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Adult-born hippocampal neurons bidirectionally modulate entorhinal inputs into the dentate gyrus | Science

Young adult-born granule cells (abGCs) in the dentate gyrus (DG) have a profound impact on cognition and mood. However, it remains unclear how abGCs distinctively contribute to local DG information processing. We found that the actions of abGCs in the DG depend on the origin of incoming afferents.

Exercise benefits brains, changes blood flow in older adults, study finds: Exercise can impact biomarkers of brain function in a way that might prevent or postpone the onset of dementia -- ScienceDaily

A control group of cognitively healthy older adults without mild cognitive impairment also underwent the exercise training program, consisting of four 30-minute sessions of moderate-intensity treadmill walking per week. But the program yielded different responses from each group. Unlike the group with MCI, whose exercise training decreased cerebral blood flow, the exercise training increased cerebral blood flow in the frontal cortex in the healthy group after 12 weeks. Their performance on the cognitive tests also significantly improved, as was observed the MCI group. For this study, changes in cerebral blood flow were measured in specific brain regions that are known to be involved in the pathogenesis of Alzheimer's disease, including the insula (involved in perception, motor control, self-awareness, cognitive functioning), the anterior cingulate cortex (involved in decision making , anticipation, impulse control and emotion) and the inferior frontal gyrus (involved in language processing and speech).

Near bottom: focus triggered by new activity or movement?

Research has shown that the electrical activity of the neocortex of the brain changes, when we focus our attention. Neurons stop signalling in sync with one another and start firing out of sync. This is helpful, says Williams, because it allows individual neurons to respond to sensory information in different ways. Thus, you can focus on a car speeding down the road or on what a friend is saying in a crowded room. It's known that the cholinergic system in the brain plays an important role in triggering this desynchronization. The cholinergic system consists of clusters of special neurons that synthesise and release a signalling molecule called acetylcholine, he explains, and these clusters make far reaching connections throughout the brain. Not only does this cholinergic system act like a master switch, but mounting evidence suggests it also enables the brain to identify which sensory input is the most salient -- i.e. worthy of attention -- at any given moment and then shine a spotlight on that input. "The cholinergic system broadcasts to the brain, 'this thing is really important to be vigilant to'," says Williams. He adds that the cholinergic system has been proposed to have a far-reaching impact on our cognitive abilities. "Destruction of the cholinergic system in animals profoundly degrades cognition, and the formation of memory," he says. "Importantly, in humans a progressive degeneration of the cholinergic system occurs in devastating diseases that blunt cognition and memory, such as Alzheimer's disease." But precisely which neurons in the cortex are being targeted by this master switch and how it's able to influence their function was unknown. Williams and QBI researcher Lee Fletcher wondered if layer 5 B-pyramidal neurons, the 'output' neurons of the neocortex, might be involved, because they are intimately involved in how we perceive the world. "The output neurons of the neocortex perform computations that are thought to underlie our perception of the world," says Williams. Williams and Fletcher wanted to know if the cholinergic system is able to influence the activity of these output neurons. Using a technique called optogenetics, they modified neurons in the cholinergic system in the brains of mice so that they could be activated with a flash of blue light, triggering a sudden release of acetylcholine. This allowed the researchers to closely monitor the interaction between the cholinergic system and the output neurons. They discovered that if the output neurons were not currently active, not much happened. But when those neurons received excitatory input to their dendrites, the cholinergic system was able to massively increase their activity. "It's as if the cholinergic system has given a 'go' signal," says Fletcher, enabling the output neurons of the neocortex to powerfully respond. Importantly, this change was selective, and only apparent when excitatory input was being processed in the dendrites of the 'output' neurons. "We have known for some time that the dendrites of the output neurons of the neocortex only become active when animals are actively performing a behaviour, and that this activity is correlated with perception and task performance," says Williams. This new work demonstrates that the cholinergic system is critical to this transition in mice and rats, allowing the output neurons to perform computations in a state-dependent manner. "We suggest that this switch also occurs in the human neocortex, allowing us to rapidly switch our state of vigilance and attention," says Williams. "Our work therefore provides important insight into how the progressive degeneration of the cholinergic system in disease blunts human cognition."

