Posts tagged hippocampus
Articles and news from the latest research reports.
Brain structure of infants predicts language skills at 1 year
Using a brain-imaging technique that examines the entire infant brain, researchers have found that the anatomy of certain brain areas – the hippocampus and cerebellum – can predict children’s language abilities at 1 year of age.
The University of Washington study is the first to associate these brain structures with future language skills. The results are published in the January issue of the journal Brain and Language.
“The brain of the baby holds an infinite number of secrets just waiting to be uncovered, and these discoveries will show us why infants learn languages like sponges, far surpassing our skills as adults,” said co-author Patricia Kuhl, co-director of the UW’s Institute for Learning & Brain Sciences.
Children’s language skills soar after they reach their first birthdays, but little is known about how infants’ early brain development seeds that path. Identifying which brain areas are related to early language learning could provide a first glimpse of development going awry, allowing for treatments to begin earlier.
“Infancy may be the most important phase of postnatal brain development in humans,” said Dilara Deniz Can, lead author and a UW postdoctoral researcher. “Our results showing brain structures linked to later language ability in typically developing infants is a first step toward examining links to brain and behavior in young children with linguistic, psychological and social delays.”
Brain cells activated, reactivated in learning and memory
Memories are made of this, the song says. Now neuroscientists have for the first time shown individual mouse brain cells being switched on during learning and later reactivated during memory recall. The results are published Dec. 13 in the journal Current Biology.
We store episodic memories about events in our lives in a part of a brain called the hippocampus, said Brian Wiltgen, now an assistant professor at the Center for Neuroscience and Department of Psychology at the University of California, Davis. (Most of the work was conducted while Wiltgen was working at the University of Virginia.) In animals, the hippocampus is important for navigation and storing memories about places.
"The exciting part is that we are now in a position to answer a fundamental question about memory," Wiltgen said. "It’s been assumed for a long time that the hippocampus is essential for memory because it drives reactivation of neurons (nerve cells) in the cortex. The reason you can remember an event from your life is because the hippocampus is able to recreate the pattern of cortical activity that was there at the time."
According to this model, patients with damage to the hippocampus lose their memories because they can’t recreate the activity in the cortex from when the memory was made. Wiltgen’s mouse experiment makes it possible to test this model for the first time.
Mammalian brain knows where it’s at
A new study in the journal Neuron suggests that the brain uses a different region than neuroscientists had thought to associate objects and locations in the space around an individual. Knowing where this fundamental process occurs could help treat disease and brain injury as well as inform basic understanding of how the brain supports memory and guides behavior.
“Understanding how and where context is represented in the brain is important,” said study senior author Rebecca Burwell, professor of psychology and neuroscience at Brown University. “Context, or the place in which events occur, is the hallmark of episodic memory, but context is more than a place or a location. This room, for example, has a window, furniture, and other objects. You walk into a room and all that information helps you remember what happened there.”
Pinpointing where the brain puts together objects and places to form a context could also matter for treating traumatic brain injuries or neuropsychiatric diseases, such as schizophrenia and depression, that involve that part of the brain, said Burwell, who is also affiliated with the Brown Institute for Brain Science.
“We know that contextual representations are disrupted in mental disorders, particularly schizophrenia and depression,” Burwell said. “Individuals with these disorders have trouble using context to plan actions or choose appropriate behaviors.”
How Driving a Taxi Changes London Cabbies’ Brains
Every black-cab driver in central London has to have “The Knowledge” — a memorized map of the capital, including some 25,000 streets and thousands of landmarks, right down to the order of theaters on Shaftesbury Avenue.
It’s a brutal learning process that can take three to four years to complete, with a final test — the Knowledge of London Examination System — that often takes 12 attempts to pass. Even then, ultimately only half of the trainee cabbies ace the exam.
According to a report published in the journal Current Biology, successfully learning this mental atlas of London’s spaghetti streets causes structural changes in the brain, affects memory and creates a greater volume of nerve cells in the brain’s hippocampus.
Research discovers two opposite ways our brain voluntarily forgets unwanted memories
If only there were a way to forget that humiliating faux pas at last night’s dinner party. It turns out there’s not one, but two opposite ways in which the brain allows us to voluntarily forget unwanted memories, according to a study published by Cell Press October 17 in the journal Neuron. The findings may explain how individuals can cope with undesirable experiences and could lead to the development of treatments to improve disorders of memory control.
"This study is the first demonstration of two distinct mechanisms that cause such forgetting: one by shutting down the remembering system, and the other by facilitating the remembering system to occupy awareness with a substitute memory," says lead study author Roland Benoit of the MRC Cognition and Brain Sciences Unit at the University of Cambridge.
Previous studies have shown that individuals can voluntarily block memories from awareness. Although several neuroimaging studies have examined the brain systems involved in intentional forgetting, they have not revealed the cognitive tactics that people use or the precise neural underpinnings. Two possible ways to forget unwanted memories are to suppress them or to substitute them with more desirable memories, and these tactics could engage distinct neural pathways.
(Source: medicalxpress.com)
Study links hippocampus with unconscious bias
The hippocampus is an area of the brain known to be one in which links between memories are formed, but until now it was not known that this brain region is involved in steering the brain towards making particular choices over others when faced with new decisions for which we have no previous experiences to draw on.
