NEUROLOGISTS DECODE BRAIN MAPS TO DISCOVER HOW WE TAKE AIM
Serena Williams won
her third consecutive US Open title a few days ago, thanks to reasons including
obvious ones like physical strength and endurance. But how much did her brain
and its egocentric and allocentric functions help the American tennis star
retain the cup?
Quite significantly,
according to York University neuroscience researchers whose recent study shows
that different regions of the brain help to visually locate objects relative to
one's own body (self-centred or egocentric) and those relative to external
visual landmarks (world-centred or allocentric).
"The current
study shows how the brain encodes allocentric and egocentric space in different
ways during activities that involve manual aiming," explains Distinguished
Research Professor Doug Crawford, in the Department of Psychology. "Take
tennis for example. Allocentric brain areas could help aim the ball toward the
opponent's weak side of play, whereas the egocentric areas would make sure your
muscles return the serve in the right direction."
The study finding will
help healthcare providers to develop therapeutic treatment for patients with
brain damage in these two areas, according to the neuroscientists at York
Centre for Vision Research. "As a neurologist, I am excited by the finding
because it provides clues for doctors and therapists how they might design
different therapeutic approaches," says Ying Chen, lead researcher and PhD
candidate in the School of Kinesiology and Health Science.
The study,
"Allocentric versus Egocentric Representation of Remembered Reach Targets
in Human Cortex," published in the Journal of Neuroscience,
was conducted using the state-of-the-art fMRI scanner at York U's Sherman
Health Science Research Centre. A dozen participants were tested using the
scanner, which Chen modified to distinguish brain areas relating to these two functions.
The participants were
given three different tasks to complete when viewing remembered visual targets:
egocentric reach (remembering absolute target location), allocentric reach
(remembering target location relative to a visual landmark) and a nonspatial
control, colour report (reporting color of target).
When participants
remembered egocentric targets' locations, areas in the upper occipital lobe (at
the back of the brain) encoded visual direction. In contrast, lower areas of
the occipital and temporal lobes encoded object direction relative to other
visual landmarks. In both cases, the parietal and frontal cortex (near the top
of the brain) coded reach direction during the movement.
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