Transcript Mechanism for Understanding and Imitating Actions

Understanding Actions:
Mu Rhythms and Mirror Neurons
Jaime A. Pineda, Ph.D.
Cognitive Neuroscience Laboratory
November 23, 2004
Reading Minds

Understanding the behavior of others
The capacity to achieve internal
descriptions of actions and use them to
organize one’s own future behaviors

Neural mechanisms for understanding
actions and their intentions



Mirror neurons
Mu rhythms
The effects on learning and social
interactions
What Is It Like To Be a Bat?
“Consciousness and subjective
experience cannot be reduce to
brain activity.”
Thomas Nagel, The Philosophical Review 83 (1974).
Questions


What are mirror neurons?
How might these neurons help us understand actions
and their intentions?
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Can they help us understand “what it is like to be …?”
How is mirror neuron activity related to imitation
learning?
Is imitation learning important for social interactions?
What’s the relationship between mirror neurons and EEG
mu rhythms?
Why would a dysfunctional mirror system produce
autistic-like behaviors?
What Is an Action?
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Intentional motor behavior
Goal-directed behavior that produces a reward

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Attainment of the goal
Increased dopamine release
Rizzolatti et al., Nature Reviews, 2001, 2, 661-670
How Do We Understand Actions?

Visual hypothesis
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Involves striate, extrastriate,
inferotemporal lobe and superior
temporal sulcus, among others
An Observation/Execution Matching System?

Direct-matching hypothesis

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Map visual information onto
motor representations of
the same action
Mirror system: direct bridge
between perception and action
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
Mirror neurons
Mu rhythms
An Observation/Execution Matching System?

A dysfunctional “mirror
system” produces problems
in understanding actions
Biological Motion

Visual system's ability to
recover object information
from sparse input

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Gender
Activity engaged in
Emotional state
Biological Motion Perception: Monkeys

Perret and colleagues
(1989; 1990; 1994)
Cells in superior
temporal polysensory
area (STPa) of the
macaque temporal
cortex appear sensitive
to biological motion
Oram & Perrett, J. Cog. Neurosci., 1994, 6(2), 99-116
Biological Motion Perception: Humans


An area in the superior
temporal sulcus (STS) in
humans responds to
biological motion
Other areas, including the
amygdala, do as well
Grossman et al. J. Cog. Neurosci., 2000, 12(5), 711-720
Brain Circuit for Social Perception (SP)
• SP is processing of
information that results
in the accurate analysis
of the intentions of
others
• STS involved in the
processing of a variety of
social signals
Allison et al., Trends in Cog. Sci., 2000, 4, 267-272
Reading Other Minds

We understand actions (and intentions) when we
map the visual representation of the observed
action onto our motor representation of the same
action
Rizzolatti et al., Nature Reviews, 2001, 2, 661-670
Mirror Neurons

Found in:
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area F5 of monkey (homolog of Broca’s area?)
STSa (homolog of Wernicke’s area?), and
inferior parietal cortex (7b)
Activated by:
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Goal directed actions (reaching, grasping, holding)
performed by “biological” agents
Observation of similar actions
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Strictly versus broadly congruent
Do not respond to target alone or intransitive
gestures (i.e., nonobject directed)
Di Pellegrino et al., Exp. Brain Res., 1992, 91, 176-80
Mirror Neuron Activity
Rizzolatti et al., Cogn. Brain Res., 1996, 3:131-141
Understanding Actions?
Grasping
Mimicking
Umilta et al. Neuron, 2001, 32: 91-101
Functional Significance

