Brains learn
how to anticipate future occurrences from patterns. This process is called
"anticipatory timing," and it allows us to successfully interact with
the world around us. How does it work?
Anticipatory timing is, in part, what allows us to make the most
appropriate decisions in a very dynamic world.
But what does this process rely on?
A new study conducted by researchers from the University of
California, Berkeley, explains that, in anticipating an occurrence, the human
brain counts on two distinct systems.
"Whether it's sports, music, speech or even allocating
attention, our study suggests that timing is not a unified process, but that
there are two distinct ways in which we make temporal predictions and these
depend on different parts of the brain," says lead study author Assaf
Breska, a postdoctoral researcher in neuroscience.
"Together," states senior study
author Prof. Richard Ivry, "these brain systems allow us to not just exist
in the moment, but to also actively anticipate the future."
One system, the researchers found, allows us to anticipate
future occurrences based on our past experiences, while another system is based
on the identification of rhythmic patterns.
How do these two systems work, however? Do they "kick
in" at different times, depending on the context to which we need to
respond?
Answering this question, the study authors believe, could also
help us better understand how the brain works in different neurodegenerative
conditions.
In turn, this would allow specialists to come up with better
strategies to care for people living with such a condition.
The brain regions tasked with 'timing'
In the recent study — the findings of
which now appear in the journal PNAS — the scientists worked with
people with either Parkinson's disease or
cerebellar degeneration.
Both of these conditions are characterized by problems with
coordination and balance, though they seem to affect different regions of the
brain.
While Parkinson's impacts neural pathways in the basal ganglia,
which is a region embedded deep inside the cerebral cortex, in cerebellar
degeneration, it is nerve cells in the cerebellum that progressively die.
The researchers compared the ways in which people with each
condition used temporal cues to respond to different tests.
All of the study participants responded to two different
sequences of colored squares flashing out on a computer screen. In the first
exercise, the colored squares succeeded one another at a steady, rhythmic pace.
In the second exercise, the colored squares succeeded one
another in a different pattern that did not follow the same steady rhythm.
During these tests, the researchers observed that participants
with Parkinson's disease tended to perform better on the complex pattern
exercise, while those with cerebellar degeneration responded better to the
rhythmic succession test.
"We show that patients with cerebellar degeneration are
impaired in using nonrhythmic temporal cues while patients with basal ganglia
degeneration associated with Parkinson's disease are impaired in using rhythmic
cues," says Prof. Ivry.
These findings allowed the team to identify
which brain areas were linked to which anticipatory timing system. The authors
concluded that rhythmic timing corresponds to the basal ganglia, whereas interval
timing — based on memories of previous experience — corresponds to the
cerebellum.
Source: Medical News Today
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