Brain Plasticity Is Possible in Adulthood Recent research has demonstrated that training-induced plasticity is not restricted to the developing brain. Even in the mature brain, increased reliance of a particular skill or a body part can lead to structural modifications. For example, Maguire and others (2000) found that taxi drivers had larger posterior hippocampi than did controls (non–taxi drivers), and the amount of time spent as a taxi driver predicted larger hippocampal volumes. Although these between-group structural differences do not necessarily imply structural changes, they nonetheless provide information about potential causality. Structural changes in brain anatomy have been observed in longitudinal studies that examined the effects of intensive skill learning on the adult brain. Individuals (20 years old) who had learned to juggle daily for 3 months showed increased gray matter volume in the midtemporal area (Draganski and others 2004), but these changes returned to baseline levels 3 months after cessation of juggling. Similar outcomes were also observed when elderly individuals (60 years old) learned to juggle under the same experimental conditions (Boyke and others 2008). Interestingly, a different study, which focused on DTI-derived measures, found that learning to juggle led to changes in parietal regions (Scholz and others 2009). In another study, students who engaged in daily study sessions for 3 months in preparation for a medical examination showed increases in gray matter volume in the posterior parietal regions and the hippocampus (Draganski and others 2006). Together, these studies demonstrate the malleability of the mature brain; that is, intensive skills learning in adulthood can induce structural adaptations that allow the brain to accommodate the demands of the environment. Although no research in the music domain has directly investigated structural plasticity in the healthy adult brain, recent studies have reported functional changes in the brain following relatively short-term musical training in adulthood. For example, adult nonmusicians who learned to play a musical sequence on the piano over a 2-week period showed larger mismatch negativity in the auditory cortex compared to baseline (Lappe and others 2008). In another longitudinal study, the neural responses of music academy students in acoustic novelty detection were compared before and after 2 semesters of intensive aural skills training (Herdener and others 2010). Increased responses in the hippocampus following the training period were observed using fMRI. This was also the first study to show that functional plasticity is possible in the adult hippocampus. Go to: Training Can Slow Cognitive Decline in the Elderly Aging is associated with the progressive loss of function across various domains including perception, cognition, memory, and motor control. Although brain plasticity is known to occur throughout the life span, the degree of plasticity typically declines with age (Berardi and others 2000; Stiles 2000). This relationship has been shown in studies of recovery from brain injuries (e.g., Mahncke and others 2006; Mosch and others 2005). Brain injury during childhood results in less severe behavioral and cognitive deficits than comparable injury in adulthood, although recovery from injury may still be possible in the adult brain (Kolb 1995). The developmental limits in brain plasticity have been characterized in neurophysiological studies. Studies of nonhuman primates have shown that 35% of axons and neurons disappear between the peak of development and adulthood. In humans, the adult synaptic density is only 60% of the maximum density that is reached during development (Huttenlocher and Decourten 1987). Studies have shown that perceptual motor performance, such as reaction time, speed of movement, and motor coordination, declines with age (e.g., Kauranen and Vanharanta 1996; Guan and Wade 2000). In addition to behavioral decline, a number of studies have reported reductions in frontal brain volumes with age (e.g., Jäncke 2004; Sowell and others 2004; Apostolova and Thompson 2008). Degeneration of brain tissues and cognitive decline may represent an inevitable trajectory of the normal aging process. The effects of intensive training on the aging adult brain have been investigated by a handful of studies. For example, Sluming and others (2002) reported that practicing musicians have greater gray matter volume in the left inferior frontal gyrus compared to that of matched nonmusicians. For the nonmusicians, significant age-related reductions in total brain volumes and in regions such as the dorsolateral prefrontal cortex and the left inferior frontal gyrus were not observed in musicians. Thus, musicians appear to be less susceptible to age-related degenerations in the brain, presumably as a result of their daily musical activities (Fig. 6). In their juggling study, Boyke and others (2008) observed that 60-year-old elderly individuals were able to learn 3-ball cascade juggling but with less proficiency compared with young adults. Nonetheless, these elderly individuals showed gray matter increases in the midtemporal area, the hippocampus, and the nucleus accumbens. Taken together, these findings suggest the potential value of plasticity-based training in preserving brain functions in the elderly. Figure 6 Figure 6 The arcuate fasciculus, an auditory-motor tract, enhanced by music training. (A) The arcuate fasciculus of a healthy 65-year-old instrumental musician and (B) the arcuate fasciculus of a healthy 63-year-old nonmusician, otherwise matched with regard to … The human aging