Researchers have long known that specific parts of the brain activate when people view particular images. For example, a region called the fusiform face area turns on when the eyes glance at faces, and another region called the parahippocampal place area does the same when a person looks at scenes or buildings. However, it’s been unknown whether such specialization also exists for visual working memory, a category of memory that allows the brain to temporarily store and manipulate visual information for immediate tasks. Now, scientists have found evidence that visual working memory follows a more general pattern of brain activity than what researchers have shown with initial visual activity, instead activating a more diffuse area in the front of the brain for all categories of visual stimuli.

The researchers worked with 18 healthy adults with normal or corrected vision. Using functional MRI (fMRI), a technique that examines brain activity while subjects are actively performing tasks in an MRI scanner, the researchers had each volunteer view and memorize three sequentially presented images that represented one of four categories: faces, bodies, scenes, or flowers. Between each image, there was a one second delay. Then, after a 10 second delay, the researchers flashed an image from the same category and asked the volunteers to indicate through a button press whether this last image matched one of the previous pictures (half of these “test” images matched one of the previous pictures). The volunteers did 80 of these trials, 20 of each category. To help make sure they weren’t verbally memorizing what they were seeing, which might change the fMRI results, a radio news program ran continuously in the background during the task. Afterwards, the researchers analyzed the fMRI data, looking for which brain areas activated during the short delay between pictures (brain areas active in initial visual activity and encoding) and during the long delay (brain areas active during working memory).

The fMRI data showed that the brain areas previously shown to activate during visualization, all located near the rear of the brain, declined in activity during the 10 second delay, although subtle differences between categories could still be extracted from the data. However, different areas near the front of the brain—specifically, the bilateral ventrolateral prefrontal cortex, dorsolateral prefrontal cortex and medial frontal gyrus—became active during the long delay. These areas activated without regard to what type of visual stimulus the volunteers saw, suggesting they activate in a more general pattern for visual working memory with no particular specialization based on image category.

Humans have a remarkable ability to store visual information at high detail over short periods of time. During these storage periods, some of the brain activity seems to shift from visual areas in the rear of the brain to areas in the front that have been suggested to form part of the brain’s “control center.” These areas do not appear to be specific for particular types of visual information. “We conclude that principles of cortical activation differ between encoding and maintenance of visual material,” the authors say. Their findings provide support for current models that locate memory not in specific brain modules but in the concerted action of distributed networks in the brain.

Source: neurosciencenews.com

School-age children whose mothers nurtured them early in life have brains with a larger hippocampus, a key structure important to learning, memory and response to stress.

The new research, by child psychiatrists and neuroscientists at Washington University School of Medicine in St. Louis, is the first to show that changes in this critical region of children’s brain anatomy are linked to a mother’s nurturing.
 
Their research is published online in the Proceedings of the National Academy of Sciences Early Edition.
 
“This study validates something that seems to be intuitive, which is just how important nurturing parents are to creating adaptive human beings,” says lead author Joan L. Luby, MD, professor of child psychiatry. “I think the public health implications suggest that we should pay more attention to parents’ nurturing, and we should do what we can as a society to foster these skills because clearly nurturing has a very, very big impact on later development.”
 
The brain-imaging study involved children ages 7 to 10 who had participated in an earlier study of preschool depression that Luby and her colleagues began about a decade ago. That study involved children, ages 3 to 6, who had symptoms of depression, other psychiatric disorders or were mentally healthy with no known psychiatric problems.
 
As part of the initial study, the children were closely observed and videotaped interacting with a parent, almost always a mother, as the parent was completing a required task, and the child was asked to wait to open an attractive gift. How much or how little the parent was able to support and nurture the child in this stressful circumstance — which was designed to approximate the stresses of daily parenting — was evaluated by raters who knew nothing about the child’s health or the parent’s temperament.
 
“It’s very objective,” Luby says. “Whether a parent was considered a nurturer was not based on that parent’s own self-assessment. Rather, it was based on their behavior and the extent to which they nurtured their child under these challenging conditions.”
 
The study didn’t observe parents and children in their homes or repeat stressful exercises, but other studies of child development have used similar methods as valid measurements of whether parents tend to be nurturers when they interact with their children.
 
