Posts tagged MRI

ScienceDaily (Aug. 21, 2012) — New magnetic resonance imaging (MRI) research shows that changes in brain blood flow associated with vein abnormalities are not specific for multiple sclerosis (MS) and do not contribute to its severity, despite what some researchers have speculated. Results of the research are published online in the journal Radiology.

"MRI allowed an accurate evaluation of cerebral blood flow that was crucial for our results," said Simone Marziali, M.D., from the Department of Diagnostic Imaging at the University of Rome Tor Vergata in Rome.

MS is a disease of the central nervous system in which the body’s immune system attacks the nerves. There are different types of MS, and symptoms and severity vary widely. Recent reports suggest a highly significant association between MS and chronic cerebrospinal venous insufficiency (CCSVI), a condition characterized by compromised blood flow in the veins that drain blood from the brain. This strong correlation has generated substantial attention from the scientific community and the media in recent years, raising the possibility that MS can be treated with endovascular procedures like stent placement. However, the role of brain blood flow alterations on MS patients is still unclear.

To investigate this further, Italian researchers compared brain blood flow in 39 MS patients and 26 healthy control participants. Twenty-five of the MS patients and 14 of the healthy controls were positive for CCSVI, based on Color-Doppler-Ultrasound (CDU) findings. The researchers used dynamic susceptibility contrast-enhanced (DSC) MRI to assess blood flow in the brains of the study groups. DSC MR imaging offers more accurate assessment of brain blood flow than that of CDU. MRI and CDU were used to assess two different anatomical structures.

While CCSVI-positive patients showed decreased cerebral blood flow and volume compared with their CCSVI-negative counterparts, there was no significant interaction between MS and CCSVI for any of the blood flow parameters. Furthermore, the researchers did not find any correlation between the cerebral blood flow and volume in the brain’s white matter and the severity of disability in MS patients.

The results suggest that CCSVI is not a pathological condition correlated with MS, according to Dr. Marziali, but probably just an epiphenomenon — an accessory process occurring in the course of a disease that is not necessarily related to the disease. This determination is important because, to date, studies of the prevalence of CCSVI in MS patients have provided inconclusive results.

"This study clearly demonstrates the important role of MRI in defining and understanding the causes of MS," Dr. Marziali said. "I believe that, in the future, it will be necessary to use powerful and advanced diagnostic tools to obtain a better understanding of this and other diseases still under study."

Source: Science Daily

ScienceDaily (July 24, 2012) — Neuroscientists from Wayne State University and the Massachusetts Institute of Technology (MIT) are taking a deeper look into how the brain mechanisms for memory retrieval differ between adults and children. While the memory systems are the same in many ways, the researchers have learned that crucial functions with relevance to learning and education differ.

The team’s findings were published on July 17, 2012, in the Journal of Neuroscience.

According to lead author Noa Ofen, Ph.D., assistant professor in WSU’s Institute of Gerontology and Department of Pediatrics, cognitive ability, including the ability to learn and remember new information, dramatically changes between childhood and adulthood. This ability parallels with dramatic changes that occur in the structure and function of the brain during these periods.

In the study, “The Development of Brain Systems Associated with Successful Memory Retrieval of Scenes,” Ofen and her collaborative team tested the development of neural underpinnings of memory from childhood to young adulthood. The team of researchers exposed participants to pictures of scenes and then showed them the same scenes mixed with new ones and asked them to judge whether each picture was presented earlier. Participants made retrieval judgments while researchers collected images of their brains with magnetic resonance imaging (MRI).

Using this method, the researchers were able to see how the brain remembers. “Our results suggest that cortical regions related to attentional or strategic control show the greatest developmental changes for memory retrieval,” said Ofen.

The researchers said that older participants used the cortical regions more than younger participants when correctly retrieving past experiences.

"We were interested to see whether there are changes in the connectivity of regions in the brain that support memory retrieval," Ofen added. "We found changes in connectivity of memory-related regions. In particular, the developmental change in connectivity between regions was profound even without a developmental change in the recruitment of those regions, suggesting that functional brain connectivity is an important aspect of developmental changes in the brain."

This study marks the first time that the development of connectivity within memory systems in the brain has been tested, and the results suggest that the brain continues to rearrange connections to achieve adult-like performance during development.

Ofen and her research team plan to continue research in this area, focused on modeling brain network connectivity, and applying these methods to study abnormal brain development.

Source: Science Daily

ScienceDaily (July 23, 2012) — Snack consumption and BMI are linked to both brain activity and self-control, new research has found.

