Prenatal Alcohol Exposure Alters Development of Brain Function

In the first study of its kind, Prapti Gautam, PhD, and colleagues from The Saban Research Institute of Children’s Hospital Los Angeles found that children with fetal alcohol spectrum disorders (FASD) showed weaker brain activation during specific cognitive tasks than their unaffected counterparts. These novel findings suggest a possible neural mechanism for the persistent attention problems seen in individuals with FASD. The results of this study will be published in Cerebral Cortex on August 4.

“Functional magnetic resonance imaging (fMRI) has been used to observe brain activity during mental tasks in children with FASD, but we are the first to utilize these techniques to look at brain activation over time,” says Gautam. “We wanted to see if the differences in brain activation between children with FASD and their healthy peers were static, or if they changed as children got older.”

FASD encompasses the broad spectrum of symptoms that are linked to in utero alcohol exposure, including cognitive impairment, deficits in intelligence and attention and central nervous system abnormalities. These symptoms can lead to attention problems and higher societal and economic burdens common in individuals with FASD.

During the period of childhood and adolescence, brain function, working memory and attention performance all rapidly improve, suggesting that this is a crucial time for developing brain networks. To study how prenatal alcohol exposure may alter this development, researchers observed a group of unaffected children and a group of children with FASD over two years. They used fMRI to observe brain activation through mental tasks such as visuo-spatial attention—how we visually perceive the spatial relationships among objects in our environment —and working memory.

“We found that there were significant differences in development brain activation over time between the two groups, even though they did not differ in task performance,” notes Elizabeth Sowell, PhD, director of the Developmental Cognitive Neuroimaging Laboratory at The Saban Research Institute and senior author on the manuscript. “While the healthy control group showed an increase in signal intensity over time, the children with FASD showed a decrease in brain activation during visuo-spatial attention, especially in the frontal, temporal and parietal brain regions.”

These results demonstrate that prenatal alcohol exposure can change how brain signaling develops during childhood and adolescence, long after the damaging effects of alcohol exposure in utero. The atypical development of brain activation observed in children with FASD could explain the persistent problems in cognitive and behavioral function seen in this population as they mature.

Does ‘free will’ stem from brain noise?

Our ability to make choices — and sometimes mistakes — might arise from random fluctuations in the brain’s background electrical noise, according to a recent study from the Center for Mind and Brain at the University of California, Davis.

"How do we behave independently of cause and effect?" said Jesse Bengson, a postdoctoral researcher at the center and first author on the paper. "This shows how arbitrary states in the brain can influence apparently voluntary decisions."

The brain has a normal level of “background noise,” Bengson said, as electrical activity patterns fluctuate across the brain. In the new study, decisions could be predicted based on the pattern of brain activity immediately before a decision was made.

Bengson sat volunteers in front of a screen and told them to fix their attention on the center, while using electroencephalography, or EEG, to record their brains’ electrical activity. The volunteers were instructed to make a decision to look either to the left or to the right when a cue symbol appeared on screen, and then to report their decision.

The cue to look left or right appeared at random intervals, so the volunteers could not consciously or unconsciously prepare for it.

The brain has a normal level of “background noise,” Bengson said, as electrical activity patterns fluctuate across the brain. The researchers found that the pattern of activity in the second or so before the cue symbol appeared — before the volunteers could know they were going to make a decision — could predict the likely outcome of the decision.

"The state of the brain right before presentation of the cue determines whether you will attend to the left or to the right," Bengson said.

The experiment builds on a famous 1970s experiment by Benjamin Libet, a psychologist at UCSF who was later affiliated with the UC Davis Center for Neuroscience.

Libet also measured brain electrical activity immediately before a volunteer made a decision to press a switch in response to a visual signal. He found brain activity immediately before the volunteer reported deciding to press the switch.

The new results build on Libet’s finding, because they provide a model for how brain activity could precede decision, Bengson said. Additionally, Libet had to rely on when volunteers said they made their decision. In the new experiment, the random timing means that “we know people aren’t making the decision in advance,” Bengson said.

Libet’s experiment raised questions of free will — if our brain is preparing to act before we know we are going to act, how do we make a conscious decision to act? The new work, though, shows how “brain noise” might actually create the opening for free will, Bengson said.

"It inserts a random effect that allows us to be freed from simple cause and effect," he said.

