Cell Mechanism Findings Could One Day be Used to Engineer Organs
Biologists have teamed up with mechanical engineers from the The University of Texas at Dallas to conduct cell research that provides information that may one day be used to engineer organs.
The research, published online in the Proceedings of the National Academy of Sciences, sheds light on the mechanics of cell, tissue and organ formation. The research revealed basic mechanisms about how a group of bacterial cells can form large three-dimensional structures.
“If you want to create an organism, the geometry of how a group of cells self-organizes is crucial,” said Dr. Hongbing Lu, professor of mechanical engineering and holder of the Louis Beecherl Jr. Chair at UT Dallas and an author of the study. “We found that cell death leads to wrinkles, and the stiffer the cell the fewer wrinkles.”
Organ formation is the result of individual cells teaming with others. The aggregate of the cells and their environment form a thin layer of what is known as a biofilm. These biofilms form 3-D wrinkled patterns.
Filed under wrinkled biofilms biology engineering bacterial cells organ formation science
Researchers identify brain mechanisms that regulating cocaine-seeking behavior
Researchers from the University of Wisconsin-Milwaukee (UWM) have identified mechanisms in the brain responsible for regulating cocaine-seeking behavior, providing an avenue for drug development that could greatly reduce the high relapse rate in cocaine addiction.
The research reveals that stimulation of certain brain receptors promotes inhibition of cocaine-associated memories, helping addicts to stop drug use. This inhibition is achieved through enhancing a process called “extinction learning,” in which cocaine-associated memories are replaced with associations that have no drug “reward.” This reduces drug-seeking behavior in rats.
The work was presented at the annual meeting of the Society for Neuroscience in New Orleans by Devin Mueller, UWM assistant professor of psychology, and doctoral student James Otis.
There are currently no FDA-approved medications to treat cocaine abuse, only treatments that address withdrawal symptoms, says Mueller. Abuse is maintained, in part, through exposure to environmental cues that trigger cocaine-related memories which lead to craving and relapse in recovering addicts. Currently, exposure therapy is used to help recovering addicts suppress their drug-seeking behavior, but with limited success. In exposure therapy, a patient is repeatedly exposed to stimuli that provoke craving. With repeated exposure, the patient experiences extinction, leading to reduced craving when presented with those stimuli.
If extinction could be strengthened, it would increase the effectiveness of exposure therapies in preventing relapse.
Isolating the receptor
The team found that a specific variant of the NMDA receptor, those which contain the NR2B subunit, are critical for extinction learning. They also discovered that drugs known to enhance NR2B function strengthened extinction because they act specifically in a region of the brain that regulates learned behaviors. In their investigation, researchers conditioned rats to associate one distinct chamber, but not another, with cocaine. Following conditioning, the rats were tested for a place preference by allowing drug-free access to both chambers. Rats demonstrating cocaine-seeking behavior spent significantly more time in the previously cocaine-associated chamber. Over several cocaine-free test sessions, addicted rats lost their place preference through extinction learning.
To examine the neural mechanisms of extinction, the researchers administered ifenprodil, which blocks NR2B-containing NMDA receptors, immediately after an extinction test. Ifenprodil-treated rats continued to spend more time in the cocaine-associated chamber even in the absence of cocaine, while saline-treated rats did not. These results were also replicated through specific infusion of ifenprodil into the brain’s infralimbic cortex, localizing a key brain structure in arresting cocaine-seeking.
Other avenues
The results indicate that enhancing NR2B function would boost the effectiveness of extinction-based exposure therapies. Although there are currently no NR2B-enhancing drugs, the NR2B containing receptor can be stimulated using other molecular pathways, says Mueller.
An example is the brain derived neurotrophic factor (BDNF) signaling cascade, which is implicated in neuron survival and growth. The authors targeted this cascade by directly administering BDNF into the infralimbic cortex. In extinction tests, administration of BDNF caused rats to lose their preference for the cocaine-associated chamber faster than rats given a placebo.
Mueller and Otis took these findings even further toward possible therapeutic intervention for addicts.
One issue with giving BDNF to humans is that it is unable to reach the brain through the bloodstream. Therefore, researchers next targeted the TrkB receptor, which is where BDNF normally binds. They did so with a newly synthesized drug that is able to reach the brain due to its small molecular size. This TrkB receptor agonist, known as 7,8 dihydroxyflavone, also strengthened extinction when given to rats during extinction training. The authors conclude that combining TrKB receptor stimulation simultaneously with exposure therapy could be an effective treatment for cocaine abuse, reducing craving and the potential for relapse.
(Source: eurekalert.org)
Filed under brain receptors NMDA cocaine addiction inhibition neuroscience Neuroscience 2012 science
The Power of Music: Mind Control by Rhythmic Sound
You walk into a bar and music is thumping. All heads are bobbing and feet tapping in synchrony. Somehow the rhythmic sound grabs control of the brains of everyone in the room forcing them to operate simultaneously and perform the same behaviors in synchrony. How is this possible? Is this unconscious mind control by rhythmic sound only driving our bodily motions, or could it be affecting deeper mental processes?
