Self representation across the senses:

1

• Self representation across the senses
• The neural response to ones own face and voice
• Jonas T. Kaplan1, Lisa Aziz-Zadeh3, Lucina Q.
  Uddin2, and Marco Iacoboni1
• (1) UCLA Ahmanson-Lovelace Brain Mapping Center,
  (2) UCLA Department of Psychology,
• (3) UC Berkeley Psychology Department
  International Computer Science Institute

Background We previously found that viewing
ones own face compared to a familiar other
produced signal changes in a right hemisphere
network including the inferior parietal lobule,
inferior frontal gyrus, and inferior occipital
gyrus (Uddin et al., 2005). Other research has
also found self-related processing to involve
right hemisphere structures (e.g. Feinberg
Keenan, 2005 Platek et al., 2006)  Q Are any
of the areas involved in visual self-recognition
also involved in self-voice recognition? Such a
multimodal self representation in a brain region
might indicate abstract self representation in
that region.
Results  We examined regions of interest defined
by significant voxels from the self minus other
analysis in our 2005 paper, and accepted voxels
within these regions that reached p lt .01 in the
present study. Viewing ones own face
compared with the face of a close friend produced
signal changes in all three right hemisphere
regions reported previously the inferior
parietal lobe, the inferior occipital gyrus, and
the inferior frontal gyrus. Hearing ones own
voice compared to the voice of a close friend
produced significantly greater signal change in
the inferior frontal gyrus. Other
minus self analysis produced some of the same
activations as the previous study for picture
stimuli, but not for voice stimuli. Thus there
was no brain region that responded preferentially
to other across sensory modalities.
Method We used fMRI to measure BOLD response in
12 subjects brains while viewing a picture of
themselves or of a close friend, and while
hearing their own voice and the voice of the same
friend. Subjects were asked to decide whether
they what were seeing or hearing was themselves
or not, and to respond with a button press. The
friend was someone with whom the subject had
contact with on a daily basis and was the same
sex and race as the subject.  Voices of both
the subject and the friend were digitally
recorded speaking 5 mundane sentences, e.g. The
door is open, The lights are on.  Ones own
voice does not sound the same in a recording as
it does when spoken. Transmission through the
bones of the head accentuates lower frequencies.
To account for this, we filtered our recordings
to amplify frequencies below 1000 Hz by 2 dB and
attenuate frequencies above 1000 Hz by 2 dB.
This kind of processing has been shown to make
recorded voices sound more natural and
self-like (Shuster Durrant, 2003).  Each
subject completed 4 functional scans of 5 minutes
each during which they were presented with both
faces and voices in an optimized event-related
design. Pictures appeared for 2 seconds each
with at least a 1 second gap between stimuli.
Voice recordings lasted about 2 seconds each and
were also followed by a gap of at least 1 second.
Functional images were acquired with the
following parameters TR 2s, TE 25, flip
angle 90, 36 slices each 3mm thick with 1 mm
gap and an in-plane resolution of 3 mm . Data
analysis was performed with FSL.
Voices Self minus Other
Pictures Self minus Other
Inferior frontal gyrus
Inferior parietal lobule
Inferior occipital gyrus
Discussion  We replicated our previous result
ones own face one again preferentially activated
a right hemisphere network including inferior
frontal gyrus, inferior parietal lobule, and the
inferior occipital gyrus.  The right inferior
frontal gyrus was more responsive to ones own
voice compared with a friends voice. This was
the only region that discriminated between self
and other in both sensory modalities. A right
inferior frontal activation is consistent with an
earlier PET study involving self voice
recognition (Nakamura et al., 2001). The right
inferior frontal cortex may be involved in an
abstract, cross-modal representation of the self.

References Feinberg, TE Keenan, JP (2005).
Consciousness and Cognition 14. Nakamura et al.
(2001). Neuropsychologia 39. Platek, SM, et al.
(2006). Human Brain Mapping 27. Shuster LI
Durrant JD (2003). Journal of Communication
Disorders 36. Uddin, L, Kaplan, JT,
Molnar-Szakacs, I, Zaidel, E, Iacoboni, M
(2005). NeuroImage 25.