Giacomo Rizzolatti and Corrado Sinigaglia
Basic knowledge
 Mirror mechanism
 Unifies perception and action
sensory representations of the behavior of others
motor representations of the same behavior in the
observer’s brain
 Its functional role depends on its anatomical location
(different cortical areas, different species)
 First discovered in ventral premotor F5 and particularly
F5c
Basic knowledge
 Motor act : A movement with a specific motor goal
(such as reaching, grasping and manipulating)
 Movement : A displacement of joints or body parts
without a specific goal (generated spontaneously or
produced artificially by electrical or magnetic
stimulation of motor areas)
 Motor action : Several motor acts organized in a chain,
leading to the achievement of a specific motor
intention (grasping a cup of coffee for drinking).
Aim
 Focus on the parieto-frontal mirror circuit
Anatomical
organisation
Functional role
In
macaque
and
human
brain
 Mirror based action understanding ??
The comprehension of an observed action based on the activation of a
motor programme in the observer’s brain. The observed action is
understood ‘from the inside’ as a motor possibility, rather than from the
outside’ as a mere visual description.
The parieto-frontal mirror network in macaque
STS AIP and PFG
(STShigh order visual
information about biological
motion, not motor properties ,
not mirror areas
 IT AIP (object identity)
AIP,PFG  F5
 F5 connected with F6 (preSMA) and prefrontal
cortex(area 46)
Mirror neurons also in LIP
and VIP !
The human parieto-frontal network
 Brain imaging, TMS, EEG, MEG
 two main regions
the inferior section of the precentral
gyrus , the posterior part of the
inferior frontal gyrus
the inferior parietal lobule, including
the cortex located inside the
intraparietal sulcus
Single-subject fMRI analyses
evidence that other cortical
areas (the primary
and secondary somatosensory
cortices and the middle
temporal cortex) become active
during action observation and
action execution
Evidence for goal coding in monkeys
F5 motor neurons encode
motor acts not movement
Similar results for IPL
The mirror neurons in F5 and IPL
do not differ in their motor
properties from parieto-frontal
motor neurons that do not have
visual properties. When they fire in
motor act observation, they send
information about the goal of the
observed motor acts
Different degrees of generality
 strictly congruent (grasping with
a particular grip)
 broadly congruent (grasping
achieved in different ways)
F5 mirror neurons- spatial relationships between the
agent and the observer
mirror
neurons may encode
the goal of the motor
acts of another
individual in an
observer-centred
spatial framework
The observer can
organize his own
future behavior in
cooperation or
competition with
the observed
individuals.
Evidence for goal and single-movement coding in
humans (1)
fMRI studies

video clips with human or robot arms grasping an
object or by using a tool
 activation of parieto-frontal mirror neurons
 tools a rostral sector of the left anterior supramarginal gyrus
 aplasic individuals (without arms and hands)
 parieto-frontal mirror circuit that was active during movements of
the feet and mouth was also recruited by the observation of hand
motor acts that they have never executed but the motor goals of
which they could achieve using their feet or mouth!
 TMS and fMRI studies, listening to action-related
sounds
Evidence for goal and single-movement coding in
humans (2)
 the parieto-frontal mirror circuit of humans also
becomes active during the observation of individual
movements (not goal-related), TMS experiments 
observation of movements of others results in an
activation of the muscles involved in the execution of
those movements
???
Understanding the actions of others
 Observing actions performed by another individual
elicits a motor activation in the brain of the observer
similar to that which occurs when the observer plans
their own action
 F5 mirror neurons in monkey fire in the absence of
visual information describing the motor act of the
experimenter.
Criticism (1)
 Csibra : “if mirror activity represents a copy of the
observed motor act, it is not sufficiently general to capture
the goal of that motor act; conversely, if it is sufficiently
general for goal understanding, it cannot be interpreted in
terms of a direct matching mechanism between sensory
and motor representations”
two kinds of sensory–motor transformation
movement mirroring, mapping the observed
movements onto the observer’s own motor
representation of those movements
goal mirroring, mapping the goal of the
observed motor
act onto the observer’s own motor
representation of that
motor act
Criticism (2)
 goal understanding  STS (visual analysis of actions
of others)
 Only neurons that can encode the goal of the motor
behaviour with the greatest degree of generality can be
considered to be crucial for action understanding
STS  spatio-temporally adjacent visual
representations of body part movements. not visual
representations of the same motor goal achieved by
different effectors
Parieto-frontal mirror neurons can be triggered by
different visual stimuli (for example, hand and mouth
actions) that have a common goal (for example,
grasping)
Also…TMS adaptation paradigm
specific neural populations within the stimulated cortical region
can be targeted.
One population is ‘adapted’ and will therefore be less active.
TMS targets less active neural populations  the adapted
population will be facilitated more strongly by TMS
 Adaptation-inducing videos of a hand or foot acting on various objects
and asked to respond as quickly as possible to a picture of a motor act
similar to that of the movie
 TMS over ventral premotor cortex, IPL and STS
 TMS over both premotor and IPL  reaction times to ‘adapted’ motor
acts regardless of the effector performing the observed motor act
 TMS over STS  reaction times to ‘adapted’ motor acts only if the
same effector executed the act in the movie and in the test picture
Critisism (3)
 There are several behavioural instances in which
individuals understand the actions of others even if they
are unable to perform them.
Inferential reasoning : The capacity to attribute to an agent
mental states that might account for the observed motor
action in terms of the reasons (needs, desires and beliefs)
underlying it.
Broadly congruent mirror neurons
However…non mirror mechanism ?
 What about the parieto-frontal mirror circuit when we
observe actions that do not belong to human
repertoire ??
 Dog biting vs. dog barking !!!!
 STS active in all cases
Mirror-based action understanding ? True or false ?
 STS recognition of the visual aspects of motor
behavior
 When the observed action impinges on the motor
system through the mirror mechanism, that action is
not only visually labeled but understood
the observed action is understood from the inside as a
motor possibility and not just from the outside as a mere
visual experience
Understanding motor intentions of others - macaque
 IPL, F5: action-constrained mirror neurons
‘Chains’ of neurons in which each neuron encodes a given motor act
and is linked to others that are selective for another specific motor act.
Together, they encode a specific motor action (for example, grasping
for eating or grasping for placing ). The same neurons have mirror
properties
Why the individual is performing the action
Understanding motor intentions of others -human
 fMRI right parieto-frontal mirror circuit during action
understanding
 Experiment of Cattaneo: grasping for eating and grasping
for placing, EMG myolohyoid muscle
both execution and observation of the eating action produced a
marked increase of mylohyoid muscle activity as early as the ‘reaching’
phase, whereas no mylohyoid muscle activity was recorded during the
execution and the observation of the placing action
As soon as the action starts, the entire motor program for the action
starts  intention, anticipatory representation of the motor
behavior of another individual
 Intention understanding is a multi-layer process involving
different levels of action representation, from the motor
intention that drives a given chain of motor acts to the
propositional attitudes (beliefs, desires and so on) that —
at least in humans — can be assumed to explain the
observed behavior in terms of its plausible psychological
reasons
understanding the reasons behind an agent’s motor
intention
requires additional inferential processes
 Mentalizing network anterior sector of anterior cingulate
cortex and other areas ?
The mirror mechanism and autism
Conclusions
 Mirror mechanism basic mechanism that unifies
action execution and action observation, allowing the
understanding of the actions of others from the inside
(goals, intention, anticipation, prediction)
 a primary way in which individuals relate to one
another, as shown by its presence not only in humans
and monkeys, but also in evolutionarily distant species
???
Thanks for your attention !!!