The mystery runs deeper than previously thought, according to psychologist Annett Schirmer reporting new findings today at the Society for Neuroscience meeting in New Orleans. Rhythmic sound “not only coordinates the behavior of people in a group, it also coordinates their thinking—the mental processes of individuals in the group become synchronized.”
This finding extends the well-known power of music to tap into brain circuits controlling emotion and movement, to actually control the brain circuitry of sensory perception. This discovery helps explain how drums unite tribes in ceremony, why armies march to bugle and drum into battle, why worship and ceremonies are infused by song, why speech is rhythmic, punctuated by rhythms of emphasis on particular syllables and words, and perhaps why we dance.
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Filed under brain brainwaves decision making emotion music neuroscience psychology Neuroscience 2012 science
The Neuroscience Of Music
Why does music make us feel? On the one hand, music is a purely abstract art form, devoid of language or explicit ideas. The stories it tells are all subtlety and subtext. And yet, even though music says little, it still manages to touch us deep, to tickle some universal nerves. When listening to our favorite songs, our body betrays all the symptoms of emotional arousal. The pupils in our eyes dilate, our pulse and blood pressure rise, the electrical conductance of our skin is lowered, and the cerebellum, a brain region associated with bodily movement, becomes strangely active. Blood is even re-directed to the muscles in our legs. (Some speculate that this is why we begin tapping our feet.) In other words, sound stirs us at our biological roots. As Schopenhauer wrote, “It is we ourselves who are tortured by the strings.”
We can now begin to understand where these feelings come from, why a mass of vibrating air hurtling through space can trigger such intense states of excitement. A paper in Nature Neuroscience by a team of Montreal researchers marks an important step in revealing the precise underpinnings of “the potent pleasurable stimulus” that is music. Although the study involves plenty of fancy technology, including fMRI and ligand-based positron emission tomography (PET) scanning, the experiment itself was rather straightforward. After screening 217 individuals who responded to advertisements requesting people that experience “chills to instrumental music,” the scientists narrowed down the subject pool to ten. (These were the lucky few who most reliably got chills.) The scientists then asked the subjects to bring in their playlist of favorite songs – virtually every genre was represented, from techno to tango – and played them the music while their brain activity was monitored.
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Filed under brain music emotion neuroimaging emotional arousal neuroscience psychology science
Attention, Learning, and the Value of Information
Despite many studies on selective attention, fundamental questions remain about its nature and neural mechanisms. Here I draw from the animal and machine learning fields that describe attention as a mechanism for active learning and uncertainty reduction and explore the implications of this view for understanding visual attention and eye movement control. I propose that a closer integration of these different views has the potential greatly to expand our understanding of oculomotor control and our ability to use this system as a window into high level but poorly understood cognitive functions, including the capacity for curiosity and exploration and for inferring internal models of the external world.
Filed under brain attention eye movements information neuroscience psychology science
You glimpse a stranger standing in the street. The light is hazy and the person’s face and clothing are indistinct. Who is it? Chances are you will think it is a man—and the reason for this is a survival reflex, according to an unusual study published on Wednesday.
Psychologists at the University of California at Los Angeles delved into our quest for visual clues when we assess other people.
They asked male and female students to look at 21 human silhouettes, all of them the same height, but with a progressively changing waist-to-hip ratio. The figures began with an obviously female “hourglass” figure and, after incremental changes, ended with an obviously male “hunk” figure. The volunteers were asked to say whether each of the 21 silhouettes was male or female, the idea being to identify the point where they saw a shift in gender.
What was striking, said researcher Kerri Johnson, was a preference for the volunteers to deem a shape to be a man whenever it was ambiguous—or could readily have been taken for a woman. “I was surprised by the size of the effect. It was a much stronger effect than I ever imagined,” Johnson said in a phone interview.
In the natural world, the demarcation between a woman’s shape and man’s shape comes when the ratio of the waist and hip circumferences is 0.8. But the volunteers, on average, placed the boundary at 0.68. In other words, an identifiable female shape for them was close to the idealised curves of a pinup.
Johnson’s team carried out three further studies, using a slightly different methods to see whether their approach had been skewed, and found that the bias in favour of men was unchanged. Are these errors in perception? Not so, said Johnson, who believes it to be an ancestral survival mechanism.
A man is likelier than a woman to be a bigger physical threat and our default perception is to prepare for risk: it’s better to be safe than sorry. “We suspect that this might be for a self-protective reason,” she said. “If you are walking down a dark alley at night, a woman poses no great physical threat to you in general, but if you encounter an unknown man, he’s more likely to have a physical formidability that could pose some risks.”
Johnson conceded that there could be cultural or ethnic factors which influence judgement but argued that the same kind of bias would prevail anywhere. “I think it’s entirely likely that if we were to test this in different populations we would probably have the same basic effect, the same pattern of judgement, although the strength of the judgement might vary,” she said.
The findings show how gender stereotypes can be reinforced, sometimes dangerously so, said the study. A woman could struggle if she has a body shape that is perceived as masculine and thus unattractive. “Consistent with other research, this is likely to produce preferences for extreme body shapes, particularly for women,” said the study.
