Mirror Neurons

What are mirror neurons?

Neurons that fire both: When an individual performs a goal-directed action. When the individual observes another individual performing a similar action.

Why was the discovery of mirror neurons important?

It provided evidence that action perception and action execution are closely linked in the nervous system.

What major functions are mirror neurons proposed to support?

Action understanding, Intention understanding, Imitation, Learning by observation, Communication, Social cognition, Empathy.

What is the key exam concept regarding mirror neurons?

Mirror neurons may allow understanding of others' actions by internally simulating those actions within one's own motor system.

How are visual and manual functions linked?

Through a distributed parieto-frontal sensorimotor network that transforms visual information into motor commands for reaching and grasping.

Which two visual processing streams contribute to reaching and grasping?

Dorsal stream ("Where/How"), Ventral stream ("What").

What is the dorsal visual stream?

The "Where/How" pathway.

What information does the dorsal stream process?

Object location, Spatial relationships, Motion, Visual guidance of movement, Spatial awareness.

Why is the dorsal stream important for movement?

It provides information necessary for interacting with objects in space.

What is the ventral visual stream?

The "What" pathway.

What information does the ventral stream process?

Object identity, Shape, Size, Object features, Object recognition.

Why is the ventral stream important for action?

It determines what an object is before an appropriate action can be selected.

What is the function of M1 in grasping?

Execution of voluntary movement.

What Brodmann area corresponds to the premotor cortex?

Area 6.

What are the two major subdivisions of the premotor cortex?

Dorsal premotor cortex (PMd), Ventral premotor cortex (PMv).

What is PMd primarily involved in?

Reaching movements.

What is PMv primarily involved in?

Grasping movements.

What is the role of SMA?

Planning internally generated movements and coordinating motor sequences.

Which parietal regions are active during grasping?

BA40 (Inferior parietal lobule), BA7 (Superior parietal lobule).

Functions of BA40 and BA7?

Sensorimotor integration, Object-directed actions, Spatial processing, Action planning.

Which frontal regions are active during grasping?

BA6 (Premotor cortex), BA44 (Inferior frontal cortex/Broca's region).

Functions of BA6 and BA44?

Motor planning, Action observation, Action execution, Mirror neuron activity.

What is the major reaching pathway?

Superior Parietal Cortex ↓ Dorsal Premotor Cortex (PMd/F2).

Which superior parietal regions contribute to reaching?

V6A, Medial intraparietal areas.

Functions of the reaching network?

Determine object location, Guide reaching movements, Convert visual information into arm movement commands.

What is visuomotor transformation?

Conversion of visual information into appropriate arm and hand movement commands.

What is the major grasping pathway?

AIP ↓ PMv/F5.

What does AIP stand for?

Anterior Intraparietal Area.

Where is AIP located?

Inferior parietal lobule.

What information does AIP process?

Object shape, Object size, Object orientation, Object properties.

What is AIP's main role?

Selecting the appropriate grasp type.

What does PMv contribute to grasping?

Motor planning, Hand shaping, Action representation, Grasp execution.

What is the role of area F5?

Important for: Hand actions, Mouth actions, Object-directed behaviour.

Summarise the AIP–PMv network.

AIP extracts object properties and PMv transforms this information into motor commands for grasping.

Which three techniques were crucial in mirror neuron research?

Single-neuron recording, Intracortical microstimulation, Reversible muscimol inactivation.

What does single-neuron recording allow researchers to do?

Record activity from individual neurons during behaviour.

What is intracortical microstimulation?

Electrical stimulation of specific cortical regions to determine causal roles in movement.

What is muscimol?

A GABA-A receptor agonist used to temporarily inactivate cortical regions.

What are canonical neurons?

Visuomotor neurons found mainly in area F5.

When do canonical neurons fire?

When grasping an object, When viewing a graspable object.

Do canonical neurons require observation of another individual?

No.

What do canonical neurons encode?

Object affordances.

What is an affordance?

The action possibilities offered by an object.

Example of an affordance?

A cup affords grasping.

What information do canonical neurons match?

Object shape and size to an appropriate grasp.

Why are canonical neurons important?

They link object perception to possible actions.

When and where were mirror neurons discovered?

1992, University of Parma, Italy.

In which brain area were mirror neurons first discovered?

Area F5 of the macaque ventral premotor cortex.

What observation led to the discovery of mirror neurons?

A neuron fired both when a monkey grasped an object and when it observed another individual grasping the object.

Did mirror neurons respond simply to viewing the object?

No.

Compare mirror and canonical neurons.

Feature: Canonical: Yes (Object viewing), Mirror: No; Canonical: Yes (Own action), Mirror: Yes; Canonical: No (Observation of another's action), Mirror: Yes; Canonical: Yes (Encode affordances), Mirror: Limited; Canonical: No (Encode observed actions), Mirror: Yes.

