How running preserves the memory

Exercise has long been known to combats stress, but a study by Brigham Young University suggests that it can also combat forgetfulness. The researchers found that running protects against the negative effects of stress on the hippocampus-the part of the brain responsible for learning and memory.

Within the hippocampus, memory formation and recall work best when the connections between neurons-synapses, are strengthened over time, a process called long-term potentiation (LTP). Chronic or prolonged stress, however, weakens the synapses and with them the LTP, negatively impacting memory.

The ideal situation for improving learning and memory would be to experience no stress and to exercise. To study the link between memory, stress and exercise, researchers divided mice into four groups: sedentary no stress, exercise no stress, exercise with stress, and sedentary with stress. The mice were then exposed to stress inducing situations, such as walking on an elevated platform or swimming in cold water, or put on a running wheel depending on their grouping.

To determine how the variables affected each group's memory, the researchers used electrophysiology to measure the LTP in the animals' brains. They found that the stressed mice who exercised had considerable higher LTP rates than those who had not exercised. The researchers also used a maze-running experiment to test the mice's memories. The stressed mice who exercised performed just as well as non-stressed mice who exercised.

Additionally, the exercising mice made significantly fewer memory errors in the maze than the sedentary mice. The findings suggest exercise is an effective way to protect learning and memory mechanisms from the negative cognitive impacts of chronic stress on the brain.
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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.
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High salt diet hobbles the brain

A new study has shown that mice fed with a very high-salt diet experienced declined blood flow to their brain, the integrity of blood vessels in the brain suffered, and performance on tests of cognitive function plummeted.

Researchers found that those effects were not as long has been widely believed, a natural consequence of high blood pressure. Instead, they appeared to be the result of signals sent from the gut to the brain by the immune system.

The study, conducted by researchers at Weill Cornell Medicine in New York. The research sheds light on a subject of keen interest to scientists exploring the links between what we eat and how well we think, and the mediating role that the immune system plays in that communication.

This suggests that even before a chronic high-salt diet nudges blood pressure up and compromises the health of tiny blood vessels in the brain, the oversalted gut is independently sending messages that lay the groundwork for corrosion throughout the vital network.

In the small intestines of mice, the authors of the new research found that a very high-salt diet prompted an immune response that boosted circulating levels of an inflammatory substance called interleukin-17. These high levels of IL-17 set off a cascade of chemical responses inside the delicate inner linings of the brain's blood vessels.

The result in mice fed with the high-salt diet: blood supply to two regions crucial for learning and memory-the cortex and hippocampus slowed markedly. And mental performance slid. Compared to mice fed a diet lower in salt, the maze-running skills of the mice who consumed high-salt levels faltered, and they failed to respond normally to whisker stimulation, or a new object in their cage.

In mice, that evidence of cognitive impairment was apparent even in the absence of high blood pressure. The immune system's role in sending signals between brain and gut is also seen in diseases like multiple sclerosis, rheumatoid arthritis, psoriasis and inflammatory bowel disease-all disorders that are linked to poor functioning of the brain's blood vessels.
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Causes of baby brain

Baby brain refers to increased forgetfulness, inattention, and mental "fogginess" reported by four out of five pregnant women. These changes in brain function during pregnancy have long been recognised in midwifery folklore, the new study has confirmed "baby brain"  as a real phenomenon, and also affects several cognitive areas.

Researchers combined data from different studies reporting the relationship between pregnancy and brain changes. They examined the cognitive function of pregnant women and non-pregnant women to explore how pregnancy may affect other cognitive areas beyond memory and to look specifically at how these changes might vary according to pregnancy trimesters.

The result showed that when pregnant women are compared to non-pregnant women, they perform much worse on tasks measuring memory and executive functioning which includes attention, inhibition, decision-making and planning, and the difference most pronounced during the third trimester. Women were tested with tasks such as the digit span test, which involves remembering digits in a line.

When the same women were tested at multiple points during their pregnancies, the decline appeared to start during the first trimester, then stabilise from the middle to the end of the pregnancy. Some pregnant women may notice they don't feel as smart as usual, these effects are realistically not likely to have any dramatic impact on everyday life.

Some women will simply find it seems to take more mental effort to do tasks that were previously routine. These changes might be noticeable to people very close to them such as family or friends, but this is highly dependent on each woman's personal experience of pregnancy. There were reductions in grey matter in the brains of pregnant women in regions known to be closely tied to processing social information, such as decoding infant facial expressions and establishing healthy bonding between mother and child.