The paper appears in the British journal Proceedings of the Royal Society B
(Source: medicalxpress.com)
Filed under perception bias survival mechanism gender stereotypes body shape neuroscience psychology science
Sharks see world as 50 shades of grey
Sharks are colour blind, a new molecular study by Australian scientists has confirmed, filling a gap in our knowledge about the evolution of colour vision. Dr Susan Theiss, from the University of Queensland, and colleagues, report their findings in the journal Biology Letters.
The evolution of colour vision has been studied in most vertebrates, but until recently, elasmobranchs (sharks, skates and rays) had been overlooked. Previous physiological research has shown some rays have colour vision but it suggested sharks were colour blind.
These previous studies looked at opsins, which are light-sensitive proteins found in the photoreceptor cells of the retina. Rod opsins are used in low light and produce a black and white image, while cone opsins are used in bright light, and often to see colours. Two or more different types of cone opsins are needed for colour vision.
While some ray species have multiple cone opsins as well as rods, studies in various shark species suggested they had only a single cone visual pigment.
To check whether this really was the case, Theiss and colleagues isolated the visual opsin genes from two wobbegong shark species: the spotted wobbegong Orectolobus maculatus and the ornate wobbegong O. ornatus.
Their findings confirm that wobbegongs possess only one cone opsin, meaning they see the world in shades of grey. The findings help fill in the picture of how colour vision evolved in different species.
"We know the earliest vertebrates had colour vision, but it has been lost by some groups over the course of evolution," says co-author Associate Professor Nathan Hart, a neuroecologist at the University of Western Australia.
Filed under vision visual system color vision color blind sharks evolution neuroscience science
Our eyes adapt to screens
The time most of us spend looking at a screen has rapidly increased over the past decade. If we’re not at work on the computer, we’re likely to stay tuned into the online sphere via a smart phone or tablet. Shelves of books are being replaced by a single e-book reader; and television shows and movies are available anywhere, any time.
So what does all this extra screen time mean for our eyes?
Well, you’ll be pleased to hear that like many good eye myths, there is simply no evidence to support this old wives’ tale.
Once we reach the age of ten years or so, it is practically impossible to injure the eyes by looking at something – the exception, of course, being staring at the Sun or similarly bright objects. Earlier in life, what we look at – or rather, how clearly we see – can affect our vision because the neural pathways between the eye and brain are still developing.
When we read off a piece of paper, light from the ambient environment is reflected off the surface of the paper and into our eyes. The retina at the back of the eye captures the light and begins the process of converting it into a signal that the brain understands.
The process of reading from screens is similar, except that the light is emitted directly by the screen, rather than being reflected.
Filed under brain vision visual adaptation visual system neuroscience psychology science
Electrical stimulation of the visual cortex may one day give image perception to blind people.
Work presented at the Society for Neuroscience meeting in New Orleans today suggests a way to create a completely new kind of visual prosthetic—one that restores vision by directly activating the brain.
In a poster session, researchers presented results showing how electrical stimulation of the visual cortex can evoke the sensation of simple flashes of light—including spatial information about those flashes.
While other researchers are trying to develop artificial retinas that feed visual signals into existing sensory pathways (see “A Retinal Prosthetic Powered by Light" and "Now I See You" for instance), the team behind the new work, from the Baylor College of Medicine and the University of Texas Health Science Center in Houston, is exploring the possibility of bypassing those routes all together. This could be vital for those whose retinas are unable to receive retinal stimulation.
The researchers used electrodes to stimulate the brains of three patients who were already undergoing brian surgery to treat epilepsy. All three were able to detect bright spots of light, called phosphenes, when certain regions of their brains were stimulated. And, in seven out of eight trials, the patients were able to correctly see the orientation of a phosphene—in one of two orientations, depending on the stimulation they received.
The work builds upon a study published by the same team in Nature Neuroscience this summer. In that study, the researchers defined which areas of the brain produce phosphene perception when patients’ brains were electrically stimulated.
A press release related to the earlier work says that the researchers “plan to conduct a larger patient study and create multiple flashes of light at the same time. Twenty-seven or so simultaneous flashes might allow participants to see the outline of a letter.”
Filed under blindness neuroscience prosthetics retina vision visual perception Neuroscience 2012 science
Scientists read dreams: Brain scans during sleep can decode visual content of dreams
A team of researchers led by Yukiyasu Kamitani of the ATR Computational Neuroscience Laboratories in Kyoto, Japan, used functional neuroimaging to scan the brains of three people as they slept, simultaneously recording their brain waves using electroencephalography (EEG).
The researchers woke the participants whenever they detected the pattern of brain waves associated with sleep onset, asked them what they had just dreamed about, and then asked them to go back to sleep.
This was done in three-hour blocks, and repeated between seven and ten times, on different days, for each participant. During each block, participants were woken up ten times per hour. Each volunteer reported having visual dreams six or seven times every hour, giving the researchers a total of around 200 dream reports.
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Filed under brain sleep dream neuroimaging Neuroscience 2012 neuroscience psychology science
