Brain Scans Reveal How Drinking Turns People Into Raging Assholes


We all have that friend who gets a little out of hand when they start drinking alcohol. Maybe he gets loud, or maybe she starts fights with strangers for looking at her funny. Alcohol seems to induce aggression, changing the brain in a way that makes a drunk person more likely to see minor social cues as threats, but how it does so has always been a bit of biological mystery.

Scientists found that alcohol-induced aggression was correlated to decreased activity in the prefrontal cortex.

But in a paper published in the journal Cognitive, Affective, & Behavioral Neuroscience, a team of researchers led by Thomas Denson, Ph.D., of the University of New South Wales School of Psychology use brain scans to show that alcohol changes activity in certain key parts of the brain related to aggression and emotion.

Using functional magnetic resonance imaging (fMRI), a technique that tracks changes in blood flow in the brain, the team looked at the brains of 50 young men after they consumed either two alcoholic drinks or two non-alcoholic placebo drinks. These volunteers engaged in a task that gauged their level of aggression in the face of provocation, which revealed the parts of the brain that become more active in such situations.

These scans show how alcohol-induced aggression was related to decreased activity in the prefrontal cortex, caudate, and ventral striatum, but increased activity in the hippocampus.
These scans show how alcohol-induced aggression was related to decreased activity in the prefrontal cortex, caudate, and ventral striatum, but increased activity in the hippocampus.

The researchers found that alcohol-induced aggression was correlated with decreased activity in prefrontal cortex, caudate, and ventral striatum, but increased activity in the hippocampus. These parts of the brain all control key factors in aggression: The prefrontal cortex is associated with thoughtful action and social behavior, the caudate is linked to the brain’s reward system and inhibitory control, and the ventral striatum is a part of the reward system that makes you feel good when you do something good. The hippocampus, meanwhile, is associated with emotion and memory.

These results support previous hypotheses that prefrontal cortex dysfunction is associated with alcohol-induced aggression. Taking all these brain areas together, the researchers say their findings suggest that intoxicated people have trouble processing information through their working memory. In short, they suspect that alcohol focuses a person’s attention on the cues that could instigate aggression while taking attention away from their knowledge of social norms that say violence is not acceptable.

Along similar lines, they also suspect that alcohol could make relatively minor cues seem aggressive or violent, which can cause a drunk person to overreact to a minor incident, like someone looking at them funny or accidentally bumping into them at the bar. Denson’s previous research on the angry brain found a lot of overlap in the way the prefrontal cortex behaves when someone is drunk and angry versus when they’re simply ruminating on their anger while sober.

This research proposes some possible brain biomarkers for alcohol-induced aggression, which is a significant public health issue. According to the Centers for Disease Control and Prevention, in the United States, alcohol-related violence — including homicide, child abuse, suicide, and firearm injuries — was responsible for more than 16,000 deaths between 2006 and 2010, the most recent years the agency reported figures.

While the new study doesn’t propose a solution per se, it does build on our body of knowledge around an age-old question: Why do some people become assholes when they get drunk?

Abstract: Alcohol intoxication is implicated in approximately half of all violent crimes. Over the past several decades, numerous theories have been proposed to account for the influence of alcohol on aggression. Nearly all of these theories imply that altered functioning in the prefrontal cortex is a proximal cause. In the present functional magnetic resonance imaging (fMRI) experiment, 50 healthy young men consumed either a low dose of alcohol or a placebo and completed an aggression paradigm against provocative and nonprovocative opponents. Provocation did not affect neural responses. However, relative to sober participants, during acts of aggression, intoxicated participants showed decreased activity in the prefrontal cortex, caudate, and ventral striatum, but heightened activation in the hippocampus. Among intoxicated participants, but not among sober participants, aggressive behavior was positively correlated with activation in the medial and dorsolateral prefrontal cortex. These results support theories that posit a role for prefrontal cortical dysfunction as an important factor in intoxicated aggression.

Can Your Brain Really Be “Full”?