Baby brain is an important adaptive phenomenon that might help women prepare for raising their children by allowing their brains to adapt to their new role as mothers. Importantly, this same study showed losses of grey matter in the hippocampus, an area of the brain responsible for memory function, are restored two years after the birth of a child. This supports the idea cognitive declines are not permanent.
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Exercise maintains brain size

Aerobic exercise can improve memory function and maintain brain health as we are getting older. Researchers examined the effects of aerobic exercise on a region of the brain called the hippocampus, which is critical for memory and other brain functions. Brain health decreases with age, with the average brain shrinking by approximately five per cent per decade after the age of 40.

Studies in mice and rats have consistently shown that physical exercise increases the size of the hippocampus but until now evidence in humans has been inconsistent. The researchers systematically reviewed clinical trials which examined the brain scans of different people before and after aerobic exercise programs or in control conditions.

The participants included a mix of healthy adults, people with mild cognitive impairment such as Alzheimer's and people with a clinical diagnosis of mental illness including depression and schizophrenia. Ages ranged from 24 to 76 years with an average age of 66. They examined effects of aerobic exercise, including stationary cycling, walking, and treadmill running. The length of the interventions ranged from three to 24 months with a range of 2-5 sessions per week.

Result showed that while exercise had no effect on total hippocampal volume, it increases the size of the left region of the hippocampus in humans. When you exercise you produce a chemical called brain-derived neurotrophic factor BDNF, which may prevent age-related decline by reducing the deterioration of the brain. Exercise maintains the program for the brain, prevents ageing-related neurodegenerative disorders such as Alzheimer's and dementia.
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How challenges change thinking

Challenging situations make it harder to understand where you are and what's happening around you. A team of researchers showed participants video clips of a positive, a negative and a neutral situation. After watching the challenging clips -whether positive or negative - the participants performed worse on tests measuring their unconscious ability to acquire information about where and when things happen.

This suggests that challenging situations cause the brain to drop nuanced, context-based cognition in favor of reflexive action. Previous research suggests that long-term memories formed under stress lack the context and peripheral details encoded by the hippocampus, making false alarms and reflexive reactions more likely.

The researchers predicted that study participants would be less able to acquire spatial and sequential context after watching challenging clips, and that their performance would worsen the same way faced with either a positive or a negative clip. To test this, they used clips of film footage used previously to elicit reactions in stress studies: one violent scene (which participants experienced as negative), one sex scene (which participants experienced as positive), and one neutral control scene.

Immediately after watching the clips, two groups of participants performed tasks designed to test their ability to acquire either spatial or sequential context. Both the sex scene and violent scene disrupted participants' ability to memorize where objects had been and notice patterns in two different tasks, compared to the neutral scene. This supports the hypothesis that challenging situations- positive or negative cause the brain to drop nuanced, context-based cognition in favor of reflexive action.

Researchers suggest that the answer may lie in the hippocampus region of the brain, although they caution that since no neurophysiological techniques were applied in this study, this can't be proven. Since existing evidence supports the idea that the hippocampus is deeply involved in retrieving and reconstructing spatial and temporal details, downgrading this function when faced with a potentially dangerous situation could stop this context acquisition and achieve the effect seen in this behavioral study.

Reflexive reactions are less complex and demanding, and might stop individuals from making decisions based on unreliable information from unpredictable surroundings. Changes in cognition during high arousal states play an important role in psychopathology.
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Effects of estrogen treatment on menopausal women

Hormone replacement therapy may protect menopausal women from stress-related memory loss. The sex hormone estrogen buffers working memory from the impact of stress, which is known to impair short-term working memory. Women going through menopause take hormone replacement therapy HRT which contains estrogen to offset hot flushes, night sweats, sleep disturbances, mood swings, and reduced sex drive. The treatment also blocks fluctuating hormones from affecting memory.

Estrogen can modify women's hormonal response to stress, researchers discovered that the treatment after menopause protects working memory needed for short-term cognitive tasks from the effects of stress. Stress prompts the hormonal system and the hypothalamus to release cortisol. Cortisol interferes with the activity of the hippocampus from making new neurons and neural connections, a process that is key to working memory.

