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620035994-
The Use of the Mismatch Negativity in Studies of Sound
Processing
Since the earliest days of experimental psychology
introspective and behavioural measures have been used in
the study of auditory processes (Wiseman, 2012).
Neuroimaging allows these investigations to be taken
further with measurements of the underlying activity of
brain regions providing spacial and temporal analysis of
functioning. Electroencephalography (EEG) records
electrical activity from neuronal dipoles expressed at
scalp level, Magnetoencephalography (MEG) measures the
faint magnetic fields created by neuronal activity and
Functional Magnetic Resonance Imaging (fMRI) images
hemodynamic response, the deoxygenation of blood within
neuronal tissue. Each neuroimaging method has its own
relative benefits and problems, at a general level and in
application to the field of sound processing. Considering
one measurable response, the Mismatch Negativity, this
essay examines the use of each method and the potential
for combinations in furthering research.
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Manifesting as EEG and MEG components the mismatch
negativity (MMN and MMNm respectively) provides a measure
of neuronal response to deviations. fMRI imaging studies
allow further investigation into the phenomena and may be
combined with or compared to MMN recordings. Though
manifesting in other modalities, such as visual and
olfactory (Pazo-Alvarez, Cadaveira and Amenedo, 2003),
this essay will focus on its use within auditory
research, taking a number of examples from linguistics
and stream segregation to clinical to examine the scope
of measures of this component examining the methodologies
involved.
Discovered by Näätänen et al in 1978 the MMN component is
generated by discriminable deviations from repetition in
a sequence of auditory stimuli giving an objective
measure of auditory perception. Early investigations
looked at the differences in response to two tones of
perceptively different frequencies. The first tone (A)
would be used as the standard, presented in a repeating
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sequence, while a second tone (B) was used as a deviant,
occasionally replacing A. Though EEG responses to tones A
and B would be expected to differ slightly relative to
their respective frequencies it was found that a much
larger negative EEG response occurred to the deviant than
standard stimuli, remaining after counterbalancing
frequency of the standards and deviant.
This difference was thought to reflect a perceptual
change detection process which was necessary, though not
sufficient, for conscious detection of deviation within a
presented auditory sequence. The response was
consequently taken to be an objective measure of just
noticeable differences in stimuli, improving upon
previous introspective measures (Wolf and Schroger,
2001). MMN responses were found in deviations of a large
range of different stimuli characteristics from simple
deviations in intensity, duration and timbre to complex
deviations among abstract patterns of ascending and
descending tones, silences where tones would be expected
and breaches of grammatical rules in mother tongue
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(Näätänen et al., 2007). The perceptual processing of
these more abstract patterns gave an insight into how the
brain perceives sound and how basic perceptions may
interact with interpretations in higher brain regions.
MMN responses were found in patients who were not
consciously aware of deviations and measurable in
sleeping and coma patients while fetal, newborn and
developing children also show mismatch responses allowing
insights into perceptual developments over time (Lowery
et al, 2006). To understand some of these uses we must
first take a step back to examine ERP recordings in
general and how MMN is expressed within EEG recordings.
EEG
EEG recordings involve the application of multiple
electrodes to the scalp recording expressed electrical
potentials in many channels. Various layouts and
densities of electrode placement (such as the 10-20
system (Jurcak et al 2007)) are possible depending on
experimental requirements with locations standardised
620035994-
between participants to give comparable recordings.
Measurements track changes of electrical amplitude in
near-real time as waveforms, averaged across many
repeats, from which a series of negative and positive
peaks can be derived. Scalp level recordings refer to
dipoles formed by the postsynaptic potentials of large
numbers of similarly orientated neurons firing
concurrently with recordings primarily reflecting
activity in the neural cortex. Interference of the scalp
leads to lowered spacial accuracy while deeper brain
regions and neuronal firings that do not produce mass
dipoles are inaccessible. Despite limitations EEG
recordings are thought to give good access to activity in
the neural cortex including the auditory cortex and
frontal areas involved in sound processing (Luck and
Kappenman, 2012).
