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Hub linking movement and motivation in brain identified -- ScienceDaily

lateral septum (LS), a region considered integral to modulating behavior and implicated in many psychiatric disorders, directly encodes information about the speed and acceleration of an animal as it navigates and learns how to obtain a reward in an environment. "Completing a simple task, such as acquiring food for dinner, requires the participation and coordination of a large number of regions of the brain, and the weighing of a number of factors: for example, how much effort is it to get food from the fridge versus a restaurant," said Hannah Wirtshafter, the study's lead author. "We have discovered that the LS may be aiding you in making some of those decisions. That the LS represents place, movement, and motivational information may enable the LS to help you integrate or optimize performance across considerations of place, speed, and other environmental signals."

Treatment for chronic neuropathic pain gets to the brain via a novel route, without surgery - ScienceBlog.com

“We previously showed that in neuropathic pain, the accumulation of TNF in the brain, specifically the hippocampus, causes the dysregulation of the normal analgesic response,” said Ignatowski. “We propose that enhanced levels of TNF in the brain inhibit the release of norepinephrine. Normally, norepinephrine would activate the descending inhibitory pain pathway that projects to the spinal cord, thereby alleviating pain. But when activation of this inhibitory pathway is lost, pain may transition to a chronic state.” The new method originated with the UB researchers’ discovery in 1999 of TNF, a novel therapeutic target, specifically in the brain. They previously demonstrated that peripheral nerve injury—injury to the nerves connecting the spinal cord to the rest of the body—boosts levels of this protein in the hippocampus, a part of the brain responsible for learning and memory, and which they have recently found to be involved in the experience of chronic pain.

Hippocampus and memory development

The Geneva team has been following 275 patients aged 6 to 35 years for 18 years: a control groups of 135 individuals -- i.e. individuals without genetic problems -- and 140 people with deletion syndrome, including 53 with moderate to severe psychotic symptoms. "They underwent an MRI every three years so that we could observe their brain development," says Valentina Mancini, a researcher in UNIGE's Department of Psychiatry. "This has helped us create a statistical model that measures and compares the development of the hippocampus in both groups of patients." It was discovered that the hippocampus of the group affected by deletion syndrome, although smaller from the beginning, followed a growth curve identical to that of the control group. "This meant that we could hypothesise that the smaller size of the hippocampus originates in utero during its development in the womb." The UNIGE scientists also observed the subfields of the hippocampus in detail, discovering that one of them -- called CA3 -- was not affected by the decrease in size. "This subfield plays a crucial role in the work of memorisation and seems stronger than the other sub-parts," adds professor Eliez.

Exercise activates memory neural networks in older adults: Study shows acute exercise has the ability to impact brain regions important to memory -- ScienceDaily

Dr. Smith's research team measured the brain activity (using fMRI) of healthy participants ages 55-85 who were asked to perform a memory task that involves identifying famous names and non famous ones. The action of remembering famous names activates a neural network related to semantic memory, which is known to deteriorate over time with memory loss. This test was conducted 30 minutes after a session of moderately intense exercise (70% of max effort) on an exercise bike and on a separate day after a period of rest. Participants' brain activation while correctly remembering names was significantly greater in four brain cortical regions (including the middle frontal gyrus, inferior temporal gryus, middle temporal gyrus, and fusiform gyrus) after exercise compared to after rest. The increased activation of the hippocampus was also seen on both sides of the brain. "Just like a muscle adapts to repeated use, single sessions of exercise may flex cognitive neural networks in ways that promote adaptations over time and lend to increased network integrity and function and allow more efficient access to memories," Dr. Smith explained.

(So does running) Ketamine reverses neural changes underlying depression-related behaviors in mice: Study sheds light on the neural mechanisms underlying remission of depression -- ScienceDaily

Researchers took high-resolution images of dendritic spines in the prefrontal cortex of mice before and after they experienced a stressor. Dendritic spines are protrusions in the part of neurons that receive communication input from other neurons. The researchers found that mice displaying behaviors related to depression had increased elimination of, and decreased formation of, dendritic spines in their prefrontal cortex compared with mice not exposed to a stressor. This finding replicates prior studies linking the emergence of behaviors related to depression in mice with dendritic spine loss. In addition to the effects on dendritic spines, stress reduced the functional connectivity and simultaneous activity of neurons in the prefrontal cortex of mice. This reduction in connectivity and activity was associated with behaviors related to depression in response to stressors. Liston's group then found that ketamine treatment rapidly restored functional connectivity and ensemble activity of neurons and eliminated behaviors related to depression

