Transcript Georgopoulos et al 1982

Motor cortical
areas: the
homunculus
The motor
system
Major Cortical areas involved in planning and
execution of “purposeful” movements
Directional Tuning of
MI Cells
Movement onset
(Georgopoulos et al 1982)
Set related responses in
Pre-motor Cortex
Prepare LEFT movement
Prepare RIGHT movement
Mirror neurons
Rizzolatti et al., 1996
Basic properties of the Mirror
Neurons
Rizzolatti et al. 1996
A multimodal representation of
action
Mirror neurons in the Parietal cortex: Intention understanding?
Mirror neurons show the same
specificity when actions are
preformed by the experimenter
What is represented by the MN?
Actions or goals?
unit210
opening
Hand
Umlita et al., 2008
closure
unit199
The mirror system – abstract
representation of movement goals?
• Recordings from 37 mirror
neurons in F5 in a “hidden
action” paradigm
• 19/37 mirror neurons
responded significantly in
the hidden condition.
• 7/19 – strong responses
(hidden=visual)
Full
vision
Hidden
vision
(Umilta et al., 2001).
The mirror system in humans
Cortical activation during
observation of mouth hand
and foot action
Viewed-Hand identity effects in parietal cortex
Shmuelof & Zohary 2006
Visual and motor hand areas in the
human parietal cortex
Specificity of visually defined “hand
areas” to motor actions
Functional role of the MN
• Communication
• Imitation
Mirror system: imitation?
Animated
hand
Static
hand
X
position
The role of imitation
imitate
Move
X finger
Move
X finger
Iacoboni et al., science 1999
A deeper understanding of
“mirror like voxels”
Mirror regions should be active both
during viewing action and motor action
Mirror neurons should show
cross-modal adaptation
Observation based Observation
Action
only
Right anterior parietal cx
Observation based Observation
Action
only
Left frontal operculum
BA 44
Observation based Observation
Action
only
Right parietal operculum
Functional role of the MN
• Intention/context
Mirror system in humans
• intention understanding: drinking or cleaning,
compared to grasp only or context only
• fMRI scan of 23 human subjects
(Iacoboni et al., 2005)
Functional role of the MN
•
•
•
•
Communication
Imitation
Intention/context
Social behavior
controls
ASD patients
Understanding
emotions in others:
mirror neuron
dysfunction in
children with autism
spectrum disorders
Functional role of the MN
•
•
•
•
•
Communication
Imitation
Intention/context
Social behavior
Language
The mirror system and the
evolution of language
• F5 in monkeys corresponds anatomically
(location and cytoarchitecture) to Broca’s
area (specifically to the pars opercularis of
IFG corresponding to area 44)
• Lateral F5 mirror neurons respond to mouth
movements, some of them to communicative
mouth movements
• Could the mirror system be the evolutionary
basis for the development of language?
,
self grasping
Viewed
grasping
(Hamzei et al., 2003)
Verb generation
action recognition
(active >passive)
language production
(verb > rest2 (
(Hamzei et al.,
2003)
Language within our grasp?
• Not yet…
• But:
– a mirror system exists and probably enables
understanding of actions (in primates too)
– This mirror system can also infer actions that are
not directly seen, and can infer intention
– This forms a good basis for the development of
language from hand and face expressions not
directly connected to their instructed meaning
– Therefore, the mirror system could be the
neurological basis for the development of language