Posts tagged learning
Articles and news from the latest research reports.
Sleep-deprived bees have difficulty relearning
Everyone feels refreshed after a good night’s sleep, but sleep does more than just rejuvenate, it can also consolidate memories. ‘The rapid eye movement form of sleep and slow wave sleep are involved in cognitive forms of memory such as learning motor skills and consciously accessible memory’, explains Randolf Mezel from the Freie Universtät Berlin, Germany. According to Menzel, the concept that something during sleep reactivates a memory for consolidation is a basic theory in sleep research. However, the human brain is far too complex to begin dissecting the intricate neurocircuits that underpin our memories, which is why Menzel has spent the last four decades working with honey bees: they are easy to train, well motivated and it is possible to identify the miniaturised circuits that control specific behaviours in their tiny brains. Intrigued by the role of sleep in memory consolidation and knowing that a bee is sleeping well when its antennae are relaxed and collapsed down, Menzel decided to focus on the role of sleep in one key memory characteristic: relearning (p. 3981). The challenge that Menzel set the bees was to learn a new route home after being displaced from a familiar path.
Menzel and his colleague Lisa Beyaert provided a hive with a well-stocked feeder and trained the bees to visit the feeder and return home fully laden. Then, when the duo were convinced that the bees had memorized the routine, they cunningly intercepted the bees at the feeder and transported them to a new location before releasing the insects to find their way home. According to Menzel, foragers learn the general lay of the land as novices before specialising in a few well-travelled routes later in their careers. He explains that the displaced bees had to rely on their earlier experiences to learn their new way home. How would loss of sleep affect the bee’s ability to learn the new route? To determine this, Menzel and Beyeart first had to check that the bees could learn the new route and that sleep deprivation hadn’t made them too tired or altered their motivation to forage.
Teaming up with electrical engineer Uwe Greggers, Menzel kitted the bees out with tiny RADAR transponders; the RADAR technology was particularly demanding to operate. Tracking the insects’ progress as they tried to learn the alternative route home, Menzel and his colleagues saw that by the second run home, the displaced bees had learned the new route. And when the trio disturbed the insects’ sleep during the night before the initial displacement by shaking them awake every 5 min, they found that the bees were unfazed. In fact they didn’t seem to need sleep to maintain their foraging energy levels and the foragers that were deprived of sleep before the first displacement run had no problems learning the new route home.
However, when the team disrupted the bees’ sleep after they had allowed the bees a single run along the new displaced route, the lack of sleep played havoc with their memories on the following day. Fewer than half of the sleep-deprived foragers made it home successfully, and those that did took more than twice as long as bees that had enjoyed an uninterrupted night’s sleep.
Sleep deprivation had dramatically affected the bees’ ability to alter a well-established memory and the team is now keen to see whether they can identify characteristic activity patterns in the slumbering insects’ brains that could represent memory formation.
Speed-Learning a New Language May Help Brain Grow
Learning a new language over a short period of time appears to make the brain grow, new research suggests. The new study included young recruits at the Swedish Armed Forces Interpreter Academy who went from having no knowledge of a new language to speaking it fluently within 13 months. The recruits studied at a furious pace: from morning to evening, weekdays and weekends.
The recruits were compared to medicine and cognitive science students at a university (the “control” group), who also studied hard, but weren’t learning a new language. Both groups underwent MRI brain scans before and after a three-month period of intensive study. The scans showed that the brain structure of the control group remained unchanged, but certain parts of the brain of the language students grew.
This growth occurred in the hippocampus, a structure involved in learning new material and spatial navigation, and in three areas of the cerebral cortex. Among the recruits, those who took naturally to learning a new language had greater growth in the hippocampus and areas of the cerebral cortex related to language learning, while those who had to put more effort into learning a new language had greater growth in an area of the motor region of the cerebral cortex, the investigators found.
"We were surprised that different parts of the brain developed to different degrees depending on how well the students performed and how much effort they had had to put in to keep up with the course," Johan Martensson, a researcher in psychology at Lund University in Sweden, said in a university news release.
Martensson noted that previous research has indicated that bilingual and multilingual people develop Alzheimer’s disease at a later age. “Even if we cannot compare three months of intensive language study with a lifetime of being bilingual, there is a lot to suggest that learning languages is a good way to keep the brain in shape,” Martensson said.
The study appeared in the Oct. 15 issue of the journal NeuroImage.
Fear really resides in a different area of the brain than its inhibitory mechanisms
Do you suffer from a phobia? Maybe arachnophobia? Then you know very well that even if you do not feel uneasy when imagining a huge and hairy tarantula in the therapist’s office, you still jump out of the shower screaming upon seeing a tiny spider. Why is it so hard to get rid of a phobia?