Averaged EEGs evoked in response to a stimulus are termed
Event-Related Potentials (ERP) with those produced in
response to auditory stimuli distinguished as Auditory-
Related Potentials (ARP). Components can be extracted
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from ERPs. These are inferred to reflect underlying
neurological and psychological process. Extraction is not
a straightforward process as multiple components can co-
occur with amplitude recorded at a single electrode
influenced by multiple components. Further to this the
inverse problem of tracing EEG recordings to their
neuronal areas of origin requires complex mathematical
modeling involving the comparisons of electrode
recordings from multiple scalp locations. This allows
extracted components to be traced back to their location
of generation. The MMN component is measured as an
elevated negative peak within the response to an auditory
stimuli acting as a deviant when compared to the response
to the same stimuli acting as a standard (Luck and
Kappenman, 2012).
Taking the simple frequency of tone experiment explained
above as an example we will now examine where MMN fits
into the EEG response to sound. On presentation of a
repeating auditory tone each instance generates a
waveform showing P1, N1 and P2 peaks. The N1 is a
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negative peak occurring at approximately 100ms from
stimulus onset. The P2, a positive measure peaking at
approximately 180-220ms from onset follows.
The deviant tone presented within the pattern of
standards in our example evokes a MMN. This in generated
as an elevated negativity beginning at the peak of the N1
wave lasting approximately 100-250ms. Consequently a more
negative N2 peak is produced while the positive P2 is
reduced, offset by the negativity. If the deviant tone is
consciously detected then a further P3 component is
generated, theorized by Donchin’s context updating
hypothesis to reflect updating of expectations (Näätänen
et al., 2007), and N2b and N2c components may also be
evoked (Pritchard, Sahppell and Brandt, 1991). As the P3,
Nb2 and Nb3 are not generated when attention is directed
away from stimuli some studies choose to provide a
reading task or silent video to distract conscious
attention. In addition to the expression of the MMN as a
negative peak, the positive area of the neuronal dipole
can be recorded in nose-referenced electrodes placed in
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the mastoid region allowing extraction of the component
in tasks where attention is necessary or uncontrollable
(Näätänen et al, 2007).
Within the ARP data for each participant the MMN is
extracted through a process of subtracting the averaged
EEG waveform from a tone when presented as a standard
from the averaged waveform of the same tone presented as
a deviant (Friston, 2005). This produces a subtraction
waveform showing the additional negativity. It should be
noted that the difference in ERP response to two stimuli
based on characteristics of sound are often small when
compared to that of the MMN response allowing response to
a standard to be subtracted from that of a different
deviant in some experimental contexts and
counterbalancing performed between participants rather
than within. Common measures include presence/absence of
MMN, variations in amplitude and latency from stimulus
onset (Luck and Kappenman, 2012). We will now examine
some of the applications of MMN in research in an attempt
to highlight the scope of EEG measures of the component.
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COGNITIVE APPLICATIONS
As previously touched upon, presence of the MMN is
thought to give a measure of just noticeable differences.
This can be studied either by manipulating
characteristics of a stimuli or measuring individual
differences in reactions to a single stimuli. These same
formats are taken in studies investigating echoic memory.
Approximately 10s in normal participants (Cowan et al,
1984) deviations within repeating stimuli with inter
stimulus intervals (ISI) beyond this critical duration do
not generate MMNs. This is thought to be due to a fading
of sensory memory trace over time ( Kujala, Tervaniemi
and Schröger. 2007). Consequently MMN provides an
objective measure of auditory memory. Patients with
Alzheimer’s can be studied in this way. As would be
expected the critical ISI for MMN response is much lower
than average in Alzheimer’s patients and decreases as the
condition progresses (Pekkonen et al, 1994).