The work, which was funded by the National Institutes of Health, was published online in the Journal of Cognitive Neuroscience.

Children at risk for mental disorders experience communication breakdown in brain networks supporting attention

Attention deficits are central to psychiatric disorders such as schizophrenia or bipolar disorder, and are thought to precede the presentation of the illnesses. A new study led by Wayne State University School of Medicine researcher Vaibhav Diwadkar, Ph.D. suggests that the brain network interactions between regions that support attention are dysfunctional in children and adolescents at genetic risk for developing schizophrenia and bipolar disorder.

“The brain network mechanisms that mediate these deficits are poorly understood, and have rarely been tackled using complex image analytic methods that focus on how brain regions communicate,” said Dr. Diwadkar, associate professor of psychiatry and behavioral neurosciences and co-director of the department’s Brain Imaging Research Division

The desire to understand dysfunctional brain mechanisms motivated Dr. Diwadkar and his team of colleagues and WSU medical students in the study titled, “Dysfunction and dysconnection in cortical-striatal networks during sustained attention: genetic risk for schizophrenia or bipolar disorder and its impact on brain network function,” featured in the May issue of Frontiers in Psychiatry.

The study is clinically significant because the estimated lifetime incidence of schizophrenia or bipolar disorder in the groups studied is approximately 10-20 times what is generally observed. “We believe that genetic risk may confer vulnerability for dysfunctional brain network communication. This abnormal network communication in turn might amplify risk for psychiatric illnesses. By identifying markers of network dysfunction we believe we can elucidate these mechanisms of risk. This knowledge may in turn increase focus on possible premeditative intervention strategies,” Dr. Diwadkar said.

The researchers identified dysfunctional brain mechanisms of sustained attention using functional Magnetic Resonance Imaging data and complex modeling of fMRI signals. Data were collected in 46 children and adolescents ages 8 to 20, half at genetic risk for schizophrenia or bipolar disorder by virtue of having one or both parents with either illness. During the 20-minute fMRI, participants completed a sustained attention task, adapted to engage specific brain regions.

The researchers induced variations in the degree of demand on these brain regions – a method of assessing how genetic risk might impair the brain’s ability to respond to attention challenges –by varying task difficulty. Increased attention demand led to increased engagement in the typical control group. The genetically at-risk group did not respond the same. Instead, interactions between the dorsal anterior cingulate, a principal control region in the brain, and the basal ganglia were highly dysfunctional in that group, suggesting impaired communication between specific brain networks.

The study indicates that brain networks supporting basic psychological functions such as attention do not communicate appropriately in young individuals at genetic risk for illnesses such as schizophrenia or bipolar disorder.

“Genetics and neurodevelopment are inextricably linked. How psychiatric illnesses emerge from their combination is a central question in medicine. Analytic tools developed in the last few years offer the promise of answers at the level of how these processes impact brain network communication,” Dr. Diwadkar said.

Finding the perfect balance — regulating brain activity to improve attention

Researchers from The University of Nottingham have found that balanced activity in the brain’s prefrontal cortex is necessary for attention. 

The research helps to make sense of attention deficits in people suffering from cognitive disorders — like schizophrenia — who often find it hard to sustain their attention. This has a significant effect on many aspects of their lives, including the ability to follow conversations, drive a car and hold down a job.

Activity in a healthy brain is controlled by inhibitory signals between neurons. The research shows that disrupting this healthy inhibition may be just as bad for attention as reducing neuron firing. It is often assumed that increasing brain activity has cognitive benefits, but the findings show that this is not always the case.

The research was carried out by a team in the University’s School of Psychology and involved inhibiting or disinhibiting the prefrontal cortex in rats and monitoring the effect. The researchers found that both of these extremes resulted in attentional deficits and that the ability to pay attention required an appropriate balance where neuron-firing was kept within a certain range.

Schizophrenia and attention deficits 

Studies of the brain in people with schizophrenia suggest aberrant neuron-firing in the prefrontal cortex. There is evidence that neuron firing in this part of the brain is often too high or too low.

Dr Tobias Bast, who led the study together with first author Dr Marie Pezze, said: “The implication of our findings is that the abnormalities we see in the prefrontal cortex of schizophrenia patients, for example, are indeed a plausible cause of the attention deficit these patients have.

