Frontiers in Human Neuroscience www.frontiersin.org March 2010 | Volume 4 | Article 24 | 1
HUMAN NEUROSCIENCE
METHODS ARTICLE
published: 22 March 2010
doi: 10.3389/fnhum.2010.00024
LIMITATIONS OF CURRENT TECHNIQUES
To study speech-related movements outside MRI systems, sur-
face electromyography (EMG) is widely used (Smith, 1992). In
positron emission tomography (Murphy et al., 1997) and magne-
toencephalography (Sörös et al., 2003), EMG has also been used
frequently and successfully to monitor muscle function associated
with overt speech production. The use of EMG in fMRI stud-
ies, however, is challenging (for a recent review on the recording
of electrophysiological data during fMRI, see Laufs et al., 2008).
Time-varying radiofrequency pulses and magnetic fi eld gradients
may induce artifacts in EMG recordings and, conversely, move-
ments of EMG electrodes and leads inside the magnetic fi eld may
cause artifacts in fMRI data (Ganesh et al., 2007; MacIntosh et al.,
2007). In addition, the use of EMG in an fMRI study is limited by
the need of an fMRI-compatible EMG system (e.g., BrainAmp,
Brain Products, Gilching, Germany1), specialized EMG data post-
processing (van Duinen et al., 2005; MacIntosh et al., 2007), and by
time constraints. Setting up a combined fMRI–EMG experiment
requires extra time for the preparation of the skin, the mounting
of the electrodes and the checking of the electrode impedance.
INTRODUCTION
In recent years, a growing number of functional magnetic resonance
imaging (fMRI) studies on the neural correlates of overt speaking
(Abrahams et al., 2003; Gracco et al., 2005; Bohland and Guenther,
2006; Sörös et al., 2006a; Christoffels et al., 2007; Riecker et al.,
2008) and singing (Riecker et al., 2000; Kleber et al., 2007) have
been published. A major advantage of investigating overt speech
in contrast to silent (or covert) speech is the possibility to moni-
tor the behavioral performance during the experiment (Abrahams
et al., 2003). Assessing task performance such as response latency
or movement amplitude is especially important in studies involv-
ing children, seniors, or patients with various neurological or
psychiatric conditions who might give delayed responses or even
omit responses.
The objective of the present study was to demonstrate the
use of a fi ber-optic bend sensor, fi xed to the chin, to record
speech-related jaw movements during fMRI. Fiber-optic based
bend sensors have been used in various fi elds of biomedical
research, including the monitoring of fi nger (Ku et al., 2003;
Gorbet et al., 2004; Jindrich et al., 2004; Gorbet and Sergio, 2007)
and ankle movements (Seto, 2000; Seto et al., 2001; MacIntosh
et al., 2004).
fMRI-compatible registration of jaw movements using a
fi ber-optic bend sensor
Peter Sörös1*, Bradley J. MacIntosh1,2, Fred Tam1,3 and Simon J. Graham1,3,4,5
1 Department of Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
2 Functional Magnetic Resonance Imaging of the Brain Centre, University of Oxford, Oxford, UK
3 Rotman Research Institute, Baycrest, Toronto, ON, Canada
4 Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
5 Heart and Stroke Foundation of Ontario Centre for Stroke Recovery, Ottawa, ON, Canada
A functional magnetic resonance imaging (fMRI)-compatible fi ber-optic bend sensor was
investigated to assess whether the device could be used effectively to monitor opening and
closing of the jaw during an fMRI experiment at 3 T. In contrast to surface electromyography, a
bend sensor fi xed to the chin of the participant is fast and easy to use and is not affected by strong
electromagnetic fi elds. Bend sensor recordings are characterized by high validity (compared with
concurrent video recordings of mouth opening) and high reliability (comparing two independent
measurements). The results of this study indicate that a bend sensor is able to record the
opening and closing of the jaw associated with different overt speech conditions (producing the
utterances /a/, /pa/, /pataka/) and the opening of the mouth without speech production. Data
post-processing such as fi ltering was not necessary. There are several potential applications for
bend sensor recordings of speech-related jaw movements. First, bend sensor recordings are
a valuable tool to assess behavioral performance, such as response latencies, accuracies, and
completion times, which is particularly important in children, seniors, or patients with various
neurological or psychiatric conditions. Second, the timing information provided by bend sensor
data may improve the predicted hemodynamic response that is used for fMRI analysis based
on the general linear model (GLM). Third, bend sensor recordings may be included in GLM
analyses not for statistical contrast purposes, but as a covariate of no interest, accounting for
part of the data variance to model fMRI artifacts due to motion outside the fi eld of view.
