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Neurons for numerosity: Parietal neurons 'sum up' individual items in a group
July 24, 2007As any child knows, to answer the question "how many," one must start by adding up individual objects in a group. This cognitive ability is shared by animals as diverse as humans and birds. Surprisingly, the exact brain mechanisms responsible for this process remained unknown until now. This week in the online open-access journal PLoS Biology, Jamie Roitman, Elizabeth Brannon, and Michael Platt from the University of Illinois at Chicago report novel evidence for the existence of "accumulator neurons," which respond to increasing numbers of items in a display with progressively increasing activity, in the parietal cortex of monkeys.
The authors focused on the parietal cortex based on evidence that damage to this brain region disrupts basic mathematical skills, and is activated during functional imaging studies when people perform basic computations. To understand how parietal cortex contributes to numerical behavior, the authors studied the activity of neurons in the lateral intraparietal area in monkeys while they looked at arrays of dots on a computer screen. Parietal neurons responded with progressively increasing activity as the total number of elements in the display was varied across a wide range of values (2-32). These neurons resemble "accumulator neurons" that have been suggested to serve the first stage in counting. This information could be used by other neurons that respond best for a particular cardinal number, such as "4," as have been reported in prior studies. These findings support computer models that separate the processes of summing and numerical identification, and may also explain the fact that parietal cortex damage causes both numerical and spatial confusion.
Public Library of Science
Neurons Current Events and Neurons News RSSMemory mission explores new territory in neuroscience
Astrophysicists peer into the far corners of deep space for dark matter, but for neuroscientists at the Queensland Brain Institute (QBI) exploring the unknown is much closer to home.
A good ear: Rats identify specific sounds in noisy environments
A study conducted on hundreds of rats could help us understand how the brain identifies specific sounds in a noisy environment.
In the war against diseases, nerve cells need their armor
In a new study, researchers at the Montreal Neurological Institute (MNI), McGill University, and the Université de Montréal have discovered an essential mechanism for the maintenance of the normal structure of myelin, the protective covering that insulates and supports nerve cells (neurons).
Protein can nurture or devastate brain cells, depending on its 'friends,' researchers find
Researchers at UT Southwestern Medical Center have uncovered new insights into the "Dr. Jekyll and Mr. Hyde" nature of a protein that stimulates stem-cell maturation in the brain but, paradoxically, can also lead to nerve-cell damage.
Pivotal Emory study focuses on teens at risk for psychosis
Emory University in Atlanta is playing a key role in the largest, most comprehensive study ever funded by the National Institute of Mental Health (NIMH) of adolescents and young adults at risk for developing a psychotic disorder.
Fatty diet during pregnancy makes new cells in fetal brain that cause early onset obesity
A study in rats shows that exposure to a high-fat diet during pregnancy produces permanent changes in the offspring's brain that lead to overeating and obesity early in life, according to new research by Rockefeller University scientists.
Stem Cells from Monkey Teeth Can Stimulate Growth and Generation of Brain Cells
Researchers at the Yerkes National Primate Research Center, Emory University, have discovered dental pulp stem cells can stimulate growth and generation of several types of neural cells. Findings from this study, available in the October issue of the journal Stem Cells, suggest dental pulp stem cells show promise for use in cell therapy and regenerative medicine, particularly therapies associated with the central nervous system.
Brain implants may help stroke patients overcome partial paralysis
Scientists have shown for the first time that neuroprosthetic brain implants may be able to help stroke patients with partial paralysis.
What makes an axon an axon?
Inside every axon is a dendrite waiting to get out. Hedstrom et al. converted mature axons into dendrites by banishing a protein crucial for neuron development.
Genetic study provides new insights into molecular basis of language development
Scientists have identified the first gene that is associated with a common childhood language disorder, known as specific language impairment (SLI).
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