts can indeed be tested in empirical ways.

For more than 40 years, Shevrin has led a team that has pushed at the boundaries between the disciplines of neuroscience, cognitive psychology, and psychoanalysis, looking for evidence that Freudian concepts such as the unconscious and repression could be documented through physical measures of brain activity. His work has explored the territory where neurobiology, thoughts, emotions and behavior meet.

In 1968 he published the first report of brain responses to unconscious visual stimuli in Science, thus providing strong objective evidence for the existence of the unconscious at a time when most scientists were skeptical of Freud’s ideas. In that same study, he showed that unconscious perceptions are processed in different ways from conscious perceptions, a finding consistent with Freud’s views on how the unconscious works.

In recent years, exchanges between Grunbaum and Shevrin explored the nature of the evidence for the existence and impact of unconscious conflicts. In a 1992 publication, the first study referred to, Grunbaum agreed that Shevrin had obtained objective brain based evidence for the existence of unconscious conflict, but Grunbaum noted that he had not shown that these conflicts caused psychiatric symptoms. His response to being informed of the new findings was an email stating: “I am satisfied.”

Source: Science Daily

Adrian Owen has found a way to use brain scans to communicate with people previously written off as unreachable. Now, he is fighting to take his methods to the clinic.

Adrian Owen still gets animated when he talks about patient 23. The patient was only 24 years old when his life was devastated by a car accident. Alive but unresponsive, he had been languishing in what neurologists refer to as a vegetative state for five years, when Owen, a neuro-scientist then at the University of Cambridge, UK, and his colleagues at the University of Liège in Belgium, put him into a functional magnetic resonance imaging (fMRI) machine and started asking him questions.

Incredibly, he provided answers. A change in blood flow to certain parts of the man’s injured brain convinced Owen that patient 23 was conscious and able to communicate. It was the first time that anyone had exchanged information with someone in a vegetative state.

Patients in these states have emerged from a coma and seem awake. Some parts of their brains function, and they may be able to grind their teeth, grimace or make random eye movements. They also have sleep–wake cycles. But they show no awareness of their surroundings, and doctors have assumed that the parts of the brain needed for cognition, perception, memory and intention are fundamentally damaged. They are usually written off as lost.

Read more …

ScienceDaily (June 15, 2012) — People make complex judgements about a person from looking at their face that are based on a range of factors beyond simply their race and gender, according to findings of new research funded by the Economic and Social Research Council (ESRC).

The findings question a long-held belief that people immediately put a person they meet into a limited number of social categories such as: female or male; Asian, Black, Latino or White; and young or old.

Dr Kimberly Quinn at the University of Birmingham found that people ‘see’ faces in a multiple of ways. This could have wider importance in understanding stereotyping and discrimination because it has implications on whether and how people categorise others.

Categorisation is not done purely on the physical features of the face in front of us, but depends on other information as well, including whether the person is already known and whether the person is believed to share other important identities with us.

"How we perceive faces is not just a reflection of what’s in those faces," Dr Quinn said. "We are not objective; we bring our current goals and past knowledge to every new encounter. And this happens really quickly — within a couple of hundred milliseconds of seeing the face."

Dr Quinn and her colleagues explored social categories such as sex, race and age; physical attributes such as attractiveness; personality traits such as trustworthiness; and emotional states such as anger, sadness and happiness.

She found that although social categories are used to gather information on faces, these can be easily undermined. This research found that we reject simple stereotypes when something about the situation alerts us to the fact the stereotype does not tell the whole story. If we take, for example, a racial group and the corresponding stereotype of members of that group as unintelligent, seeing a person in that group playing an intellectual game such as chess would tell us to cancel out the stereotype.

In order to investigate the causes, mechanisms, and results of social categorisation, Dr Quinn used techniques from cognitive psychology and neuroscience to investigate how people process faces. The research was designed to provide insight into when and why people categorise others according to social group membership.

Their findings differ from previous research that adopted a ‘dual process’ approach and assumed people initially categorised faces based on factors such as gender, race or age before determining whether to stereotype them or to see them as unique individuals.

Dr Quinn’s findings were more consistent with a single process that initially focuses on ‘coarse’ information that is easy to detect, and then immediately starts to include more fine-grained processing as time elapses. This model allows for either categorisation or more individuated processing to emerge, and does not assume that categorisation always comes before recognising unique identities — thereby allowing for more diverse outcomes than previously thought.