Understanding action (Rizzolatti et al., 2001)
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Imitation learning (Jeannerod, 1994)
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Only in humans and apes?
Mirror System in Humans: Neuroimaging
Buccino et al. J. Cogn. Neurosci., 2004, 16: 1-14
Mirror System in Humans
Buccino et al. Eur. J. Neurosci., 2001, 13: 400-404
Neurophysiological Evidence
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Gaustaut and Bert, 1954 and Cohen-Seat et al., 1954
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Observing actions of another person blocks mu rhythm
(8-13 Hz over sensorimotor areas) of the observer
Recently confirmed
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Pineda et al., 1997, 2000
Cochin et al., 1998, 1999
Hari et al. 1998
Frequency Analysis of Mu Rhythm
P
o
w
e
r
Frequency
Mu Rhythm: Does it Reflect Mirror Neuron
Activity?
Baseline
Move
Observe
Imagine
Pineda et al., IEEE Trans. Rehab. Engr., 2000, 8(2): 219-222
RELATIVE MU POWER (n=13)
150
% DIFFERENCE FROM BASELINE
125
100
*
75
**
50
25
0
BASELINE
VIDEO0
IMAGINE
VIDEO
CONDITIONS
DUCK
WATCH
Avikainen et al., NeuroReport, 1999, 10: 3467-3470
Cochin et al., Eur. J. Neurosci., 1999, 11: 1839-1842
Characterizing the System
generalizability?
motivational significance?
biological realism?
intentionality?
anthropomorphism?
transitive/intransitive actions?
Mu suppression
(biological actions)
social relevance?
learning?
No mu suppression
(non-biological actions)
Autism: A Dysfunctional Mirror System?
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Autistic spectrum disorders are characterized by:
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No common underlying mechanism has been identified
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Impairments in social interaction
Delayed/abnormal language development
Impaired imagination
Repetitive and restricted patterns of behavior
Deficits in imitation learning – Rogers and Pennington, 1991
If mu rhythms reflect mirror neuron activity and the capacity to
imitate then autistics should show differences in mu rhythms
compared to controls
Experimental Paradigm

Measured mu power (2 min of
EEG) in normals (n=12) and
autistics (n=10) under different
conditions:
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Self-movement of hand
Watching video of someone
moving their hand
Watching a video of a ball
moving up and down
Fraternal Twins
Normal
Autistic
The Root of Empathy?
“Understanding others as intentional agents
may be grounded in the relational nature of our
interactions with the world”
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A Fundamental Organizational Feature of the Brain?
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Beyond actions?
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Audition and other senses
Emotions
Addiction?
What Is BCI?


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Brain-based direct
communication
Extracting meaningful
patterns (signals)
Mapping signals to computer
commands
Integrated with keyboard,
mouse, and voice
recognition
BCI System
Feature
Extraction
0
Multichannel
10
(amplitude (dB) -->)
20
30
.
20 20log
X
j
40
50
60
70
80
j
(frequency (kHz) -->)
Interface
Technology
Data Acquisition
Pattern
Recognition
Mapping to
Keyboard
Commands
User
Application
BCI Use
Helping impaired individuals have greater mobility
Helping impaired individuals communicate
Augment average individual’s abilities
Recreational/entertainment purposes
A Brain-Computer Interface
Hypothesis
Learning to control brain rhythms is faster with
active engagement on the task, frequent
interactions, feedback, and connections to the real
world.
Strategies For High Mu
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Imagining movement of hands, bike riding, playing
tennis or other athletic activity
Thinking about going right
Maintaining right movement in game
Focusing on word “right”
Shifting attention from word to direction
Strategies For Low Mu
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Frustration
Math problems
Calming and relaxing body
Sad memories
Distraction
Exhaustion
Results
1400
Predictions
1200
1000
POWER
800
600
400
1400
200
1200
R = 0.9152
1000
POWER
0
2
LOW
HIGH
MU CONDITIONS
800
HIGH
600
400
LOW
200
R2 = 0.8909
0
S1
S2
S3
S4
S5
S6
TRAINING SESSIONS
Collaborators
Brendan Z. Allison
Eric L. Altschuler
Edward M. Hubbard
Joseph P. McCleery
Vilayanur S. Ramachandran
Lindsay M. Shenk
Andrey Vankov
Victor Wang