How brain imaging redefine intelligence

High-tech scans of the resting human brain can provide a new way to define and interpret the brain's actual mental capacity, new research suggests. NYU School of Medicine researchers used a specialized imaging technology to measure patients' brains for entropy , the variety of nerve circuits used to interpret the surrounding world.

Part of theories on human consciousness, the concept of entropy has become a greater research focus with recent improvements in the ability of functional magnetic resonance imaging (fMRI) to track chemical activity patterns in the brain.

By analyzing fMRI images in every region of the brains in 892 American men and women, the study authors linked greater entropy to more versatile processing of information. This is considered a key aspect of intelligence, researchers say, because of the large volume of sensory information coming into the brain from its environment.

Functional MRI scans of brain entropy are a new means to understanding human intelligence," says study lead investigator Glenn Saxe, MD, a professor in child and adolescent psychiatry at NYU School of Medicine and a member of NYU Langone Health's Neuroscience Institute.

Human intelligence is so meaningful because it is about the capacity to understand whatever may come, when there is no way beforehand to know what may come. An intelligent brain has to be flexible in the number of possible ways its nerve cells, or neurons, may be rearranged.

Functional MRI scans use magnetic fields and radio waves to measure subtle changes in blood flow to detect which brain cells and circuits are active or inactive. As part of the study, people were tested when their brains and minds were resting (not unengaged in a particular task) to get a base reading. Study participants had their brains imaged as they enrolled in the Harvard-based Brain Genomics Superstruct study over the last decade, with the stored images forming the foundation of the NYU team's analysis.

Researchers compared hundreds of fMRI scans taken milliseconds apart. The scans revealed the number of possible combinations of electrically active brain cells available to interact with each other in specific regions of the brain. The research team then used mathematical models validated by past studies to arrive at reliable, statistical entropy scores based on how well one set of active nerve-cell combinations captured by one image predicted those in the next image. Experts say the activity level of the estimated 100 billion neurons in the brain depends on how much sensory information is being processed at any instant, with many often inactive.

Scientists next compared their statistical measures of relatively higher or lower entropy with participants' scores on two standard IQ tests: the Shipley-Hartford test, which gauges verbal skills, and the Wechsler test, which assesses problem-solving abilities. If brain entropy could offer useful insight into intelligence, then it should track closely with IQ scores.

People with average intelligence have an IQ score of about 100, with current study participants having an above-average IQ, at 108. Study participants ' entropy scores were strongly tied to IQ. Using standard statistical techniques that were performed two different ways to ensure accuracy, the researchers found that higher entropy was significantly related to the brain regions where previous research has shown it matters most.

 Entropy scores closely matched IQ scores from the Shipley-Hartford test for the left side of the middle brain (the left inferior temporal lobe), which is tied to learning speech. Similarly, entropy scores tracked closely with those from the Wechsler test for the front region of the brain (bilateral anterior frontal lobes), a known center for organization, planning, and emotional control.
           haleplushearty.blogspot.com

Why people get aggressive after drinking

Researchers have used magnetic resonance imaging (MRI) scans that measure blood flow in the brain to understand why people become aggressive and violent after drinking alcohol. After only two drinks, the researchers noted changes in the working of the prefrontal cortex of the brain, the part involved in tempering a person's levels of aggression. The study was led by Thomas Denson of the University of New South Wales in Australia in the journal Cognitive, Affective, & Behavioral Neuroscience.

According to most theories, alcohol-related aggression is caused by changes in the prefrontal cortex. However, there is a lack of substantial neuroimaging evidence to substantiate these ideas. In this study, Denson and his team recruited fifty healthy young men. The participants were either given two drinks containing vodka, or placebo drinks without any alcohol. While lying in an MRI scanner, the participants then had to compete in a task which has regularly been used over the past 50 years to observe levels of aggression in response to provocation.

The functional magnetic resonance imaging allowed the researchers to see which areas of the brain were triggered when the task was performed. They could also compare the difference in scans between participants who had consumed alcohol and those who hadn't. Being provoked was found to have no influence on participants' neural responses. However, when behaving aggressively, there was a dip in activity in the prefrontal cortex of the brains of those who had consumed alcoholic drinks. This dampening effect was also seen in the areas of the brain that are involved reward. Also, heightened activity was noted in the hippocampus, the part of the brain associated with people's memory.

Although there was an overall dampening effect of alcohol on the prefrontal cortex, even at a low dose of alcohol there is a significant positive relationship between dorsomedial and dorsolateral prefrontal cortex activity and alcohol-related aggression. These regions may support different behaviors, such as peace versus aggression, depending on whether a person is sober or intoxicated.

The results are largely consistent with a growing body of research about the neural basis of aggression, and how it is triggered by changes in the way that the prefrontal cortex, the limbic system and reward-related regions of the brain function. The results of the current study are also consistent with several psychological theories of alcohol-related aggression.
          halepluhearty.blogspot.com

HIV treatment prevents cognitive decline

HIV-positive patients have the same risk of dementia as any other person if they take viral-suppressing medication and live a healthy lifestyle. One of the most debilitating effects of HIV is the neurocognitive decline, which can range from memory and language issues to dementia. Until now, research suggested that even those who take anti-retroviral therapy, the viral suppressing drug, had a higher risk of brain disorders than the general population.

Those who successfully suppress their viral load and live healthily have the same lifetime risk of dementia and other brain disorders as any other person. Older patients' brains may already have been ravaged by the disease, and medication couldn't reverse the damage, which would typically trigger symptoms within three or four years.

Researchers examined adults with HIV treated with cART with good viral suppression as well as those who did not have HIV for comparison. Both groups were about half women, with an average age of around 48 for the HIV-positive adults and 51 for the HIV-negative adults. Over the course of two years, the researchers assessed their brain changes using MRI scans.

They focused on the cortical thickness and subcortical volumes. They also assessed their cognitive performance using neuropsychological assessments. Those with HIV had poorer cognition and reduced brain thickness and volume than adults without HIV. However, by the end of the study, there were barely any differences between the two groups.
         haleplushearty.blogspot.com