For the current study, the researchers conducted brain scans on 92 of the children who had had symptoms of depression or were mentally healthy when they were studied as preschoolers. The imaging revealed that children without depression who had been nurtured had a hippocampus almost 10 percent larger than children whose mothers were not as nurturing.
 
“For years studies have underscored the importance of an early, nurturing environment for good, healthy outcomes for children,” Luby says. “But most of those studies have looked at psychosocial factors or school performance. This study, to my knowledge, is the first that actually shows an anatomical change in the brain, which really provides validation for the very large body of early childhood development literature that had been highlighting the importance of early parenting and nurturing. Having a hippocampus that’s almost 10 percent larger just provides concrete evidence of nurturing’s powerful effect.”
 
Luby says the smaller volumes in depressed children might be expected because studies in adults have shown the same results. What did surprise her was that nurturing made such a big difference in mentally healthy children.
 
“We found a very strong relationship between maternal nurturing and the size of the hippocampus in the healthy children,” she says.
 
Although 95 percent of the parents whose nurturing skills were evaluated during the earlier study were biological mothers, the researchers say that the effects of nurturing on the brain are likely to be the same for any primary caregiver — whether they are fathers, grandparents or adoptive parents.
 
The fact that the researchers found a larger hippocampus in the healthy children who were nurtured is striking, Luby says, because the hippocampus is such an important brain structure.
 
When the body faces stresses, the brain activates the autonomic nervous system, an involuntary system of nerves that controls the release of stress hormones. Those hormones help us cope with stress by increasing the heart rate and helping the body adapt. The hippocampus is the main brain structure involved in that response. It’s also key in learning and memory, and larger volumes would suggest a link to improved performance in school, among other things.
 
Past animal studies have indicated that a nurturing mother can influence brain development, and many studies in human children have identified improvements in school performance and healthier development in children raised in a nurturing environment. But until now, there has not been solid evidence linking a nurturing parent to changes in brain anatomy in children.
 
“Studies in rats have shown that maternal nurturance, specifically in the form of licking, produces changes in genes that then produce changes in receptors that increase the size of the hippocampus,” Luby says. “That phenomenon has been replicated in primates, but it hasn’t really been clear whether the same thing happens in humans. Our study suggests a clear link between nurturing and the size of the hippocampus.”
 
She says educators who work with families who have young children may improve school performance and child development by not only teaching parents to work on particular tasks with their children but by showing parents how to work with their children.
 
“Parents should be taught how to nurture and support their children,” Luby says. “Those are very important elements in healthy development.”

Source: neurosciencenews.com

Both children and the elderly have slower response times when they have to make quick decisions in some settings.
 
But recent research suggests that much of that slower response is a conscious choice to emphasize accuracy over speed.
 
In fact, healthy older people can be trained to respond faster in some decision-making tasks without hurting their accuracy – meaning their cognitive skills in this area aren’t so different from younger adults.
 
“Many people think that it is just natural for older people’s brains to slow down as they age, but we’re finding that isn’t always true,” said Roger Ratcliff, professor of psychology at Ohio State University and co-author of the studies.
 
“At least in some situations, 70-year-olds may have response times similar to those of 25-year olds.”
 
Ratcliff and his colleagues have been studying cognitive processes and aging in their lab for about a decade. In a new study published online this month in the journal Child Development, they extended their work to children.
 
Ratcliff said their results in children are what most scientists would have expected: very young children have slower response times and poorer accuracy compared to adults, and these improve as the children mature.
 
But the more interesting finding is that older adults don’t necessarily have slower brain processing than younger people, said Gail McKoon, professor of psychology at Ohio State and co-author of the studies.
 
“Older people don’t want to make any errors at all, and that causes them to slow down. We found that it is difficult to get them out of the habit, but they can with practice,” McKoon said.
 
Researchers uncovered this surprising finding by using a model developed by Ratcliff that considers both the reaction time and the accuracy shown by participants in speeded tasks. Most models only consider one of these variables.
 
“If you look at aging research, you find some studies that show older people are not impaired in accuracy, but other studies that show that older people do suffer when it comes to speed. What this model does is look at both together to reconcile the results,” Ratcliff said.
 
Ratcliff, McKoon and their colleagues have used several of the same experiments in children, young adults and the elderly.
 