Snack consumption and BMI are linked to both brain activity and self-control, new research has found. (Credit: © farbkombinat / Fotolia)

The research, carried out by academics from the Universities of Exeter, Cardiff, Bristol, and Bangor, discovered that an individual’s brain ‘reward centre’ response to pictures of food predicted how much they subsequently ate. This had a greater effect on the amount they ate than their conscious feelings of hunger or how much they wanted the food,

A strong brain response was also associated with increased weight (BMI), but only in individuals reporting low levels of self-control on a questionnaire. For those reporting high levels of self-control a stronger brain response to food was actually related to a lower BMI.

This study, which is now published in the journal NeuroImage, adds to mounting evidence that overeating and increased weight are linked, in part, to a region of the brain associated with motivation and reward, called the nucleus accumbens. Responses in this brain region have been shown to predict weight gain in healthy weight and obese individuals, but only now have academics discovered that this is independent of conscious feelings of hunger, and that self-control also plays a key role.

Following these results, academics at the University of Exeter and Cardiff have begun testing ‘brain training’ techniques designed to reduce the influence of food cues on individuals who report low levels of self-control. Similar tests are being used to assist those with gambling or alcohol addiction.

Dr Natalia Lawrence of Psychology at the University of Exeter, lead researcher in both the original research and the new studies, said: “Our research suggests why some individuals are more likely to overeat and put on weight than others when confronted with frequent images of snacks and treats. Food images, such as those used in advertising, cause direct increases in activity in brain ‘reward areas’ in some individuals but not in others. If those sensitive individuals also struggle with self-control, which may be partly innate, they are more likely to be overweight. We are now developing computer programs that we hope will counteract the effects of this high sensitivity to food cues by training the brain to respond less positively to these cues.”

Twenty-five young, healthy females with BMIs ranging from 17-30 were involved in the study. Female participants were chosen because research shows females typically exhibit stronger responses to food-related cues. The hormonal changes during the menstrual cycle affect this reaction, so all participants were taking the monophasic combined oral contraceptive pill. Participants had not eaten for at least six hours to ensure they were hungry at the time of the scan and were given a bowl containing 150 g (four and a half packets) of potato chips to eat at the end of the study; they were informed that potato chip intake had been measured afterwards.

Researchers used MRI scanning to detect the participants’ brain activity while they were shown images of household objects, and food that varied in desirability and calorific content. After scanning, participants rated the food images for desirability and rated their levels of hunger and food craving. Results showed that participants’ brain responses to food (relative to objects) in the nucleus accumbens predicted how many potato chips they ate after the scan. However, participants’ own ratings of hunger and how much they liked and wanted the foods, including potato chips, were unrelated to their potato chip intake.

This study was funded by the Wales Institute of Cognitive Neuroscience.

What this study shows:

• Brain responses to food images vary considerably between individuals.
• Brain responses to food images but not conscious feelings of hunger or desire to eat predict subsequent potato chip consumption.
• Individuals’ reported levels of self-control influence whether this brain response is associated with a higher or lower BMI.

What this study does NOT show:

• Brain responses to food cues cause overeating.
• The associations reported here are true in everyone — only healthy young women were included.
• Whether our brain response and levels of self-control are learned or innate.

Source: Science Daily

ScienceDaily (July 19, 2012) — A joint study carried out by The University of Nottingham and the multinational food company Unilever has found for the first time that fat in food can reduce activity in several areas of the brain which are responsible for processing taste, aroma and reward.

The research, now available in the Springer journal Chemosensory Perception, provides the food industry with better understanding of how in the future it might be able to make healthier, less fatty food products without negatively affecting their overall taste and enjoyment. Unveiled in 2010, Unilever’s Sustainable Living Plan sets out its ambition to help hundreds of millions of people improve their diet around the world within a decade.

This fascinating three-year study investigated how the brains of a group of participants in their 20s would respond to changes in the fat content of four different fruit emulsions they tasted while under an MRI scanner. All four samples were of the same thickness and sweetness, but one contained flavour with no fat, while the other three contained fat with different flavour release properties.

The research found that the areas of the participants’ brains which are responsible for the perception of flavour — such as the somatosensory cortices and the anterior, mid & posterior insula — were significantly more activated when the non-fatty sample was tested compared to the fatty emulsions despite having the same flavour perception. It is important to note that increased activation in these brain areas does not necessarily result in increased perception of flavour or reward.

Dr Joanne Hort, Associate Professor in Sensory Science at The University of Nottingham said: “This is the first brain study to assess the effect of fat on the processing of flavour perception and it raises questions as to why fat emulsions suppress the cortical response in brain areas linked to the processing of flavour and reward. It also remains to be determined what the implications of this suppressive effect are on feelings of hunger, satiety and reward.”

Unilever food scientist Johanneke Busch, based at the company’s Research & Development laboratories in Vlaardingen, Netherlands added: “There is more to people’s enjoyment of food than the product’s flavour — like its mouthfeel, its texture and whether it satisfies hunger, so this is a very important building block for us to better understand how to innovate and manufacture healthier food products which people want to buy.”

Source: Science Daily