Which neuron type is most strongly associated with affordances?

Canonical neurons.

Which neuron type is most strongly associated with action observation?

Mirror neurons.

What actions typically activate mirror neurons?

Goal-directed actions, Object-directed actions, Observed actions, Executed actions.

What generally does NOT activate mirror neurons?

Static objects, Meaningless movements, Actions lacking goals.

Why are mirror neurons called "mirror" neurons?

Because observed actions are mirrored within the observer's motor system.

What major discovery was made in the inferior parietal cortex?

Neurons can encode action goals rather than simply movement patterns.

What experiment demonstrated goal coding?

A monkey grasped food either to: Eat it, Place it in a container. Different neurons responded to different goals.

What three classes of goal-related neurons were found?

Active during grasp-to-eat, Active during grasp-to-place, Active during both.

Why is goal coding important?

The same movement can have different meanings depending on context.

Do mirror neurons primarily encode movements or goals?

Goals.

Give evidence that mirror neurons encode goals.

A neuron may fire when food is grasped using: Right hand, Left hand, Mouth. The movement differs, but the goal remains the same.

What common goal might activate the same mirror neuron?

Obtaining food.

What is the proposed mirror-neuron mechanism for action understanding?

Observed Action ↓ Mirror Neuron Activation ↓ Internal Motor Representation ↓ Action Understanding.

What does this mechanism link?

Perception and action.

How do mirror neurons contribute to intention understanding?

Their activity changes depending on behavioural context.

Example of contextual intention coding?

Picking up a cup may indicate: Drinking, Clearing a table depending on context.

What do mirror-neuron circuits help infer?

What someone is doing, Why they are doing it.

What happens when AIP is inactivated?

Difficulty shaping the hand, Impaired object-specific grasping.

What happens when F5 is inactivated?

Impaired hand pre-shaping, Poor grasp preparation.

What do AIP and F5 jointly contribute to?

Selection of appropriate grasp motor schemas.

Why is direct mirror-neuron recording difficult in humans?

Single-cell recordings are rarely possible in healthy individuals.

What three major sources provide evidence for mirror neurons in humans?

Lesion studies, Intracranial recordings, fMRI studies.

What grasping deficit occurs after lesions of human AIP?

Impaired hand pre-configuration.

What do intracranial recordings show?

Mirror-like neurons responding during both action observation and execution.

Which regions are activated during both action observation and execution?

Premotor cortex, BA44, BA40, BA7, Inferior parietal cortex, Superior parietal cortex.

What is hAIP?

Human anterior intraparietal area.

Functions of hAIP?

Hand shaping, Object property processing.

Functions of the rostral inferior parietal lobule?

Action sequencing, Goal representation.

Which human region is considered homologous to monkey F5?

BA44 (Inferior frontal gyrus/Broca's area).

Functions of BA44?

Action observation, Action execution, Communication, Language-related processes.

How might mirror neurons contribute to communication?

They may bridge: Action execution, Action observation, Gestural communication.

What language-evolution hypothesis involves mirror neurons?

Human language may have evolved from ancestral action-observation circuits involving Broca's area.

Is the language-evolution theory proven?

No, it remains hypothetical.

How might mirror neurons contribute to motor learning?

Through observational learning.

Outline the proposed motor learning pathway.

Observe Action ↓ Mirror Neuron Activation ↓ Internal Motor Representation ↓ Practice ↓ Motor Learning.

What is motor simulation?

The brain rehearsing observed actions using its own motor circuits.

What evidence supports motor simulation?

Experts show greater mirror-system activation when observing actions they already know how to perform.

Which groups were compared in mirror-system expertise studies?

Ballet dancers, Capoeira dancers, Non-experts.

Which regions showed increased activation in experts?

Premotor cortex, Intraparietal sulcus, Superior parietal lobe, Posterior superior temporal sulcus.

What processes are required for imitation?

Observation, Motor representation, Practice, Memory, Attention, Feedback.

What role do mirror neurons play in imitation?

They may provide the link between observation and motor representation.

Can imitation be fully explained by mirror neurons?

No. Additional cognitive processes are required.

How might mirror-like systems contribute to empathy?

Observation of emotions activates overlapping neural systems involved in producing those emotions.

What social functions may involve mirror systems?

Emotion recognition, Social understanding, Empathy.

Which additional brain region contributes to emotional awareness?

Insula.

Which region contributes to emotional evaluation?

Anterior cingulate cortex.

Which region contributes to emotional significance and social processing?

Amygdala.

Why can't empathy be explained solely by mirror neurons?

Empathy depends on broader limbic networks including the insula, ACC and amygdala.

What is the "broken mirror" hypothesis?

The proposal that autism results from dysfunction of the mirror neuron system.