First evidence for necessary role of human hippocampus in planning -- ScienceDaily

The work centers on the hippocampal "cognitive map," the brain's spatial localization system discovered by University College of London's John O'Keefe, who was awarded the 2014 Nobel Prize in Physiology or Medicine. The hippocampal cognitive map has been long thought to allow us to "mentally simulate" the future outcomes of our actions as we plan into the future. However, there had previously been no direct evidence in humans that the hippocampus is actually necessary for planning. "Our results show that both goal-directed planning and remembering locations in space depend on the human hippocampus" says Oliver Vikbladh, a doctoral candidate at New York University's Center for Neural Science and the paper's lead author. "By clarifying the scope of hippocampal contributions to behavior, the study may have implications for diseases that affect the hippocampus, such as epilepsy and Alzheimer's disease."

A new way by which the human brain marks time: Novel findings may further understanding of age-related dementia -- ScienceDaily

In the UCI study, participants sat with their heads inside a high-resolution fMRI scanner while watching the TV show and then viewing still frames from the episode, one at a time. The researchers found that when subjects had more precise answers to questions about what time certain events occurred, they activated a brain network involving the lateral entorhinal cortex and the perirhinal cortex. The team had previously shown that these regions, which surround the hippocampus, are associated with memories of objects or items but not their spatial location. Until now, little had been known about how this network might process and store information about time. "The field of neuroscience has focused extensively on understanding how we encode and store information about space, but time has always been a mystery," said Yassa, a professor of neurobiology & behavior. "This study and the Moser team's study represent the first cross-species evidence for a potential role of the lateral entorhinal cortex in storing and retrieving information about when experiences happen." "Space and time have always been intricately linked, and the common wisdom in our field was that the mechanisms involved in one probably supported the other as well," added Maria Montchal, a graduate student in Yassa's lab who led the research. "But our results suggest otherwise."

People with schizophrenia experience emotion differently from others, 'body maps' show -- ScienceDaily

The outcomes differed radically between groups, with the control group showing distinct maps of sensations for 13 different emotions, indicating specific patterns of increased arousal and decreased energy across the body for each emotion. However, in individuals with schizophrenia, there was an overall reduction of bodily sensation across all emotions. The study also found that individuals with schizophrenia don't differentiate on their body maps for varying emotions. That may pose a problem for them in identifying, recognizing and verbalizing their emotions or trying to understand the emotions of others. Torregrossa said the research will allow the team to move forward in developing ways to help people with schizophrenia process emotions, which, in turn, could improve interpersonal relationships. "The main outcome of this research is that we have a better understanding of why people with schizophrenia might have trouble interacting with others," she said. "What we can do now is help them learn to attend to physiological sensations arising from their bodies and use them to process emotions."

How the brain reacts to loss of vision: Going blind affects all senses, and disrupts memory ability -- ScienceDaily

Before any changes had developed in the sensory cortices, the researchers observed that loss of vision was first followed by changes in the density of neurotransmitter receptors and impairments of synaptic plasticity in the hippocampus. In subsequent months, hippocampal plasticity became more impaired and spatial memory was affected. During this time the density of neurotransmitter receptors also changed in the visual cortex, as well as in other cortical areas that process other sensory information. "After blindness occurs, the brain tries to compensate for the loss by ramping up its sensitivity to the missing visual signals," explains Denise Manahan-Vaughan, who led the study. When this fails to work, the other sensory modalities begin to adapt and increase their acuities. "Our study shows that this process of reorganisation is supported by extensive changes in the expression and function of key neurotransmitter receptors in the brain. This is a major undertaking, during which time the hippocampus' ability to store spatial experiences is hampered," says Manahan-Vaughan.

An Amygdala-Hippocampus Subnetwork that Encodes Variation in Human Mood: Cell

The most common subnetwork, found in 13 of 21 subjects, was characterized by β-frequency coherence (13-30 Hz) between the amygdala and hippocampus. Increased variability of this subnetwork correlated with worsening mood across these 13 subjects. Moreover, these subjects had significantly higher trait anxiety than the 8 of 21 for whom this amygdala-hippocampus subnetwork was absent.

