Download Understanding mirror neurons : A bio

Understanding mirror neurons
: A bio-robotic approach
인지과학 협동과정
VCC 석사 2학기 김시온
1.Introduction
Understanding action
사과
때리다
왜?
미워서, 웃겨서, 짜증나서
까불어서, 사랑의 마음으로
잘되라고, 말 안들어서…
-> 의도 파악의 필요성
1.Introduction
Speech understanding machine
• Alvin Liberman(May 10, 1917 - Jan. 13, 2000)
Analyzing the acoustic characteristics
of spoken words
Subjects
Context
Failed because of the limited
computational power available
Sound
Articulatory gestures
1.Introduction
Acoustically –evoked motor “Resonance”
Production에 관여한 지식들이
Perception에도 관여한다.
Action과 관련하여
이러한 역할을 하는 것으로
보이는 영역이 발견되었다!!
2. Physiological properties of monkey rostroventral premotor area (F5)
Inferior premotor area
2. Physiological properties of monkey rostroventral premotor area (F5)
Motor Neurons
• Goal-Directed action들에 반응
(grasping, manipulating, tearing, holding)
-비슷한 손동작이 사용될지라도 목적이
다르면 발화하지 않음
• 많은 Grasping neuron들은 특정한 종류
의 Grasping에만 선택적 반응
(precision, finger prehension, whole hand grasping)
-> a repository of
motor actions
2. Physiological properties of monkey rostroventral premotor area (F5)
Visuomotor Neurons
- Canonical Neurons
•
움직임이 있기 전에,
움직일 수 있는 대상을
보았을 때에도 발화
•
많은 canonical neurons들은 하나, 혹은
소수의 대상에 선택적으로 반응한다.
2. Physiological properties of monkey rostroventral premotor area (F5)
Visuomotor Neurons
- Mirror Neurons
•
내가 행동할 때 뿐만 아니라,
다른 행위자가 동일한 목표-지향적
행동을 할 때에도 발화
•
최근 연구 결과 F5 이외에도 PF에서도
발견됨
•
다른 행위자가 손이나 입을 이용해
물체와 상호작용할 때 활발하게 반응
•
도구를 이용했을 때에는 반응하지 않음
•
대부분의 Mirror Neuron들은 한 종류의
행동에만 선택적으로 반응
(Highly congruent neurons)
2. Physiological properties of monkey rostroventral premotor area (F5)
Visuomotor Neurons
- Mirror Neurons
3. A model of area F5 and the mirror system
A role of F5
Visual appearance of the hand
Object affordance
Controller
Classifier
3. A model of area F5 and the mirror system
Controller-predictor formulation
Acting
Desired action, timing
Specific Motor Plan
Comparison
F5 forward information
≒ Sensory feedback(VMM)
Desired action
Context
※ Feedback : to counteract disturbances and
to learn from mistakes
3. A model of area F5 and the mirror system
Controller-predictor formulation
Observing an action
Transforming visual cues
into motor information as before
Mirror Neurons
Bayesian approach??
3. A model of area F5 and the mirror system
Ontogenesis of mirror neurons
• 아기들이 행위자의
목표를 판단할 때
사용하는 Cue는?
(Path? Object?)
• Results
6,9 mos : new>old goal
Woodward(1998)
3. A model of area F5 and the mirror system
How do we achieve an action recognizing?
Specific goals
Canonical Neuron
Mirror Neuron
1) Certain actions are more likely to be applied to a particular object
2) Objects are used to perform actions
Linking
Particular action
= particular effect
Question!!
• 과연 VMM 정보가 Action 인식에 도움을
줄까??
• 로봇를 가지고 한번 직접 실험해 보자!
4. A machine with hands
Motor-kinesthetic information + visual information vs only visual information
Recording “motor awareness”
• Cyber-glove, a pair of CCD cameras,
a magnetic tracker, two touch sensors
• Data was sampled at frame rate,
synchronized and stored to disk
by a Pentium class PC
• Cyber-glove has 22 sensors
, recording the kinematics of the
hand at up to 112Hz
• Two touch sensors were mounted on
the thumb and index finger to detect
the moment of contact with the object
• Matlab was employed for post-processing
4. A machine with hands
Grasping type followed Napier’s taxonomy
4. A machine with hands
• Each grasping action was recorded
from six different subjects.
• Moving the cameras to 12 different
locations
• Images of the scene from the two camera
synchronized with the cyber-glove
and magnetic tracker data
=> Bayesian Classifier
•
The visual features were extracted from
pre-processed image data
• Using a simple color segmentation algorithm
• The data set was filtered through Principal
Component Analysis
Classification Task
Motor-kinesthetic information + visual information vs only visual information
4. A machine with hands
VMM
• Using a simple back-propagation neural
network with sigmoidal units
• The input of the VMM was the vector of the
mapping of the images onto the space
spanned by the first N PCA vectors
• The output was the vector of joint angle
acquried the data glove.
4. A machine with hands
Experiment 1 - Classification
>
-> 운동정보가 Action recognition에 도움을 줄 수 있다!!!
5. Robotic experiment
Cog
Flipper
A mirror neuron-like representation could be acquired
by simply relying on the information exchanged during the robot- environment interaction
(로봇-환경 간의 상호작용에서 mirror-neuron과 같은 표상을 획득할 수 있는가?)
5. Robotic experiment
Causal indirection, brain area and function
1
If any neural unit is active in these two situations(both when acting and observing)
Then it can be regarded in all respects as a “mirror” unit.
by repetitive exposure and manipulation
6. Learning object affordances
Rolling affordances
Grasping(x)
Touching, poking, prodding, sweeping(o)
6. Learning object affordances
Rolling affordances
6. Learning object affordances
Generic poking actions
Can this information be re-used when acting to generate anything useful
Showing exploitation of the object affordance?
100/15 … 3번만 완전 실패( ≒ Canonical Neuron)
Another interesting question is whether knowledge about object directed actions
can be reused in interpreting observed actions performed by a human experimenter.
7. Developing mirror neurons
mimicry
Same segmentation procedure section 6 generated by human and robot
… LEARNING??
7. Developing mirror neurons
Passive vs Active imitation
Demiris & Hayes, 2002
7. Developing mirror neurons
mimicry
Learning of mirror neurons can be carried out
by a process of autonomous development
7. Conclusion
• The motor information plays a role in the
recognition process
• A mirror-like representation can be developed
autonomously on the basis of the interaction
between an individual and the environment
감사합니다.