In a paper published in the journal Science, research psychologists G. Elliott Wimmer and Daphna Shohamy of Columbia University in New York report on their study, which used functional magnetic resonance imaging (fMRI) of regions of the brain. In the study, they asked 31 volunteers to complete a three-part task while in the machine. Throughout the task their brain activity was determined by the fMRI.
The results suggest that several areas of the brain are involved in evaluating new stimuli and associating them with previous memories, but the process is strongly associated with the hippocampus.
The findings could have application, for example, in the design of new products, which could incorporate aspects of earlier products (such as color, logo or font) to stimulate the association and produce an unconscious bias towards those products over other equally new products.
The findings also suggest that misguided biases such as racism could stem from unconscious associations. (Guilt by association is a commonly known bias.) These biases have long been known, but the current study clearly shows their association with the hippocampus.
Discovery of gatekeeper nerve cells explains the effect of nicotine on learning and memory
Researchers at Uppsala University have, together with Brazilian collaborators, discovered a new group of nerve cells that regulate processes of learning and memory. These cells act as gatekeepers and carry a receptor for nicotine, which can explain our ability to remember and sort information.
The discovery of the gatekeeper cells, which are part of a memory network together with several other nerve cells in the hippocampus, reveal new fundamental knowledge about learning and memory. The study is published today in Nature Neuroscience.
The hippocampus is an area of the brain that is important for consolidation of information into memories and helps us to learn new things. The newly discovered gatekeeper nerve cells, also called OLM-alpha2 cells, provide an explanation to how the flow of information is controlled in the hippocampus.
“It is known that nicotine improves cognitive processes including learning and memory, but this is the first time that an identified nerve cell population is linked to the effects of nicotine”, says Professor Klas Kullander at Uppsala University.
The Obese Brain May Thwart Weight Loss
New research by Terry Davidson, director of American University’s Center for Behavioral Neuroscience, indicates that diets that lead to obesity—diets high in saturated fat and refined sugar—may cause changes to the brains of obese people that in turn may fuel overconsumption of those same foods and make weight loss more challenging.
“It is a vicious cycle that may explain why obesity is so difficult to overcome,” said Davidson, also a professor of psychology at AU.
Davidson recently published his research, “The Effects of a High-Energy Diet on Hippocampal-Dependent Discrimination Performance and Blood-Brain Barrier Integrity Differ for Diet-Induced Obese and Diet-Resistant Rats,” in the journal Physiology & Behavior.
Specific regions of the hippocampus connected to discrete steps of task mastery, study finds
In a study published in Nature Neuroscience, neurobiologists from the Friedrich Miescher Institute for Biomedical Research have been linking synapse formation in the hippocampus to distinct learning steps. They show how different regions of the hippocampus have specific and sequential functions in the mastery of a complex task.
The setup is natural. The mouse finds herself in the water and is looking for a dry place. But how does she solve this task? And what happens if she finds herself in the same situation again? Here is what the scientists observed: At the beginning, the mouse swims all around the little pool, randomly searching for the platform. After two days, there is a change in search approach: The mouse has learned where about the platform is and will start to search right away in the area of the platform. Finally, after another five days, the mouse knows exactly where the platform is and swims directly for it. What is astonishing is that every mouse behaves same way and all the mice learn to find the platform in about the same time, through the same trial and error search strategy stages.
Pico Caroni, senior group leader at the Friedrich Miescher Institute for Biomedical Research, and his team not only described for the first time how mice learn to master such a complex task step by step, but they have also been able to show how one region of the brain, the hippocampus, is engaged in these learning processes. The hippocampus is the region of the brain that is the relay station for a lot of sensory information. In this function, the hippocampus is extremely important for learning and the consolidation of memory. The hippocampus can be divided into three areas termed ventral (vH), intermediate (iH) and dorsal hippocampus (dH). Even though the composition of the neuronal networks in each area is comparable, they differ in gene expression, connectivity, tuning and function.
Caroni and his team could now show that this difference has functional implications in learning. It has been known that during learning new synapses are formed in the hippocampus by so called mossy fibers. In their study published in Nature Neuroscience the scientists show that each search strategy, each level of learning, is associated with a different region of the hippocampus. First, mossy fiber synapses are formed in vH. With the first change in search strategy, mossy fiber formation moves to iH. The mice now have a clear understanding of the relative position of the platform, e.g. distance from the pool wall. Finally, synapse formation moves to dH. By now the mouse has a clear map of the pool, the platform and her position in these surroundings. From now on the mouse will always know where the platform is and will directly head for it.
"We believe that many complex learning tasks are achieved through sub-tasks and that the three areas of the hippocampus are involved in similar ways," comments Caroni. "Our experiments indicate further that this approach is innate, which indicates that similar processes may play as we learn to bike or become proficient in playing tennis."
(Source: medicalxpress.com)
By stitching together 40 high-resolution shots of the hippocampal region of a mouse model of Down syndrome, neurobiologist Ahmad Salehi created this single hyper-informative image which presents a global view of the hippocampus with enough resolution to examine the connections of individual dendrites.
(Source: the-scientist.com)