Hockenbury Discovering Psychology 5th txtbk

64 CHAPTER 2 Neuroscience and BehaviorFOCUS ON NEUROSCIENCEJuggling and Brain PlasticityWhat happens to the brain when youlearn a new, challenging skill? Doeslearning affect the brain’s physicalstructure?German researcher Bogdan Draganskiand his colleagues (2004) have compellingexperimental evidence showingthat learning a new skill produces structuralchanges in the human brain. In theirstudy, 24 young adults—21 women and3 men—were assigned to either the“jugglers” or “nonjugglers” group. Abaseline MRI scan indicated that therewere no significant regional brain differencesbetween the two groups at thebeginning of the study.Then the juggling group memberswere given three months to masterand practice a basic juggling routinecalled the three-ball cascade. Whenthe participants were able to showthat they could juggle the three ballsfor at least 60 seconds, a second brain scan wasperformed.The nonjugglers were also scanned at the samepoint.The researchers used a sophisticated whole-brain imagingtechnique to detect regional changes in gray and white matter.Compared to their baseline brain scans, the jugglers showed a3 to 4 percent increase in the size of gray matter in two brainregions involved in perceiving, remembering, and anticipatingcomplex visual motions. These two regions are shown in yellowin the composite MRI scans shown below. In comparison, therewere no brain changes in the scans of the nonjugglers over thesame three-month period.After the second brain scan, the participantsin the juggling group were told tostop practicing their newly acquired skills.Three months later, the third and finalround of brain scans was taken of bothgroups. Now, the same regions that hadgrown while the jugglers were practicingtheir skills every day had decreased insize. While still larger than before the participantshad learned to juggle, the regionswere 1 to 2 percent smaller thanwhen the participants were juggling everyday. In comparison, the same regions inthe nonjuggling control group remainedunchanged.Because they couldn’t take direct tissuesamples of the affected brain areas, Draganskiand his colleagues (2004) could notdefinitively identify the nature of thechanges in the gray matter. However, itseems likely that the number and shape ofneuronal dendrites and axon terminalsprobably increased, enhancing the communication ability ofneurons (Grutzendler & others, 2002; Trachtenberg & others,2002). It’s also likely that the number of glial cells increased(Haydon, 2001).In a later study, novice jugglers showed changes in brain regionswithin just seven days after learning to juggle(Driemeyer & others, 2008). And, demonstrating the plasticityof even the aging brain, similar changes were found in agroup of senior citizens after they learned to juggle (Boyke &others, 2008).As co-researcher Arne May (Draganski & others, 2004)noted, their results challenged prevailing views of the humancentral nervous system. “Human brains,” he observed, “mustThree-Ball CascadeLearning a New Skill Makes Its Mark on the Brain Theyellow in these MRIs shows the brain areas that temporarilyincreased by 3 to 4 percent in size in those participants wholearned to juggle. These brain regions are involved in theability to perceive, remember, and anticipate complex visualmotions.