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MMN has been used to study linguistics with stable long
term phoneme perceptions linked to MMN production. In
Finnish /e/ and / ä/ are separate phonemes while in
Hungarian they are not. Hungarians who did not speak
Finnish were not seen to produce MMNs to the distinction
while Finnish speakers did (Winkler et al. 1999). This
may suggest that high-level top down expectations based
upon permanent memory traces can impact on processing
even when attention is directed elsewhere.
While some studies examine the presence or absence of MMN
response, others study variations in its size and
duration. Shorter ISIs lead to larger MMN responses
(Javitt et al, 1998) and larger amplitude MMNs are evoked
when a deviant occurs after more repetitions of the
standard stimuli (Haenschel et al. 2005). Increases in
numbers of deviant instances leads to a smaller MNN
response both to a deviant that repeats (Ritter et al
1992) and with multiple varying deviants varying along
the same dimension (Sams et al 1984).
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As well as the presence and waveform characteristics of
MMNs, recordings have given an insight into the temporal
course of auditory processing. Shown to occur in two
streams with an early auditory cortex response followed
by a later frontal element, temporal differences between
these responses are thought to relate to the multiple
stages of neuronal processing with low level perceptual
elements processed by the auditory cortex followed by
higher level analysis in frontal regions. Within this
differences can be seen between language and musical
sounds with second stage localisation occurring in the
right hemisphere in music and left in speech processing.
Phoneme generated MMNs are larger over the left
hemisphere than the right while responses to musical
tones show the opposite localisation (Sharma and Kraus,
1995). An example of the MMNs applicability to studies of
the temporal course of processing is found in Sussman et
al (1999, 1998) use of the component to investigate
auditory stream analysis.
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When in complex sound environments with multiple sound
streams it is necessary to cognitively separate input
into streams and attend only to those of relevance. This
separation can be elicited both through conscious
attentional choice and unconsciously as a consequence of
stimuli features. Firstly, examining how unconscious
characteristics of sound can lead to perceptual
separation Sussman et al (1999) used an oscillating sound
of alternating high and low pitches with occasional
deviants in both. When presented at slow speeds (750ms
intervals between high and low pitches) no MMN response
was evoked by deviants in the high or low pitches. At
high speeds (100ms intervals) MMNs were evoked by
deviants in both streams. This was taken as evidence that
high-speed oscillations are pre-attentively perceived as
two separate streams of repeating notes while slow-speed
are not separated, perceived instead as a single
oscillating tone.
In a follow up study, conscious stream segregation was
investigated. Between the two extremes of oscillation
620035994-
speed investigated above is a region of ambiguity where
stream separation is thought to occur dependent upon top
down processes. In Sussman et al (1998) participants were
presented with an ambiguous tone changing from high to
low pitch. In a control condition participants were asked
to listen to the stimuli while EEG recordings were made.
Deviants were introduced in both the high and low pitches
but neither evoked MMN responses. In a second condition
participants were asked only to attend to the high
pitches looking for deviants. In this condition MMNs were
shown for the attended high pitch and for the unattended
low pitch. This suggests that top down processes are able
to impact upon perception at a pre-attentive level of
processing.
CLINICAL APPLICATIONS
MMN has shown much value in clinical contexts. Its
production is predictive of recovery to consciousness in
early stage coma patients (Wijnen et al, 2007). The
passive pre-attentive aspect of the measure has further
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been put to use in assessment of functioning in newborns
including those born prematurely (Näätänen et al 2012).
MMNs are thought to be the earliest discriminable ERP
component (Cheour-Luhtanen et al, 1996) and are seen
developmentally to originate as a positive rather than
negative change-dependent response flipping in early
maturation (Leppänen et al, 2004). At later stages of
childhood development MMN studies have been used to
investigate dyslexia (Schulte-Körne, 1998), dysphasia
(Korpilahti and Lang, 1994), ADHD (Rothenberger at al,
2000) and hearing problems (Huttunen-Scott et al, 2008).