In one experiment, participants are seated in front of a computer screen. Asterisks appear on the screen and the participants have to decide as quickly as possible whether there is a “small” number (31-50) or a “large” number (51-70) of asterisks. They press one of two keys on the keyboard, depending on their answer.
 
In another experiment, participants are again seated in front of a computer screen and are shown a string of letters. They have to decide whether those letters are a word in English or not. Some strings are easy (the nonwords are a random string of letters) and some are hard (the nonwords are pronounceable, such as “nerse”).
 
In the Child Development study, the researchers used the asterisk test on second and third graders, fourth and fifth graders, ninth and tenth graders, and college-aged adults. Third graders and college-aged adults participated in the word/nonword test.
 
The results showed that there was a rise in accuracy and decrease in response time on both tasks from the second and third-graders to the college-age adults.
 
The younger children took longer than older children and adults to respond in the experiment, Ratcliff said. They, like the elderly, were taking longer to make up their mind. But the younger children were also less accurate than younger adults in this study.
 
“Younger children are not able to make as good of use of the information they are presented, so they are less accurate,” Ratcliff said. “That improves as they mature.”
 
Older adults show a different pattern. In a study published in the journal Cognitive Psychology, Ratcliff and colleagues compared college-age subjects, older adults aged 60-74, and older adults aged 75-90. They used the same asterisk and word/nonword tests that were in the Child Development study. They found that there was little difference in accuracy among the groups, even the oldest of participants.
 
However, the college students had faster response times than did the 60-74 year olds, who were faster than the 75-90 year olds.
 
But the slower response times are not all the result of a decline in skills among older adults. In a previous study, the researchers encouraged older adults to go faster on these same tests. When they did, the difference in their response times compared to college-age students decreased significantly.
 
“For these simple tasks, decision-making speed and accuracy is intact even up to 85 and 90 years old,” McKoon said.
 
That doesn’t mean there are no effects of aging on decision-making speed and accuracy, Ratcliff said. In a study in the Journal of Experimental Psychology: General, Ratcliff, McKoon and another colleague found (like in studies from other laboratories) that accuracy for “associative memory” does decline as people age. For example, older people were much less likely to remember if they had studied a pair of words together than did younger adults.
 
But Ratcliff said that, overall, their research suggests there should be greater optimism about the cognitive skills of seniors.
 
“The older view was that all cognitive processes decline at the same rate as people age,” Ratcliff said.

Source: neurosciencenews.com
 
“We’re finding that there isn’t such a uniform decline. There are some things that older people do nearly as well as young people.”
 
Ratcliff co-authored the Child Development paper with Jessica Love and John Opfer of Ohio State and Clarissa Thompson of the University of Oklahoma. Ratcliff and McKoon co-authored the Cognitive Psychology and Journal of Experimental Psychology: General papers with Anjali Thapar of Bryn Mawr College.
 
Some of the research was supported with grants from the National Institute on Aging and the National Institute of Mental Health.

Source: neurosciencenews.com

Compared to our other senses, scientists don’t know much about how our skin is wired for the sensation of touch. Now, research reported in the December 23rd issue of the journal Cell, a Cell Press publication, provides the first picture of how specialized neurons feel light touches, like a brush of movement or a vibration, are organized in hairy skin.

Looking at these neurons in the hairy skin of mice, the researchers observed remarkably orderly patterns, suggesting that each type of hair follicle works like a distinct sensory organ, each tuned to register different types of touches. Each hair follicle sends out one wire-like projection that joins with others in the spinal cord, where the information they carry can be integrated into impulses sent to the brain. This network of neurons in our own skin allows us to perceive important differences in our surroundings: a raindrop versus a mosquito, a soft fingertip versus a hard stick.

“We can now begin to appreciate how these hair follicles and associated neurons are organized relative to one another and that organization enables us to think about how mechanosensory information is integrated and processed for the perception of touch,” says David Ginty of The Johns Hopkins University School of Medicine.
 
Mice have several types of hair follicles with three in particular that make up their coats. Ginty’s team made a technical breakthrough by coming up with a way to label distinct populations of known low-threshold mechanoreceptors (LTMRs). Before this study, there was no way to visualize LTMRs in their natural state. The neurons are tricky to study in part because they extend from the spinal cord all the way out to the skin. The feeling in the tips of our toes depends on cells that are more than one meter long.
 
