Andrea Norton

Musical Training Shapes Structural Brain Development

The human brain has the remarkable capacity to alter in response to environmental demands. Training-induced structural brain changes have been demonstrated in the healthy adult human brain. However, no study has yet directly related structural brain changes to behavioral changes in the developing brain, addressing the question of whether structural brain differences seen in adults (comparing experts with matched controls) are a product of “nature” (via biological brain predispositions) or “nurture” (via early training). Long-term instrumental music training is an intense, multisensory, and motor experience and offers an ideal opportunity to study structural brain plasticity in the developing brain in correlation with behavioral changes induced by training. Here we demonstrate structural brain changes after only 15 months of musical training in early childhood, which were correlated with improvements in musically relevant motor and auditory skills. These findings shed light on brain plasticity and suggest that structural brain differences in adult experts (whether musicians or experts in other areas) are likely due to training-induced brain plasticity.

Evidence for Plasticity in White‐Matter Tracts of Patients with Chronic Broca's Aphasia Undergoing Intense Intonation‐based Speech Therapy

Recovery from aphasia can be achieved through recruitment of either perilesional brain regions in the affected hemisphere or homologous language regions in the nonlesional hemisphere. For patients with large left‐hemisphere lesions, recovery through the right hemisphere may be the only possible path. The right‐hemisphere regions most likely to play a role in this recovery process are the superior temporal lobe (important for auditory feedback control), premotor regions/posterior inferior frontal gyrus (important for planning and sequencing of motor actions and for auditory‐motor mapping), and the primary motor cortex (important for execution of vocal motor actions). These regions are connected reciprocally via a major fiber tract called the arcuate fasciculus (AF), however, this tract is not as well developed in the right hemisphere as it is in the dominant left. We tested whether an intonation‐based speech therapy (i.e., melodic intonation therapy [MIT]), which is typically administered in an intense fashion with 75–80 daily therapy sessions, would lead to changes in white‐matter tracts, particularly the AF. Using diffusion tensor imaging (DTI), we found a significant increase in the number of AF fibers and AF volume comparing post‐ with pretreatment assessments in six patients that could not be attributed to scan‐to‐scan variability. This suggests that intense, long‐term MIT leads to remodeling of the right AF and may provide an explanation for the sustained therapy effects that were seen in these six patients.

Effects of Music Training on the Child's Brain and Cognitive Development

Abstract: Research has revealed structural and functional differences in the brains of adult instrumental musicians compared to those of matched nonmusician controls, with intensity/duration of instrumental training and practice being important predictors of these differences. Nevertheless, the differential contributions of nature and nurture to these differences are not yet clear. The musician‐nonmusician comparison is an ideal model for examining whether and, if so, where such functional and structural brain plasticity occurs, because musicians acquire and continuously practice a variety of complex motor, auditory, and multimodal skills (e.g., translating visually perceived musical symbols into motor commands while simultaneously monitoring instrumental output and receiving multisensory feedback). Research has also demonstrated that music training in children results in long‐term enhancement of visual‐spatial, verbal, and mathematical performance. However, the underlying neural bases of such enhancements and whether the intensity and duration of instrumental training or other factors, such as extracurricular activities, attention, motivation, or instructional methods can contribute to or predict these enhancements are yet unknown. Here we report the initial results from our studies examining the brain and cognitive effects of instrumental music training on young children in a longitudinal study and a cross‐sectional comparison in older children. Further, we present a comparison of the results in these childrens studies with observations from our cross‐sectional studies with adults.

Practicing a Musical Instrument in Childhood is Associated with Enhanced Verbal Ability and Nonverbal Reasoning

Background In this study we investigated the association between instrumental music training in childhood and outcomes closely related to music training as well as those more distantly related. Methodology/Principal Findings Children who received at least three years (M = 4.6 years) of instrumental music training outperformed their control counterparts on two outcomes closely related to music (auditory discrimination abilities and fine motor skills) and on two outcomes distantly related to music (vocabulary and nonverbal reasoning skills). Duration of training also predicted these outcomes. Contrary to previous research, instrumental music training was not associated with heightened spatial skills, phonemic awareness, or mathematical abilities. Conclusions/Significance While these results are correlational only, the strong predictive effect of training duration suggests that instrumental music training may enhance auditory discrimination, fine motor skills, vocabulary, and nonverbal reasoning. Alternative explanations for these results are discussed.

Melodic Intonation Therapy: Shared Insights on How it is Done and Why it Might Help

For more than 100 years, clinicians have noted that patients with nonfluent aphasia are capable of singing words that they cannot speak. Thus, the use of melody and rhythm has long been recommended for improving aphasic patients’ fluency, but it was not until 1973 that a music‐based treatment [Melodic Intonation Therapy (MIT)] was developed. Our ongoing investigation of MITs efficacy has provided valuable insight into this therapys effect on language recovery. Here we share those observations, our additions to the protocol that aim to enhance MITs benefit, and the rationale that supports them.

The effects of musical training on structural brain development: a longitudinal study.