Language problems, both extreme and more minor can be
investigated through MMN recordings. Patients with
aphasia do not produce phoneme MMN but do produce general
frequency change MMNs to non-phoneme stimuli (Aaltonen et
al, 1993). MMN response to frequency deviants is of a
lower amplitude in dyslexic adults, with this amplitude
attenuation showing correlation to levels of reading
disturbance (Baldeweg et al. 1999). The production of
MMNs to the contrast between /da/ and /ga/ is only seen
620035994-
in those children who are able to behaviourally
discriminate between the two (Kraus et al. 1996). Many of
the children who could not distinguish were in ‘problem-
learner’ categories and one possible interpretation would
be that their inability to distinguish phonemes was
causal in this. Phoneme discrimination training such as
FastForWord (Hook, Jones and Macaruzo, 2001) may help
with this and MMN studies would be able to measure
changes in discrimination ability. Experimental phoneme
distinguishing training was seen to produce behavioural
discriminations between two variations of /ba/. Over the
course of training MMNs to these variations arose earlier
in the learning process than behavioural abilities to
distinguish (Tremblay, Kraus and McGee, 1998).
A limitation found in oddball EEG paradigms using sparse
deviants is session duration. Each block required many
standards to be presented for each deviant meaning long
duration experiments are required to generate gather even
small amounts of data. Näätänen, Pakarinen, Rinne and
Rika (2004) showed that it was possible to record many
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different types of stimuli deviance in a single sequence.
It was found to be possible to present different deviants
concurrently. If each deviated by a different dimension
then standardisation among other dimensions would
continue to build. The design used a repeating cycle with
every second sound deviating along one of five
alternating characteristics (D1-5). This means each
deviant type is 10 stimuli apart (see figure 1). The
paradigm increases the scope for investigations and is
especially relevant to clinical patients about whom
profiles of performance along a number of attributes may
be quickly created.
MEG
MEG recordings, though similar to EEG in scope are not
susceptible to interference of the skull or scalp
allowing better spacial resolution. The MEG measures
mismatch negativity fields (MMNm). As with EEG these
S D1 S D2 S D3 S D4 S D5 S D1 S D2 S D3 S D4 S D5 S D1
(S:Standard , D:Deviant)Figure 1: Stimuli presentation in multiple deviants paradigm
620035994-
reflect dipoles after neuronal firings. Less common than
EEG recordings due to lower availability and increased
price MEG is theoretically more suited to the measure of
mismatch negativity giving better imaging of the auditory
cortex (Thönnessen et al, 2008).
Herrmann et al (2009) used MEG in an attempt to localise
the effect of syntactic deviance on MMNm. Syntactically
correct deviations are seen to produce smaller mismatch
negativities than those deviations which do not conform
to the syntactical structure of the stimuli sequence
(Shtyrov et al, 2003). Rare but grammatically valid
stimuli do not produce a MMN (Pulvemüller and
Assadollahi, 2007) so this effect is thought to
demonstrate the application of syntactical rules at an
early stage of speech processing. In the study MMNm
activation was found in the Sylvian fissure and superior
temporal sulcus with stronger activation in the left
hemisphere. No frontal response was found. Frontal
responses had been seen in similar EEG studies (eg.
Pulvermüller and Shtyrov, 2003) and this is thought to be
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a demonstration of the differences in sensitivity between
the two methods with increased error seen in EEG relative
to MEG recordings (Leahy et al, 1998).
In studying ERP components such as the MMN it is possible
to take advantage of the capacity for concurrent
recording from both methods that is offered. EEG and MEG
recordings compliment each other with EEG giving
increased sensitivity to radial generators while MEG
allows for a greater measure of tangential dipoles and
hemispherical localisation (Thonnessen et al 2008).
fMRI
fMRI recordings measure the increased blood flow to
cerebral areas of high metabolic activity. Differing
magnetic resonances between oxygenated and deoxygenated
hemoglobin are detected within a fluctuating magnetic
field. These are reduced to patterns of voxel activations
allowing standardisation for analysis and comparison
between participants. The hemodynamic response is
620035994-
relatively slow leading to a more limited temporal
accuracy compared to the previously discussed methods.
