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?

Thomas Nagel, The Philosophical Review 83 (1974).

“Consciousness and subjectiveexperience cannot be reduce tobrain activity.”

Questions

What are mirror neurons? How might these neurons help us understand

actions and their intentions? 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?

Intentional motor behavior Goal-directed behavior that produces a reward

Attainment of the goal Increased dopamine release

Rizzolatti et al., Nature Reviews, 2001, 2, 661-670

How Do We Understand Actions?

Visual hypothesis Involves striate, extrastriate,

inferotemporal lobe and superior temporal sulcus, among others

An Observation/Execution Matching System?

Direct-matching hypothesis Map visual information onto

motor representations of the same action

Mirror system: direct bridge between perception and action

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

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)

Allison et al., Trends in Cog. Sci., 2000, 4, 267-272

• 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

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: area F5 of monkey (homolog of Broca’s area?) STSa (homolog of Wernicke’s area?), and inferior parietal cortex (7b)

Activated by: Goal directed actions (reaching, grasping,

holding) performed by “biological” agents Observation of similar actions

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

Rizzolatti et al., Cogn. Brain Res., 1996, 3:131-141

Mirror Neuron Activity

Understanding Actions?

Umilta et al. Neuron, 2001, 32: 91-101

Grasping Mimicking

Functional Significance

Understanding action (Rizzolatti et al., 2001)

Imitation learning (Jeannerod, 1994) Only in humans and apes?

Buccino et al. J. Cogn. Neurosci., 2004, 16: 1-14

Mirror System in Humans: Neuroimaging

Buccino et al. Eur. J. Neurosci., 2001, 13: 400-404

Mirror System in Humans

Neurophysiological Evidence

Gaustaut and Bert, 1954 and Cohen-Seat et al., 1954

Observing actions of another person blocks mu rhythm (8-13 Hz over sensorimotor areas) of the observer

Recently confirmed Pineda et al., 1997, 2000 Cochin et al., 1998, 1999 Hari et al. 1998

Frequency Analysis of Mu Rhythm

Power

Frequency

Pineda et al., IEEE Trans. Rehab. Engr., 2000, 8(2): 219-222

Mu Rhythm: Does it Reflect Mirror Neuron Activity?

Baseline

Move

Observe

Imagine

RELATIVE MU POWER (n=13)

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BASELINE VIDEO0 IMAGINE VIDEO DUCK WATCH

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Cochin et al., Eur. J. Neurosci., 1999, 11: 1839-1842

Avikainen et al., NeuroReport, 1999, 10: 3467-3470

Mu suppression(biological actions)

No mu suppression(non-biological actions)

intentionality?

anthropomorphism?

biological realism?motivational significance?

transitive/intransitive actions?

generalizability?

Characterizing the System

learning?

social relevance?

Autism: A Dysfunctional Mirror System?

Autistic spectrum disorders are characterized by: Impairments in social interaction Delayed/abnormal language development Impaired imagination Repetitive and restricted patterns of behavior

No common underlying mechanism has been identified 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:

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”

A Fundamental Organizational Feature of the Brain? Beyond actions?

Audition and other senses Emotions

Addiction?

What Is BCI?

Brain-based direct communication

Extracting meaningful patterns (signals)

Mapping signals to computer commands

Integrated with keyboard, mouse, and voice recognition

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User

InterfaceTechnology

Multichannel

Data Acquisition

FeatureExtraction

PatternRecognition

Mapping toKeyboardCommands

Application

BCI System

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

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 Frustration Math problems Calming and relaxing body Sad memories Distraction Exhaustion

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POWER

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Results

Predictions

R2 = 0.9152

R2 = 0.89090

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TRAINING SESSIONS

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SINGLE SUBJECT: LEARNING HIGH MU CONTROL OVER A SINGLE SESSION

R2 = 0.2598

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MEAN MISSED DISTANCE

R2 = 0.4789

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ALL SUBJECTS: LEARNING LOW MU CONTROL OVER ALL SESSIONS

R2 = 0.2982

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Collaborators

Brendan Z. AllisonEric L. Altschuler Edward M. HubbardJoseph P. McCleeryVilayanur S. RamachandranLindsay M. Shenk Andrey VankovVictor Wang