Experiment 2 found that that biting on a pen, an activity that has been shown to consistently activa

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The role of the mirror neuron system in emotion
recognition and judgments of others imitation
Lindsay M. Oberman1,2 , Piotr Winkielman2 V.S.
Ramachandran1,2,3 1 Center for Brain and
Cognition, UC San Diego, La Jolla, California
92093 2 Department of Psychology, UC San Diego,
La Jolla, California 92093 3 Department of
Neurosciences, UC San Diego, La Jolla, California
92093
NN5

Experiment 1 Results
Introduction
Experiment 2 Behavioral Effect of Manipulations
In 1890, James observed that Every
representation of a movement awakens in some
degree the actual movement which is its object.
Since then, a large number of Early behavioral
studies found indicate that observers when
individuals are in the presence of others, the
observer ttends to overtly and covertly match
synchronize his/her movements to match their
behavior to those those around them. Embodied
cognition theories suggest that mimicry occurs
because the actions and emotions of others are
recognized or empathized with using a shared
action observation/execution mechanism that
internally simulates the corresponding body
movement and facial expression. The discovery of
the mirror neuron system (MNS) has inspired a
resurgence of investigations into the role of
sensorimotor neural systems in perception.
Participants saw a series of morphed photographs
taken from the Ekman-Friesen database1. On each
trial, participants were shown one face, and then
given a four-alternative-forced-choice
recognition task. Recognition scores were
obtained during a baseline condition as well as
the three manipulations that were examined in
experiment 1. The order of the conditions was
counterbalanced for each subject.
Experiment 1 EMG response to behavioral
manipulations
EMG data was collected during several
manipulation conditions to investigate the
specific muscle activity that resulted when the
participant was forced to perform these actions.
Bite Gum
Lip Rest
Z-Score of EMG Activity
2 1.5 1 0.5 0 -0.5 -1

• Chewing Gum
• Holding a pen horizontally with the lips while
  not allowing it to touch the teeth
• Holding a pen horizontally with the teeth while
  not allowing it to touch the lips
• 4. Produce facial expressions of happy, sad,
  fear, and disgust

Discussion
Experiment 2 found that that biting on a pen, an
activity that has been shown to consistently
activate mouth muscles, also specifically impairs
the ability to recognize happy faces. This
finding is consistent with the prediction based
on results from Experiment 1 that biting
manipulation reliably activates facial muscles
and that happy expression involve muscles
activity. No reliable effects were observed on
recognition of fear and sadness expressions
that were not associated with elevated
activations of measured muscles. The results
suggest that mimicry depends on a system that is
somatotopically specific, perhaps down to the
level of the muscle that is utilized. Given this
finding, it is likely that the premotor and
primary motor cortex are involved in recognition
of emotional expressionsfacial mimicry. Based on
imaging data a likely mechanism can be attributed
to the mirror neuron system2. The same neurons
in the premotor cortex respond to both the
observed and the executed action of the same
somatotopic area3. Thus if the mirror neurons
are already activated by the execution of the
action, as in this study, they are unable to be
modulated by the observation of the same action.
This modulation has been proposed to be involved
in the ability to recognize such an action by
means of internal simulation2. It has also been
proposed that the mirror neuron system is
involved in theory of mind and our ability to
recognize facial expressions and understand
emotions in others4,5. Based on this study, it
appears that impairing ones ability to use the
necessary muscles for facial expression leads to
a selective deficit in the recognition of the
emotions which involve those muscles.
1
2
Happy Disgust Fear Sad
Rest
Discussion
Experiment 1 had two goals. The first goal was
to examine effects of bite and gum
manipulations used in previous studies of facial
mimicry on muscles involved in production of
facial expressions. Results showed that the bite
manipulation causes activation of all measured
facial muscles, with the pattern being constant
over time. The gum manipulation also activates
all measured muscles, with greatest activation in
the Buccinator/Risorius and Orbicularis Oris, but
the pattern is oscillating. The second goal was
to examine muscle involvements in facial
expressions. Results revealed that the happiness
expression was associated with most muscle
activity, especially in the classic cheek
region. The activation in disgust was elevated
but much weaker than happiness and was restricted
to the nose region. The effects for fear were
marginal, and sadness produced no elevated
activity.
References

• Ekman, P., Friesen, W. 1978!. Facial Action
  Coding System A technique for the measurement of
  facial movement. Palo Alto, CA Consulting
  Psychologists Press.
• Rizzolatti, G., Fadiga, L., Gallese, V.,
  Fogassi, L. (1996). Premotor cortex and the
  recognition of motor actions. Brain Research.
  Cognitive Brain Research, 3(2), 131-141.
• Buccino, G., Binkofski, F., Fink, G.R., Fadiga,
  L., Fogassi, L., Gallese, V., Seitz, R.J.,
  Zilles, K., Rizzolatti, G., Freund, H.J.
  (2001). Action observation activates premotor and
  parietal areas in a somatotopic manner A fMRI
  study. European Journal of Neuroscience, 13,
  400-404.
• Gallese, V. Goldman, A. (1998). Mirror Neurons
  and the Simulation Theory of Mind-Reading.
  Trends in Cognitive Science, 3, 493-501.
• Carr, L., Iacoboni, M., Dubeau, M.C., Mazziotta,
  J.C., Lenzi, G.L. (2003). Neural mechanisms of
  empathy in humans A relay from neural systems
  for imitation to limbic areas. PNAS, 100(9),
  5497-5502.

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