Posts tagged psychology
Articles and news from the latest research reports.
Biologists Locate Brain’s Processing Point for Acoustic Signals Essential to Human Communication
ScienceDaily (Mar. 8, 2012) — In both animals and humans, vocal signals used for communication contain a wide array of different sounds that are determined by the vibrational frequencies of vocal cords. For example, the pitch of someone’s voice, and how it changes as they are speaking, depends on a complex series of varying frequencies. Knowing how the brain sorts out these different frequencies — which are called frequency-modulated (FM) sweeps — is believed to be essential to understanding many hearing-related behaviors, like speech. Now, a pair of biologists at the California Institute of Technology (Caltech) has identified how and where the brain processes this type of sound signal.
This diagram shows areas in the midbrain region where direction- selective neurons were found. (Credit: Guangying Wu/Caltech)
Their findings are outlined in a paper published in the March 8 issue of the journal Neuron.
Cannabinoid 2 Receptors Regulate Impulsive Behaviour
ScienceDaily (Mar. 8, 2012) — A new study led by the Neuroscience Institute of Alicante reveals how manipulating the endocannabinoid system can modulate high levels of impulsivity. This is the main problem in psychiatric illnesses such a schizophrenia, bipolar disorder and substance abuse.
Spanish researchers have for the first time demonstrated that the CB2 receptor, which has modulating functions in the nervous system, is involved in regulating impulsive behaviour.
"Such a result proves the relevance that manipulation of the endocannabinoid system can have in modulating high levels of impulsivity present in a wide range of psychiatric and neurological illness," explains Jorge Manzanares Robles, a scientist at the Alicante Neuroscience Institute and director of the study.
Carried out on mice, the study suggests the possibility of undertaking future clinical trials using drugs that selectively act on the CB2 and thus avoid the psychoactive effects deriving from receptor CB1 manipulation, whose role in impulsivity has already been proven.
However, the authors of the study published in the British Journal of Pharmacology remain cautious. Francisco Navarrete, lead author of the study, states that “it is still very early to be able to put forward a reliable therapeutic tool.”
New way to image bleeding in arteries of the brain
March 8, 2012
New research from the University of Calgary’s Hotchkiss Brain Institute shows that by using a CT scan (computerized tomography), doctors can predict which patients are at risk of continued bleeding in the brain after a stroke. This vital information will allow doctors to utilize the most powerful blood clotting medications for those with the highest risk.
One in three individuals will continue to accumulate blood in the brain from a leak in a small artery. Pooling blood in the brain has serious consequences, and could lead to disability or even death. Previously, doctors in emergency stroke situations could not discern whether or not a patient’s brain bleeding had stopped. Using CT scan images, researchers can now identify “spot signs” that are seen as a small area of contrast on the CT scan. This spot sign is the actual location of bleeding within an artery in the brain.
"Technology that has emerged has allowed us to see the brain’s blood flow system in exquisite detail to precisely identify the source of the problem," explains Dr. Andrew Demchuk, Professor in the departments of clinical neurosciences and radiology, and lead author of this study. "We are now at a point where we can harness this technology to develop better treatments for patients with a blockage or breakage in a brain artery. Ultimately this research will confirm when immediate treatment is necessary – essentially, as soon as you see the spot sign."
This research provides validation of a new imaging marker to identify patients that may need to be treated with clotting medications versus those that don’t. “We must be very careful when and to whom these drugs are administered because they are so powerful at forming clots. These drugs can cause clots not only where there are holes and leaks – but also in intact arteries –potentially causing stroke and heart attacks,” says Demchuk. “Therefore this CT scan selection is critical for targeting only those patients at highest risk of continued bleeding.”
Clinical trials have now begun to test powerful clotting drugs in these patients.
This University of Calgary-led “PREDICT” study was coordinated with researchers at the Universities of Ottawa and Toronto, along with collaboration amongst nine other centres around the world. Their results were published in the March 8th online edition of the prestigious journal Lancet Neurology.
Provided by University of Calgary
Source: medicalxpress.com
Discovery of brain’s natural resistance to drugs may offer clues to treating addition
March 8, 2012
The left image shows GABA inhibitory neurons (labeled green) in the brain’s reward pathway. The right panel shows electrical activity of GABA inhibitory neuron in a saline-injected or methamphetamine (METH)-injected mouse. Activation of the GABA type B receptor normally silences electrical activity, but has no effect in a mouse 24 hours after a single injection of methamphetamine Credit: Courtesy of Kelly Tan and Claire Padgett, Salk Institute for Biological Studies
A single injection of cocaine or methamphetamine in mice caused their brains to put the brakes on neurons that generate sensations of pleasure, and these cellular changes lasted for at least a week, according to research by scientists at the Salk Institute for Biological Studies.