Neuroimaging aids investigation into what happens in the brain when we try to remember information that’s very similar to what we already know

If the hippocampus is the search engine, the prefrontal cortex is the filter determining which memory is the most relevant.
The following essay is reprinted with permission from The Conversation, an online publication covering the latest research.The brain is truly a marvel. A seemingly endless library, whose shelves house our most precious memories as well as our lifetime’s knowledge. But is there a point where it reaches capacity? In other words, can the brain be “full”?The answer is a resounding no, because, well, brains are more sophisticated than that. A study published in Nature Neuroscience earlier this year shows that instead of just crowding in, old information is sometimes pushed out of the brain for new memories to form.

Previous behavioural studies have shown that learning new information can lead to forgetting. But in this study, researchers used new neuroimaging techniques to demonstrate for the first time how this effect occurs in the brain.

The experiment
The paper’s authors set out to investigate what happens in the brain when we try to remember information that’s very similar to what we already know. This is important because similar information is more likely to interfere with existing knowledge, and it’s the stuff that crowds without being useful.

To do this, they examined how brain activity changes when we try to remember a “target” memory, that is, when we try to recall something very specific, at the same time as trying to remember something similar (a “competing” memory). Participants were taught to associate a single word (say, the word sand) with two different images—such as one of Marilyn Monroe and the other of a hat.

They found that as the target memory was recalled more often, brain activity for it increased. Meanwhile, brain activity for the competing memory simultaneously weakened. This change was most prominent in regions near the front of the brain, such as the prefrontal cortex, rather than key memory structures in the middle of the brain, such as the hippocampus, which is traditionally associated with memory loss.

The prefrontal cortex is involved in a range of complex cognitive processes, such as planning, decision making, and selective retrieval of memory. Extensive research shows this part of the brain works in combination with the hippocampus to retrieve specific memories.

If the hippocampus is the search engine, the prefrontal cortex is the filter determining which memory is the most relevant. This suggests that storing information alone is not enough for a good memory. The brain also needs to be able to access the relevant information without being distracted by similar competing pieces of information.

Better to forget
In daily life, forgetting actually has clear advantages. Imagine, for instance, that you lost your bank card. The new card you receive will come with a new personal identification number (PIN). Research in this field suggests that each time you remember the new PIN, you gradually forget the old one. This process improves access to relevant information, without old memories interfering.

When we acquire new information, the brain automatically tries to incorporate it within existing information by forming associations. And when we retrieve information, both the desired and associated but irrelevant information is recalled.

The majority of previous research has focused on how we learn and remember new information. But current studies are beginning to place greater emphasis on the conditions under which we forget, as its importance begins to be more appreciated.

The curse of memory
A very small number of people are able to remember almost every detail of their life in great detail; they have hyperthymestic syndrome. If provided with a date, they are able to tell you where and what they were doing on that particular day. While it may sound like a boon to many, people with this rare condition often find their unusual ability burdensome.

Some report an inability to think about the present or the future, because of the feeling of constantly living in the past, caught in their memories. And this is what we all might experience if our brains didn’t have a mechanism for superseding information that’s no longer relevant and did indeed fill up.

At the other end of the spectrum is a phenomenon called “accelerated long-term forgetting”, which has been observed in epilepsy and stroke patients. As the name suggests, these people forget newly learnt information at a much faster rate, sometimes within a few hours, compared to what’s considered normal.

It’s believed this represents a failure to “consolidate” or transfer new memories into long-term memory. But the processes and impact of this form of forgetting are still largely unexplored.

What studies in this area are demonstrating is that remembering and forgetting are two sides of the same coin. In a sense, forgetting is our brain’s way of sorting memories, so the most relevant memories are ready for retrieval. Normal forgetting may even be a safety mechanism to ensure our brain doesn’t become too full.

