Embed Size (px)
Citation preview
Social Cognition and the Mirror Neuron System of the Brain
Jaime A. Pineda, Ph.D.Cognitive Neuroscience Laboratory
COGS1 class
Motivating Questions
How do our brains perceive the mental states of others despite their inaccessibility?
How do we read other minds?
How do we understand the actions, emotions and the intentions of others?
Rationally? Intuitively?
How do we understand first-and third-person experiences?
Classic Explanation
Theory-Theory(argument from analogy; disembodied knowledge; visual hypothesis)
Involves striate, extrastriate, inferotemporal lobe and superior temporal sulcus, among others
A Different Perspective
Simulation Theory(Direct-matching hypothesis; embodied knowledge)
Map visual information onto motor representations of the same action
Mirroring systems bridges between perception and action that allow for simulation
Mirror neuronsEEG Mu rhythms
A Different Perspective
Simulation Theory(Direct-matching hypothesis; embodied knowledge)
Map visual information onto motor representations of the same action
Mirroring systemsbridges between perception and action that allow for simulation
Mirror neuronsEEG Mu rhythms
The Mirror Neuron System
Iacoboni and Dapretto, Nature Reviews, 2006,7:942-951
Biological Motion
Visual system's ability to recover object information from sparse input
GenderActivity engaged inEmotional 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 do as well, including frontal cortex, SMA, insula, thalamus, amygdala
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
Mirror Neurons
A specific class of neurons that discharge both when the monkey performs an action and when it observes a similar action done by another monkey or an experimenter
Found in:area F5 (homolog of Broca’s area); 10-20%inferior parietal cortex (PF/7b)
Activated by:Goal directed actions (reaching, grasping, holding)Observation of similar actions performed by “biological” agents
Di Pellegrino et al., Exp. Brain Res., 1992, 91, 176-80
Mirror Neuron Activity
Rizzolatti et al., Cogn. Brain Res., 1996, 3:131-141
Perception-to-Action Mapping Selectivity
Logically-Related(effector independent; 2X)
Congruent(effector dependent)
Perception
Action
Understanding Intentions
MimickingGrasping
Umilta et al. Neuron, 2001, 32: 91-101
Functional Significance
Response facilitationMimicrySimulationImitation learning Understanding actions Understanding intentionsEmpathyTheory of MindLanguage
Characterizing the System
intentionality?anthropomorphism?
biological realism?motivational significance?
generalizability?
social relevance?
transitive/intransitive actions? learning?
MNS activity No MNS Activity
Rolandic “en arceau” rhythm(7-11 Hz)
“…blocked when the subject performs a movement or simply when he changes his postural tone.”
“…disappears when the subject identifies himself with an active person represented on the screen.”
The Mirror Neuron System
Iacoboni and Dapretto, Nature Reviews, 2006,7:942-951
Mu Rhythm
8-13 Hz oscillation over sensorimotor cortex
Normal Oscillation Self Action Observed Action
Frequency Analysis of Mu Rhythm
Power
Frequency
(8-13 Hz)
(10-14 Hz)
Does Mu Suppression Reflect Mirror Activity?
Baseline
Move
Observe
Imagine
Pineda et al., IEEE Trans. Rehab. Engr., 2000, 8(2): 219-222
Action Observation and Social Interaction
To what degree do mu rhythms, like mirror neurons, reflect social interaction?
Oberman et al., Social Cognitive and Affective Neuroscience, 2007, 2, 62-66
Experimental Paradigm
Measured mu power (2 min of EEG) in normals (n=20) ages 18-34 (mean=21.1, SD=3.40 ) under different observation conditions:
Non-interactingSocial Action - Spectator Social Action - InteractiveVisual white noise
Engaged in continuous performance task during observation
Non-interacting Social Action - Spectator
Social Action - Interactive
Results
0
0.5
1
1.5
2
2.5
3
3.5
4
Non-Interacting Social Action,Spectator
Social Action,Interactive
Deg
ree
of S
ocia
l Int
erac
tion
Results
-0.4
-0.3
-0.2
-0.1
0
0.1
Social Action, InteractiveSocial Action, SpectatorNon-Interacting
C3 CZ C4
Understanding Facial Expressions
Are mu rhythms sensitive to processing of facial expressions?
Understanding Facial Expressions
Anger HappyDisgust
Emotion versus gender discrimination task
Results
Results (cont.)
r = -0.5 r = -0.04
r = 0.73
Autism Spectrum Disorder
ASD shows impairments in: social interactionsdelayed/abnormal language developmentbehavior
Impaired imitationRepetitive patterns of behavior
No common underlying mechanism
Deficits in imitation learning (Rogers and Pennington, 1991)Deficits in mirror neuron system (Williams et al., 2001)
Activation for Imitation of Facial Emotions
Dapretto et al., Nat Neurosci., 2006
Hypothesis
If mu rhythms reflect MNS activity and the capacity to understand actions as well as learn through imitation, then autistics should show differences in mu rhythms compared to controls
Oberman et al., Cog. Brain Res. 2005, 24: 190-198
Experimental Paradigm
Measured mu power (2 min of EEG) in normals (n=12) and autistics (n=10) under different conditions:
Self-movement of hand
Watching video of someone moving their hand
Watching a video of a ball moving up and down
Oberman et al., Brain Res Cogn Brain Res. 2005, 24(2):190-8.