Their findings, reported March 7 in Neuron, suggest this powerful reaction to the drug assault may be a protective, anti-addiction response. The scientists theorize that it might be possible to mimic this response to treat addiction to these drugs and perhaps others, although more experiments are required to explore this possibility.
"It was stunning to discover that one exposure to these drugs could promote such a strong response that lasts well after the drug has left the body," says Paul Slesinger, an associate professor in the Clayton Foundation Laboratories for Peptide Biology. "We believe this could be the brain’s immediate response to counteract the stimulation of these drugs."
Surgical Treatment for Epilepsy Should Not Be Viewed as a Last Resort, Study Shows
ScienceDaily (Mar. 7, 2012) — While the thought of any type of surgery can be disconcerting, the thought of brain surgery can be downright frightening. But for people with a particular form of epilepsy, surgical intervention can literally be life-restoring.
A PET scan of a brain from a patient with epiepsy, between seizures. The red indicates healthy tissue. On the right side of the image, there is less red in the mesial temporal area. This is hypometabolism, reflecting decreased brain function in the area where seizures begin. (Credit: Image courtesy of University of California - Los Angeles)
Yet among people who suffer from what’s known as medically intractable epilepsy, in which seizures are resistant to drugs, only a small fraction will seek surgery, seeing it only as a last resort. As a result, they continue to suffer seizures year after year. They can’t drive, they can’t work and they lose cognitive function as the years pass. Premature death is not uncommon.
But a multi-center study led by researchers at UCLA shows that for people suffering from intractable temporal lobe epilepsy, the most common form of intractable epilepsy, early surgical intervention followed by antiepileptic drugs stopped their seizures, improved their quality of life and helped them avoid decades of disability.
The report appears in the March 7 edition of the Journal of the American Medical Association.
"In short, they got their lives back," said Dr. Jerome Engel, the study’s principal investigator and director of the UCLA Seizure Disorder Center.
But the frustration of Engel and his colleagues is this: Few patients are referred to them for surgical evaluation, and those who are have had epilepsy for an average of 22 years.
New Depression Treatment ‘Safe and Effective’, Experts Say
ScienceDaily (Mar. 7, 2012) — Stimulating the brain with a weak electrical current is a safe and effective treatment for depression and could have other surprise benefits for the body and mind, a major Australian study of transcranial Direct Current Stimulation (tDCS) has found.
Medical researchers from the University of New South Wales (UNSW) and the Black Dog Institute have carried out the largest and most definitive study of tDCS and found up to half of depressed participants experienced substantial improvements after receiving the treatment.
A non-invasive form of brain stimulation, tDCS passes a weak depolarising electrical current into the front of the brain through electrodes on the scalp. Patients remain awake and alert during the procedure.
"We are excited about these results. This is the largest randomised controlled trial of transcranial direct current stimulation ever undertaken and, while the results need to be replicated, they confirm previous reports of significant antidepressant effects," said trial leader, Professor Colleen Loo, from UNSW’s School of Psychiatry.
The trial saw 64 depressed participants who had not benefited from at least two other depression treatments receive active or sham tDCS for 20 minutes every day for up to six weeks.
"Most of the people who went into this trial had tried at least two other antidepressant treatments and got nowhere. So the results are far more significant than they might initially appear — we weren’t dealing with people who were easy to treat," Professor Loo said.
Significantly, results after six weeks were better than at three weeks, suggesting the treatment is best applied over an extended period. Participants who improved during the trial were offered follow up weekly ‘booster’ treatments, with about 85 percent showing no relapse after three months.
"These results demonstrate that multiple tDCS sessions are safe and not associated with any adverse cognitive outcomes over time," Professor Loo said, adding tDCS is simple and cost effective to deliver, requiring a short visit to a clinic.
The study also turned up additional unexpected physical and mental benefits, including improved attention and information processing.
"One participant with a long-standing reading problem said his reading had improved after the trial and others commented that they were able to think more clearly.
"Another participant with chronic neck pain reported that the pain had disappeared during the trial. We think that is because tDCS actually changes the brain’s perception of pain. We believe these cognitive benefits are another positive aspect of the treatment worthy of investigation," Professor Loo said.
The researchers are now looking at an additional trial to include people with bipolar disorder, with early results from overseas suggesting tDCS is just as effective in this group.
Source: Science Daily
What does chronic stress in adolescence mean at the molecular level?
