Mirror Neurons 1996-2005

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Mirror Neurons1996-2005
WELLCOME DEPARTMENT OF IMAGING NEUROSCIENCE Functi
onal Imaging Laboratory

• Thus I regard Rizzolati's discovery of mirror
  neurons and my purely speculative conjectures
  on their key role in our evolution as the most
  important unreported story of the last decade.
• Ramachandran, V.S. 2000, MIRROR NEURONS and
  imitation learning as the driving force behind
  "the great leap forward" in human evolution

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Mirror Neurons in Premotor Area

• Neurons in monkey cortex have been found that
  respond not only to seeing the monkeys hand
  grasp an item, but when other hands grasp it as
  well, including the homologous human hand.
• The neuron does not respond to a pliers picking
  up the item.
• Most mirror neurons respond best to one type of
  action, like picking up.
• Mirror neurons may help us to understand what
  others are doing, how to react to their actions,
  but also how to imitate them

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Mirror neurons and action representation
Brain, 1996 Exp Brain Res, 1996.

• 92 of 532 premotor F5 neurons (15-20) discharge
  when the monkey makes active movements and when
  he observes specific meaningful actions performed
  by the experimenter.

• Specific to one or a few hand actions such as
  Grasping,Holding, Manipulating, and some to
  specific grasp (e.g. precision grip, finger
  prehension).
• ---activated by view of grasping with hand, but
  not when grasping is done with a tool
• Possible role discharge of neurons in mirror
  system generates an internal representation of
  the movement which is involved in the
  understanding of motor events.

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Neuron, 2001
Mirror neurons infer hidden goals

• activity represent observed goal-directed
  action.

• Activity of F5 Mirror Neurons was recorded in a
  2x2 factorial design
• Full vision and Hidden condition
• Object-directed and mimed action
• 3 types of actions (Grasping, Holding, Placing)

• 19 out of 37 recorded F5 Mirror Neurons (50)
  were active during
• Object-directed action, visible or hidden
• Not in the absence of object

• Half of the F5 Mirror Neurons recorded respond
  selectively to the observation of specific hand
  actions even when the final part of the action,
  i.e., the most crucial in triggering the response
  in full vision, is hidden from the monkeys
  vision.

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Science, 2002 Exp Brain Res, 2003.
Mirror neurons with auditory properties

• activity represent observed goal-directed
  action
• can fire in response to actions even when
  goals are inferred.

• Activity of F5 Mirror Neurons was recorded in
  response to action-related sound
• Perceive action (visual) and sound (auditory)
  VS
• Visual only V Sound only S
• Motor execution of the action M

• 63 out of 497 neurons discharged during M and S
  peanut breaking, paper ripping, dropping stick

• 22 out of the 63 neurons showed the same action
  selectivity in V and S audiovisual Mirror
  Neurons, and the amplitude of response to V, S
  and VS was the same for 16 neurons

• Receiver Operator Characteristics (ROC) analysis
  using spike-count distribution yielded a 97
  accuracy with VS in predicting the action the
  monkey is observing (and only 81 for the action
  he is performing).

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Brocas and Wernickes Areas
Perception
Production
Brocas Area (Negative Image)
The two classic loci where brain damage impairs
language performance. Warning Localization of
Aphasias is HIGHLY Variable Claim The function
of these areas reflects genetically-grounded
language readiness and experience-based language
adaptations.
MRI-scans from Keith A. Johnson, M.D. and J. Alex
Becker The Whole Brain Atlas http//www.med.harvar
d.edu./AANLIB/home.html
Wernickes Area
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F5 is Homologous to Area 45 of Brocas Area
Monkey
Massimo Matelli (in Rizzolatti and Arbib 1998)
provides the key to relating F5 in the Monkey to
Area 45 in the Human.
Human
Broca's Area Areas 44 45
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F5 is homologous to Broca's Area Areas 44 45
Massimo Matelli (in Rizzolatti and Arbib 1998)
provides the key to relating F5 in the Monkey to
Area 45 in the Human.

• The superior frontal sulcus (SF) and the superior
  precentral sulcus (SP) of human ? Superior limb
  of the monkey arcuate sulcus (AS).
• The inferior frontal sulcus (IF) and the
  ascending branch of the inferior precentral
  sulcus (IPa) of human brain ? The inferior limb
  of the monkey arcuate sulcus (AI).
• The descending branch of the inferior precentral
  sulcus (Ipd) of human brain ? The inferior
  precentral dimple (ipd) of the monkey brain