Results
Is the Mirror Broken and Unrepairable?
Oberman et al., Neuropsychologia, 2008
Creating a Temporary “Autistic” Brain
Inferior parietallobule
Superior temporalsulcus
Inferior frontal gyrus
Sensorimotorcortex
RATIONALE
If mirror neurons in IFG are involved in the direct modulation of sensorimotor mu rhythms, then temporary inhibition of these neurons should prevent suppression of mu rhythms and cause “autistic-like” behaviors.
Method
Measured EEG in typically developing adults (n=8) before and after IFG stimulation
Observation of movement (4 videos)
Simple (hand movements) and complex (social interactions)
Baron-Cohen’s Eyes TaskEmotion and gender discrimination
1 Hz rTMS (5 min at ~ 40-50% absolute threshold) targeted at left IFG
Eyes Task
Results
AccuracyReaction Time
0
5
10
15
20
25
30
Emotion Recognition Gender Recognition
Rea
ctio
n Ti
me
(sec
)
Before IFG stimulation After IFG stimulation
0
0.2
0.4
0.6
0.8
1
Emotion Recognition Gender Recognition
Acc
urac
y
Before IFG stimulation After IFG stimulation
Results
IFG STIMULATION
-0.1
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
0.08
0.1
C3 C4 C3 C4
SIMPLE COMPLEXMOVEMENT TYPE
MU
SU
PPR
ESSI
ON
PRE
POST
Neurofeedback Training Rationale
Frontoparietal areas in an ASD brain may be underconnected
If we change the dynamics of the sensorimotor mu oscillations,
And these oscillations are functionally linked to the MNS network (IFG, IPL, STS),
Then we may change functional connectivity via neuroplasticityand recover MNS engagement,
leading to positive changes.
IPL
STS
SM Cortex
IFG
Reversing Social Deficits in Autism
Training 30 min x 3/week x 10 weeksHF ASD: 7-17 yr olds; n=20
Experimental/Control groups Mu activity above threshold (E)EMG activity below threshold (E/C)
Pineda et al., Research in ASD, 2008
Assessments
Verification of diagnosis (IQ, ADI, ADOS)Quantitative EEG (QEEG)Test of Variable Attention (TOVA)Imitation ability (De Renzi’sApraxia imitation test)Mu suppression index (MSI)Autism Treatment Evaluation Checklist (ATEC - parental assessment)Neuroimaging (fMRI, fcMRI)
Interpreting Facial Expressions: Nonverbal
Emotion/Gender discrimination
Decoding Thoughts and Intentions
Mental attribution Physical causation
Behavioral Performance
R2 = 0.7068
0
50
100
150
200
250
300
350
400
0 2 4 6 8 10 12 14 16 18
SESSIONS
(HIT
S/M
IN)*T
HRES
HR2 = 0.7673
0
50
100
150
200
250
300
350
400
0 5 10 15 20 25
SESSIONS
(HIT
S/M
IN)*T
HRES
H
ASD
TD
Mu-Suppression Normalizes Following Training
Baseline Hand Social
MU SUPPRESSION INDEX
-0.1
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
HAND SOCIAL HAND SOCIAL
PRE-TRAINING POST-TRAINING
LOG
[CO
ND
ITIO
N/B
ASE
LIN
E]
CONTROLS
EXPERIMENTALS
Positive Changes in Sustained Attention
Improved ability to maintain attention in experimental group
Positive Changes in Parental Assessment
Autism Treatment Evaluation Checklist
Imitation
Future: Neuroimaging Techniques
structural Diffusion Tensor Imaging
Functional connectivityfunctional
A Fundamental Feature of Brain Organization?
“Understanding others as intentional agents may be groundedin the relational nature of our interactions with the world”
Beyond understanding actionsemotions: the root of empathy?sounds and other senses language
Other problems in “mirroring”Aberrant imitation learning: addiction?
What Is It Like To Be…?
Can aspects of subjective experience be reduced to brain activity?
Thomas Nagel, The Philosophical Review 83 (1974).
Collaborators and Students
Adrienne MooreRajiv RaoChris RobinsonHanie ElfenbeinAlex BresslerSteven ThurmanJena DavisDong SukChrista FutagakiJudith KayeLee EdwardsRalph-Axel MuellerBrandon Keehn
Oriana ClarkJia-Min BaiDerrick AsherDane ChambersMatt EarhardtHeather PeltonAlicia TrigerioAlbert AyalaStephen JohnsonSteve GilmoreNick Pojman
VilayanurRamachandranLindsay ObermanEric AltschulerAndrey VankovBill SkinnerChulie UlloaBrendan AllisonEd HubbardJoe McCleeryErin HechtDavid BrangScott Carey Kelly Head