Brain signature of depressed mood unveiled in new study: Direct recordings of human brain activity link memory, emotion, and anxiety during bouts of low mood -- ScienceDaily

Then, to compare results across the unique brains and distinct electrode placements of all 21 research participants, the researchers mapped each subject's ICNs onto neural connectivity diagrams. Comparing these standardized records of network activity across subjects revealed several "cliques" -- groups of brain regions that repeatedly became synchronized at specific frequencies, and were therefore likely to represent functional brain networks. One such clique was highly active and coordinated in 13 research participants, all of whom had also scored high on a psychological assessment of baseline anxiety conducted prior to the start of the study. In these same individuals, changes in the activity of this brain network were also highly correlated with day-to-day bouts of low or depressed mood. This mood-related network was characterized by so-called beta waves -- synchronized oscillations between 13 and 30 cycles per second -- in the hippocampus and amygdala, two deep brain regions which have long been linked, respectively, to memory and to negative emotion. Sohal said the research team was at first taken aback by the clarity of the finding. "We were quite surprised to identify a single signal that almost completely accounted for bouts of depressed mood in such a large set of people," said Sohal. "Finding such a powerfully informative biomarker was more than what we'd expected at this stage of the project." Surprisingly, this powerful link between of mood-associated beta waves in the amygdala and hippocampus was entirely absent from eight other research participants, all of whom had comparatively low preexisting anxiety, suggesting new questions about how the brains of people prone to anxiety may differ from others in how they process emotional situations.

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.

Hippocampus maps relationship of scenes?

Aya Ben-Yakov and Richard Henson found that the hippocampus responded most strongly to the films at the points that independent observers identified as the end of one event and the beginning of a new one. The researchers found a strong match between these event boundaries and participants’ hippocampal activity, varying according to the degree to which the independent observers agreed on the transition points between events. While watching the two-hour long Forrest Gump, hippocampal response was more strongly influenced by the subjective event boundaries than by what the filmmaker may consider a transition between scenes, such as a change in location.

Resynchronizing Neurons to Erase Schizophrenia - Neuroscience News

he Geneva neuroscientists chose to focus on neural networks of the hippocampus, a brain structure notably involved in memory. They studied a mouse model that reproduces the genetic alteration of DiGeorge syndrome as well as some behavioural changes associated with schizophrenia. In the hippocampus of a control mouse, the thousands of neurons that make up the network coordinate according to a very precise sequence of activity, which is dynamic in time and synchronized. However, in the neural networks of their mouse models, the scientists observed something completely different: the neurons showed the same level of activity as in control animals, but without any coordination, as if these cells were incapable of communicating properly with each other. “The organization and synchronization of neural networks is achieved through the intervention of subpopulations of inhibitory neurons, including parvalbumin neurons,» says Carleton. “However, in this animal model of schizophrenia, these neurons are much less active. Without proper inhibition to control and structure the electrical activity of other neurons in the network, anarchy rules. ”

Bravery cells found in the hippocampus -- ScienceDaily

In an article published in the journal Nature Communications the authors show that neurons known as OLM cells, when stimulated, produce a brain rhythm that is present when animals feel safe in a threatening environment (for example, when they are hiding from a predator but aware of the predator's proximity). The study, produced by Drs. Sanja Mikulovic, Ernesto Restrepo, Klas Kullander and Richardson Leao among others, showed that anxiety and risk-taking behaviour can be controlled by the manipulation of OLM cells. To find a pathway that quickly and robustly modulates risk-taking behaviour is very important for treatment of pathological anxiety since reduced risk-taking behaviour is a trait in people with high anxiety levels.

Neurons ripple while brains rest to lock in memories: How quiet minds encode spatial maps while 'introspecting' -- ScienceDaily

"Animals encode a memory of an environment as they run around," said Kemere, an assistant professor of electrical and computer engineering who specializes in neuroscience. "They form a spatial map as individual neurons are activated in different places. When they're awake in our experiments, they're probably doing that exploration process 40 to 60 percent of the time. "But for the other 40 percent, they're scratching themselves, or they're eating, or they're sort of snoozing," he said. "They're not asleep, but they're paused; I like to call it introspecting." Those periods of introspection provided the critical data for the study that inverted the usual process of matching brain activity to movement while the animals were active. The primary data was gathered over the course of many experiments under the direction of Diba, an associate professor and leader of the Neural Circuits and Memory Lab at Michigan Medicine. As the animals explored either back-and-forth tracks or maze-like environments, electrodes in their brains sensed sharp wave-associated bursts of neural activity called population burst events (PBEs). In these events, between 50,000 and 100,000 neurons all fire within 100 milliseconds and send ripples throughout the brain that are not yet fully understood.