Navigating our thoughts: Fundamental principles of thinking -- ScienceDaily

The very regular activation pattern of grid cells can also be observed in humans -- but importantly, not only during navigation through geographical spaces. Grids cells are also active when learning new concepts, as shown by a study from 2016. In that study, volunteers learned to associate pictures of birds, which only varied in the length of their necks and legs, with different symbols, such as a tree or a bell. A bird with a long neck and short legs was associated with the tree whereas a bird with a short neck and long legs belonged to the bell. Thus, a specific combination of bodily features came to be represented by a symbol. In a subsequent memory test, performed in a brain scanner, volunteers indicated whether various birds were associated with one of the symbols. Interestingly, the entorhinal cortex was activated, in much the same way as it is during navigation, providing a coordinate system for our thoughts. "By connecting all these previous discoveries, we came to the assumption that the brain stores a mental map, regardless of whether we are thinking about a real space or the space between dimensions of our thoughts. Our train of thought can be considered a path though the spaces of our thoughts, along different mental dimensions," Jacob Bellmund, the first author of the publication, explains.

Mind’s quality control center found in long-ignored brain area: Cerebellum checks and corrects thoughts, movement -- ScienceDaily

"The biggest surprise to me was the discovery that 80 percent of the cerebellum is devoted to the smart stuff," said senior author Nico Dosenbach, MD, PhD, an assistant professor of neurology, of occupational therapy and of pediatrics. "Everyone thought the cerebellum was about movement. If your cerebellum is damaged, you can't move smoothly -- your hand jerks around when you try to reach for something. Our research strongly suggests that just as the cerebellum serves as a quality check on movement, it also checks your thoughts as well -- smoothing them out, correcting them, perfecting things." Dosenbach is a founding member of the Midnight Scan Club, a group of Washington University neuroscientists who have taken turns in an MRI scanner late at night, scanning their own brains for hours to generate a massive amount of high-quality data for their research. A previous analysis of Midnight Scan Club data showed that a kind of brain scan called functional connectivity MRI can reliably detect fundamental differences in how individual brains are wired. Postdoctoral researcher and first author Scott Marek, PhD, decided to apply a similar analysis to the cerebellum. In the better-known cerebral cortex -- the crumpled outer layer of the brain -- wiring maps have been drawn that connect distant areas into networks that govern vision, attention, language and movement. But nobody knew how the cerebellum is organized in individuals, partly because a quirk of MRI technology means that data obtained from the underside of the brain tend to be low quality. In the Midnight Scan Club dataset, however, Marek had access to more than 10 hours of scans on each of 10 people, enough to take a serious look at the cerebellum. Using the cortex's networks as a template, Marek could identify the networks in the cerebellum. Notably, the sensory networks are missing -- vision, hearing and touch -- and only 20 percent of the cerebellum is devoted to movement, roughly the same amount as in the cerebral cortex. The remaining 80 percent is occupied by networks involved in higher-order cognition: the attention network; the default network, which has to do with daydreaming, recalling memories and just idly thinking; and two networks that oversee executive functions such as decision-making and planning.

I see therefore I think

For example, in the seven or so seconds, on average, that it took students in the study to solve a logical reasoning problem, researchers recorded at least 23 eye movements. Among other clues, ocular activity indicated which data students absorbed, or disregarded, to arrive at their conclusions. The study builds on previous findings by Bunge and fellow researchers that track cognitive changes in students during mentally challenging learning tasks. For example, a 2012 study found that a three-month LSAT course strengthened the circuitry in the brain's frontoparietal network and boosted the reasoning skills of two dozen young adults, compared to pre-law students who did not complete the course.

Teen cannabis use is not without risk to cognitive development -- ScienceDaily

"However, further increases in cannabis use, but not alcohol consumption, showed additional concurrent and lagged effects on cognitive functions, such as perceptual reasoning, memory recall, working memory and inhibitory control," Conrod said. "Of particular concern was the finding that cannabis use was associated with lasting effects on a measure of inhibitory control, which is a risk factor for other addictive behaviours, and might explain why early onset cannabis use is a risk factor for other addictions." Morin added: "Some of these effects are even more pronounced when consumption begins earlier in adolescence."

Even Quick Meditation Aids Cognitive Skills - Neuroscience News

College students who listen to a 10-minute meditation tape complete simple cognitive tasks more quickly and accurately than peers who listen to a “control” recording on a generic subject, researchers at Yale University and Swarthmore College report. The study, published Aug. 6 in the journal Frontiers of Neuroscience, shows even people who have never meditated before can benefit from even a short meditation practice. “We have known for awhile that people who practice meditation for a few weeks or months tend to perform better on cognitive tests, but now we know you don’t have to spend weeks practicing to see improvement,” said Yale’s Hedy Kober, associate professor of psychiatry and psychology and senior author of the study.