Hippocampus Shape, Not Bulk Volume, Indicates How Well Our Memory Functions


Is bigger always better? A new investigation of the hippocampus — the brain structure where we consolidate factual memories — may not overturn the usual bias in favor of size, but it adds a new spin to the argument. A group of neuroscientists demonstrated that broader hippocampal shape related to better working memory, while greater hippocampal volume, the usual measure of brain size, did not.

hippocampus

Memory is not handled in a uniform way by our brains. Different regions and systems sort and collect our declarative memories, while other systems within our brains handle procedural memories. Declarative memory includes the facts we remember — for example, I ate a cheese sandwich while sitting beside the river on Tuesday. Procedural memory, sometimes referred to as implicit or unconscious memory, governs the recollection of learned skills — riding a bike, for instance. Due to this mental division of labor, the hippocampus is king when it comes to declarative memory, yet plays no part in procedural memory.

Notably, the hippocampus, which is shaped like a seahorse and hidden beneath the surface folds, is the first brain region eroded by Alzheimer’s, a disease that steals our memories. Learning more about the hippocampus, then, may have direct implications for this disease.

Shape vs. Volume

Typically, scientists view the size of the hippocampus as a way to determine the integrity of an older person’s memory, while neglecting all consideration of this brain structure’s shape. For the current study, scientists led by Dr. Mallar Chakravarty, an assistant professor at McGill University, collaborated with researchers from the Centre for Addiction and Mental Health to explore the relationship between hippocampus size and memory. Chakravarty and his team began by developing an algorithmic technique to map the hippocampus.

After they identified a variety of hippocampus shapes, they performed a close analysis and then characterized and sorted hippocampal types based on relative appearance of head, tail, and body.

Strangely enough, they discovered stereotypic shapes exist for the hippocampus.

Taking this observation one step further, they found that people with a broader shaped hippocampus tended to perform better on memory tests than others. In fact, shape differences were better predictors of memory function than volume.

“This exciting new finding may help us improve our understanding of how to preserve the memory circuit and its function,” Chakravarty stated in a press release. For all who fear Alzheimer’s, this study represents new hope for future treatments and prevention.

Source: Voineskos AN, Winterburn JL, Felsky D, et al. Hippocampal (subfield) volume and shape in relation to cognitive performance across the adult lifespan. Human Brain Mapping.2015.

Obesity Tied to Brain Volume Loss


Being overweight or obese is associated with poorer brain health in cognitively healthy adults in their 60s, according to new data from the long-running Australian PATH Through Life Study.

After adjustment for multiple factors, participants who were overweight or obese had smaller hippocampal volume at baseline and experienced greater hippocampal atrophy over 8 years than their normal-weight peers.

“The results further underscore the importance of reducing the rate of obesity through education, population health interventions, and policy,” Nicolas Cherbuin, PhD, from the Australian National University in Canberra, Australia, said in a statement.

He reported the findings in Washington, DC, at the Society for Neuroscience 2014 Annual Meeting.

Increased Dementia

Obesity is a “major concern” and has been linked to an increased risk for dementia, Dr Cherbuin said during a media briefing. The hippocampus plays a key role in long-term memory, and hippocampal atrophy is a hallmark of cognitive decline.

Dr Cherbuin reported on 420 cognitively healthy adults aged 60 to 64 years participating in the PATH study on aging. As part of the study, body mass index (BMI) was recorded and high-resolution T1-weighted MRI was performed at study outset and then 4 and 8 years later.

At baseline, BMI was negatively correlated with left hippocampal volume (estimate per unit BMI above 25: –10.65 mm3; P = .027) and right hippocampal volume (estimate: –8.18 mm3; P = .097).

During follow-up, participants with higher BMI experienced greater atrophy in the left (P = .001) but not the right (P = .058) hippocampus, even after adjustment for age, sex, education, diabetes, hypertension, smoking, and depression.

Each 2-point increment in BMI at baseline was associated with a 7.2% decrease in left hippocampal volume during follow-up. “This is particularly significant in an aging population, and further research should be conducted to determine how obesity affects thinking abilities,” Dr Cherbuin said.