Keywords: bend sensor, functional magnetic resonance imaging, speech production, articulation, oro-facial
movement
Edited by:
Srikantan S. Nagarajan,
University of California, San Francisco,
USA
Reviewed by:
Lee M. Miller,
University of California, Davis, USA
John F. Houde,
University of California, San Francisco,
USA
*Correspondence:
Peter Sörös,
Department of Communication
Sciences and Disorders,
University of South Carolina, 915
Greene Street, Columbia, SC 29208,
USA.
e-mail: peter.soros@gmail.com
1http://www.brainproducts.com

Frontiers in Human Neuroscience www.frontiersin.org March 2010 | Volume 4 | Article 24 | 2
Sörös et al. fMRI-compatible recording of oro-facial movement
Increasing the length of an fMRI experiment is especially prob-
lematic in studies involving participants for whom the monitoring
of behavioral performance is most important, such as the popula-
tions named above.
To record high-quality acoustic signals associated with overt
speech production during an fMRI experiment, noise cancelling
optical microphones have been utilized (e.g., FOMRI II microphone,
Optoacoustics Ltd., Or-Yehuda, Israel2). These microphones reduce
the intense acoustic noise, often exceeding 100 dB SPL, during fMRI
experiments by real-time adaptive noise cancelling (Chambers et al.,
2007) and can be used even during continuous scanning. Acoustic
recordings of overt responses are essential for the assessment of
response accuracy, but do not represent oro-facial movements.
To record oro-facial movements associated with speech produc-
tion, MRI-compatible cameras have been used successfully (e.g.,
MRC Systems, Heidelberg, Germany3) (Graham et al., 2009). Such
cameras, which must be integrated with a dedicated video cap-
ture system, can be diffi cult to mount in the magnet bore without
obstructing the patient and head coil as they move to and from
isocenter, and require appropriate line-of-sight from the camera
to the mouth through apertures in the head coil. To determine the
onset and the amplitude of movements based on video recordings,
extensive image processing is also required.
MATERIALS AND METHODS
BEND SENSOR
Bend sensor recordings were performed using a fl exible, fMRI-
compatible fi ber-optic bend sensor (S700 ShapeSensor, Measurand
Inc., Fredericton, NB, Canada4) that allows one degree of freedom
measurements (Figure 1) (Seto et al., 2001).
This sensor contains a single strand plastic optical fi ber (trans-
mit and return paths, diameter = 0.25 mm) encased in a plastic
cylindrical sheath of suffi cient length (i.e., 6 m) to route from
the operator console to the center of the magnet bore through
an appropriately located wave guide in the radiofrequency shield
enclosing the magnet room. The refl ectiveness of one side of the
optical fi ber cladding is purposely degraded in the “U-shaped”
active zone within the cylindrical sheath, such that attenuation
of light in the fi ber is proportional to how much the fi ber is bent.
Bend sensor signals were recorded with an associated electronics
box, consisting primarily of one light emitting diode (LED) for
transmission and two photodiodes for signal reception, which was
located near the operator console outside the magnet room.
CHARACTERISTICS OF THE BEND SENSOR SIGNAL
To determine the warm-up characteristics of the bend sensor, the
sensor was fi xed in position outside the magnet. Measurements of
the sensor signal were acquired (USB-6008, National Instruments,
Austin, TX, USA) at 400 Hz for 20 min.
To assess the stability of bend sensor measurements after the warm-
up phase, the bend sensor was fi xed in place and allowed to warm
up for over 30 min. The sensor signal was then sampled at 400 Hz
for 5 min to assess stability. Measurements were conducted inside
the magnet during a routine fMRI scan (EPI, TR/TE/FA = 2000 ms/
30 ms/70°, 64 × 64 matrix, 200 mm FoV, 28 axial slices, 5 mm thick),
with a phantom, in a 3-T MR imager (Magnetom Tim Trio, Siemens,
Erlangen, Germany). The tip of the sensor was about 35 cm from
isocenter such that it was possible to position and manipulate the sen-
sor tip appropriately by reaching into the magnet bore and without
moving the patient table, which would disrupt scanning.
To assess the dynamic performance and MRI-compatibility of the
bend sensor, the sensor tip was manually slid between two points in
space that were 2 cm apart on a ruler to simulate a moderate mouth
movement, using music for temporal reference. Movements were
repeated at two speeds (approximately 0.25 and 0.5 Hz), both inside
the magnet and outside the MRI room. Inside-magnet measure-
ments were conducted during a routine fMRI scan (see above).
