Mirror Neurons

Question 1

MIRROR NEURONS

Answer 1

• neurons that become active (aka. fire) both when:
  1. individuals perform specific motor act
  2. individuals observe similar act done by others
• neurons “mirror” beh of other as though they were acting
• directly observed in both human/primate species
• some argue that mirror neuron systems in human brain help understand actions/intentions of others

Question 2

PUBLISHED PAPER TOPICS

Answer 2

• 800+ papers proposing mirror neurons = neuronal substrate underlying vast function array:
  GAZZOLA ET AL. (2006)
• empathy
  DAPRETTO ET AL. (2006)
• autistic behaviour
  D’AUSILIO ET AL. (2009)
• speech perception
  AZIZ-ZADEH ET AL. (2006)
• comprehension
  IACOBONI (2005)
• imitation

Question 3

SINGLE-UNIT RECORDINGS

Answer 3

• requires surgical skull opening & implanting of recording microelectrodes
• provide measuring method of electro-physiological responses in 1 neuron
• microelectrode (glass micro-pipettes/metal microelectrodes made of platinum) inserted into brain to record change rate in voltage VS time
• microelectrodes placed close to cell allowing ability to record extracellularly

Question 4

SINGLE-UNIT RECORDINGS: PATIENTS

Answer 4

• mostly done w/animals as invasive
• BUT some exceptional cases regarding Parkinson’s disease/epilepsy patients
• gives ^ spatial/temporal resolution assessing relationship between brain structure/function/behaviour

Question 5

SINGLE-UNIT RECORDINGS: BORAUND ET AL. (2002)

Answer 5

• by looking at brain activity at neuron level researcher can link brain activity/beh -> create neuronal maps describing info flow through brain

Question 6

RIZZOLATI (1992): PROCEDURE

Question 7

RIZZOLATI (1992): RESULTS

Question 8

RIZZOLATI (1992): FIRST EVIDENCE

Answer 8

• premotor cortex = crucial brain part; believed to have direct control over voluntary muscle movements
• mirror neuron discovery played role in understanding actions of others/using abstract rules to perform specific tasks

Question 9

AUDITORY MIRROR NEURONS: KOHLER ET AL. (2012) (DESIGN)

Question 10

AUDITORY MIRROR NEURONS: KOHLER ET AL. (STIMULI)

Answer 10

• action related stimuli = peanut breaking/paper ripping/plastic crumbling/dry food manipulation/dropping stick/metal hitting metal
• all stimuli = presented in/out of sight
• non-action related sounds = white noise/pure tone/clicks/monkey & animal calls

Question 11

AUDITORY MIRROR NEURONS: KOHLER ET AL. (EXPERIMENTAL PARADIGM)

Answer 11

• authors addressed neuron capacity issue to differentiate between 2 dif actions based on vision/sound
• 2 actions = randomly presented in “vision & sound” (V+S)/”sound” (S)/”vision” (V)/motor (M aka. monkeys performing object-directed actions) conditions

Question 12

AUDITORY MIRROR NEURONS: KOHLER ET AL. (NEURON I)

Answer 12

• responded to vision/sound of tearing action (ripping paper (VS))
• same action sound performed out of sight = equally effective (S)
• non-action related sounds (white noise/monkey calls) didn’t evoke excitatory responses (control sounds: CS1/CS2)

Question 13

AUDITORY MIRROR NEURONS: KOHLER ET AL. (NEURON II)

Answer 13

• responded to vision/sound of hand dropping stick (VS) & sound of stick hitting floor (S)
• non-action related arousing sounds didn’t produce any consistent excitation (CS1/CS2)

Question 14

AUDITORY MIRROR NEURONS: KOHLER ET AL. (NEURON III)

Answer 14

• discharged when monkey observed experimenter breaking peanut (VS/V) & when monkey heard peanut breaking w/o seeing action (S)
• also discharged when monkey made same action (M); grasping ring & resulting sound evoked small responses

Question 15

AUDITORY MIRROR NEURONS: KOHLER ET AL. (NEURON IV)

Answer 15

• another selective audio-visual mirror neuron example
• responded vigorously when monkey broke peanut; less when it ripped paper (M)
• selectivity also observed when monkey saw/heard experimenter breaking peanut (VS)

Question 16

FIRST EVIDENCE: KOHLER ET AL. FINDINGS

Answer 16

• what makes neuron a mirror = active both when animal engages in activity (ie. grabbing peanut) & when animal observed experimenter engage in same/closely related activity
  KOHLER ET AL. (2002)
• area F5 contains audio-visual mirror neuron pop; discharge to execution/observation of specific action & when action is only heard
• 1/3 of them = “strictly congruent” aka. require close match in action production/perception while 2/3 = broadly congruent & respond to actions w/same goal (ie. grabbing peanut) BUT dif movement specifics (ie. using tool not hand)

Question 17

MUKAMEL ET AL. (2010)

Answer 17

• reported on experiments using single-units recording in humans
• electrodes implanted as prelude to surgery rather than primarily for research
• aka. electrode location not selected to test various hypotheses BUT data provides convincing evidence of individual cells w/mirror properties in humans

Question 18

MUKAMEL ET AL. (2010): EXPERIMENTAL PROCEDURE

Answer 18

• recorded extracellular single activity from 21 patients w/pharmacologically intractable epilepsy
• patients implanted w/intracranial depth electrodes to identify seizure areas for potential surgical treatment
• electrode location = based on clinical criteria; patients provided written informed consent to participate in experiments

Question 19

MUKAMEL ET AL. (2010): CELLS RECORDING PROCEDURE

Question 20

MUKAMEL ET AL. (2010): RESULTS I

Question 21

MUKAMEL ET AL. (2010): RESULTS II

Question 22

MUKAMEL ET AL. (2010): RESULTS III

Answer 22

• single unit in left entorhinal cortex (EC) increases firing rate during both frown execution/observation (functions = memory/navigation/time perception)
• single unit in right parahippocampal gyrus increases firing rate during whole hand grasp execution/observation (functions = memory encoding/retrieval)

Question 23

MUKAMEL ET AL. (2010): RESULTS IV

Answer 23

• single unit in left entorhinal cortex increases firing rate during smile execution/observation
• single unit in right parahippocampal gyrus increasing firing rate during precision grip execution & precision grip observation

Question 24

MUKAMEL ET AL. (2010): DISCUSSION

Answer 24

• results provide evidence of mirroring spiking activity during action-execution/action-observation in medial frontal/temporal cortex (neural systems where mirroring responses at single-cell lvl NOT been previously recorded)
• suggest multiple system existence in human brain w/neural mirroring mechanisms for flexible integration/differentiation of perceptual/motor aspects of actions performed by self/others