“We did not investigate the relationship between shrinkage and function, but other studies in this research field have shown that greater shrinkage in the hippocampus is linked with a greater risk of cognitive decline and a greater risk of dementia as well,” he said.

In an interview with Medscape Medical News, Ralph DiLeone, PhD, from Yale University in New Haven, Connecticut, who moderated the media briefing, said more information on outcomes would be of interest.

“Because the hippocampus is so important for memory function, mood regulation and is implicated in cognitive aging and dementia, it will be very interesting to see if the researchers can correlate some of those brain changes with specific behavioral deficits or disease states,” he said.

NEW RESEARCH SHEDS LIGHT ON HOW CHILDREN’S BRAINS MEMORIZE FACTS


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As children shift from counting on their fingers to remembering math facts, the hippocampus and its functional circuits support the brain’s construction of adultlike ways of using memory.

As children learn basic arithmetic, they gradually switch from solving problems by counting on their fingers to pulling facts from memory. The shift comes more easily for some kids than for others, but no one knows why.

Now, new brain-imaging research gives the first evidence drawn from a longitudinal study to explain how the brain reorganizes itself as children learn math facts. A precisely orchestrated group of brain changes, many involving the memory center known as the hippocampus, are essential to the transformation, according to a study from the Stanford University School of Medicine.

The results, published online Aug. 17 in Nature Neuroscience, explain brain reorganization during normal development of cognitive skills and will serve as a point of comparison for future studies of what goes awry in the brains of children with learning disabilities.

“We wanted to understand how children acquire new knowledge, and determine why some children learn to retrieve facts from memory better than others,” said Vinod Menon, PhD, the Rachael L. and Walter F. Nichols, MD, Professor and  professor of psychiatry and behavioral sciences, and the senior author of the study. “This work provides insight into the dynamic changes that occur over the course of cognitive development in each child.”

The study also adds to prior research into the differences between how children’s and adults’ brains solve math problems. Children use certain brain regions, including the hippocampus and the prefrontal cortex, very differently from adults when the two groups are solving the same types of math problems, the study showed.

“It was surprising to us that the hippocampal and prefrontal contributions to memory-based problem-solving during childhood don’t look anything like what we would have expected for the adult brain,” said postdoctoral scholar Shaozheng Qin, PhD, who is the paper’s lead author.

Charting the shifting strategy

In the study, 28 children solved simple math problems while receiving two functional magnetic resonance imaging brain scans; the scans were done about 1.2 years apart. The researchers also scanned 20 adolescents and 20 adults at a single time point. At the start of the study, the children were ages 7-9. The adolescents were 14-17 and the adults were 19-22. The participants had normal IQs. Because the study examined normal math learning, potential participants with math-related learning disabilities and attention deficit hyperactivity disorder were excluded. The children and adolescents were studying math in school; the researchers did not provide any math instruction.

During the study, as the children aged from an average of 8.2 to 9.4 years, they became faster and more accurate at solving math problems, and relied more on retrieving math facts from memory and less on counting. As these shifts in strategy took place, the researchers saw several changes in the children’s brains. The hippocampus, a region with many roles in shaping new memories, was activated more in children’s brains after one year. Regions involved in counting, including parts of the prefrontal and parietal cortex, were activated less.

The scientists also saw changes in the degree to which the hippocampus was connected to other parts of children’s brains, with several parts of the prefrontal, anterior temporal cortex and parietal cortex more strongly connected to the hippocampus after one year. Crucially, the stronger these connections, the greater was each individual child’s ability to retrieve math facts from memory, a finding that suggests a starting point for future studies of math-learning disabilities.

Although children were using their hippocampus more after a year, adolescents and adults made minimal use of their hippocampus while solving math problems. Instead, they pulled math facts from well-developed information stores in the neocortex.