To assess the reliability of the bend sensor signal, a Pearson correla-
tion coeffi cient was computed between these two independent bend
sensor recordings (inside the magnet and outside the MRI room).
To study the validity of bend sensor recordings, the relation-
ship between the bend sensor signal and mouth movements was
assessed. The bend sensor was taped to the chin of a volunteer
(Figure 2) and allowed to warm up for several minutes. The signal
FIGURE 1 | The fi ber-optic bend sensor to monitor jaw movements. The
active zone of the sensor (right, indicated in blue) is attached to the
participant’s chin. The electronics (middle) are located outside the magnet
room and consist of an LED and two photodiodes for transmission and
detection of the light, respectively. A matchstick is shown for scale.
FIGURE 2 | Mounting of the bend sensor. The sensor (red) is fi xed to the
chin and chest of the participant with adhesive tape (3M Durapore, white).
2http://www.optoacoustics.com
3http://www.mrc-systems.de
4http://www.measurand.com/products/ShapeSensor.html

Frontiers in Human Neuroscience www.frontiersin.org March 2010 | Volume 4 | Article 24 | 3
Sörös et al. fMRI-compatible recording of oro-facial movement
was measured at 400 Hz, and an MRI-safe video camera (12M,
MRC Systems GmbH, Heidelberg, Germany) in conjunction with
a specially developed video capture system (Graham et al., 2009)
was used to record video at 30 Hz within the magnet bore. An
electrical trigger was used to synchronize the sensor and video
recordings before the volunteer performed several mouth move-
ments. The video analysis consisted of manually selecting the
center of a tape mark on the chin in each video frame and noting
the pixel location.
BEND SENSOR RECORDINGS DURING OVERT SPEECH PRODUCTION
Participants
To study jaw movements in an actual fMRI experiment involv-
ing overt speech production, bend sensor signals were recorded
in seven healthy younger volunteers (three women, four men;
mean age = 25 years) and in eight healthy older adults (four
women, four men; mean age = 70 years). All participants were
right-handed and fl uent speakers of English. The study was
approved by the Research Ethics Board at Sunnybrook Health
Sciences Centre. Informed consent for participation in the project
was obtained from all subjects according to the Declaration of
Helsinki. The present study is part of a broader project investi-
gating the neural correlates of overt speech production (Sörös
et al., 2006a,b, 2009).
Tasks and fMRI data acquisition
Subjects were asked to repeat acoustically presented sub-lexical
speech sounds of different complexity and to perform oral move-
ments without articulation. The required responses were the long
vowel /a/, a consonant-vowel syllable (/pa/), a three-syllabic utter-
ance (/pataka/), and oral movements (opening the mouth or pro-
truding the lips). Instructions were delivered through the audio
Silent Scan Audio System at a constant onset-to-onset interstimu-
lus interval of 10 s using padded headphones with a noise reduc-
tion rating of 30 dB to reduce acoustic fMRI noise. Subjects were
asked to perform the given task or articulate the required response
immediately after the end of the verbal instruction. Six experimen-
tal sessions were performed. Each session comprised six separate
blocks of speech (fi ve events per block, 50 s duration each), two
blocks of oral movement (fi ve events, 50 s duration each) and three
blocks of baseline (30 s, no verbal cues). Blocks were grouped in a
pseudo-randomized order with sessions 1, 3, 5 and 2, 4, 6 having
the same order. For fMRI, clustered image acquisition (sparse tem-
poral sampling) was performed (Edmister et al., 1999). All instruc-
tions were delivered and all responses were made within the silent
interval between the acquisition of the fMR images thus separating
the hemodynamic brain activation signals associated with acous-
tic fMRI noise from the speech-related behaviors of interest. The
experiment is illustrated in Figure 3. For a discussion of the details
time (s)
40 50 60 70 80 90
A
B
C
fMRI acoustic
noise
response
(microphone)
response
(bend sensor)
instruction
jaw open
jaw closed
FIGURE 3 | Recordings of jaw movements and speech during the
acquisition of fMRI data. The fi gure displays fi ve events in a representative data
set. (A) The pre-recorded auditory instruction used for the vowel condition
(“say a”). (B) Microphone recording of the subject’s overt responses (/a/) and of
the fMRI acoustic noise during image acquisition. Both the auditory cue (A) and
the overt response (B) fall within the silent interval between multislice data
acquisition. (C) Bend sensor recording. The opening of the jaw precedes the
speech signal. The bend sensor recording is not affected by fMRI data acquisition.