“It also means that if we want to treat this pharmacologically, we can’t just boost activity of the prefrontal cortex or inactivate it, because that would actually result in an impairment. What we need to do is look at restoring balance of activity through drugs which keep the activity within a certain range.”

Cognitive deficits associated with schizophrenia

In people with schizophrenia, cognitive deficits — such as problems with attention — are less striking than other issues associated with the disorder, such as hallucinations, but are nevertheless a major problem.

Dr Bast said: “Initially people focused on the so-called ‘psychotic symptoms’, including hallucinations and delusions, so that’s what probably comes to mind when you think of schizophrenia. They have been in the fore because they have been so striking and that’s why referrals are made. But these can be treated, at least in a large proportion of patients, by using anti-psychotic medication, which we have had since the late 1950s.

“The problem is that unfortunately anti-psychotic drugs don’t improve cognitive deficits which are very debilitating, affecting many aspects of the patients’ lives. Cognitive deficits are a big problem and something that is currently not treated so finding something that helps this is really important.”

Researchers use rhythmic brain activity to track memories in progress

University of Oregon researchers have tapped the rhythm of memories as they occur in near real time in the human brain.

Using electroencephalogram (EEG) electrodes attached to the scalps of 25 student subjects, a UO team led by psychology doctoral student David E. Anderson captured synchronized neural activity while they held a held a simple oriented bar located within a circle in short-term memory. The team, by monitoring these alpha rhythms, was able to decode the precise angle of the bar the subjects were locking onto and use that brain activity to predict which individuals could store memories with the highest quality or precision.

The findings are detailed in the May 28 issue of the Journal of Neuroscience. A color image illustrating how the item in memory was tracked by rhythmic brain activity in the alpha frequency band (8 to 12 beats per second) is on the journal’s cover page to showcase the research.

Although past research has decoded thoughts via brain activity, standard approaches are expensive and limited in their ability to track fast-moving mental representations, said Edward Awh, a professor in the UO’s Department of Psychology and Institute of Neuroscience. The new findings show that EEG measures of synchronized neural activity can precisely track the contents of memory at almost the speed of thought, he said.

"These findings provide strong evidence that these electrical oscillations in the alpha frequency band play a key role in a person’s ability to store a limited number of items in working memory," Awh said. “By identifying particular rhythms that are important to memory, we’re getting closer to understanding the low-level building blocks of this really limited cognitive ability. If this rhythm is what allows people to hold things in mind, then understanding how that rhythm is generated — and what restricts the number of things that can be represented — may provide insights into the basic capacity limits of the mind.”

The findings emerged from a basic research project led by Awh and co-author Edward K. Vogel — funded by the National Institutes of Health — that seeks to understand the limits of storing information. “It turns out that it’s quite restricted,” Awh said. “People can only think about a couple of things at a time, and they miss things that would seem to be extremely obvious and memorable if that limited set of resources is diverted elsewhere.”

Past work, mainly using functional magnetic resonance imaging (fMRI), has established that brain activity can track the content of memory. EEG, however, provides a much less expensive approach and can track mental activity with much a higher temporal resolution of about one-tenth of a second compared to about five seconds with fMRI.

"With EEG we get a fine-grained measure of the precise contents of memory, while benefitting from the superior temporal resolution of electrophysiological measures," Awh said. “This EEG approach is a powerful new tool for tracking and decoding mental representations with high temporal resolution. It should provide us with new insights into how rhythmic brain activity supports core memory processes.”

Losing the left side of the world: Rightward shift in human spatial attention with sleep onset

Unilateral brain damage can lead to a striking deficit in awareness of stimuli on one side of space called Spatial Neglect. Patient studies show that neglect of the left is markedly more persistent than of the right and that its severity increases under states of low alertness. There have been suggestions that this alertness-spatial awareness link may be detectable in the general population. Here, healthy human volunteers performed an auditory spatial localisation task whilst transitioning in and out of sleep. We show, using independent electroencephalographic measures, that normal drowsiness is linked with a remarkable unidirectional tendency to mislocate left-sided stimuli to the right. The effect may form a useful healthy model of neglect and help in understanding why leftward inattention is disproportionately persistent after brain injury. The results also cast light on marked changes in conscious experience before full sleep onset.