The images show something unexpected and fascinating, Ginty says. Each hair follicle type includes a distinct combination of mechanosensory endings. Those sensory follicles are also organized in a repeating and stereotypical pattern in mouse skin.
 
The neurons found in adjacent hair follicles stretch to a part of the spinal cord that receives sensory inputs, forming narrow columns. Ginty says there are probably thousands of those columns in the spinal cord, each gathering inputs from a particular region of the skin and its patch of 100 or so hairs.
 
Of course, we don’t have hair like a mouse, and it’s not yet clear whether some of these mechanosensory neurons depend on the hairs themselves to pick up on sensations and whether others are primarily important as scaffolds for the underlying neural structures. They don’t know either how these inputs are integrated in the spinal cord and brain to give rise to perceptions, but now they have the genetic access they need to tinker with each LTMR subtype one by one, turning them on or off at will and seeing what happens to the brain and to behavior. Intriguingly, one of the LTMR types under study is implicated as “pleasure neurons” in people, Ginty notes.
 
At this point, he says they have no clue how these neurons manage to set themselves up in this way during development. The neurons that form this sensory network are born at different times, controlled by different growth factors, and “yet they assemble in these remarkable patterns.” And for Ginty that leads to a simple if daunting question to answer: “How does one end of the sensory neuron know what the other end is doing?”

Source: neuroscience.com

A recent study has shown that rather than having all areas of the brain fully functioning when awake and then resting when asleep, regions of the brain “go off line” at different times during sleep where they lose their ability to communicate with other regions of the brain. This may to some degree explain such phenomenon as sleepwalking. Also, it is similar to the characteristic of dolphins where sleep occurs in one part of the brain while another part regulates swimming to the surface to breathe. According to Dr. Yuval Nir, a researcher at the University of Wisconsin, “We usually think of sleep as an all-or-nothing event, but these findings reflect a piecemeal type of sleep in which parts of the brain go off line when others are still communicating. Before this, we weren’t entirely sure that there was such a thing as ‘local’ sleep.”

In the research study conducted jointly by scientists at the University of Wisconsin and UCLA, 13 epilepsy patients, who were being monitored for the sources of their seizures, had electrodes implanted deeply into their brains.  It was found that the sleep of these patients resembled the normal sleep of healthy people, and the bursts of activity that occurred with epilepsy were removed from the analysis.  The deep electrodes recorded activity in 12 regions of the brain.  Also, scalp EEG, depth EEG and the electrical spikes of individual neurons were recorded.

The results showed that the electrical markers for sleep, slow brainwaves and oscillating spindles, appeared mostly in local regions of the brain, and the “local” sleep occurred mainly later in the night.  Dr. Nir compared this phenomenon to fans at a baseball game who eventually need a bathroom or food break:  “They all need a seventh-inning stretch, but some of them take it in the sixth inning and some in the eighth.”

Our memories work better when our brains are prepared to absorb new information, according to a new study by MIT researchers. A team led by Professor John Gabrieli has shown that activity in a specific part of the brain, known as the parahippocampal cortex (PHC), predicts how well people will remember a visual scene.

The new study, published in the journal NeuroImage, found that when the PHC was very active before people were shown an image, they were less likely to remember it later. “When that area is busy, for some reason or another, it’s less ready to learn something new,” says Gabrieli, the Grover Hermann Professor of Health Sciences and Technology and Cognitive Neuroscience and a principal investigator at the McGovern Institute for Brain Research at MIT.

The PHC, which has previously been linked to recollection of visual scenes, wraps around the hippocampus, a part of the brain critical for memory formation. However, this study is the first to investigate how PHC activity before a scene was presented would affect how well the scene was remembered. Lead author of the paper is Julie Yoo, a postdoc at the McGovern Institute.

Subjects were shown 250 color photographs of indoor and outdoor scenes as they lay in a functional magnetic resonance imaging (fMRI) scanner. They were later shown 500 scenes — including the 250 they had already seen — as a test of their recollection of the first batch of images. The fMRI scans revealed that images were remembered better when there was lower activity in the PHC before the scenes were presented.