Frontiers in Human Neuroscience www.frontiersin.org March 2010 | Volume 4 | Article 24 | 4
Sörös et al. fMRI-compatible recording of oro-facial movement
of the experimental setup, imaging parameters, and the subsequent
functional brain maps the reader is referred to previous papers of
our group (Sörös et al., 2006a, 2009).
Bend sensor recordings
The sensor was attached to the chin and the chest of each par-
ticipant immediately before the fMRI experiment using adhesive
tape (Figure 2). Paper tape (3M, St. Paul, MN, USA) was used in
the initial experiments, which was not adhesive enough and led to
a dislocation of the sensor tip at the chin. Medical silk tape (3M
Durapore, St. Paul, MN, USA), in contrast, was used in all following
measurements and provided suffi cient adhesion.
Bend sensor signals were digitized at 40 Hz and recorded using
a custom-written Labview program (National Instruments, Austin,
TX, USA5). Collection of bend sensor and fMRI data were synchro-
nized by the stimulation software E-Prime (Psychology Software
Tools, Pittsburgh, PA, USA6). The onset latency and the amplitude
of jaw opening were calculated using a custom-written program
for the statistical package R7. Bend sensor recordings were baseline
corrected and normalized to the largest amplitude in the entire
session. The relative peak amplitude and the onset of jaw opening
were determined for each epoch separately. To assess the onset of
jaw opening, the mean and standard deviation (SD) of the data
points prior to the fi rst instruction in each experimental run were
calculated to quantify the bend sensor signal baseline. The length
of the baseline was 1600 points (40 s). Task timing details are given
below. Movement onset was defi ned as the time point at which the
signal exceeded the mean value of the baseline + 5 SD. For com-
parison between jaw movements and the acoustic speech signal,
the participants’ overt responses were recorded via the microphone
channel of the fMRI-compatible Silent Scan Audio System (Avotec,
Stuart, FL, USA8), digitized at 44.1 kHz, and stored as an audio
fi le on a PC.
RESULTS
CHARACTERISTICS OF THE BEND SENSOR SIGNAL
During the warm-up phase with the sensor fi xed, the signal drifts
slowly by about 4% over approximately 15 min (Figure 4). After the
warm-up phase, the SD of the signal is 1.56% (inside the magnet)
and 1.86% (outside the magnet room) during a 5-min recording
(sampling rate 400 Hz, 120,000 data points; data not shown).
A comparison of bend sensor recordings inside the magnet
and outside the magnet room with different frequencies (0.25 and
0.5 Hz) revealed no artefacts or distortions of the sensor signal due
to fMRI scanning (Figure 5).
A Pearson correlation was performed between these bend sen-
sor recordings (Figure 5). For an alpha level of 0.05, the correla-
tion between the two recordings at a frequency of 0.25 Hz was
found to be statistically signifi cant [r(7998) = 0.98, p < 0.0001,
R2 = 0.96]. A statistically signifi cant correlation was also found
between two recordings at a higher frequency of approximately
0.5 Hz [r(7998) = 0.92, p < 0.0001, R2 = 0.84].
time (min)
se
n
so
r
si
gn
al
(%
fro
m
me
an
)
0 5 10 15 20
10
5
0
5
10
FIGURE 4 | Warm-up characteristics of the bend sensor signal.
A Pearson correlation addressed the relationship between
mouth opening as determined by the analysis of a video record-
ing of chin movement and the concurrent bend sensor signal
(Figure 6). For an alpha level of 0.05, the correlation between
mouth opening and sensor signal was found to be statistically sig-
nifi cant [r(164) = 0.94, p < 0.0001, R2 = 0.89]. Figure 6 also shows
that the onset and offset of mouth movement are measured very
similarly by both recordings.
BEND SENSOR RECORDINGS DURING OVERT SPEECH PRODUCTION
The MRI-compatible bend sensor was able to record the opening and
closing of the jaw for all overt speech conditions (/a/, /pa/, /pataka/)
used in this experiment. Bend sensor recordings from 6 individual
participants are shown in Figure 7. In two initial measurements,
however, the sensor was dislocated during the experiment, prob-
ably due to perspiration and an insuffi ciently adhesive tape. In the
movement condition, two different oral movements were required,
opening the mouth and protruding the lips without mouth opening.