Memory scaffold

“What this means is that the hippocampus is providing a scaffold for learning and consolidating facts into long-term memory in children,” said Menon, who is also the Rachel L. and Walter F. Nichols, MD, Professor at the medical school. Children’s brains are building a schema for mathematical knowledge. The hippocampus helps support other parts of the brain as adultlike neural connections for solving math problems are being constructed. “In adults this scaffold is not needed because memory for math facts has most likely been consolidated into the neocortex,” he said. Interestingly, the research also showed that, although the adult hippocampus is not as strongly engaged as in children, it seems to keep a backup copy of the math information that adults usually draw from the neocortex.

The researchers compared the level of variation in patterns of brain activity as children, adolescents and adults correctly solved math problems. The brain’s activity patterns were more stable in adolescents and adults than in children, suggesting that as the brain gets better at solving math problems its activity becomes more consistent.

The next step, Menon said, is to compare the new findings about normal math learning to what happens in children with math-learning disabilities.

“In children with math-learning disabilities, we know that the ability to retrieve facts fluently is a basic problem, and remains a bottleneck for them in high school and college,” he said. “Is it that the hippocampus can’t provide a reliable scaffold to build good representations of math facts in other parts of the brain during the early stages of learning, and so the child continues to use inefficient strategies to solve math problems? We want to test this.”

 

Childhood Poverty Linked to Poor Brain Development.


Exposure to poverty in early childhood negatively affects brain development, but good-quality caregiving may help offset this effect, new research suggests.

A longitudinal imaging study shows that young children exposed to poverty have smaller white and cortical gray matter as well as hippocampal and amygdala volumes, as measured during school age and early adolescence.

“These findings extend the substantial body of behavioral data demonstrating the deleterious effects of poverty on child developmental outcomes into the neurodevelopmental domain and are consistent with prior results,” the investigators, with lead author Joan Luby, MD, Washington University School of Medicine in St. Louis, Missouri, write.

However, the investigators also found that the effects of poverty on hippocampal volume were influenced by caregiving and stressful life events.

The study was published online October 28 in JAMA Pediatrics.

Powerful Risk Factor

Poverty is one of the most powerful risk factors for poor developmental outcomes; a large body of research shows that children exposed to poverty have poorer cognitive outcomes and school performance and are at greater risk for antisocial behaviors and mental disorders.

However, the researchers note, there are few neurobiological data in humans to inform the mechanism of these relationships.

“This represents a critical gap in the literature and an urgent national and global public health problem based on statistics that more than 1 in 5 children are now living below the poverty line in the United States alone,” the authors write.

To examine the effects of poverty on childhood brain development and to understand what factors might mediate its negative impact, the researchers used magnetic resonance imaging (MRI) to examine total white and cortical gray matter as well as hippocampal and amygdala volumes in 145 children aged 6 to 12 years who had been followed since preschool.

The researchers looked at caregiver support/hostility, measured observationally during the preschool period, and stressful life events, measured prospectively.

The children underwent annual behavioral assessments for 3 to 6 years prior to MRI scanning and were annually assessed for 5 to 10 years following brain imaging.

Household poverty was measured using the federal income-to-needs ratio.

“Toxic” Effect

The researchers found that poverty was associated with lower hippocampal volumes, but they also found that caregiving behaviors and stressful life events could fully mediate this negative effect.

“The finding that the effects of poverty on hippocampal development are mediated through caregiving and stressful life events further underscores the importance of high-quality early childhood caregiving, a task that can be achieved through parenting education and support, as well as through preschool programs that provide high-quality supplementary caregiving and safe haven to vulnerable young children,” the investigators write.

In an accompanying editorial, Charles A. Nelson, PhD, Boston Children’s Hospital and Harvard Medical School, in Massachusetts, notes that the findings show that early experience “weaves its way into the neural and biological infrastructure of the child in such a way as to impact development trajectories and outcomes.”

“Exposure to early life adversity should be considered no less toxic than exposure to lead, alcohol or cocaine, and, as such it merits similar attention from health authorities,” Dr. Nelson writes.

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