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ID:
137660
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| Summary/Abstract |
As the gateway to human communication, the sense of hearing is of enormous importance in our lives. Research on hearing has recently been revolutionized by the demonstration that the ear is not simply a passive receiver for sound, but also an amplifier that augments, filters, and compresses its inputs. Hair cells, the ear's sensory receptors, use two distinct methods to implement an active process that endows our hearing with these remarkable properties. First, the vibration-sensitive structures of the ear, called hair bundles, display a mechanical instability that allows them to oscillate in response to stimulation. And second, the membranes of hair cells are replete with proteins that contract in response to electrical stimuli, thus enabling the cells to act like tiny muscles. The activity of these two motile processes can be so exuberant as to cause normal ears to emit sounds.
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| 2 |
ID:
137677
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| Summary/Abstract |
Why can your brain store a lifetime of experiences but process only a few thoughts at once? In this article we discuss “cognitive capacity” (the number of items that can be held “in mind” simultaneously) and suggest that the limit is inherent to processing based on oscillatory brain rhythms, or “brain waves,” which may regulate neural communication. Neurons that “hum” together temporarily “wire” together, allowing the brain to form and re-form networks on the fly, which may explain a hallmark of intelligence and cognition: mental flexibility. But this comes at a cost; only a small number of thoughts can fit into each wave. This explains why you should never talk on a mobile phone when driving.
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