Mouth opening without speech production was also associated with
a reliable signal in all participants, often with the highest amplitude
across all conditions. As expected, protruding the lips did not reveal
consistent signals (Figure 7). Figure 8 illustrates the consistency of
bend sensor recordings between blocks of responses for one condi-
tion (here: /a/ condition, data of one participant). Inter-individual
variability of the onset of the bend sensor signal during opening of
the jaw is shown in Figure 9. Signal onset times were not signifi cantly
different between younger and older participants.
DISCUSSION
In many speech production experiments, monitoring the behavio-
ral performance of the participants is desired. Outside the scanner,
recording of speech-related muscle activity and of overt speech
5http://www.ni.com/labview/
6http://www.pstnet.com/products/e-prime/
7http://www.r-project.org
8http://www.avotec.org/silentscan.htm

Frontiers in Human Neuroscience www.frontiersin.org March 2010 | Volume 4 | Article 24 | 6
Sörös et al. fMRI-compatible recording of oro-facial movement
the tape used, the angle of the sensor tip relative to the chin, the
participant’s skin surface environment and the condition of the
participant’s clothing on which the sensor is fi xed.
The bend sensor assesses the opening and closing of the
mouth, which appears to be more closely related to the activa-
tion of cortical and subcortical cognitive and motor areas than
voice onset. In a variety of sounds, mouth movements can start
substantially earlier than sound production, e.g., in the stop con-
sonant /p/. Thus, the bend sensor signal is useful to determine the
response latency for mouth movement, but, in general, cannot
be used to differentiate between the mouth movements associ-
ated with different sounds produced during an experiment. It
has to be noted that the onset of the bend sensor signal showed
considerable inter-individual variability (Figure 9), which should
be minimized to improve comparisons across conditions or sub-
ject groups. Subject variability could be reduced by giving an
explicit instruction (“respond as rapidly as possible with equal
amplitude”) and adding a short training session before starting
with the actual experiment.
The preparation of the volunteer, in particular fi xing the sensor
with adhesive tape and testing the signal, was considerably faster
than the preparation usually needed for EMG studies. The bend
sensor, however, has to be carefully fi xed at the chin. Probably due to
perspiration and insuffi ciently adhesive paper tape, the sensor was
dislocated during two of the initial measurements. In the following
experiments, the sensor was fi xed with silk tape without dislocation
kiss /pa/
-
20
40
10
0
time (s)
a
m
pl
itu
de
(%
)
A
B
-
20
40
10
0
a
m
pl
itu
de
(%
)
-
20
40
10
0
a
m
pl
itu
de
(%
)
-
20
40
10
0
a
m
pl
itu
de
(%
)
-
20
40
10
0
a
m
pl
itu
de
(%
)
-
20
40
10
0
a
m
pl
itu
de
(%
)
/a/ /pataka/ /pa/ /a/ /pataka/ mouth
0 100 200 300 400 500
0 100 200 300 400 500
0 100 200 300 400 500
0 100 200 300 400 500
0 100 200 300 400 500
0 100 200 300 400 500
FIGURE 7 | Bend sensor recording of 6 individual participants. Data
from one run of three younger (A) and three older individuals (B) are shown
in blue. In the runs shown here, the participants performed all verbal tasks
correctly as verifi ed by the concurrent audio recording. All bend sensor
recordings are baseline-corrected (0–40 s prior to the beginning of the
fi rst block) and normalized to the largest defl ection in the entire data set
which was set to a relative amplitude of 100%. The dotted lines mark the
beginning and end of blocks of fi ve responses. Kiss denotes protruding
the lips. Mouth denotes opening the mouth without producing
an utterance.

Frontiers in Human Neuroscience www.frontiersin.org March 2010 | Volume 4 | Article 24 | 7
Sörös et al. fMRI-compatible recording of oro-facial movement
during the entire measurement. To ensure a tight contact between
the adhesive tape and the skin, the participants should be asked to
wash or shave their chin before the experiment. In addition, par-
ticipants should wear light clothing to avoid excessive perspiration.
In contrast to EMG (Ganesh et al., 2007), Figure 5 indicates that
fMRI data acquisition has no impact on the quality of bend sensor
recordings. Previous work has shown that use of fi ber-optic bend
sensing technology has no statistically signifi cant impact on fMRI
data quality (Di Diodato et al., 2007).