Spacial activity however is much higher and all brain
areas can be accessed. Though showing much potential in
the study of visual perception progress in fMRI studies
of sound was initially slow with the main obstacle being
scanner noise (Di Salle at al, 2003).
fMRI scanners produce a loud pulsed noise of
approximately 100dB (Hedeen and Edelstein, 1997).
Generated by the gradient switches of magnetic field this
noise leads to a BOLD response in the auditory cortex
that may remain throughout the session causing a
saturation of response against which stimuli dependent
responses can be difficult to extract. Beyond this
scanner noise can also interfere with perception of
auditory stimuli in unpredictable ways modulating
responses (Seifritz et al, 2006).
Mustovic et al (2004) overcame this problem by using
scanner noise as the experimental stimuli. In an
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experiment attempting to locate the source of echoic
memory, deviants of increased volume and absence of
expected scan noise were used, achieved by adding
additional artificial scanner noise and skipping gradient
switches. Use of silence and additional noise captured a
cognitive conjunction (Price and Friston, 1997) in that a
common neurological process is shared between the
radically different stimuli of silence and noise. The
right planum temporale and temporopariental junction were
seen to be involved suggesting their importance in the
formation of echoic memory with the planum temporale
involved in segregation of sound streams. Right
lateralisation preference was shown to these non-speech
sounds. Though demonstrating the potential of fMRI
studies in the area, this experimental design is limited
in the stimuli characteristics available for
investigation. To fully utilise the potential of fMRI
scans clearer methods for presenting auditory stimuli
were required.
620035994-
One proposed solution was use of a quasi-continuous
gradient switch pattern (Seifritz et al, 2006) giving a
perceptually continuous sound. This use of continuous
sound leads to reduced baseline BOLD response relative to
pulsed scanner sound. An alternative approach is to use
Sparse Temporal Sampling (STS) with long gaps between
single scans. This use of infrequent gradient switches
allows presentation of auditory stimuli in low noise
periods. However this limits the amount of data that can
be collected and reduces experimental design
possibilities as time of peak response must be predicted
(Josephs and Henson, 1999) but variations exist which aim
to tackle these problems.
Interleaved Silent Steady State (ISSS) paradigms consist
of longer low volume periods for stimuli presentation
followed by periods of multiple scans. This reduces the
need for prior predictions of time course of BOLD
response and allows changes in response to be tracked
temporally to a limited extent. It is achieved by
producing silent slice selective pulses throughout the
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period of stimuli presentation. These dummy scans allow
acquisition scans to be made at the same short gradient
switch intervals. Variations exist which allow, different
fidelity of acquisition, for example 5 volumes of 15
slices or 2 volumes of 32 slices with a trade off between
the number of slices per scan and the number of scans
made. Mueller et al. (2011) found that the ISSS has
increased sensitivity when compared to STS and allowing
acquisition of more data in the same time periods while
retaining the advantages of noise reduction of that
method. (Mueller et al, 2011). These periods of silence
within fMRI recordings open up the possibility for
concurrent EEG recordings. Truly concurrent EEG
recordings made at the time of fMRI image acquisition
would be effectively obliterated by the scanner but as
EEG measured activity occurs at the time of stimuli
presentation and slightly after while the BOLD response
measured by fMRI occurs after this point the techniques
can be combined under STS or ISSS paradigms.
fMRI and EEG
620035994-
Broadly speaking fMRI and EEG recordings can be combined
in two ways. Firstly it is possible to record each
separately with data collected from one method informing
the other. This allows the multiple repeats required for
a reliable measure of EEG to be made without the cost of
multiple fMRI studies, an expensive waste as comparable
correlation on a trial-by-trial basis is not required
(Debener et al, 2006).
