Posts tagged psychology
Articles and news from the latest research reports.
The Neuronal Organization of the Retina
The mammalian retina consists of neurons of >60 distinct types, each playing a specific role in processing visual images. They are arranged in three main stages. The first decomposes the outputs of the rod and cone photoreceptors into ∼12 parallel information streams. The second connects these streams to specific types of retinal ganglion cells. The third combines bipolar and amacrine cell activity to create the diverse encodings of the visual world—roughly 20 of them—that the retina transmits to the brain. New transformations of the visual input continue to be found: at least half of the encodings sent to the brain (ganglion cell response selectivities) remain to be discovered. This diversity of the retina’s outputs has yet to be incorporated into our understanding of higher visual function.
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)
Understanding Alzheimer’s: Study gives insights into how disease kills brain cells
Exactly how Alzheimer’s disease kills brain cells is still somewhat of a mystery, but University of Michigan researchers have uncovered a clue that supports the idea that small proteins prick holes into neurons.
The team also found that a certain size range of clumps of these proteins are particularly toxic to cells, while smaller and larger aggregates of the protein appear to be benign.
The findings, which appear in the journal PLOS ONE, add important detail to the knowledge base regarding this disease that affects 5.4 million Americans in 2012 but remains incurable and largely untreatable. The results could potentially help pharmaceutical researchers target drugs to the right disease mechanisms.
Small proteins called amyloid-beta peptides are the prime suspect for causing cell death in Alzheimer’s. They make up most of the senile plaque fibers found in the brains of autopsied patients. Researchers offer several hypotheses for how the peptides might cause the disease. They blame inflammation, oxidative stress or an imbalance of calcium ions possibly caused by holes in the cell membranes.
The U-M findings strongly support the idea that amyloid peptides damage the membrane around nerve cells and lead to uncontrolled movement of calcium ions into them. Calcium signaling is an important way that cells communicate and healthy cells regulate its flow precisely. The toxic mechanism implicated in the new study could act on its own or together with the other proposed courses and ultimately lead to a loss of brain cells in patients, the researchers say.
Berkeley Lab scientists surprised to find significant adverse effects of CO2 on human decision-making performance.
Overturning decades of conventional wisdom, researchers at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have found that moderately high indoor concentrations of carbon dioxide (CO2) can significantly impair people’s decision-making performance. The results were unexpected and may have particular implications for schools and other spaces with high occupant density.
“In our field we have always had a dogma that CO2 itself, at the levels we find in buildings, is just not important and doesn’t have any direct impacts on people,” said Berkeley Lab scientist William Fisk, a co-author of the study, which was published in Environmental Health Perspectives online last month. “So these results, which were quite unambiguous, were surprising.” The study was conducted with researchers from State University of New York (SUNY) Upstate Medical University.
On nine scales of decision-making performance, test subjects showed significant reductions on six of the scales at CO2 levels of 1,000 parts per million (ppm) and large reductions on seven of the scales at 2,500 ppm. The most dramatic declines in performance, in which subjects were rated as “dysfunctional,” were for taking initiative and thinking strategically. “Previous studies have looked at 10,000 ppm, 20,000 ppm; that’s the level at which scientists thought effects started,” said Berkeley Lab scientist Mark Mendell, also a co-author of the study. “That’s why these findings are so startling.”
Read more: Elevated Indoor Carbon Dioxide Impairs Decision-Making Performance
New findings illuminate basis in brain for social decisions, reactions
The social brain consists of the structures and circuits that help people understand others’ intentions, beliefs, and desires, and how to behave appropriately. Its smooth functioning is essential to humans’ ability to cooperate. Its dysfunction is implicated in a range of disorders, from autism, to psychopathology, to schizophrenia.
New findings show that:
• Primates employ three different parts of the prefrontal cortex in decisions about whether to give or keep prized treats. These findings illuminate a poorly understood brain circuit, and offer possible insights into human sharing and other social behavior (Steve Chang, PhD, abstract 129.10).
• Different brain regions are engaged in altruistic behavior that is motivated by genuine caring versus altruistic behavior motivated by a concern for reputation or self-image (Cendri Hutcherson, PhD, abstract 129.06).
• The experience of racial discrimination triggers activity in the same brain regions that respond to pain, social rejection, and other stressful experiences (Arpana Gupta, PhD, abstract 402.06).Another recent finding discussed shows that:
• Competition against a human opponent or a computer engages the same parts of the brain, with one exception: the temporal parietal junction is used to predict only a human’s upcoming actions (Ronald Carter, PhD).
Studies report early childhood trauma takes visible toll on brain; changes found in regions controlling heart and behavior
Trauma in infancy and childhood shapes the brain, learning, and behavior, and fuels changes that can last a lifetime, according to new human and animal research released today. The studies delve into the effects of early physical abuse, socioeconomic status (SES), and maternal treatment. Documenting the impact of early trauma on brain circuitry and volume, the activation of genes, and working memory, researchers suggest it increases the risk of mental disorders, as well as heart disease and stress-related conditions in adulthood.
Today’s findings show:
• Physical abuse in early childhood may realign communication between key “body-control” brain areas, possibly predisposing adults to cardiovascular disease and mental health problems (Layla Banihashemi, PhD, abstract 691.12).
• Rodent studies provide insight into brain changes that allow tolerance of pain within mother-pup attachment (Regina Sullivan, PhD, abstract 399.19).