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(Image: ALAMY)

Structurally-Constrained Relationships between Cognitive States in the Human Brain

The anatomical connectivity of the human brain supports diverse patterns of correlated neural activity that are thought to underlie cognitive function. In a manner sensitive to underlying structural brain architecture, we examine the extent to which such patterns of correlated activity systematically vary across cognitive states. Anatomical white matter connectivity is compared with functional correlations in neural activity measured via blood oxygen level dependent (BOLD) signals. Functional connectivity is separately measured at rest, during an attention task, and during a memory task. We assess these structural and functional measures within previously-identified resting-state functional networks, denoted task-positive and task-negative networks, that have been independently shown to be strongly anticorrelated at rest but also involve regions of the brain that routinely increase and decrease in activity during task-driven processes. We find that the density of anatomical connections within and between task-positive and task-negative networks is differentially related to strong, task-dependent correlations in neural activity. The space mapped out by the observed structure-function relationships is used to define a quantitative measure of separation between resting, attention, and memory states. We find that the degree of separation between states is related to both general measures of behavioral performance and relative differences in task-specific measures of attention versus memory performance. These findings suggest that the observed separation between cognitive states reflects underlying organizational principles of human brain structure and function.

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How your brain works during meditation

Mindfulness. Zen. Acem. Meditation drumming. Chakra. Buddhist and transcendental meditation. There are countless ways of meditating, but the purpose behind them all remains basically the same: more peace, less stress, better concentration, greater self-awareness and better processing of thoughts and feelings.

But which of these techniques should a poor stressed-out wretch choose? What does the research say? Very little – at least until now.

Nondirective or concentrative meditation?

A team of researchers at the Norwegian University of Science and Technology (NTNU), the University of Oslo and the University of Sydney is now working to determine how the brain works during different kinds of meditation.

Different meditation techniques can actually be divided into two main groups. One type is concentrative meditation, where the meditating person focuses attention on his or her breathing or on specific thoughts, and in doing so, suppresses other thoughts. The other type may be called nondirective meditation, where the person who is meditating effortlessly focuses on his or her breathing or on a meditation sound, but beyond that the mind is allowed to wander as it pleases. Some modern meditation methods are of this nondirective kind.

“No one knows how the brain works when you meditate. That is why I’d like to study it,” says Jian Xu, who is a physician at St. Olavs Hospital and a researcher at the Department of Circulation and Medical Imaging at NTNU.

Two different ways to meditate

Fourteen people who had extensive experience with the Norwegian technique Acem meditation were tested in an MRI machine. In addition to simple resting, they undertook two different mental meditation activities, nondirective meditation and a more concentrative meditation task. The research team wanted to test people who were used to meditation because it meant fewer misunderstandings about what the subjects should actually be doing while they lay in the MRI machine.

The results were recently published in the journal “Frontiers in Human Neuroscience”.

Nondirective meditation led to higher activity than during rest in the part of the brain dedicated to processing self-related thoughts and feelings. When test subjects performed concentrative meditation, the activity in this part of the brain was almost the same as when they were just resting.

A place for the mind to rest

“I was surprised that the activity of the brain was greatest when the person’s thoughts wandered freely on their own, rather than when the brain worked to be more strongly focused,” said Xu. “When the subjects stopped doing a specific task and were not really doing anything special, there was an increase in activity in the area of the brain where we process thoughts and feelings. It is described as a kind of resting network. And it was this area that was most active during nondirective meditation.”

Provides greater freedom for the brain

“The study indicates that nondirective meditation allows for more room to process memories and emotions than during concentrated meditation,” says Svend Davanger, a neuroscientist at the University of Oslo, and co-author of the study.

“This area of the brain has its highest activity when we rest. It represents a kind of basic operating system, a resting network that takes over when external tasks do not require our attention. It is remarkable that a mental task like nondirective meditation results in even higher activity in this network than regular rest,” says Davanger.

Meditating researchers

Most of the research team behind the study do not practice meditation, although three do: Professors Are Holen and Øyvind Ellingsen from NTNU and Professor Svend Davanger from the University of Oslo.

Acem meditation is a technique that falls under the category of nondirective meditation. Davanger believes that good research depends on having a team that can combine personal experience with meditation with a critical attitude towards results.

“Meditation is an activity that is practiced by millions of people. It is important that we find out how this really works. In recent years there has been a sharp increase in international research on meditation. Several prestigious universities in the US  spend a great deal of money to research in the field. So I think it is important that we are also active,” says Davanger.