"Time" is the most popular noun in the English language, yet how would we tell time if we didn’t have access to the plethora of watches, clocks and cell phones at our disposal?
For decades, scientists have believed that the brain possesses an internal clock that allows it to keep track of time. Now a UCLA study in the Feb. 1 edition of Neuron proposes a new model in which a series of physical changes to the brain’s cells helps the organ to monitor the passage of time.
"The value of this research lies in understanding how the brain works," said Dean Buonomano, associate professor of neurobiology and psychiatry at the David Geffen School of Medicine at UCLA and a member of the university’s Brain Research Institute. "Many complex human behaviors -- from understanding speech to playing catch to performing music -- rely on the brain’s ability to accurately tell time. Yet no one knows how the brain does it."
The most popular theory assumes that a clock-like mechanism – which generates and counts regular fixed movements -- underlies timing in the brain. In contrast, Buonomano suggests a physical model that operates without using a clock. He offers an analogy to explain how it works.
"If you toss a pebble into a lake," he explained, "the ripples of water produced by the pebble’s impact act like a signature of the pebble’s entry time. The farther the ripples travel the more time has passed.
"We propose that a similar process takes place in the brain that allows it to track time," he added. "Every time the brain processes a sensory event, such as a sound or flash of light, it triggers a cascade of reactions between brain cells and their connections. Each reaction leaves a signature that enables the brain-cell network to encode time."
The UCLA team used a computer model to test this theory. By simulating a network of interconnected brain cells in which each connection changed over time in response to stimuli, they were able to show that the network could tell time.
Their simulations indicated that a specific event is encoded within the context of events that precede it. In other words, if one could measure the response of many neurons in the brain to a tone or a flash of light, the response would not only reveal the nature of the event, but the other events that preceded it and when they occurred.
The UCLA team tested the model by asking research volunteers in the study to judge the interval between two auditory tones under a variety of different conditions. The researchers found that volunteers’ sense of timing was impaired when the interval was randomly preceded by a "distracter" tone.
"Our results suggest that the timing mechanisms that underlie our ability to recognize speech and enjoy music are distributed throughout the brain, and do not resemble the conventional clocks we wear on our wrists," said Buonomano.
Because time-related information is critical to understanding speech, determining how the brain tells time represents an important step toward understanding the causes of diseases, such as dyslexia, that result in impaired linguistic abilities, he noted.
The next step for the research will be recording the response from a large number of brain cells to determine whether they encode information about the timing of stimuli.
Elaine Schmidt | EurekAlert!
Immune Defense Without Collateral Damage
23.01.2017 | Universität Basel
The interactome of infected neural cells reveals new therapeutic targets for Zika
23.01.2017 | D'Or Institute for Research and Education
For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.
According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
23.01.2017 | Health and Medicine
23.01.2017 | Physics and Astronomy
23.01.2017 | Process Engineering