grounded cognition: mirror neurons

Mirror Neurons in MonkeysMirror 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 andSinigaglia, 2010)empathy, mind-reading (Gallese et al., 2004)

action = meaningful sequence of movementsoriginally discovered in monkeys, recently confirmed in humans




Discovery of Mirror Neurons

Macaca Nemestrina, single-cell recordingdiscovered 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 movementssuch as grasping, holding, or tearingactivity noticed when the monkeys observed the experimentercollecting objects used in experimentsfirst theory: mirror neurons mediate action-understanding(Gallese et al., 1996; Rizzolatti et al., 1996)




Mirror Neurons in Monkeys




Action Understanding

Direct-matching hypothesismirror neurons match the observed with the motor plan fromthe observer’s own motor repertoirethis "motor simulation" is necessary to understand theobserved action

Visual hypothesisthe observed action is assessed solely from the visualinformation in STSpatients with motor impairments are able to recognize motionwithout ability to repeat it (Mahon and Carramaza, 2005)mirror neurons as an epiphenomenon (Hickok a Hauser, 2010)

Reconciliationinformation circulates around the responsible areas, activity ofthe mirror neurons influences - facilitates visual perception inSTS (Tessitore et al, 2010)




Mirror Neuron System (MNS)

Rizzolatti et al. (2001), Rizzolatti and Sinigaglia (2010), ..etcparieto-frontal action observation-action execution circuitobject-oriented motor acts (grasping,...)

MNS in the brainareas F5, PFG (rostral IPL), and AIPthe two latter parts receive high-ordervisual information from areas locatedinside the superior temporal sulcus(STS)mirror neurons also discovered in otherareas: LIP (joint attention), VIP(body-directed motor acts), recently M1(primary motor), etc.




Superior Temporal Sulcus

encodes biological movement similarly to F5, but has largerrepertoirelacks motor properties: reacts to movement only on the basisof visual inputinseparable, but not a true part of the Mirror Neuron Systemcontains variant and invariant neurons Perrett et. al (1991)

neurons in the upper part of STS encode facesvariant neurons react only to one view angle, invariant neuronsreact to all angleshierarchical organization: variant neurons feed the invariantones

similar principles found in MNS in area F5 Caggiano et al. (2011)




Variant and Invariant Neurons




Mirror and Canonical Neurons

mirror neuronsin F5 and PF (and other areas)a subset is active while observing similar action from repertoire

canonical neurons (Grezes et al., 2003)

in F5are active when the monkey performs certain actions (but notwhen observes actions performed by others)fire when presented with a graspable object, irrespective ofwhether the grasp was performedinferred condition (the monkey is aware that it is possible tograsp it)Affordances (Gibson, 1977)




Human MN: Indirect Evidence

studies on motor resonance (partial activation of motor areasduring a sole observation of a movement)mu rhythm

an EEG oscillation in 8 to 13 Hz and 20 Hz bandstypical for motor restgets desynchronized, diminishes, or vanishes when the subjectobserves motor actsfirst 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 Rizzolattiand Craighero (2004)




Human MN: Direct Evidence

first single cell study: Mukamel et al. (2011)patients with intractable epilepsy (electrodes according tomedical locations)subjects presented with hand movements and facial gesturesmirroring activity found in various parts of the brain: medialfrontal lobe (SMA), medial temporal lobe (hippocampus,parahippocampal gyrus, entorhinal cortex)subset of mirror neurons with opposite patterns of excitationand inhibition during observation versus execution of anaction: might serve for inhibitory purposes (similar phenomenon

found in monkeys by Kraskov et al., 2009)




Differences of the Human MNS

mirror neurons in monkeysreact only when the action iscomplete and when thetarget is present (or obvious)react only to appropriateeffectors: monkey/humanhandsreact also when the target ishidden, but there must besufficient clues present

mirror neurons in humansreact also to meaninglessand intransitive actionsreact also to various differenteffectors including tools androbotic arms (Oberman and

Ramachandran, 2007; Peeters et al.,

2009)

encode sole bodymovements from which themotor acts and actions arebuilt - a parsing mechanism(Rizzolatti and Sinigaglia, 2010)




Understanding of actions and imitation

motor and non-motor understanding (Rizzolatti and Sinigaglia, 2010)

imitation: observing - (understanding) - copyingdispute whether animals imitate (humans do)copying of both means and endsmirror neurons might play a role in understanding of theunknown actions and parsing them to primitives of alreadyknown and similar actions




Understanding of Goals

strictly and broadly congruentmirror neurons (Rizzolatti and Fogassi,

2001, Rizzolatti and Sinigaglia, 2010)

broadly congruent react to a wholecategory of actions leading to thesame goalexperiment with normal and reversepliers (Umilta et al., 2008)

fMRI study with aplasic individuals(born without arms) revealedactivation regardless the effector(Gazzola et al., 2007)




Understanding of Emotions

Gallese et al. (2004) describe the mirror mechanism as a basicfunctional mechanism that provides an insight into other mindsmirror neurons for disgust found in insulainsula and amygdala react to fearful facial expressions (Phillipset al.,1997, 1998)impairment in insula causes disgust deafness, which extends tothe prosody of speech




Mirror Neurons and Autism




Role of MNS in the Evolution of Language

a “missing link” between animalcommunication and human language(Arbib, 2005)area F5 and Broca’s area are anatomicalhomologues and share functionalproperties crucial for development,production and understanding ofcommunication 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 evolutioncapacity to “mirror” is inherent

Heyes (2009)mirror neurons are not an adaptation,but merely a byproduct of associativelearning (Pavlovian conditioning)motor resonance during actionobservation occurs due to memoryretrieval of the execution of observedaction (of memory formed during theexecution of the particular action withvisual guidance)




The End

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grounded cognition: mirror neurons

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observed action