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stimuli is then presented using a procedure adapted from MIT (see Norton et al., 2009). These stimuli include common objects, actions, and social phrases. In addition to intonation, a key component of AMMT is the use of a set of tuned drums to facilitate sound-motor mapping. The therapist introduces the target words or phrases by intoning (singing) the words on two pitches and playing the drums at the same time. As in the MIT protocol, the child progresses from passive listening, to unison singing, to partially-supported singing, to immedi- ate repetition, and finally to producing the target word or phrase on their own.
Testing is currently underway in our laboratory to exam- ine the efficacy of AMMT in facilitating speech output in non- verbal children with ASD. Because AMMT enhances interac- tions between the auditory and motor systems, it may repre- sent an effective therapeutic strategy through which individu- als with autism can develop their communication skills.
Concluding remarks
In the present article, we have reviewed a substantial body of behavioral and neuroscience studies on singing, including investigations of trained singers, tone-deaf individ- uals who have trouble singing, and the therapeutic effects of singing on recovery of language functions in patients with severe non-fluent aphasia and children with non-verbal forms of autism. Singing is a set of abilities enabled by the auditory-motor system, involving continuous perception, production, feedback and feedforward control mechanisms, and mental representation of vocal sounds. Because of the complex requirements that singing places on the brain, the study of disorders in singing abilities provides a useful model for the neural basis of singing. Tone-deafness, which is phe- notypically best described as an inability to sing in tune, helps us understand how the auditory-motor system func- tions: in particular, knowledge regarding how pitch changes in speech and music engage similar brain networks is useful for informing the development of therapies for other neuro- logical disorders.
Singing represents a promising therapeutic tool in a vari- ety of neurological disorders. Music-based interventions are useful for recovery from aphasia: Melodic Intonation Therapy (MIT) effectively slows down regular speech into pitched vocalizations that engage right-hemisphere-domi- nant functions, while simultaneously engaging rhythm net- works via left-hand rhythmic tapping. Functional MRI and DTI studies have highlighted several possible mechanisms that may underlie the efficacy of singing in ameliorating impairments in speech production in aphasic patients, with the effects of therapy being most dominant in auditory- motor networks in the right hemisphere. A similar intona- tion-based intervention, termed Auditory-Motor Mapping Training (AMMT), has been designed with the added bene- fit of capitalizing on relatively intact musical functioning of nonverbal children with autistic spectrum disorders with the end goal of helping them develop verbal expressive language.
Although it might be difficult to test the contribution of all of the variables that are incorporated into an intervention on speech motor output, it is important to test the efficacy of
any new experimental intervention against a controlled or established intervention in a randomized, well-controlled trial. Equally important is the basic understanding of the neural mechanisms underlying singing and auditory-motor mapping. Elucidating these mechanisms will allow us to tai- lor the interventions, to select the most appropriate patients for efficient interventions, and to make predictions about recovery.AT
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