In this approach participants are required to perform the
same experiment under each measure. As well as order
effects such as task learning, the impact of differences
in experimental design such as short durations in fMRI
recordings and multiple repeats under EEG must be
considered. For example fMRI recordings are made while
the participant lies horizontally and so any EEG
recordings taken for comparison should attempt to match
this. As discussed above fMRI noise can affect stimuli
perception and so artificial fMRI sounds should be played
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while collecting EEG measurements, even though poorer
quality of EEG recording may be a consequence.
An example of this is Opitz et al (2002). The study
looked at the involvement of the temporal and frontal
lobes in connection to MMN evoking stimuli. Three levels
of deviants were used, with changes in volume of 10%, 30%
and 100%. In silent EEG recordings MMNs were produced by
all three but in further EEG recordings in the presence
of artificial scanner noise MMN only occurred in response
to 30% and 100% deviants. In consequence 10% deviations
were not included in the fMRI study. Later fMRI scans of
the same participants were compared with the EEG
recordings using strength of activation correlations
whereby ERP distributions were modeled to fMRI
activations. It was found that the main MMN generators
were around the auditory cortex with temporal activity
related to size of deviance in the right temporal cortex
and right inferior frontal gyrus.
620035994-
The second method for combining is to make EEG recordings
in the fMRI scanner. Many issues arise from this. fMRI
images are warped slightly by the metal in electrodes
while vibration of the scanner and the BA artifact caused
by the QRS complex of blood flow occurs as an artifact on
the EEG waveform and must be modeled and subtracted. This
combined with the effect of noise means that combination
is quite a challenge and currently rare in studies of
audition where EEG variations are relatively small.
An example can be found in Eichele et al (2008) which
argues against separate EEG as a predictor of fMRI
activity as neither the EEG nor the fMRI responses
recorded at any one location necessarily relate to a
single neurological event. Instead it advocates unmixing
both modalities concurrently at a single-trail level.
Using Infomax independent component analysis (ICA) where
ICAs were collected as spacial maps for fMRI (sICA) and
temporal ICA for EEG (tICA).
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The above essay has covered some of the uses of MMN in
examining auditory perception. From insight into how
phonemes are perceived to prognostic measures of coma
outcome the MMN component demonstrates the importance of
preattentive perceptual processes and with it gives
insights into the role of conscious attention. These
findings, while specific to the auditory modality, may
give some insight into other modalities, most notably
visual perception. While research into a visual MMN is at
a much earlier stage, evidence may support its existence
(Pazo-Alvarez, 2003). Future technological developments
in EEG, MEG and fMRI technology will likely lead to a
more definitive answer and increase the potential of this
component to inform understanding in the area.
(3997 words)
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References
Aaltonen, O., Tuomainen, J., Laine, M., & Niemi, P. (1993).
Cortical differences in tonal frequency versus vowel
processing as revealed by an ERP component called the
mismatch negativity (MMN). Brain and Language, 44, 139–152.
Cheour-Luhtanen, M., Alho, K., Sainio, K., Rinne, T.,
Reinikainen, K., Pohjavuori, M., Renlund, M., Aaltonen,
O., Eerola, O. and Nätänen, R. (1996). The
ontogenetically earliest discriminative response of the
human brain. Psychophysiology, 33, 478– 481.
Debener, S., Ullsperger, M., Siegel, M. and Engel, A.
(2006). Single-trial EEG-fMRI reveals the dynamics of
cognitive function. Trends Cogn. Sci, 10, 12, 558–563.
Eichele, T., Calhoun, V., Moosmann, M., Specht, K., Jongsma,
M., Quiroga, R., Nordby, H. and Hugdahl, K. (2008).
