Neuroscience
Letters
518 (2012) 96–
100
Contents
lists
available
at
SciVerse
ScienceDirect
Neuroscience
Letters
j
our
nal
ho
me
p
ag
e:
www.elsevier.com/locate/neulet
Effect
of
observation
combined
with
motor
imagery
of
a
skilled
hand-motor
task
on
motor
cortical
excitability:
Difference
between
novice
and
expert
Izumi
Tsukazaki,
Kazumasa
Uehara
1
,
Takuya
Morishita
1
,
Masato
Ninomiya,
Kozo
Funase
∗
Human
Motor
Control
Laboratory,
Graduate
School
of
Integrated
Arts
and
Sciences,
Hiroshima
University,
1-7-1
Kagamiyama,
Higashi-Hiroshima
739-8521,
Japan
a
r
t
i
c
l
e
i
n
f
o
Article
history:
Received
12
March
2012
Received
in
revised
form
20
April
2012
Accepted
23
April
2012
Keywords:
Action
observation
Motor
imagery
Skilled
hand-motor
task
Motor
cortex
excitability
Novice
and
expert
TMS
a
b
s
t
r
a
c
t
We
examined
the
effects
of
observation
combined
with
motor
imagery
(MI)
of
a
skilled
hand-motor
task
on
motor
cortex
excitability,
which
was
assessed
by
transcranial
magnetic
stimulation
(TMS).
Novices
and
experts
at
3-ball
cascade
juggling
(3BCJ)
participated
in
this
study.
In
one
trial,
the
subjects
observed
a
video
clip
of
3BCJ
while
imagining
performing
it.
In
addition,
the
subjects
also
imagined
performing
3BCJ
without
video
clip
observation.
Motor
evoked
potentials
(MEPs)
were
recorded
from
the
hand
muscles
that
were
activated
by
the
task
during
each
trial.
In
the
novices,
the
MEP
amplitude
was
significantly
increased
by
video
clip
observation
combined
with
MI.
In
contrast,
MI
without
video
clip
observation
significantly
increased
the
MEP
amplitude
of
the
experts.
These
results
suggest
that
action
observation
of
3BCJ
increases
the
ability
of
novices
to
make
their
MI
performing
the
task.
Meanwhile,
experts
use
their
own
motor
program
to
recall
their
MI
of
the
task.
© 2012 Elsevier Ireland Ltd. All rights reserved.
Action
observation
and
motor
imagery
(MI)
might
play
important
roles
during
the
early
stages
of
motor
learning
of
a
new
skilled
motor
task,
such
as
playing
an
instrument
or
engaging
in
sport-
ing
activity,
especially
in
novices
[3,18,28,32].
In
fact,
it
has
been
reported
that
action
observation
increases
the
excitability
of
the
motor
cortex
innervating
the
muscles
that
are
activated
during
the
performance
of
the
action
being
observed
[10,22,33],
as
does
during
motor
imagery
of
the
action
[11,16,31].
However,
in
the
above-mentioned
reports,
the
motor
tasks
were
relatively
simple
hand-motor
tasks,
even
for
novices,
such
as
hand
grasping
or
wrist
flexion.
Moreover,
efficient
motor
learning
of
a
skilled
hand-motor
task
is
crucial
for
novices
who
have
not
been
trained
to
perform
the
task
in
question.
Experience
teaches
us
that
when
we
try
to
learn
a
skilled
hand-motor
task,
we
observe,
imagine,
and
imitate
the
motor
task
being
performed
well
by
another
person.
MI
is
a
covert
cognitive
process
that
involves
imagining
the
motor
task
according
to
a
forward
internal
model
without
performing
any
actual
move-
ments
[19,23,40,41].
Therefore,
it
might
be
difficult
for
novices
to
imagine
a
skilled
hand-motor
task
because
they
have
no
forward
internal
model
of
it.
These
facts
led
us
to
the
following
question:
would
presenting
a
video
depicting
a
skilled
hand-motor
task
being
performed
well
by
another
person
to
a
novice
enhance
their
MI
of
that
action?
∗
Corresponding
author.
Tel.:
+81
82
424
6590;
fax:
+81
82
424
6590.
E-mail
address:
funase@hiroshima-u.ac.jp
(K.
Funase).
1
Research
Fellow
of
Japan
Society
for
the
Promotion
of
Science.
To
explore
this
issue,
we
examined
the
effect
of
observing
a
video
clip
showing
3-ball
cascade
juggling
(3BCJ),
a
skilled
hand-
motor
task,
on
the
subject’s
MI
of
that
task.
The
3BCJ
is
a
bimanual,
skillful,
and
cyclic
hand-motor
task
involving
the
handling
of
3
balls.
In
a
previous
study
[17],
the
characteristics
of
3BCJ
were
described
as
follows:
“Jugglers
move
their
hands
along
two
more
or
less
elliptical
trajectories,
one
a
clockwise
direction
and
the
other
in
an
anticlockwise
direction,
at
an
average
phase
difference
of
180
◦
.
Each
ball
is
released
at
the
point
in
the
ellipse
closest
to
the
mid-sagittal
line
of
the
performer’s
body
and
caught
at
the
point
in
the
ellipse
furthest
from
the
mid-sagittal
line.
The
ball
is
thrown
toward
the
contralateral
hand
along
a
parabolic
path.
As
a
result,
it
travels
along
a
figure-of-eight
pattern
(rotated
by
90
◦
)”.
It
is
therefore
thought
that
the
sensorimotor
systems
in
both
brain
hemispheres
including
the
cortical
and
subcortical
substrates
must
be
activated
to
perform
3BCJ,
making
it
much
more
diffi-
cult
than
the
simple
hand-motor
tasks
mentioned
above.
Experts
in
3BCJ
also
participated
in
this
study
so
that
we
could
compare
their
brain
activity
with
that
of
the
novices.
It
has
been
demon-
strated
that
MI
of
muscle
contraction
enhanced
the
motor
cortical
excitability
[1,11,12,20,31,42].
Thus,
the
effects
of
action
obser-
vation
and
MI
on
motor
cortical
excitability
were
assessed
by
measuring
the
amplitude
of
the
motor
evoked
potential
(MEP)
evoked
by
transcranial
magnetic
stimulation
(TMS).
The
MEPs
were
recorded
from
the
first
dorsal
interosseous
(FDI),
the
abductor
pol-
licis
brevis
(APB),
and
the
abductor
digiti
minimi
(ADM)
of
right
hand
because
these
muscles
are
activated
during
the
ball
handling
process,
i.e.,
catching,
holding,
and
releasing
a
ball,
involved
in
the
3BCJ.
0304-3940/$
–
see
front
matter ©
2012 Elsevier Ireland Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.neulet.2012.04.061