Mirror Neurons

Question 1

1. Operational definition of a mirror neuron (how do we measure mirror neurons)

Answer 1

= Neurons that activate both when individuals show and observe a certain action or behaviour (not limited to the motor cortex)

Studied with single cell recordings or fMRI
• Many studies just look at neural activation during observation of motor task, some also compare this to activation during task execution

Action goals (=”outcome to which the action is directed)
•	Test what MN respond to, by varying goal and keeping movement constant, and vice versa, or varying the sensory information
•	MN activation pattern stays the same when the action goal is the same, but reached e.g. with different tools and also when sensory information differs; activation changes when goal changes
•	 Mirror neurons encode action goals

Question 2

2. Transitive vs non-transitive actions

Answer 2

Transitive = include interaction with an object

More MNS answer to transitive than to non-transitive actions

Question 3

3. Canonical vs. mirror neurons

Answer 3

Two sets of visuomotor neurons
• Canonical
o Activated by plain sight of graspable objects
• Mirror neurons
o Fire when goal-specific action is performed and when that same action is passively observed.

Question 4

4. Broadly and strictly congruent MN

Answer 4

Strictly congruent are activated by exactly the same action

Broadly are a bit more liberal, also answer if the effector-object relation differs a little

Question 5

5. MNS and action understanding

Answer 5

Observing an action  activation of action goals  The MNS has a role in understanding actions

Evidence:
• The depth of interlinking of observing and executing actions
o Observing an action facilitates performance of a congruent and inhibits performance of an incongruent action
o action performance can increase the ability to judge what someone else is doing
• Influence of own motor expertise
o The greater one’s expertise, the more sensitive the MNS and the better at judging outcomes
• Influence of lesions
o Transient PMv lesions impair action-goal recognition
o TMS stimulation over hand area impairs identifying hand action goals, over lip area impairs mouth action goals

Vitality forms
• = the way in which an action is performed
• Inherent to each action and crucial to interpersonal relations
• Some evidence for a mirror mechanism underlying execution and observing an action with a specific vitality form
• Dorsocentral insula might play a role here

Question 6

6. MNS and language

Answer 6

• Mirror neurons help in language understanding by mirroring the movements
o McGurk effect
• Sentence comprehension requires partial emotional bodily state re-enactment wherefore reenactment of the emotions facilitate or inhibit language comprehension
• Evidence: Pencil and comic study, are sentences (un)pleasant?
o (1) Blocking: comic evaluation as less pleasant vs. smiling (Strack et al., 1988)
o (2) Smiling + pleasant sentence = Funnier + faster reading time + easy to understand
o Blocked + unpleasant sentence = Faster reading time + easy to understand (Hayes et al., 2007)

Question 7

7. MNS and empathy

Answer 7

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Question 8

8. MNS and autism

Answer 8

ASD is characterized by social impairment and lack of Theory of Mind
 Dysfunction in MNS!

Vitality-form
• Selective impairment in vitality form recognition
o Task: videos showing two actors performing the same or a different action with the same or a different vitality form; what-task related to the goal, how-task related to the style
o Similar performance at what task, impairment in how task
• Movement imitation
o General imitation of goal-directed action is intact
o But imitation of style impaired, especially when style not important for goal achievement

Question 9

9. MNS and the Theory of Mind

Answer 9

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Question 10

10. MNS and emotions (additional, no question on this)

Answer 10

Disgust
• Relevant brain region: Anterior insula (stimulation elicits disgust)
• Sight of facial expressions of disgust activates AI, plus other limbic-cortico-striatal-thalamic areas when expression is strong
• Observing, imagining and experiencing disgust activates same region
• Might also hold for other basic emotions like fear, pleasure or pain

Understanding emotions of others
• Lesions, e.g. of insula, can lead to selective impairment in recognising disgust (while the other basic emotions can be intact)
• This deficit might be accompanied by impairment in experiencing disgust
• Insular grey matter volume correlates with recognition of (only) disgust

 what about more complex, social emotions like envy and shame?