UHNW Blog

 
  • neuroticthought: neurosciencestuff: Researchers Uncover Cellular Mechanisms for Attention in the Brain The ability to pay attention to relevant information while ignoring distractions is a core brain function. Without the ability to focus and filter out “noise,” we could not effectively interact with our environment. Despite much study of attention in the brain, the cellular mechanisms responsible for the effects of attention have remained a mystery… until now. In a study appearing in the journal Nature, researchers from Dartmouth’s Geisel School of Medicine and the University of California Davis studied communications between synaptically connected neurons under conditions where subjects shifted their attention toward or away from visual stimuli that activated the recorded neurons. Using this highly sensitive measure of attention’s influence on neuron-to-neuron communication, they were able to demonstrate that attention operates at the level of the synapse to improve sensitivity to incoming signals, sharpen the precision of these signals, and selectively boost the transmission of attention-grabbing information while reducing the level of noisy or attention-disrupting information. The results point to a novel mechanism by which attention shapes perception by selectively altering presynaptic weights to highlight sensory features among all the noisy sensory input. “While our findings are consistent with other reported changes in neuronal firing rates with attention, they go far beyond such descriptions, revealing never-before tested mechanisms at the synaptic level,” said study co-author Farran Briggs, PhD, assistant professor of Physiology and Neurobiology at the Geisel School of Medicine. Here’s the abstract: Attention is a critical component of perception. However, the mechanisms by which attention modulates neuronal communication to guide behaviour are poorly understood. To elucidate the synaptic mechanisms of attention, we developed a sensitive assay of attentional modulation of neuronal communication. In alert monkeys performing a visual spatial attention task, we probed thalamocortical communication by electrically stimulating neurons in the lateral geniculate nucleus of the thalamus while simultaneously recording shock-evoked responses from monosynaptically connected neurons in primary visual cortex.  The monkeys were trained to focus on a central fixation on a screen. They would then attend to one of two gratings that were located at a positions correlating to the receptive fields of the V1 neurons being measured. We found that attention enhances neuronal communication by increasing the efficacy of presynaptic input in driving postsynaptic responses, by increasing synchronous responses among ensembles of postsynaptic neurons receiving independent input, and by decreasing redundant signals between postsynaptic neurons receiving common input. The results demonstrate that attention finely tunes neuronal communication at the synaptic level by selectively altering synaptic weights, enabling enhanced detection of salient events in the noisy sensory environment.

     
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  • pewinternet: Who uses the internet the most? http://www.pewinternet.org/Static-Pages/Trend-Data-(Adults)/Whos-Online.aspx

     
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  • latimes: A crisis of management at the CIA The beginning of this story from reporter Ken Dilanian speaks for itself: For the Central Intelligence Agency, he was a catch: an American citizen who had grown up overseas, was fluent in Mandarin and had a master’s degree in his field. He was working in Silicon Valley, but after the terrorist attacks of Sept. 11, 2001, he wanted to serve his country. The analyst, who declined to be named to shield his association with the CIA, was hired in 2005 into the agency’s Directorate of Intelligence, where he was assigned to dig into Chinese politics. He said he was dismayed to discover that unimpressive managers wielded incredible power and suffered no consequences for mistakes. Departments were run like fiefdoms, he said, and “very nasty internecine battles” were a fixture. By 2009, he had left the CIA. He now does a similar job for the U.S. military. Read more on the CIA’s troubled inner workings, as revealed by a series of internal documents and interviews, here. Photos: Saul Loeb / AFP/Getty Images, Los Angeles Times

     
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