process is often associated with reduced schedules of activities, resulting in overall brain disuse (Mahncke and others 2006). As people age, they tend to engage less in cognitive-demanding activities, particularly in the case of retirement. This reduced activity may further undermine the learning and memory capacities of the elderly. The idea that age-related cognitive decline may be slowed, arrested, or even reversed through appropriately designed training or activities is supported by some research. Studies have shown that the frequency of cognitive activities in the elderly is associated with lower risk of cognitive disorders such as dementia. For example, elderly participants who were diagnosed with dementia were assessed on the overall frequency of cognitive activities: reading, writing, crossword puzzles, games, group discussions, or playing music (Hall and others 2009). Increasing frequency of cognitive activities predicted a delay in the onset of accelerated memory decline. In a longitudinal study, the relative contribution of specific activities was investigated (Verghese and others 2003). Participants aged over 75 years were followed for 5 years. Those participants who frequently played a musical instrument were less likely to have developed dementia compared to those who rarely played a musical instrument. This protective effect of playing music was stronger than those of other cognitive activities such as reading, writing, or doing crossword puzzles. Physical activities (e.g., walking, swimming) did not appear to confer any protective benefit in the development of dementia. To minimize the deleterious effects of aging on brain function, elderly individuals need to engage in demanding multisensory, cognitive, and motor activities on an intensive basis. Accordingly, a training program that is designed specifically to facilitate brain plasticity, or engage multiple brain regions (especially the frontal and prefrontal areas), may counteract some of the negative consequences underlying disuse associated with aging. One activity that has the potential to stimulate and preserve cognition is music making. The beneficial effects of playing music in old age were examined in an experimental study in which musically naïve elderly participants (aged 60–85 years) were randomly allocated to an experimental group (6 months of intensive piano lessons) or a no-treatment control group (Bugos and others 2007). The experimental group received a half-hour lesson each week and was required to practice independently for a minimum of 3 hours per week. Following this period of musical training, they showed improvements on tests of working memory, perceptual speed, and motor skills, while the control group did not show such improvements. Go to: Concluding Remarks Over the past decade, there has been increasing evidence describing the cognitive and brain effects of music making in both children and adults. Music making involves a combination of sensory, cognitive, and motor functions. Engaging in musical activities may result in improved performances in related cognitive domains, although its effects on more distant domains remain unclear. One possible interpretation is that of cross-modal transfer plasticity: that is, music making leads to changes in poly-modal integration regions (e.g., regions surrounding the intraparietal sulcus), which may alter task performance in other domains. For example, instrumental music making has been shown to lead to structural and functional changes in the vicinity of the intraparietal sulcus (Fig. 7A). The intraparietal sulcus (IPS) region has also been found to be the region for neural representation of all types of numerical representation and operations (Dehaene 1997; Dehaene and others 1998; Pinel and others 2004; Piazza and others 2007; Cohen Kadosh and others 2007) (Fig. 7B). Thus, adaptations in brain regions that are involved in musical tasks may have an effect on mathematical performance because of shared neural resources in the vicinity of the IPS, which could be involved in the meaning of symbols and the mental manipulation of symbolic representation. The studies reviewed here have provided compelling evidence for brain plasticity following musical training, with adaptations observed not only in the primary and secondary motor and auditory regions of the brain but also in multi-modal integration regions in the frontal and parietal regions. Music training in children, when commenced at a young age, results in improved cognitive performance and possibly the development of exceptional musical abilities such as absolute pitch. Because the human brain can be shaped by musical experience, one promising application of a music-making program is in the treatment of neurological and developmental disorders (Schlaug and others 2010; Wan and others 2010a). Research to date has indicated functional improvements following an intensive music-based training program. However, longitudinal stu dies that examine the efficacy of music making in clinical settings are still limited but beginning to emerge (Schlaug and others 2009; Wan and others 2010a; Schlaug 2009; Schneider and others 2010). It is our hope that the use of music making as a therapeutic strategy will continue to be tested in future studies and ultimately be applied to the treatment of various neurological and developmental conditions. Figure 7 Figure 7 Shared brain resources of a music-motor imagery task and a mental calculation task. The functional magnetic resonance image on the left (A) shows significant activations of an fMRI experiment in which subjects were asked to imagine playing scales and …