Extinguishing the fear response does not consist of erasing the memory of the fear provoking stimuli, but creating new, competitive memory traces. It has been suspected for some time that neuronal brain circuits responsible for extinguishing fear differ from circuits involved in reoccurrence of the fear response. This assumption has finally been experimentally confirmed. Novel experiments, described in PNAS, a prestigious journal of the American National Academy of Sciences, have been conducted by scientists from the Nencki Institute of Experimental Biology of the Polish Academy of Sciences and the International Institute of Molecular and Cell Biology in Warsaw. This research team was headed by Dr Ewelina Knapska, Dr Jacek Jaworski and Prof. Leszek Kaczmarek.
“Research has been carried out using a special, genetically modified strain of rats developed in the Nencki Institute. As a result we were able to observe the connections between neurons activated in the brains of animals experiencing fear”, explains Dr Ewelina Knapska, head of the Laboratory of Emotions Neurobiology in the Nencki Institute.
New merciful treatment method for children with brain tumours
Children who undergo brain radiation therapy run a significant risk of suffering from permanent neurocognitive adverse effects. These adverse effects are due to the fact that the radiation often encounters healthy tissue. This reduces the formation of new cells, particularly in the hippocampus – the part of the brain involved in memory and learning.
Researchers at the University of Gothenburg’s Sahlgrenska Academy have used a model study to test newer radiation therapy techniques which could reduce these harmful adverse effects. The researchers based their study on a number of paediatric patients who had undergone conventional radiation treatment for medulloblastoma, a form of brain tumour that almost exclusively affects children, and simulated treatment plans using proton therapy techniques and newer photon therapy techniques.
Each treatment plan was personalised by physician Malin Blomstrand, physicist Patrik Brodin and their colleagues. The results show that the risk of neurocognitive adverse effects can be reduced significantly using the new radiation treatment techniques, particularly proton therapy.
“This could mean a better quality of life for children who are forced to undergo brain radiation therapy,” says Malin Blomstrand.
Study finds that like human children, vervet monkeys learn by copying others
The new study, by Professor Andrew Whiten and Dr Erica van de Waal, shows that vervet monkeys learn by copying others in their group, as human children do.
The research found that monkeys were able to discover new techniques for obtaining food by mimicking the behaviour of others within their group. Not only that, but the same techniques then spread to other group members in the same way.
In four different groups, three different techniques spread, supporting the theory that these methods were passed on rather than learned individually.
The researchers believe vervet monkeys, like human children, are shaped by copying others and in this way come to be members of their cultural group.
Professor Whiten, Wardlaw Professor in the School of Psychology and Neuroscience, commented, “Our research is revealing that primates other than humans share some of our own reliance on doing as others do in our group.”
![Singing Mice Show Signs of Learning
Guys who imitate Luciano Pavarotti or Justin Bieber to get the girls aren’t alone. Male mice may do a similar trick, matching the pitch of other males’ ultrasonic serenades. The mice also have certain brain features, somewhat similar to humans and song-learning birds, which they may use to change their sounds, according to a new study.
"We are claiming that mice have limited versions of the brain and behavior traits for vocal learning that are found in humans for learning speech and in birds for learning song," said Duke neurobiologist Erich Jarvis, who oversaw the study. The results appear Oct. 10 in PLOS ONE and are further described in a review article in Brain and Language.[Arriaga, G. et. al. (2012) “Mouse vocal communication system: are ultrasounds learned or innate?” Brain and Language]
The discovery contradicts scientists’ 60-year-old assumption that mice do not have vocal learning traits at all. “If we’re not wrong, these findings will be a big boost to scientists studying diseases like autism and anxiety disorders,” said Jarvis, who is a Howard Hughes Medical Institute investigator. “The researchers who use mouse models of the vocal communication effects of these diseases will finally know the brain system that controls the mice’s vocalizations.”](http://41.media.tumblr.com/tumblr_mbq8pdtDce1rog5d1o1_400.jpg)
Singing Mice Show Signs of Learning
Guys who imitate Luciano Pavarotti or Justin Bieber to get the girls aren’t alone. Male mice may do a similar trick, matching the pitch of other males’ ultrasonic serenades. The mice also have certain brain features, somewhat similar to humans and song-learning birds, which they may use to change their sounds, according to a new study.
"We are claiming that mice have limited versions of the brain and behavior traits for vocal learning that are found in humans for learning speech and in birds for learning song," said Duke neurobiologist Erich Jarvis, who oversaw the study. The results appear Oct. 10 in PLOS ONE and are further described in a review article in Brain and Language.