Basing everyday decisions on risk of pain or loss linked to increased anxiety -- ScienceDaily

They found that people were more likely to generalize from negative events, compared to safe or neutral outcomes. In addition, different parts of the decision-making process were linked to activity in different brain regions, including areas involved in vision, fear response and safety learning. They also found that those people who generalized more from the negative events (pain or loss) reported a greater experience of anxious feelings and intrusive thoughts (negative thoughts that enter your mind against your will and are hard to get rid of). "We hope that these findings will contribute to a greater understanding of the thought processes that underlie anxiety in some people," said senior author Dr Ben Seymour, Clinical Research Associate at the University of Cambridge. "Our results show the benefits of analysing complex behavioral processes such as generalization into separate components that can be examined and linked back to brain activity and symptoms. By better understanding what causes these symptoms in different cases, we might be able to tailor treatments more effectively to people with anxiety in future."

Seven-year follow-up shows lasting cognitive gains from meditation -- ScienceDaily

The new study shows that those gains in attention observed immediately after retreat were partly maintained seven years later, especially for older participants who maintained a more diligent meditation practice over the seven years. Compared to those who practiced less, these participants maintained cognitive gains and did not show typical patterns of age-related decline in sustained attention.

How Meth Destroys The Body | The Meth Epidemic | FRONTLINE | PBS

"There [are] a whole variety of reasons to try methamphetamine," explains Dr. Richard Rawson, associate director of UCLA's Integrated Substance Abuse Programs. "[H]owever, once they take the drug … their reasons are pretty much the same: They like how it affects their brain[s]." Meth users have described this feeling as a sudden rush of pleasure lasting for several minutes, followed by a euphoric high that lasts between six and 12 hours, and it is the result of drug causing the brain to release excessive amounts of the chemical dopamine, a neurotransmitter that controls pleasure. All drugs of abuse cause the release of dopamine, even alcohol and nicotine, explains Rawson, "[But] methamphetamine produces the mother of all dopamine releases." For example, in lab experiments done on animals, sex causes dopamine levels to jump from 100 to 200 units, and cocaine causes them to spike to 350 units. "[With] methamphetamine you get a release from the base level to about 1,250 units, something that's about 12 times as much of a release of dopamine as you get from food and sex and other pleasurable activities," Rawson says. "This really doesn't occur from any normally rewarding activity. That's one of the reasons why people, when they take methamphetamine, report having this euphoric [feeling] that's unlike anything they've ever experienced." Then, when the drug wears off, users experience profound depression and feel the need to keep taking the drug to avoid the crash.

Cognitive dysfunction in major depression and bipolar disorder: Assessment and treatment options - MacQueen - 2016 - Psychiatry and Clinical Neurosciences - Wiley Online Library

Exercise may have positive effects on cognition in healthy people and is being investigated as a possible strategy for maintaining cognitive function throughout aging. It also improves symptoms of depression.[76-79] The degree to which it actually improves cognitive function in those with a mood disorder is not well known.[80] High-dose exercise was associated with improvement in spatial working memory while other cognitive domains, including attention, visual memory, and spatial planning, improved regardless of dose in one study.[81] Another study included a subset of patients with BD (3/12, while the other participants had schizophrenia) and found that intense circuit training was associated with improvement in memory and processing speed; depressive symptoms also improved.[82] There are therefore a variety of factors that require investigation to understand how to maximize the benefits of exercise on cognition in patients with mood disorders. These include better understanding of the individual variability in response to training, optimal dosing or training schedules, the synergistic effects of exercise in combination with other interventions[83] and the actual mechanisms through which exercise works on the neural circuits that are disrupted in depression.

Adderall Concentration Benefits in Doubt: New Study

The last question they asked their subjects was: "How and how much did the pill influence your performance on today's tests?" Those subjects who had been given Adderall were significantly more likely to report that the pill had caused them to do a better job on the tasks they'd been given, even though their performance did not show an improvement over that of those who had taken the placebo.

Differential effects of acute and regular physical exercise on cognition and affect. - PubMed - NCBI

Participants were evaluated on novel object recognition (NOR) memory and a battery of mental health surveys before and after engaging in either (a) a 4-week exercise program, with exercise on the final test day, (b) a 4-week exercise program, without exercise on the final test day, (c) a single bout of exercise on the final test day, or (d) remaining sedentary between test days. Exercise enhanced object recognition memory and produced a beneficial decrease in perceived stress, but only in participants who exercised for 4 weeks including the final day of testing. In contrast, a single bout of exercise did not affect recognition memory and resulted in increased perceived stress levels.