Hockenbury Discovering Psychology 5th txtbk

Observational Learning219FOCUS ON NEUROSCIENCEMirror Neurons: Imitation in the Brain?Psychologists have only recently begun to understand the neuralunderpinnings of the human ability to imitate behavior. Thefirst clue emerged from an accidental discovery in a lab inPalermo, Italy, in the mid-1990s. Neuroscientist Giacomo Rizzolattiand his colleagues were studying neurons in the premotorcortex of macaque monkeys. Using tiny electrodes to record theactivity of individual neurons, Rizzolatti’s team had painstakinglyidentified the specific motor neurons involved in simple behaviors,such as picking up a peanut or grabbing a toy (see Rizzolatti& Sinigaglia, 2008).Then Rizzolatti noticed something odd. As one of the wiredupmonkeys watched a lab assistant pick up a peanut, a neuronfired in the monkey’s brain—the same neuron that fired whenthe monkey itself picked up a peanut. At first, the researchersthought that the monkey must be making tiny muscle movements,and that these movements were responsible for themotor neuron activity. But the monkey was sitting perfectly still.The researchers were baffled, because a motor neuron wasthought to fire only if a motor behavior was occurring.The explanation? Rizzolatti’s team had discovered a new classof specialized neurons, which they dubbed mirror neurons.Mirror neurons are neurons that fire both when an action isperformed and when the action is simply perceived (lacoboni,2009). In effect, these neurons imitate or “mirror” the observedaction as though the observer were actually carryingout the action.It’s important to note that mirror neurons are not a new physicaltype of neurons. A mirror neuron is defined by its function,rather than its physical structure.Do mirror neurons simply reflect visual stimuli, or are theysomehow involved in providing a mental representation of anaction? Rizzolatti’s team conducted a series of experiments tofind out (see Rizzolatti & Sinigaglia, 2008; Rizzolatti & others,2006). First, Evelyne Kohler and her colleagues (2002) showedthat the same neurons that activated when a monkey crackedopen a peanut shell also activated when a monkey simply hearda peanut shell breaking.Another study extended the idea that mirror neurons are involvedin the mental representation of an action. M. AlessandraUmiltà and her colleagues (2001) identified the motor mirrorneurons that fired when a monkey saw the researcher’s handreaching for and grasping food. Then a screen was placed infront of the food. Now the monkey could see the researcher’shand moving towards the screen but could not actually see thehand touching the food. Would the motor mirror neurons fire ifthe monkey could only imagine the action of grasping thefood? Yes. Even when the action was hidden from view andcould only be inferred, the mirror neurons associated with thataction fired.Following their discovery in the motor cortex, mirror neuronshave since been identified in many other brain regions(see lacoboni, 2009; Oberman & Ramachandran, 2007). Today,many psychologists use the term mirror neuron system todescribe mirroring in the brain. That’s because even simple behaviorsand sensations often involve groups of mirror neuronsfiring together rather than single neurons (Rizzolatti &Craighero, 2004).Evidence of Human Mirror NeuronsBrain-imaging studies like the one illustrated below have providedindirect evidence of mirror neurons in the human brain(see Oberman & Ramachandran, 2007; Slack, 2007). A recentstudy provided the first direct evidence for the existence ofmirror neurons in humans. Electrodes were temporarily implantedin the brains of epileptic patients as part of their preparationfor surgery. A team led by Marco Iacoboni (2009) recordedthe activity of individual neurons as the patients performed simpleactions, such as grasping a cup and making facial expressions.Then the researchers recorded neuron activity while thepatients simply viewed short video clips and photographs of othersexecuting the same actions. The result? The researchers identified34 neurons that were activated by both the performanceand observation of a behavior—the first direct evidence of individualmirror neurons in the human brain (Slack, 2007).Many neuroscientists and psychologists believe that mirrorneurons play an important role in imitation and observationallearning (Rizzolatti, 2005; Iacoboni & Depretto, 2006). Researchhas also implicated the mirror neuron system in highly complexhuman behavior, ranging from empathy to language (Rizzolatti& Sinigaglia, 2008; Iacoboni, 2008, 2009). Some scientists thinkthat dysfunctions in the mirror system may be involved in autismand other disorders that are associated with impaired socialfunctioning (Oberman & Ramachandran, 2007). Although suchspeculations are intriguing, more scientific evidence is neededbefore such conclusions can be drawn (Dinstein & others, 2008).(a) Trained-Music(b) Untrained-Different-Notes-MusicMusical Mirror Neurons Non-musicians were trained to play apiece of music by ear on a piano keyboard, then underwenta series of fMRI scans (Lahav & others, 2007). Panel (a) shows theparticipants’ brain activity as they listened to the same music theyhad already learned to play. Even though they were not movingas they laid in the scanner, motor areas of the brain were activated(dark red). The brighter red/yellow color indicates activationin the brain’s auditory areas. Panel (b) shows participants’ brainactivity while they listened to unfamiliar music utilizing the samemusical notes but in a different sequence.As you compare the scans in (a) and (b), notice the extensiveactivation in motor-related brain regions when the participantslistened to the music that they had already learned to play (a)but not when they listened to the unfamiliar music that they hadnever played (b).