Long‐term instrumental music training is an intense, multisensory and motor experience that offers an ideal opportunity to study structural brain plasticity in the developing brain in correlation with behavioral changes induced by training. Here, for the first time, we demonstrate structural brain changes after only 15 months of musical training in early childhood, which were correlated with improvements in musically relevant motor and auditory skills. These findings shed light on brain plasticity, and suggest that structural brain differences in adult experts (whether musicians or experts in other areas) are likely due to training‐induced brain plasticity.

Training‐induced Neuroplasticity in Young Children

As the main interhemispheric fiber tract, the corpus callosum (CC) is of particular importance for musicians who simultaneously engage parts of both hemispheres to process and play music. Professional musicians who began music training before the age of 7 years have larger anterior CC areas than do nonmusicians, which suggests that plasticity due to music training may occur in the CC during early childhood. However, no study has yet demonstrated that the increased CC area found in musicians is due to music training rather than to preexisting differences. We tested the hypothesis that approximately 29 months of instrumental music training would cause a significant increase in the size of particular subareas of the CC known to have fibers that connect motor‐related areas of both hemispheres. On the basis of total weekly practice time, a sample of 31 children aged 5–7 was divided into three groups: high‐practicing, low‐practicing, and controls. No CC size differences were seen at base line, but differences emerged after an average of 29 months of observation in the high‐practicing group in the anterior midbody of the CC (which connects premotor and supplementary motor areas of the two hemispheres). Total weekly music exposure predicted degree of change in this subregion of the CC as well as improvement on a motor‐sequencing task. Our results show that it is intense musical experience/practice, not preexisting differences, that is responsible for the larger anterior CC area found in professional adult musicians.

Non-Invasive Brain Stimulation Enhances the Effects of Melodic Intonation Therapy

Research has suggested that a fronto-temporal network in the right hemisphere may be responsible for mediating melodic intonation therapy’s (MIT) positive effects on speech recovery. We investigated the potential for a non-invasive brain stimulation technique, transcranial direct current stimulation (tDCS), to augment the benefits of MIT in patients with non-fluent aphasia by modulating neural activity in the brain during treatment with MIT. The polarity of the current applied to the scalp determines the effects of tDCS on the underlying tissue: anodal-tDCS increases excitability, whereas cathodal tDCS decreases excitability. We applied anodal-tDCS to the posterior inferior frontal gyrus of the right hemisphere, an area that has been shown both to contribute to singing through the mapping of sounds to articulatory actions and to serve as a key region in the process of recovery from aphasia, particularly in patients with large left hemisphere lesions. The stimulation was applied while patients were treated with MIT by a trained therapist. Six patients with moderate to severe non-fluent aphasia underwent three consecutive days of anodal-tDCS + MIT, and an equivalent series of sham-tDCS + MIT. The two treatment series were separated by 1 week, and the order in which the treatments were administered was randomized. Compared to the effects of sham-tDCS + MIT, anodal-tDCS + MIT led to significant improvements in fluency of speech. These results support the hypothesis that, as the brain seeks to reorganize and compensate for damage to left hemisphere language centers, combining anodal-tDCS with MIT may further recovery from post-stroke aphasia by enhancing activity in a right hemisphere sensorimotor network for articulation.

From music making to speaking: Engaging the mirror neuron system in autism

Individuals with autism show impairments in emotional tuning, social interactions and communication. These are functions that have been attributed to the putative human mirror neuron system (MNS), which contains neurons that respond to the actions of self and others. It has been proposed that a dysfunction of that system underlies some of the characteristics of autism. Here, we review behavioral and imaging studies that implicate the MNS (or a brain network with similar functions) in sensory-motor integration and speech representation, and review data supporting the hypothesis that MNS activity could be abnormal in autism. In addition, we propose that an intervention designed to engage brain regions that overlap with the MNS may have significant clinical potential. We argue that this engagement could be achieved through forms of music making. Music making with others (e.g., playing instruments or singing) is a multi-modal activity that has been shown to engage brain regions that largely overlap with the human MNS. Furthermore, many children with autism thoroughly enjoy participating in musical activities. Such activities may enhance their ability to focus and interact with others, thereby fostering the development of communication and social skills. Thus, interventions incorporating methods of music making may offer a promising approach for facilitating expressive language in otherwise nonverbal children with autism.

Intensive therapy induces contralateral white matter changes in chronic stroke patients with Broca's aphasia

Using a pre-post design, eleven chronic stroke patients with large left hemisphere lesions and nonfluent aphasia underwent diffusion tensor imaging and language testing before and after receiving 15 weeks of an intensive intonation-based speech therapy. This treated patient group was compared to an untreated patient group (n=9) scanned twice over a similar time period. Our results showed that the treated group, but not the untreated group, had reductions in fractional anisotropy in the white matter underlying the right inferior frontal gyrus (IFG, pars opercularis and pars triangularis), the right posterior superior temporal gyrus, and the right posterior cingulum. Furthermore, we found that greater improvements in speech production were associated with greater reductions in FA in the right IFG (pars opercularis). Thus, our findings showed that an intensive rehabilitation program for patients with nonfluent aphasia led to structural changes in the right hemisphere, which correlated with improvements in speech production.