fNIRS data on auditory cortical activation in CI users presented at 8th international symposium on Objective Measures in Auditory Implants

1. Audiovisual
integra0on
in
the
implanted
auditory
cortex
measured
by
near-­‐infrared
spectroscopy
L.P.H.
van
de
Rijt,
E.A.M.
Mylanus,
A.F.M.
Snik,
M.M.
van
Wanrooij
17
October
2014

2. Research
problem
• Early
hearing
loss
disrupts
normal
development
of
the
auditory
system.
• How
does
restoraKon
of
peripheral
hearing
by
implanKng
a
cochlear
implant
(CI)
affect
central
auditory
processing?

3. Objec0ves
• To
determine
the
feasibility
of
recording
brain
acKvity
of
postlingually
deaf
individuals
aSer
cochlear
implantaKon
with
near-­‐infrared
spectroscopy.
• To
compare
the
cross-­‐sensory
acKvaKon
of
auditory
cortex
of
implanted
and
normal-­‐hearing
individuals
with
near-­‐infrared
spectroscopy

4. Methods
• Par0cipants.
• 21
normal-­‐hearing
adults
(male
vs.
female)
and
(age
range)
• 5
postlingually
deaf
CI-­‐users
• Task.
• View
and
listen
to
segments
of
a
story
(‘passive
listening’).

5. Methods
• Recordings
• Schema0c
layout
of
optodes
2
lasers
=
1
source

6. Background
• Near-­‐infrared
spectroscopy
• Biological
Kssue
is
relaKvely
transparent
to
light
in
the
near
infrared
region
(700-­‐1300
nm).
• It
is
possible
to
transmit
enough
photons
through
organs
for
in
situ
monitoring.
• Hemodynamic
response

7. Results
-­‐
Raw
• Example
trace

8. Results
–
average
normal-­‐hearing
• Hemodynamic
responses
of
all
normal-­‐hearing
subjects

9. Results
–
average
CI
user
• Group-­‐averaged
hemodynamic
responses
of
all
CI
users

10. Integra0on
effect
Stein,
B.
E.,
Stanford,
T.
R.,
Ramachandran,
R.,
Perrault,
T.
J.,
&
Rowland,
B.
A.
(2009).
Exp
Brain
Res,
198(2-­‐3)

11. Results
–
normal
hearing
Auditory
response
amplitude
>
visual
The
audiovisual
response
amplitude
demonstrates
a
sub-­‐addi0ve
effect
for
deoxyhemoglobin
only.
For
oxyhemoglobin,
the
audiovisual
does
not
differ
significantly
from
the
auditory
response.

12. Results
–
CI
Auditory
response
amplitude
>
visual
The
audiovisual
response
amplitude
hints
at
a
sub-­‐addi0ve
effect
for
oxyhemoglobin
only.
For
deoxyhemoglobin,
the
audiovisual
does
not
differ
significantly
from
the
auditory
response.

13. Conclusion
• Auditory
corKcal
responses
are
evoked
for
all
sKmulus
modaliKes
in
both
hemispheres;
• Largest
unisensory
changes
for
auditory
s0muli.
• smallest
concentraKon
changes
for
the
unisensory
visual
s0mula0on.
• IntegraKon
effects
are
small
or
negligible:
preliminary
results
hint
at
subaddiKve
effects
both
for
normal-­‐hearing
and
for
CI
users
Overall,
normal-­‐hearing
parKcipants
and
postlingually
deaf
CI
users
tend
to
demonstrate
similar
responses.

14. Acknowledgements
− L.P.H.
van
de
Rijt1,2
− A.F.M.
Snik2
− L.V.
Straatman2
− H.Y.
Hu1
− A.J.
van
Opstal1
− M.M.
van
Wanrooij1,2
1. Radboud
University,
Donders
InsKtute
for
Brain,
CogniKon
and
Behavior,
Department
of
Biophysics,
Nijmegen,
the
Netherlands
2. Radboudumc,
Department
of
Otorhinolaryngology,
Nijmegen,
the
Netherlands
Supported
by
Cochlear