1. Introduction
Auditory Evoked Potentials: Auditory event-related potentials
are electric potentials and magnetic fields (AEF) generated by
the synchronous activity of large neural populations in the
brain, which are time-locked to some actual or expected sound
event1.
N1 Response Suppression: The
auditory-evoked N1 response
becomes significantly attenuated
when the sound is self-generated
(e.g. hearing ones own speech).
Forward Models of Motor Control: During preparation for a
movement, the motor cortex generates a copy of the intended
sound (efferent copy) and sends it to the auditory cortex. If the
auditory input matches the prediction, the evoked N1 response
gets attenuated.
*Cem Anil1, *Eva Huang1, and Bernhard Ross1,2
1Rotman Research Institute, Baycrest Centre, Toronto, ON, Canada; 2Department of Medical Biophysics, University of Toronto
*contributed equally and are listed in alphabetical order
The Effect of Intention and Motor Planning in Sound Making
on the Auditory Evoked N1 Brain Response
Expectations and Hypothesis
• We expect the auditory evoked N1 response to be
suppressed significantly when the participants are actively
generating sounds.
• We expect to observe a positive correlation between the
activation in the motor cortex preceding sound making and
the amount of auditory evoked N1 suppression.
Observations, Discussion and Future Plans
This poster resulted from preliminary analysis of mainly
qualitative nature. More quantitative analysis are currently
under way. The main findings were:
1. Auditory Evoked N1 response attenuation:
Our data experimentally confirmed that self-generation of
sounds significantly suppresses in the N1 peak amplitude.
2. More motor planning in the self-initiated condition:
Time-frequency analysis confirms that the self-initiated
section contains a longer and higher motor preparation when
compared to the cued section. The decrease in alpha
oscillation power prior to sound making in the self-initiated
section is evidence for this observation. These results
suggest that the different sound making tasks indeed
involved different motor programs.
3. More N1 response suppression in self-initiated
condition:
Preliminary data suggests that the N1 response was
stronger attenuated in self-initiated compared to cued sound
making. Further analysis regarding the factors effecting N1
response magnitude and the statistical power of the data is
required to reach to a conclusive result.
Future plans:
• Source localization: Carrying out source localization to
estimate the locations of the sources of brain activity
more accurately and isolating activity in specific regions.
• Statistical confidence: Finding out the confidence range of
the data using bootstrap resampling.
• Isolating the target parameter: Trying to estimate the
quantitative effects of other parameters (such as sound
making pace, sound loudness) on the N1 suppression
effects.
Objectives and Methods
Objective: Searching for a link between the activation in the
motor cortex preceding sound making and the amount of the
suppression in the auditory evoked N1 response.
Methods: We recorded brain activity
with magnetoencephalography
(MEG) from healthy participants with
normal hearing in four blocks:
The participants were asked to carefully listen to
the recorded sounds from a chime.
The participants were asked to actively generate
sounds using the chime that they have been hearing
the sounds of, immediately after receiving a cue.
The participants were asked to actively generate
sounds using the chime that they have been
hearing the sounds at their own will, without a cue.
A repetition of the first listening section.
Results
Auditory Evoked Responses:
Event Related Synchronization in Motor Cortex During Sound-Making:
References
1Winkler, I., Denham, S., & Escera, C. (2015). Auditory event-related
potentials. In Jaeger, D. and Jung, R. (Eds.), Encyclopedia of
Computational Neuroscience (pp. 209-233). Springer New York.
2Shahin, A. (2011). Neurophysiological influence of musical training on speech
perception. Frontiers In Psychology
3Miall, R., & Wolpert, D. (1996). Forward Models for Physiological Motor
Control. Neural Networks, 9(8), 1265-1279.
4Manoonpong, P. (n.d.). Open-source multi sensori-motor robotic
platform AMOS II.
Significance and Applications
1.Engineering applications: Research done on control
systems in human and animal central nervous systems will
help us understand how more adaptive motor planning and
robust perception-action systems can be built.4
2.Impact on Neuroscience: The research paradigm
explored here can be expanded into different sensory
domains, (such as somatosensory domain) where similar
suppression effects are observed.
3.Clinical applications: Research in sensory event related
responses is proven to have numerous clinical applications.
This study can specifically be used to understand the
underlying neural mechanism of stuttering.
Figure 1: An Auditory
Evoked Potential2
Figure 2:
A flowchart on the
forward models of
motor control3
−0.5 0 0.5 1
−300
−200
−100
0
100
200
Time (s)
Amplitude(fT)
1st
Listening
2
nd
Listening
self initiated
cued
−0.5 0 0.5 1
−200
−150
−100
−50
0
50
100
Time (s)
Amplitude(fT)
self initiated
cued
−1.5 −1 −0.5 0 0.5 1
−20
−10
0
10
Time (s)
ERS/ERD(%)
self initiated
cued
Figure 3: Topographic map of the magnetic field of
the auditory evoked response. The bilateral dipolar
patterns suggest that the source of activation is
stemming from left and right auditory cortices.
Figure 5: Auditory evoked responses during self-initiated
and visually-cued sound making. The waveforms suggests
that the N1 suppression effect was more pronounced in
the self-initiated block.
Figure 4: Auditory evoked responses during all four
experimental conditions. The size of the N1 response
was clearly reduced when participants listened to self-
generated sounds.
Figure 8: Time course of alpha ERS/ERD in an MEG
sensor above the left motor cortex during self initiated
and cued sound making. The decrease in the event
related synchronization prior to sound making in the
self-initiated section shows a bigger extent of motor
preparation and intention.
Figure 7: Time-frequency representation of ERS/ERD above the left motor cortex during self-initiated and
visually-cued sound making. Decreased in amplitude of oscillations at beta frequencies (15-25 Hz) during
preparation for the movement relates to a release from inhibition and gradual activation of the left motor cortex,
which controls the right hand. Beta increase after the movement relates the inhibition of right hand movement.
Large decrease of alpha (8 Hz – 12 Hz) oscillation power prior to self-initiated sound making indicates a long
period motor preparation and likely reflecting stronger intention compared to cued sound making.
−2 −1.5 −1 −0.5 0 0.5 1
−0.08
−0.06
−0.04
−0.02
0
0.02
Time (s)
1st
PCofERS/ERD
Figure 6: Principal component analysis of beta oscillations resulted in a time course of the largest principal
component (left) and a topographic map of the magnetic field distribution (right). The maxima above central
regions of the cortex suggest sources in left and right sensorimotor areas.