Week 8 Lecture 8 - imitation and mirror neurons Flashcards
we can map visual representations of actions onto our motor system
What is this called?
Cross modal transfer
we can map visual representations of actions onto our motor system to produce what?
a copy of the action
What is perception-action mapping?
mapping visual representations
of actions onto our motor systems to produce a copy of the action
Humans are good at PAM, what might this suggest?
that this ability is innate
What is some developmental evidence for PAM?
- Infants can imitate caregiver’s facial expressions, hand and mouth movements, head turns, etc.
- Babies must build up a representation of the visual image of the caregiver’s face/mouth and map this onto their own motor representation of the movement
Meltzoff and Moore (1977) studied facial imitation in babies
What were the results?
- Babies aged 12 – 21 days could imitate certain facial expressions
- Imitate specific acts (i.e., lip protrusion vs. tongue protrusion) not just whole
body parts even after a delay
What evidence is there against neonate imitation?
- Longitudinal study - 1, 3, 6, and 9 weeks
- Large number of alternative control model behaviours
- Behaviour matching model more likely compared to some but not other control
behaviours - Tongue protrusion may be elicited by observing faces
True imitation may emerge later (6-9 months) as proposed by Piaget (who proposed it occurred at 1 year)
What is Active Intermodal Matching (AIM)?
- Neonates recognise equivalences between body transformations they see and those of their own body that they ‘feel’ themselves make
- Baby’s emotional expressions induce adults to produce similar expressions, which provides the infant with a
visual input to match his motor
output
What does AIM involve?
- perception and action having independent coding/representation
- A “specialist” module for imitation
What do alternative models to AIM such as IM and ASL posit?
- Common coding for perception and action
- Imitation part of “generalist” processes for motor control and learning
What is Ideomotor (IM) theory?
- suggests that actions are represented by their perceivable effects.
- Thus, any activation of the effect image, either endogenously or exogenously, will trigger the corresponding action.
What is Associative Sequence Learning (ASL)?
- emphasises learning through experience; - e.g. see consequence of own hand action
What is the Dual route model of imitation?
- Incorporates aspects of the other models
- Semantic route –meaningful actions, stored in repertoire (draws on own stored actions, would copy in your own way)
- Visuomotor/direct route –meaningless actions (unknown actions which you would copy carefully) –> mirror neurons
What are some general properties of mirror neurons?
- Bimodal, visuo-motor neurons (i.e., respond to both visual and motor stimuli)
- Discharge when individual performs an
action and when they observe the same
action performed by another individual
How do mirror neurons underpin action understanding?
Umiltà et al. (2001):
- Mirror neurons active during observation of partially hidden actions (predicts action
outcome even in absence of complete visual information)
Kohler et al. (2002):
- Audio-visual mirror neurons respond
to the sound typically produced by the action
What are the anatomical properties of mirror neurons?
- Found in monkey area F5 of premotor cortex and inferior parietal lobe
- Human homologue in Broca’s area (BA44), ventral inferior frontal gyrus (BA6), posterior parietal lobe and superior
temporal lobe - Somatotopically organised
F5 contains 3-types of neurons
What are they?
– ‘action observation-related’ visuomotor
neurons (mirror neurons)
– motor neurons
– Canonical visuomotor neurons (also
called ‘object observation-related’
neurons)
What direct and indirect evidence is there for human mirror neurons?
Indirect Evidence
- Close link between perception and action
- Behavioural
- Brain Imaging (fMRI)
- Transcranial Magnetic Stimulation (TMS)
Direct Evidence
- Recording from neurones
What is automatic imitation?
Faster responses when compatibility between observed and executed movements
What did brain imaging for mirror neurons in humans find?
- Somatotopic activation of pre-motor and parietal cortex (Buccino et al, 2001)
- Areas correspond to observations of actions of different body parts
What is motor imagery?
imagined movement without action
Is there overlap in brain activity between
imagined, observed and executed movements?
yes
- meta analysis support
A TMS study on human mirror neurons used motor evoked potentials to show what?
to show that observing an action produces increased motor excitability
Mukamel et al., 2010 recorded from 1177 neurons in 21 patients undergoing surgery for intractable epilepsy
What did they find?
- They observed and executed grasping actions and facial gestures
- Action observation-related (‘mirror’) neurons found in medial frontal lobe (supplementary motor area; SMA) and medial temporal lobe (hippocampus)
- Some cells respond with excitation during action execution during action observation
- Others respond with inhibition
Mukamel et al., 2010 recorded from 1177 neurons in 21 patients undergoing surgery for intractable epilepsy
What type of evidence for mirror neurons is this an example of?
Direct evidence –> direct recording
Is there similarities across species for mirror neurons?
- yes
Human, monkey and dog actions:
- Same areas activated to movements common to all three species i.e., biting
- Speech and lip-smacking activates same area in human and monkey but dog barking does not
What are some species-specific differences in humans and monkeys concerning mirror neurons?
Human
- Action does not need to be goal-directed or contain an object
- Meaningless movements are represented
Monkey
- Action must be goal-directed (often involve actual object)
- Cannot learn novel and complex acts (involve BA46 not present in monkey) – THEY DON’T IMITATE
- Rather than for imitation MNs may underpin understanding intentions