The precise area of activation was slightly different in each person studied, but was always located in the PHC.

In a second experiment, the researchers used real-time fMRI, which can monitor subjects’ brain states from moment to moment, to determine when the brain was “ready” or “not ready” to recall images. Those states were used as triggers to present new visual scenes. As expected, images presented while the brain was in a “ready” state were better remembered.

The finding adds a new element to the longstanding question of why we remember certain things better than others, says Nicholas Turk-Browne, assistant professor of psychology at Princeton University, who was not involved in this study. Traditionally, scientists have believed that memory is based on the inherent memorability of specific events, with strongly emotional events likeliest to be remembered. More recently, cognitive neuroscientists have found that the brain’s ability to consolidate, store and retrieve information is also important.

“The significance of this study is that it suggests that beyond the inherent memorability of things, and how well the memory systems are working, there’s a huge role to be played by how well prepared you are to process what’s coming in,” Turk-Browne says.

In theory, this method could be used to determine when a student is best prepared to learn new material, or to monitor workers who need to stay alert. “That’s what we would like to think — that we are able to measure states of receptivity for learning, or preparedness for learning,” Gabrieli says. “In terms of how that would be translated to real life, there are still a few steps to go.”

The main hurdle is that fMRI scanners are very large, and at this point, they cannot be made into small, portable devices. A possible alternative is using electroencephalography (EEG), a more easily miniaturized technology that measures electrical activity along the scalp. The researchers are now working on ways to use EEG to measure activity in the PHC.

Source: neurosciencenews.com

Engineering researchers at four U.S. universities are embarking on a four-year project to design a prosthetic arm that amputees can control directly with their brains and that will allow them to feel what they touch. While it may sound like science fiction, the researchers say much of the technology has already been proven in small-scale demonstrations.

Older bilingual adults compensate for age-related declines in brainpower by developing new strategies to process language, according to a recent study published in the journal Aging, Neuropsychology, and Cognition.

A link was found between cannabis use at a young age and the onset of psychotic illness...

Researchers from the CHUM Research Centre (CRCHUM) have identified a new gene that predisposes people to both autism and epilepsy.

Led by the neurologist Dr. Patrick Cossette, the research team found a severe mutation of the synapsin gene (SYN1) in all members of a large French-Canadian family suffering from epilepsy, including individuals also suffering from autism. This study also includes an analysis of two cohorts of individuals from Quebec, which made it possible to identify other mutations in the SYN1 gene among 1% and 3.5% of those suffering respectively from autism and epilepsy, while several carriers of the SYN1 mutation displayed symptoms of both disorders.

“The results show for the first time the role of the SYN1 gene in autism, in addition to epilepsy, and strengthen the hypothesis that a deregulation of the function of synapse because of this mutation is the cause of both diseases,” notes Cossette, who is also a professor with the Faculty of Medicine at the Université de Montréal.

He adds that “until now, no other genetic study of humans has made this demonstration.”

The different forms of autism are often genetic in origin and nearly a third of people with autism also suffer from epilepsy. The reason for this comorbidity is unknown. The synapsin gene plays are crucial role in the development of the membrane surrounding neurotransmitters, also referred to as synaptic vesicles. These neurotransmitters ensure communication between neurons. Although mutations in other genes involved in the development of synapses (the functional junction between two neurons) have previously been identified, this mechanism has never been proved in epilepsy in humans until the present study.

Notes about this autism and epilepsy research

The results of the present study were published in the latest online edition of Human Molecular Genetics. They provide the key to a common cause of epilepsy and autism and will make it possible to gain a better understanding of the pathophysiology of these devastating diseases that seriously perturb brain development. They will also contribute to the development of new treatment strategies.

Facts and figures relating to autism and epilepsy in Canada

Invasive development disorders, also called the autism spectrum, include five diagnoses: autism, the most well known; RETT syndrome; childhood disintegrative disorder; Asperger syndrome; and unspecified pervasive developmental disorder. It is estimated that 60 to 70 people (including 10 children) out of every 10,000 people are affected by pervasive development disorders in Canada.

Epilepsy affects around 85 out 10,000 people in Canada. There are several kinds of epileptic seizures and syndromes.

April 2011
Source: www.neuroscience.com