Grounded Cognition: Mirror Neurons

Mirror Neurons in Monkeys
Mirror Neurons in Humans
Roles of Mirror Neurons
Mirror Neurons
Kristína Rebrová
[Grounded Cognition 2012]
Kristína Rebrová [Grounded Cognition 2012] Mirror Neurons

Outline
1 Mirror Neurons in Monkeys
2 Mirror Neurons in Humans
3 Roles of Mirror Neurons

Mirror Neurons
motor neurons with perceptual properties (visual, auditory)
facilitate (mediate) understanding
understanding of the actions “from the inside” (Rizzolatti and
Sinigaglia, 2010)
empathy, mind-reading (Gallese et al., 2004)
action = meaningful sequence of movements
originally discovered in monkeys, recently conﬁrmed in humans

Discovery of Mirror Neurons
Macaca Nemestrina, single-cell recording
discovered accidentally during research of motor area F5:
rostral part of inferior premotor cortex (Di Pellegrino et al., 1992)
neurons sensitive to goal-oriented hand and mouth movements
such as grasping, holding, or tearing
activity noticed when the monkeys observed the experimenter
collecting objects used in experiments
ﬁrst theory: mirror neurons mediate action-understanding
(Gallese et al., 1996; Rizzolatti et al., 1996)

Action Understanding
Direct-matching hypothesis
mirror neurons match the observed with the motor plan from
the observer’s own motor repertoire
this "motor simulation" is necessary to understand the
observed action
Visual hypothesis
the observed action is assessed solely from the visual
information in STS
patients with motor impairments are able to recognize motion
without ability to repeat it (Mahon and Carramaza, 2005)
mirror neurons as an epiphenomenon (Hickok a Hauser, 2010)
Reconciliation
information circulates around the responsible areas, activity of
the mirror neurons inﬂuences - facilitates visual perception in
STS (Tessitore et al, 2010)

Mirror Neuron System (MNS)
Rizzolatti et al. (2001), Rizzolatti and Sinigaglia (2010), ..etc
parieto-frontal action observation-action execution circuit
object-oriented motor acts (grasping,...)
MNS in the brain
areas F5, PFG (rostral IPL), and AIP
the two latter parts receive high-order
visual information from areas located
inside the superior temporal sulcus
(STS)
mirror neurons also discovered in other
areas: LIP (joint attention), VIP
(body-directed motor acts), recently M1
(primary motor), etc.

Superior Temporal Sulcus
encodes biological movement similarly to F5, but has larger
repertoire
lacks motor properties: reacts to movement only on the basis
of visual input
inseparable, but not a true part of the Mirror Neuron System
contains variant and invariant neurons Perrett et. al (1991)
neurons in the upper part of STS encode faces
variant neurons react only to one view angle, invariant neurons
react to all angles
hierarchical organization: variant neurons feed the invariant
ones
similar principles found in MNS in area F5 Caggiano et al. (2011)

Variant and Invariant Neurons

Mirror and Canonical Neurons
mirror neurons
in F5 and PF (and other areas)
a subset is active while observing similar action from repertoire
canonical neurons (Grezes et al., 2003)
in F5
are active when the monkey performs certain actions (but not
when observes actions performed by others)
ﬁre when presented with a graspable object, irrespective of
whether the grasp was performed
inferred condition (the monkey is aware that it is possible to
grasp it)
Aﬀordances (Gibson, 1977)

Human MN: Indirect Evidence
studies on motor resonance (partial activation of motor areas
during a sole observation of a movement)
mu rhythm
an EEG oscillation in 8 to 13 Hz and 20 Hz bands
typical for motor rest
gets desynchronized, diminishes, or vanishes when the subject
observes motor acts
ﬁrst studies by Cohen-Seat et al. (1954), Gastaut and Bert
(1954)
recent studies, e.g. Oberman and Ramachandran (2007)
various EEG, MEG, and TMS studies summarized by Rizzolatti
and Craighero (2004)

Human MN: Direct Evidence
ﬁrst single cell study: Mukamel et al. (2011)
patients with intractable epilepsy (electrodes according to
medical locations)
subjects presented with hand movements and facial gestures
mirroring activity found in various parts of the brain: medial
frontal lobe (SMA), medial temporal lobe (hippocampus,
parahippocampal gyrus, entorhinal cortex)
subset of mirror neurons with opposite patterns of excitation
and inhibition during observation versus execution of an
action: might serve for inhibitory purposes (similar phenomenon
found in monkeys by Kraskov et al., 2009)

Differences of the Human MNS
mirror neurons in monkeys
react only when the action is
complete and when the
target is present (or obvious)
react only to appropriate
effectors: monkey/human
hands
react also when the target is
hidden, but there must be
sufficient clues present
mirror neurons in humans
react also to meaningless
and intransitive actions
react also to various different
effectors including tools and
robotic arms (Oberman and
Ramachandran, 2007; Peeters et al.,
2009)
encode sole body
movements from which the
motor acts and actions are
built - a parsing mechanism
(Rizzolatti and Sinigaglia, 2010)

Understanding of actions and imitation
motor and non-motor understanding (Rizzolatti and Sinigaglia, 2010)
imitation: observing - (understanding) - copying
dispute whether animals imitate (humans do)
copying of both means and ends
mirror neurons might play a role in understanding of the
unknown actions and parsing them to primitives of already
known and similar actions

Understanding of Goals
strictly and broadly congruent
mirror neurons (Rizzolatti and Fogassi,
2001, Rizzolatti and Sinigaglia, 2010)
broadly congruent react to a whole
category of actions leading to the
same goal
experiment with normal and reverse
pliers (Umilta et al., 2008)
fMRI study with aplasic individuals
(born without arms) revealed
activation regardless the eﬀector
(Gazzola et al., 2007)

Understanding of Emotions
Gallese et al. (2004) describe the mirror mechanism as a basic
functional mechanism that provides an insight into other minds
mirror neurons for disgust found in insula
insula and amygdala react to fearful facial expressions (Phillips
et al.,1997, 1998)
impairment in insula causes disgust deafness, which extends to
the prosody of speech

Mirror Neurons and Autism

Role of MNS in the Evolution of Language
a “missing link” between animal
communication and human language
(Arbib, 2005)
area F5 and Broca’s area are anatomical
homologues and share functional
properties crucial for development,
production and understanding of
communication gestures
the evolution of the manual gestural system, facilitated by the action-execution –
action-observation matching property of neurons in Broca’s area paved the way to the
evolution of the open vocalization system present in humans (speech) (Rizzolatti and
Arbib, 1998)

Where Do Mirror Neurons Come From?
Rizzolatti, Gallese, Arbib, and others:
mirror neurons favored by the evolution
capacity to “mirror” is inherent
Heyes (2009)
mirror neurons are not an adaptation,
but merely a byproduct of associative
learning (Pavlovian conditioning)
motor resonance during action
observation occurs due to memory
retrieval of the execution of observed
action (of memory formed during the
execution of the particular action with
visual guidance)

The End
Thank you for your attention
kristina.rebrova@gmail.com

Grounded Cognition: Mirror Neurons

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