The memory part of the brain may also hold clues for anxiety and depression | University of Toronto Scarborough - News and Events

Ito says this finding is important because the conventional thinking is that these areas, along with another part called the dentate gyrus, form a circuit through which information flow occurs in one direction. Information processed by the dentate gyrus gets passed along to the CA3, and then on to CA1. In other words, the CA1 and CA3 should carry out the same function because they’re both part of the same information processing circuit. “But that’s not the case, the CA1 and CA3 in the ventral hippocampus seem to do very opposite things in relation to conflict processing,” says Ito. “It’s this strange bi-directional or oppositional effect, and that goes against traditional thinking of how information processing takes place in this part of the brain,” she says.  Because of its possible role in basic motivational behaviour, it may also offer important insights into a range of mental health illnesses. Addiction, for example, could be linked to deficits of approach motivation. Anxiety and depression on the other hand could be linked to avoidance behaviours, all of which could manifest itself in this part of the brain.

Reduced hippocampal volume observed in currently but not previously depressed older adults

By analyzing MRI brain scans, Calati and her colleagues observed hippocampal volume reduction in currently depressed participants compared to the healthy control group. But they found no significant difference between those with a history of past, but not current, depression and the healthy controls. “When we compared the three groups, we found left posterior hippocampal volume reduction in currently depressed individuals when compared to healthy subjects. This reduction was not present when we compared past depressed subjects to healthy controls,” Calati explained.

Running helps brain stave off effects of chronic stress: Exercise protects vital memory and learning functions -- ScienceDaily

"Exercise is a simple and cost-effective way to eliminate the negative impacts on memory of chronic stress," said study lead author Jeff Edwards, associate professor of physiology and developmental biology at BYU. Inside the hippocampus, memory formation and recall occur optimally when the synapses or connections between neurons are strengthened over time. That process of synaptic strengthening is called long-term potentiation (LTP). Chronic or prolonged stress weakens the synapses, which decreases LTP and ultimately impacts memory. Edwards' study found that when exercise co-occurs with stress, LTP levels are not decreased, but remain normal.

Stimulating the entorhinal cortex (Ent) suppresses depression

Yun identified a protein in the Ent-hippocampal pathway, called TRIP8b, that increases during stress, and inhibits cell firing. In the current study, the researchers used mice genetically engineered to “knock down” or eliminate TRIP8b in Ent neurons. Ent neurons in those mice were more likely to fire, and produced new hippocampal neurons at a faster rate.

Attention deficit disorders could stem from impaired brain coordination: Researchers uncover link absent between brain regions in attention deficit hyperactivity disorder, schizophrenia -- ScienceDaily

When the researchers attached probes to the mice to measure brain activity, they found mice without ErbB4 had brain regions that were acting independently, rather than together in synchrony. In particular, the researchers studied the prefrontal cortex -- normally associated with decision-making -- and the hippocampus -- a region that supports memory. These two regions coordinate for a variety of brain tasks, including memory and attention. "We found top-down attention, previously thought to be controlled by the prefrontal cortex, also involves the hippocampus in a manner where the two regions are highly synchronized when attention is high," says Mei. "Our findings give importance to synchrony between the prefrontal cortex and hippocampus in top-down attention and open up the possibility that attention deficit disorders, like ADHD, might involve impairments in the synchrony between these two regions." According to the new study, ErbB4 coordinates a cascade of brain signals that "bridge" the two regions. ErbB4 itself encodes a receptor found on the surface of brain cells. The study found that when a protein (neuregulin-1) attaches to the ErbB4 receptor, it triggers a chain reaction that ultimately determines neurotransmitter levels in the prefrontal cortex and hippocampus. Without ErbB4, neurotransmitter levels go awry. The researchers discovered mice lacking ErbB4 have low levels of a particular neurotransmitter -- GABA, or gamma-aminobutyric acid -- in their brain. Low GABA levels can lead to impaired top-down attention in the prefrontal cortex, and impairs how the prefrontal cortex can efficiently coordinate with the hippocampus. The researchers concluded that ErbB4 helps link the two brain regions to maintain attention.