Based on these specifi cations, a bend sensor is not only advan-
tageous for recording speech-related jaw movements, but also for
monitoring oral movements that serve as control conditions in
speech production experiments (Sörös et al., 2006a). The use of a
chin-mounted bend sensor, however, is limited to speech sounds
and oral movements involving the opening of the mouth such as
the vowel /a/. Close vowels without considerable mouth opening
such as /i/ or mouth movements such as protruding the lips cannot
be monitored with a single bend sensor fi xed at the chin. Other
mounting arrangements of a one degree of freedom sensor or the
use of multiple sensors or even a higher degree of freedom device
(e.g., ShapeTape, Measurand Inc., Fredericton, NB, Canada) are
possible and should be tested.
Bend sensor recordings can also be used as purely behavioral
measurements to assess response latencies and accuracies. Bend
sensor recordings have already been employed to compare the
latency of verbal responses between younger and older adults
with the experimental setup presented here (Sörös et al., 2009).
Bend sensor recordings are also valuable for assessing responses of
patients who, when an overt response is required, perform articula-
tory movements without vocalization (e.g., in aphasia).
For fMRI data analysis, bend sensor recordings could help to
improve the predicted hemodynamic response function that is used
for statistical analysis based on the general linear model by incor-
porating the actual timing of movements and by omitting missing
responses. In addition, bend sensor recordings may be included in
the linear model as covariate of no interest (confound explanatory
variable). Covariates of no interest are expected to account for part
of the data variance without being used for statistical contrasts.
Covariates of no interest were used, e.g., to model the effect of head
motion (Johnstone et al., 2006) and laryngeal motion (Sörös et al.,
2008) on fMRI data. In experiments on speech production, bend
sensor recordings could be employed to model artifacts associated
with jaw movements (Birn et al., 1999). Motion outside the fi eld of
view, such as movement of the oral cavity, the sinuses or the phar-
ynx, might cause magnetic fi eld inhomogeneities masking brain
activation or generating artifactual intensity changes (Yetkin et al.,
1996). For future research, the effect of introducing jaw motion
as covariate of no interest in a fMRI analysis should be compared
with the effect of other techniques of artifact reduction, such as the
use of head motion parameters as covariates of no interest or the
removal of artifactual signal components based on independent
component analysis (Sörös et al., 2008).
ACKNOWLEDGMENTS
The authors wish to thank Nicole Baker for developing the data
acquisition software used for bend sensor recordings and Dr. Gary
Glover for providing his spiral-in/out pulse sequence. The authors
also wish to thank two reviewers for insightful comments and sug-
gestions that improved substantially the manuscript. This study
was supported by the Heart and Stroke Foundation of Ontario
through its Centre for Stroke Recovery, the Ontario Research and
Development Challenge Fund and GE Healthcare Canada.
10 20 30 40 50
time (s)
0
FIGURE 8 | Overlay of bend sensor data containing all 12 blocks of
the /a/ condition recorded in one participant. The recordings are
baseline-corrected (0–5 s prior to the beginning of the block).
FIGURE 9 | Inter-individual variability of signal onset. Individual data is
shown for all four experimental conditions. Mouth denotes the opening of the
mouth without articulation. /a/, /pa/, /pataka/ denote the overt production of
the respective utterance. Data of younger participants are shown in red, of
older participants in blue. Average signal onset times in the younger
participants were (mean ± SD): 1.27 ± 0.17 s (mouth), 1.77 ± 0.20 s (/a/),
1.97 ± 0.26 s (/pa/) and 2.94 ± 0.26 s (/pataka). Signal onset times in the older
participants were: 1.09 ± 0.18 s (mouth), 1.50 ± 0.17 s (/a/), 1.71 ± 0.31 s (/pa/)
and 2.80 ± 0.42 s (/pataka/). Signal onset times were not signifi cantly different
between age groups (ANOVA).

Frontiers in Human Neuroscience www.frontiersin.org March 2010 | Volume 4 | Article 24 | 8
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Conflict of Interest Statement: The
authors declare that the research was
conducted in the absence of any com-
mercial or financial relationships that
could be construed as a potential confl ict
of interest.
Received: 13 April 2009; paper pending
published: 18 June 2009; accepted: 04
March 2010; published online: 22 March
2010.
Citation: Sörös P, MacIntosh BJ, Tam F and
Graham SJ (2010) fMRI-compatible regis-
tration of jaw movements using a fi ber-optic
bend sensor. Front. Hum. Neurosci. 4:24.
doi: 10.3389/fnhum.2010.00024
Copyright © 2010 Sörös, MacIntosh, Tam
and Graham. This is an open-access arti-
cle subject to an exclusive license agreement
between the authors and the Frontiers
Research Foundation, which permits unre-
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