Further information: http://www.esrc.ac.uk/my-esrc/grants/RES-061-23-0130/read

Source: Science Daily

ScienceDaily (June 15, 2012) — Researchers at The University of Nottingham have identified three sets of genetic markers that could potentially pave the way for new diagnostic tools for a deadly type of brain tumour that mainly targets children.

The study, published in the latest edition of the journal Lancet Oncology, was led by Professor Richard Grundy at the University’s Children’s Brain Tumour Research Centre and Dr Suzanne Miller, a post doctoral research fellow in the Centre.

It focuses on a rare and aggressive cancer called Central Nervous System primitive neuro-ectodermal brain tumours. Patients with CNS PNET have a very poor prognosis and current treatments, including high dose chemotherapy and cranio-spinal radiotherapy are relatively unsuccessful and have severe lifelong side-effects. This is particularly the case in very young children.

Despite the need for new and more effective treatments, little research has been done to examine the underlying causes of CNS PNET, partly due to their rarity. The Nottingham study aimed to identify molecular markers as a first step to improving the treatments and therapies available to fight the cancer.

The Nottingham team collaborated with researchers at the Hospital for Sick Kids in Toronto, Canada, to perform an International study collecting 142 CNS PNET samples from 20 institutions in nine countries.

Professor Richard Grundy said: “Following our earlier research we realised that an international effort was needed to bring sufficient numbers of cases together to make the breakthrough we needed to better understand this disease or indeed diseases identified in our study. The next step is to translate this knowledge into improving treatments.”

By studying the genetics of the tumours, they discovered that instead of one cancer, the tumours have three sub-types featuring distinct genetic abnormalities and leading to different outcomes for patients.

They found that each group had its own genetic signature through subtle differences in the way they expressed two genetic markers, LIN28 and OLIG2.

When compared with clinical factors including age, survival and metastases (the spread of the tumours through the body), they discovered that group 1 tumours (primitive neural) were found most often in the youngest patients and had the poorest survival rates. Patients with group 3 tumours had the highest incidence of metastases at diagnosis.

Ultimately, the research has identified the two genetic markers LIN28 and OLIG2 as a promising basis for more effective tools for diagnosing and predicting outcomes for young patients with these types of brain tumours.

The research was funded by the Canadian Institute of Health Research, the Brainchild/Sick Kids Foundation and the Samantha Dickson Brain Tumour Trust.

Chief Executive of Samantha Dickson Brain Tumour Trust, Sarah Lindsell, said: “As the UK’s leading brain tumour charity, and the largest dedicated funder of brain tumour research, we are delighted that our investment has led to such significant success. It is great to see that understanding of these tumours is improving — this is desperately needed given the poor outcomes for children with this tumour. Samantha Dickson Brain Tumour Trust is proud to have been instrumental in this work.”

Source: Science Daily

ScienceDaily (June 15, 2012) — A study recently published in the Endocrine Society’s Journal of Clinical Endocrinology and Metabolism (JCEM) suggests that vitamin D — when taken with calcium — can reduce the rate of mortality in seniors, therefore providing a possible means of increasing life expectancy.

During the last decade, there has been increasing recognition of the potential health effects of vitamin D. It is well known that calcium with vitamin D supplements reduces the risk of fractures. The present study assessed mortality among patients randomized to either vitamin D alone or vitamin D with calcium. The findings from the study found that the reduced mortality was not due to a lower number of fractures, but represents a beneficial effect beyond the reduced fracture risk.

"This is the largest study ever performed on effects of calcium and vitamin D on mortality," said Lars Rejnmark, PhD, of Aarhus University Hospital in Denmark and lead author of the study. "Our results showed reduced mortality in elderly patients using vitamin D supplements in combination with calcium, but these results were not found in patients on vitamin D alone."

In this study, researchers used pooled data from eight randomized controlled trials with more than 1,000 participants each. The patient data set was composed of nearly 90 percent women, with a median age of 70 years. During the three-year study, death was reduced by 9 percent in those treated with vitamin D with calcium.

"Some studies have suggested calcium (with or without vitamin D) supplements can have adverse effects on cardiovascular health," said Rejnmark. "Although our study does not rule out such effects, we found that calcium with vitamin D supplementation to elderly participants is overall not harmful to survival, and may have beneficial effects on general health."

Source: Science Daily