Unmixing concurrent EEG-fMRI with parallel independent
component analysis. International journal of psychophysiology, 67,
222-234.
27
620035994-
Herrmann, B., Maess, B., Hasting, A. and Freiderici, D.
(2009). Localization of the syntactic mismatch
negativity in the temporal cortex: An MEG study.
Neuroimage, 48, 590-600.
Hook, P., Jones, S. and Macaruzo, P. (2001). The efficacy of
FastForWord training on facilitating acquisition of
reading skills in children with specific reading
disabilities – a longitudinal study. Annals of Dyslexia, 51,
75-96.
Huttunen-Scott, T., Kaartinen, J., Tolvanen, A. and
Lyytinen, H. (2008). Mismatch negativity (MMN) elicited
by duration deviations in children with reading
disorder, attention deficit or both. International Journal or
Psychophysiology, 69, 69-77.
Josephs, O. and Henson, R. (1999). Event-related functional
magnetic resonance imaging: modelling, inference and
optimization. Biol. Sci, 354, 1215–1228.
Jurcak, A., Tsuzuji, D. and Dan, I. (2007) 10/20, 10/10, and
10/5 systems revisited: Their validity as relative head-
surface-based positioning systems. Neuroimage, 34, 1600-1611.
620035994-
Korpilahti, P. and Lang, H. (1994). Auditory components and
mismatch negativity in dysphasic children.
Electroencephalography and clinical neurophysiology, 91, 256-264.
Kraus, N., McGee, T., Carrell, T. D., Zecker, S. G., Nicol,
T. G., and Koch, D. B. (1996). Auditory neurophysiologic
responses and discrimination deficits in children with
learning problems. Science, 273, 971–973.
Leahy, R., Mosher, J., Spencer, M., Huang, M. and Lewine, J.
(1998). A study of dipole localization accuracy for MEG
and EEG using a human skull phantom. Electroencephalography
and Clinical Neuropytsiology, 107, 2, 159-173.
Leppänen, P., Guttorm, T., Pihko, E., Takkinen, S., Eklund,
K. and Lyytinen, H. (2004) Maturational effects on
newborn ERPs measured in the mismatch negativity
paradigm. Experimental Neurology, 190, 91-101
Lowery, C., Eswaran, H., Murphy, P. and Preissl, H. (2006).
Fetal magnetoencephalography. Seminars in Fetal and Neonatal
Medicine, 11, 6, 430-436.
Luck, S. and Kappenman, E. (2012). The Oxford Handbook of Event-
Related Potential Components. Oxford: Oxford University Press.
29
620035994-
Mueller, K., Mildner, T., Fritz, T., Lepsien, J.,
Schwarzbauer, C., Schroeter, L. and Moller, H. (2011)
Investigating brain response to music: a comparison of
different fMRI acquisition schemes. Neuroimage, 54, 377-343
Mustovic, H., Scheffler, K., Di Salle, F., Esposito, F.,
Neuhoff, J., Hennig, J. and Seifritz, E. (2004).
Temporal integration of sequential auditory events:
silent period in sound pattern activates human planum
temporale. Neuroimage, 20, 429-434.
Näätänen, R., Paavilainen, P., Rinne, T. and Alho K. The
mismatch negativity (MMN in basic research of central
auditory processing: A review. Clinical Neurophysiology.
118, 12, 2544-2590.
Näätänen, R., Pakarinen, S., Rinne, T. and Takegata, R.
(2007). The mismatch negativity (MMN): towards the
optimal paradigm, Clinical Neurophysiology, 115, 140-
144.
Näätänen, R., Kujala, T., Escera, C., Baldeweg, T.,
Kreegipuu, K., Carlson, S. and Ponton, C. (2012). The
mismatch negativity (MMN) – A unique window to disturbed
620035994-
central auditory processing in ageing and different
clinical conditions. Clinical Neurophysiology, 123, 3, 424-458.
