Lecture 8, Imitation and Mirror Neurons Flashcards
Perception-Action Mapping
Humans can map visual representations of actions onto their motor systems to produce a copy of the action.
This ability is innate and called Perception-Action Mapping (PAM).
Infants can imitate caregiver’s facial expressions, hand and mouth movements, head turns, etc.
To imitate, babies must build up a representation of the visual image of the caregiver’s face/mouth and map it onto their own motor representation of the movement.
Developmental Evidence for PAM
Meltzoff and Moore (1977) found that babies aged 12-21 days could imitate certain facial expressions, not just whole body parts, even after a delay.
Piaget thought this ability occurred no earlier than 1 year.
Evidence challenges this claim, suggesting neonates can imitate specific acts, such as lip protrusion vs. tongue protrusion.
Evidence Against Neonate Imitation
A recent study (Oostenbroek et al., 2016) challenges previous evidence for neonate imitation.
The study used a longitudinal design over 1, 3, 6, and 9 weeks with a large number of alternative control model behaviors.
A behavior matching model was more likely compared to some but not other control behaviors.
Tongue protrusion may be elicited by observing faces, and true imitation may emerge later (6-9 months) as proposed by Piaget.
Active Intermodal Matching (AIM)
Neonates can recognize equivalences between body transformations they see and those of their own body that they ‘feel’ themselves make.
A baby’s emotional expressions can induce adults to produce similar expressions, providing the infant with a visual input to match their motor output.
AIM involves perception and action having independent coding/representation, and it posits a “specialist” module for imitation.
AIM Versus Other Models
AIM is different from other theories, such as the imitation model (IM) and the associative sequence learning (ASL) model, which posit common coding for perception and action.
Imitation is part of “generalist” processes for motor control and learning in other models, while AIM involves a specialized mechanism for imitation.
Ideomotor (IM) Theory
IM theory proposes that imagining an action can create a similar response to actually performing that action.
According to this theory, the brain forms an association between a specific action and the intended outcome of that action, and imagining the action can activate this association, leading to a response similar to actually performing the action.
Associative Sequence Learning (ASL)
ASL emphasizes learning through experience, particularly through observing the consequences of one’s actions.
The theory suggests that actions are learned and reinforced based on the outcomes they produce, and these learned associations can influence future behavior.
Dual Route Model of Imitation
The dual route model incorporates aspects of both IM theory and ASL.
It suggests that imitation can occur through two routes: semantic (meaningful actions) and visuomotor/direct (mirror neurons).
Mirror neurons are bimodal, visuo-motor neurons that discharge both when an individual performs an action and when they observe the same action performed by another individual.
Mirror Neurons - General Properties
Mirror neurons are important for action understanding, and they respond to both visual and motor stimuli.
They are found in the monkey area F5 of premotor cortex and inferior parietal lobe, as well as in the human homologue in Broca’s area (BA44), ventral inferior frontal gyrus (BA6), posterior parietal lobe, and superior temporal lobe.
Mirror neurons are somatotopically organized, meaning they are organized according to specific body parts and actions.
Mirror Neurons - Anatomical Properties
F5 contains three types of neurons: action observation-related visuomotor neurons (mirror neurons), motor neurons, and canonical visuomotor neurons (also called object observation-related neurons).
Mirror neurons are active during the observation of partially hidden actions and respond to the sound typically produced by the action.
Human Mirror Neurons - Indirect Evidence
There is a close link between perception and action in humans.
Behavioral studies have shown faster responses when there is compatibility between observed and executed movements.
Brain imaging studies (fMRI) have shown somatotopic activation of pre-motor and parietal cortex, with areas corresponding to observations of actions of different body parts.
Transcranial magnetic stimulation (TMS) has been used to show that observing an action produces an increase in motor excitability.
Human Mirror Neurons - Direct Evidence
Recording from neurons has been done in 21 patients undergoing surgery for intractable epilepsy.
These patients observed and executed grasping actions and facial gestures, and action observation-related (mirror) neurons were found in the medial frontal lobe (supplementary motor area; SMA) and medial temporal lobe (hippocampus).
Some cells respond with excitation during action execution and during action observation, while others respond with inhibition.
Perception-Action Overlap
There is an overlap in brain activity between imagined, observed, and executed movements.
Motor imagery (imagining movement without action) can activate similar brain regions to those used in actual movement.
TMS has been used to show that observing an action produces an increase in motor excitability.
Similarities across Species
Human, monkey, and dog actions activate the same areas for movements common to all three species, such as biting.
Speech and lip-smacking activate the same area in humans and monkeys but not in dogs.
Species-Specific Differences
Human mirror neurons can represent meaningless movements, while monkey mirror neurons require goal-directed actions involving an actual object