• Childhood poverty is associated with changes in working memory and attention years later in adults; yet training in childhood is associated with improved cognitive functions (Eric Pakulak, PhD, abstract 908.04).
• Chronic stress experienced by infant primates leads to fearful and aggressive behaviors; these are associated with changes in stress hormone production and in the development of the amygdala (Mar Sanchez, PhD, abstract 691.10).Another recent finding discussed shows that:
• Parent education and income is associated with children’s brain size, including structures important for memory and emotion (Suzanne Houston, MA).
Attack! Silent watchmen charge to defend the nervous system
In many pathologies of the nervous system, there is a common event - cells called microglia are activated from surveillant watchmen into fighters. Microglia are the immune cells of the nervous system, ingesting and destroying pathogens and damaged nerve cells. Until now little was known about the molecular mechanisms of microglia activation despite this being a critical process in the body. Now new research from the Montreal Neurological Institute and Hospital – The Neuro - at McGill University provides the first evidence that mechanisms regulated by the Runx1 gene control the balance between the surveillant versus activated microglia states. The finding, published in the Journal of Neuroscience, has significant implications for understanding and treating neurological conditions.
Link between creativity and mental illness confirmed
People in creative professions are treated more often for mental illness than the general population, there being a particularly salient connection between writing and schizophrenia. This according to researchers at Karolinska Institutet, whose large-scale Swedish registry study is the most comprehensive ever in its field.
Last year, the team showed that artists and scientists were more common amongst families where bipolar disorder and schizophrenia is present, compared to the population at large. They subsequently expanded their study to many more psychiatric diagnoses - such as schizoaffective disorder, depression, anxiety syndrome, alcohol abuse, drug abuse, autism, ADHD, anorexia nervosa and suicide - and to include people in outpatient care rather than exclusively hospital patients.
The present study tracked almost 1.2 million patients and their relatives, identified down to second-cousin level. Since all were matched with healthy controls, the study incorporated much of the Swedish population from the most recent decades. All data was anonymized and cannot be linked to any individuals.
The results confirmed those of their previous study: certain mental illness - bipolar disorder - is more prevalent in the entire group of people with artistic or scientific professions, such as dancers, researchers, photographers and authors. Authors specifically also were more common among most of the other psychiatric diseases (including schizophrenia, depression, anxiety syndrome and substance abuse) and were almost 50 per cent more likely to commit suicide than the general population.
The researchers also observed that creative professions were more common in the relatives of patients with schizophrenia, bipolar disorder, anorexia nervosa and, to some extent, autism. According to Simon Kyaga, consultant in psychiatry and doctoral student at the Department of Medical Epidemiology and Biostatistics, the results give cause to reconsider approaches to mental illness.
"If one takes the view that certain phenomena associated with the patient’s illness are beneficial, it opens the way for a new approach to treatment," he says. "In that case, the doctor and patient must come to an agreement on what is to be treated, and at what cost. In psychiatry and medicine generally there has been a tradition to see the disease in black-and-white terms and to endeavour to treat the patient by removing everything regarded as morbid."
(Source: ki.se)
Neuroscientists find Broca’s area is really two subunits, each with its own function
A century and a half ago, French physician Pierre Paul Broca found that patients with damage to part of the brain’s frontal lobe were unable to speak more than a few words. Later dubbed Broca’s area, this region is believed to be critical for speech production and some aspects of language comprehension.
However, in recent years neuroscientists have observed activity in Broca’s area when people perform cognitive tasks that have nothing to do with language, such as solving math problems or holding information in working memory. Those findings have stimulated debate over whether Broca’s area is specific to language or plays a more general role in cognition.
A new study from MIT may help resolve this longstanding question. The researchers, led by Nancy Kanwisher, the Walter A. Rosenblith Professor of Cognitive Neuroscience, found that Broca’s area actually consists of two distinct subunits. One of these focuses selectively on language processing, while the other is part of a brainwide network that appears to act as a central processing unit for general cognitive functions.
"I think we’ve shown pretty convincingly that there are two distinct bits that we should not be treating as a single region, and perhaps we shouldn’t even be talking about ‘Broca’s area’ because it’s not a functional unit," says Evelina Fedorenko, a research scientist in Kanwisher’s lab and lead author of the new study, which recently appeared in the journal Current Biology.
How Neuroscience is Changing the Talking Cure
What’s the Latest Development?
A new book which attempts to reconcile psychoanalysis with neuroscience may have practical implications in the treatment of neurological disorders such as Alzheimer’s and PTSD. Catherine Malabou’s What Should We Do With Our Brain? argues that “we have failed to understand ourselves because we have failed to acknowledge recent scientific discoveries, particularly ‘plasticity,’ or the brain’s ability to change.” Through the course of the argument, Malabou updates psychotherapy’s concept of clinical treatment by recognizing that mental wounds do not come from a buried subconscious but from events that befall us in the real world.
What’s the Big Idea?
Malabou references clinical trials with patients who have acquired neurological disorders (rather than being born with them) and finds that patients do not identify with a stable psyche—the sort required by traditional psychological investigation. Rather, patients experience themselves as a different person, one with whom they are unfamiliar. “The old onion of the psyche, with its layers upon layers of meaning, is simply not there to peel apart in analysis; rather, it has been replaced by a new self, which requires a different clinical approach.”