[Arriaga, G. et. al. (2012) “Mouse vocal communication system: are ultrasounds learned or innate?” Brain and Language]The discovery contradicts scientists’ 60-year-old assumption that mice do not have vocal learning traits at all. “If we’re not wrong, these findings will be a big boost to scientists studying diseases like autism and anxiety disorders,” said Jarvis, who is a Howard Hughes Medical Institute investigator. “The researchers who use mouse models of the vocal communication effects of these diseases will finally know the brain system that controls the mice’s vocalizations.”
Memory: Do animals ever forget?
From pigeons that can recognise faces to a chimp that stores rocks to throw at visitors, all animals have memories. But how similar are they to ours?
(Image: Matt Jacob/Tendance Floue)
EVERY morning, you take a walk in the park, bringing some bread to feed the pigeons. As the days wear on, you begin to see the birds as individuals; you even start to name them. But what do the pigeons remember of you? Do they think kindly of you as they drop off to sleep at night, or is your face a blank, indistinguishable from the others strolling through the park?
These questions may seem whimsical, but knowing what other creatures recall is crucial if we are to understand their inner lives. It turns out that the range of mnemonic feats in the wild is nearly as varied as life itself.
If you take memory to mean any ability to store and respond to past events, even the simplest organisms meet the grade. Blobs of slime mould, for instance, which can slowly crawl across a surface, seem to note the timing of changes to their climate, slowing their movement in anticipation of an expected dry spell - even when it never actually arrives.
With the emergence of the first neurons about half a billion years ago, memories became more intricate as information could be stored in the patterns of electrical connections within the nervous system. This type of learning may have been behind the Cambrian explosion - the sudden appearance and rapid evolution of more complex species about 530 million years ago - because it enabled animals to exploit new niches, say Eva Jablonka at Tel Aviv University and Simona Ginsburg at the Open University of Israel.
Over the following few hundred million years, increasingly advanced skills could emerge with different forces driving the evolution of each creature’s mind. The result is a surprising range of mnemonic feats throughout the animal kingdom. Migratory cardinal fish, for instance, can remember where they laid their eggs during the breeding season and, after over-wintering in deep water, return to within half a metre of the same spot. Animals as diverse as lizards, bees and octopuses can learn the way out of a maze, and pigeons have an excellent visual recognition, learning to recognise more than a thousand different images. They can even recognise individual humans and aren’t fooled by a change of clothes.
Such skills, although impressive, don’t match our experiences of episodic memory, in which we immerse ourselves in specific events. A pigeon might learn to associate your face with food, but it probably can’t remember your last meeting in the way you might be able to recall details of your last trip to the park.
Brain connectivity predicts reading skills
The growth pattern of long-range connections in the brain predicts how a child’s reading skills will develop, according to research published today in Proceedings of the National Academy of Sciences
Literacy requires the integration of activity in brain areas involved in vision, hearing and language. These areas are distributed throughout the brain, so efficient communication between them is essential for proficient reading.
Jason Yeatman, a neuroscientist at Stanford University in California, and his colleagues studied how the development of reading ability relates to growth in the brain’s white-matter tracts, the bundles of nerve fibres that connect distant regions of the brain.
They tested how the reading skills of 55 children aged between 7 and 12 years old developed over a three-year period. There were big differences in reading ability between the children, and these differences persisted — the children who were weak readers relative to their peers at the beginning of the study were still weak three years later.
The researchers also scanned the brains of 39 of the children at least three times during the same period, to visualize the growth of two major white-matter tracts: the arcuate fasciculus, which conects the brain’s language centres, and the inferior longitudinal fasciculus, which links the language centres with the parts of the brain that process visual information.
Differences in the growth of both tracts could predict the variations in reading ability. Strong readers started off with a weak signal in both tracts on the left side of the brain, which got stronger over the three years. Weaker readers exhibited the opposite pattern.
Google simulates brain networks to recognize speech and images
This summer Google set a new landmark in the field of artificial intelligence with software that learned how to recognize cats, people, and other things simply by watching YouTube videos (see “Self-Taught Software“).
That technology, modeled on how brain cells operate, is now being put to work making Google’s products smarter, with speech recognition being the first service to benefit, Technology Review reports.
Google’s learning software is based on simulating groups of connected brain cells that communicate and influence one another. When such a neural network, as it’s called, is exposed to data, the relationships between different neurons can change. That causes the network to develop the ability to react in certain ways to incoming data of a particular kind — and the network is said to have learned something.
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.