Näätänen, R., Gaillard, A. W. K., and Mäntysalo, S. (1978).
Early selective attention effect on evoked potential
reinterpreted. Acta Psychologica, 42, 313–329.
Nudds, M. and O’Callaghan, C. (2009). Sounds and Perception: New
Philosophical Essays. Oxford: Oxford University Press.
Opitz, B., Rinne, T., Mecklinger, A., von Cramon, Y. and
Schroger, E. (2002) Differential contribution of frontal
and temporal cortices to auditory change detection: fMRI
and ERP results. Neuroimage, 15, 167-174
Pazo-Alvarez, P., Cadaveira, F. and Amenedo, E. (2003). MMN
in the visual modality: a review. Biological Psychology, 63,
199-236.
Price, C. and Friston, K. (1997) Cognitive conjunction: a
new approach to brain activation experiments. Neuroimage,
5, 261-270.
Pulvermuller, F. and Assadollahi, R. (2007) Grammar or
serial order?: discrete combinatorial brain mechanisms
reflected by the syntactic mismatch negativity. J Cogn
Neurosci. 19, 971-80.
31
620035994-
Pulvermuller, F. and Shtyrov, Y. (2003). Automatic
processing of grammar in the human brain as revealed by
the mismatch negativity. Neuroimage, 20(1), 159-72.
Rothenberger, A., Banaschewski, T., Heinrich, H., Moll, G.,
Schmidt, M. and van’t Klooster B. (2000). Comorbidity in
ADHD-children: effects of coexisting conduct disorder or
tic disorder on event-related brain potentials in an
auditory selective-attention task. Clin Neurosci, 250, 101–10.
Di Salle, F., Esposito, F., Sacrabino, T., Formisano, E.,
Marciano, E., Saulino, C., Cirillo, S., Elefante, R.,
Scheffler, K. and Seifritz, E. (2003) fMRI of the
auditory system: understanding the neural basis of
auditory gestalt. Magnetic Resonance Imaging, 21, 1213-1224.
Schulte-Korne G, Deimel W, Bartling J and Remschmidt H.
(1998). Auditory processing and dyslexia: evidence for a
specific speech processing deficit. NeuroReport, 9, 337–40.
Seifritz, E., Di Salle, F., Esposito, F., Herdener, M.,
Neuhoff, J. and Scheffler, K. (2006) Enhancing BOLD
response in the auditory system by neurophysiologically
tuned fMRI sequence. Neuroimage, 29, 1013-1022.
Sharma, A. and Kraus, N. (1995). Effects of contextual
620035994-
variations in pitch and phonetic processing:
Neurophysiologic correlates. Association for Research in
Otolaryngology, 729, 183.
Shtyrov, Y., Pulvermuller, F., Näätänen, R. and Ilmoniemi,
R. (2003). Grammar processing outside the focus of
attention: an MEG study. J. Cogn. Neurosci, 15, 1195–1206.
Thönnessen, H., Zvyagintsev., Harke, K., Boers, F., Dammers,
J., Norra, C. and Mathiak, K. (2008). Optimised mismatch
negativity paradigm reflects defecits in schizophrenia
patients a combined EEG and MEG study. Biological Psychology,
77 205-216.
Tremblay, K., Kraus, N. and McGee, T. (1998). The time-
course of auditory perceptual learning: Which comes
first, the chicken or the egg. NeuroReport, 9, 3557–3560.
Wijnen, V., van Boxtel, G., Eilander, H. and Gelder, B
(2007) Mismatch negativity predicts recovery from
vegetative state. Clinical Neurophysiology, 118, 597-605.
Winkler, I., Kujala, T., Tiitinen, H., Sivonen, P., Alku,
P., Lehtokoski, A., Czigler, I., Csépe, V., Ilmoniemi,
R. J. and Näätänen, R. (1999). Brain responses reveal
the learning of foreign language phonemes.
33