HRT may reduce the response and cortisol, when there are environmental or immune system stressors. Stress can interference with prefrontal cognitive processes such as working memory.
HRT can reduce the HPA response to stress, the hormone may also mitigate the effects of stress on working memory by limiting the cortisol response to the stressor. Researchers examined different study participants, some received estrogen therapy for menopausal symptoms and others received a placebo for five years. The women provided saliva samples so their levels of cortisol, a hormone associated with stress, was measured.

During two separate sessions, each woman completed a memory task where they were instructed to remember the final word of each sentence. Prior to one of the sessions, the women submerged their non-dominant hand in ice water for as long as possible, for a maximum of three minutes. During the other session, the women submerged the same hand in warm water before completing the memory test.

Although the women who were receiving estrogen therapy reported feeling more stressed by the cold water exposure than the women who received the placebo, they had lower levels of cortisol than their counterparts following the stress test. Women receiving HRT performed about the same on the memory task, regardless of whether they were exposed. sed to the cold water stressor in advance or not. Women who were taking the placebo performed worse on the memory task because of exposure to the cold water than they did when they were not exposed to a physical stressor.
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New molecules may prevent stroke and neurodegenerative diseases

Researchers have discovered a new class of molecules in the brain that synchronize cell-to-cell communication and immune activity in response to injury or diseases. Elovanoids ELVs are bioactive chemical messengers made from omega-3 very long chain polyunsaturated fatty acids VLC-PUFAs,n-3. They are released on demand when cells are damaged or stressed.

Working in neuronal cell cultures from the cerebral cortex and from the hippocampus and a model of ischemic stroke, the researchers found that elovanoids not only protected neuronal cells and promoted their survival, but maintained their integrity and stability.

This can proffer solution in the understanding of how the complexity and resiliency of the brain are sustained when confronted with adversities such as stroke, Parkinson's or Alzheimer's and neuroprotection signaling needs to be activated and how neurons communicate among themselves.

These novel molecules participate in communicating messages to overall synaptic organization to ensure an accurate flow of information through neuronal circuits. We know how neurons make synaptic connections with other neurons, however these connections have to be malleable to change strength appropriately.

Elovanoids might play a central role as synaptic organizers, especially important in conditions resulting from synaptic dysfunction such as autism or amyotropic lateral sclerosis, for which there is no therapeutic solutions.

The researchers discovered the structure and characteristics of two elovanoids - ELV-N32 and ELV-N34 - in the brain. Starting with neuron cell cultures and then an experimental model of stroke, they found that elovanoids were activated when cells underwent either oxygen deprivation or excitotoxicity - early events associated with stroke, epilepsy, Parkinson's, traumatic brain injury and other neurodegenerative diseases.

They determined the concentrations and therapeutic windows at which elovanoids conferred neuroprotection. They discovered that elovanoids overcame the damaging effects and toxicity of these early events. In the stroke model, elovanoids reduced the size of the damaged brain area, initiated repair mechanisms and improved neurological recovery.
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Playing video games can change your brain performance

 Playing video games can change the part of brain responsible for attention and visuospatial skills and make them more efficient.

Reserchers examined structural changes in the brain and how video games change the structure of brain.

They discovered that playing video games can change brain's performance and structure. The right hippocampus was enlarged in long-term gamers compared to those that doesn't play game.

The brain regions involved in attention are also more efficient in gamers and require less activation to sustain attention on demanding tasks.

Video games can increase the size and efficiency of brain regions related to visuospatial skills. Action video games enhance flexibility and multitasking; abilities to switch rapidly without error between tasks that have different demands.

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Effects of sleep deprivation on memory formation

Nicolette Ognjanovski of the Department of Molecular, Cellular and Development Biology at Michigan and colleagues discovered that sleep deprivation interfere with the rhythm of neuronal firing in hippocampus part of the brain that is responsible for formation of long-term memories.

National Sleep Foundation recommend 7 to 9 hours of sleep per night for sound health.  Sleep deprivation prevents memory formation because it prevents brain from converting short-term memory to long-term memory.

The researchers examined the hippocampal of mice and discovered that those that had sufficient sleep displayed better sleep-related oscillations than sleep-deprived mice.

This discovery shows that memories are not stored in one cell, but distributed through the network. The dominant oscillatory activities for learning is being controlled by cells in hippocampus.