Older adults grow just as many new brain cells as young people -- ScienceDaily

The researchers from Columbia University and New York State Psychiatric Institute found that even the oldest brains they studied produced new brain cells. "We found similar numbers of intermediate neural progenitors and thousands of immature neurons," they wrote. Nevertheless, older individuals form fewer new blood vessels within brain structures and possess a smaller pool of progenitor cells -- descendants of stem cells that are more constrained in their capacity to differentiate and self-renew.

Running helps brain stave off effects of chronic stress: Exercise protects vital memory and learning functions -- ScienceDaily

"Exercise is a simple and cost-effective way to eliminate the negative impacts on memory of chronic stress," said study lead author Jeff Edwards, associate professor of physiology and developmental biology at BYU. Inside the hippocampus, memory formation and recall occur optimally when the synapses or connections between neurons are strengthened over time. That process of synaptic strengthening is called long-term potentiation (LTP). Chronic or prolonged stress weakens the synapses, which decreases LTP and ultimately impacts memory. Edwards' study found that when exercise co-occurs with stress, LTP levels are not decreased, but remain normal.

Does dim light make us dumber? -- ScienceDaily

Spending too much time in dimly lit rooms and offices may actually change the brain's structure and hurt one's ability to remember and learn, indicates groundbreaking research by Michigan State University neuroscientists. The researchers studied the brains of Nile grass rats (which, like humans, are diurnal and sleep at night) after exposing them to dim and bright light for four weeks. The rodents exposed to dim light lost about 30 percent of capacity in the hippocampus, a critical brain region for learning and memory, and performed poorly on a spatial task they had trained on previously. The rats exposed to bright light, on the other hand, showed significant improvement on the spatial task. Further, when the rodents that had been exposed to dim light were then exposed to bright light for four weeks (after a month-long break), their brain capacity -- and performance on the task -- recovered fully.

Depression, antidepressants, and the shrinking hippocampus

Both the tragic components and the intellectual challenge of depression have deepened in the last decade with a series of high-visibility reports that indicate prolonged, major depression is associated with atrophy within the central nervous system. A report in this issue of PNAS by Czéh et al. (1) adds support to a possible route for reversing these morphological changes. Such atrophy is centered in a brain region called the hippocampus. This structure plays a critical role in learning and memory, and the magnitude of the hippocampal volume loss (nearly 20% in some reports; refs. 2–4) helps explain some well-documented cognitive deficits that accompany major depression. These were careful and well-controlled studies, in that the atrophy was demonstrable after controlling for total cerebral volume and could be dissociated from variables such as history of antidepressant treatment, electroconvulsive therapy, or alcohol use. Moreover, more prolonged depressions were associated with more severe atrophy. These findings of hippocampal atrophy raise immediate questions. First, is it permanent? Tentatively, this appears to be the case, as the atrophy persisted for up to decades after the depressions were in remission. In addition, the extent of atrophy did not lessen with increasing duration of remission (2–4).

'Anxiety cells' identified in the brain's hippocampus: Neuroscientists have found, in mice, that certain cells fire when the animal is anxious, triggering anxiety-related behaviors -- ScienceDaily

"We call these anxiety cells because they only fire when the animals are in places that are innately frightening to them," Hen says. "For a mouse, that's an open area where they're more exposed to predators, or an elevated platform." The firing of the anxiety cells sends messages to other parts of the brain that turn on anxious behaviors -- in mice, those include avoiding the dangerous area or fleeing to a safe zone. Though many other cells in the brain have been identified as playing a role in anxiety, the cells found in this study are the first known to represent the state of anxiety, regardless of the type of environment that provokes the emotion. "This is exciting because it represents a direct, rapid pathway in the brain that lets animals respond to anxiety-provoking places without needing to go through higher-order brain regions," said Mazen Kheirbek, PhD, an assistant professor of psychiatry at UCSF and study's other senior investigator. "Now that we've found these cells in the hippocampus, it opens up new areas for exploring treatment ideas that we didn't know existed before," says the study's lead author Jessica Jimenez, PhD, an MD/PhD student at Columbia University's Vagelos College of Physicians & Surgeons.