In response to repeated stress, Yan and her colleagues found there was a loss of glutamate receptor expression and function in the prefrontal cortex. That loss resulted in a significant impairment in the ability of the adolescent animals to remember and recognize objects they had previously seen. The same cognitive deficit was not seen in the similarly stressed adults.
"Because dysfunction in the prefrontal cortex has been implicated in stress-related mental illness, this research identifying how stress affects prefrontal cortical functions will help further unravel how and why mental illnesses occur and how to treat them," says Yan.
Do you hear what I hear?
March 8, 2012 By Katie Neith
(Medical Xpress) — In both animals and humans, vocal signals used for communication contain a wide array of different sounds that are determined by the vibrational frequencies of vocal cords. For example, the pitch of someone’s voice, and how it changes as they are speaking, depends on a complex series of varying frequencies. Knowing how the brain sorts out these different frequencies—which are called frequency-modulated (FM) sweeps—is believed to be essential to understanding many hearing-related behaviors, like speech. Now, a pair of biologists at the California Institute of Technology (Caltech) has identified how and where the brain processes this type of sound signal.
Their findings are outlined in a paper published in the March 8 issue of the journal Neuron.
Knowing the direction of an FM sweep—if it is rising or falling, for example—and decoding its meaning, is important in every language. The significance of the direction of an FM sweep is most evident in tone languages such as Mandarin Chinese, in which rising or dipping frequencies within a single syllable can change the meaning of a word.
In their paper, the researchers pinpointed the brain region in rats where the task of sorting FM sweeps begins.
"This type of processing is very important for understanding language and speech in humans," says Guangying Wu, principal investigator of the study and a Broad Senior Research Fellow in Brain Circuitry at Caltech. "There are some people who have deficits in processing this kind of changing frequency; they experience difficulty in reading and learning language, and in perceiving the emotional states of speakers. Our research might help us understand these types of disorders, and may give some clues for future therapeutic designs or designs for prostheses like hearing implants."
This diagram shows areas in the midbrain region where direction- selective neurons were found.Credit: Guangying Wu/Caltech
Deafening affects vocal nerve cells within hours
March 7, 2012
Neurons (nerve cells) are labeled with green fluorescent protein, and other neurons in the brain are labeled in the background with either red or blue tracers. The small bulbs (i.e., dendritic spines) on the spidery dendrites show places where nerve cells connect and communicate, called synapses, and when these spines shrank over time, this predicted vocal degradation in the songbirds. Credit: Katie Tschida, Duke Department of Neurobiology
Portions of a songbird’s brain that control how it sings have been shown to decay within 24 hours of the animal losing its hearing.
The findings, by researchers at Duke University Medical Center, show that deafness penetrates much more rapidly and deeply into the brain than previously thought. As the size and strength of nerve cell connections visibly changed under a microscope, researchers could even predict which songbirds would have worse songs in coming days.
"When hearing was lost, we saw rapid changes in motor areas in that control song, the bird’s equivalent of speech," said senior author Richard Mooney, Ph.D., professor of neurobiology at Duke. "This study provided a laser-like focus on what happens in the living songbird brain, narrowed down to the particular cell type involved."
The study was published in Neuron journal online on March 7, 2012.
Scientists Pinpoint How Vitamin D May Help Clear Amyloid Plaques Found in Alzheimer’s
ScienceDaily (Mar. 6, 2012) — A team of academic researchers has identified the intracellular mechanisms regulated by vitamin D3 that may help the body clear the brain of amyloid beta, the main component of plaques associated with Alzheimer’s disease.
Published in the March 6 issue of the Journal of Alzheimer’s Disease, the early findings show that vitamin D3 may activate key genes and cellular signaling networks to help stimulate the immune system to clear the amyloid-beta protein.
Previous laboratory work by the team demonstrated that specific types of immune cells in Alzheimer’s patients may respond to therapy with vitamin D3 and curcumin, a chemical found in turmeric spice, by stimulating the innate immune system to clear amyloid beta. But the researchers didn’t know how it worked.
"This new study helped clarify the key mechanisms involved, which will help us better understand the usefulness of vitamin D3 and curcumin as possible therapies for Alzheimer’s disease," said study author Dr. Milan Fiala, a researcher at the David Geffen School of Medicine at UCLA and the Veterans Affairs Greater Los Angeles Healthcare System.
For the study, scientists drew blood samples from Alzheimer’s patients and healthy controls and then isolated critical immune cells from the blood called macrophages, which are responsible for gobbling up amyloid beta and other waste products in the brain and body.