MOTOR OVERFLOW

In principle, enough is now understood about the functional organization of the human brain that this knowledge should be able to play a role in the creative process of composing music, such that the music can be "aimed" at different brain structures, regions, and systems, affecting the emotional and cognitive response of the listener in novel and predictable ways. The purpose of the Motor Overflow project is to experiment with doing exactly this. I am a musician, neuroscientist, researcher, clinician, and medical school professor in human brain function attempting to use principles of cerebral functional organization derived from decades of scientific research to engage specific localized areas and distributed systems in the brains of listeners during music. What follows is a brief conceptual explanation of my approach to sound design and composing music as Motor Overflow.

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It is well established that neurons in different regions of the brain have different receptive field properties; that is, they fire in response to receiving different kinds of information from the outside world. For example, right primary auditory cortex shows faster and higher amplitude responses to some simple and often artificial tones like sinusoidal waveforms, while left primary auditory cortex shows faster and higher amplitude neural activity to many natural, more complex sounds rich with harmonic distortion and features like fast formant transitions, such as human speech (shown during anatomically constrained magnetoencephalography (aMEG) recordings). Just based on this knowledge alone about auditory sensory cortex, acoustic stimuli can be systematically manipulated to evoke brain activity responses with directed, initial dominant access to either the left or right cerebral hemisphere. But this is just the initial cortical response. While neurons in primary sensory regions code for the incoming low-level physical properties of sounds related to pitch/frequency, amplitude, and duration in the auditory modality, neurons downstream from sensory areas code for increasingly complex and high-level, contextual, and abstract properties of the acoustic stream as sound processing moves through the hierarchy of cerebral functional organization. So even beyond sensory cortex, auditory streams should be able to be created to selectively engage different parts of the functional brain organization from sensation to perception to cognition (attention, memory, language, executive control) and even to motor outputs by manipulating any and all properties of the sound signal coming into the brain over short and long time intervals. 

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The human brain not only responds to all aspects of the auditory signal during music listening, but it also actively integrates, synthesizes, analyzes, compares, and interprets the auditory information into its lifelong stores of prior knowledge, feeling, and experience. These brain processes, which operate automatically, come together to produce the perception of a specific piece of music as being pleasing, strange, surprising, exciting, soothing, raucous, dissonant, nostalgic, and the like. Music that is highly predictable and conforms strongly to common conventions that have already been repeatedly experienced (such as in time signatures, chords progressions, rhythmic complexities, and melodic lines), though often pleasing and sometimes preferred by the listener, will be less potent at forging new neural pathways and likely will not engage new circuits and networks in the listener as compared to music that is perceived as more novel and less predictable by the brain, less like what has been experienced before. Perceived novelty also interacts with musical complexity, with more information-rich auditory streams driving more neural processing resources. Even when a specific song is new to the ears of the listener, it may fail to produce novel brain activity because the brain quickly identifies it as being mostly familiar. Neurophysiologically, complexity, dissonance, dyssynchrony, delay of gratification, violation of statistical regularities, and surprise will be better at driving brain activity patterns that haven't before been experienced. This may produce new pleasures of listening that are unobtainable by listening to familiar, predictable, and conventional sounds, chords, tones, chord progressions, melodic forms, rhythms and beats, and song structures.

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Typically, listeners judge music that is new to their ears by evaluating whether it makes them immediately feel gratified. That is a fair and natural way to judge music. But in principle, some music might be good for the health and well being of the listener without being immediately pleasing or instantly emotionally rewarding. Some music may produce other, perhaps less superficial and short-term, benefits and pleasures to the listener. Certainly, much music already exists that seeks to evoke complex cognitive and emotional responses from listeners. But thus far this music has not been created in a way that is guided by the principles of human functional brain organization. It remains an open empirical question whether our now quite advanced scientific understanding of human brain function can be used to guide the creation of music for these purposes.

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Motor Overflow is an ongoing attempt to use scientific knowledge about the cognitive neuroscience of music and sound processing to create works that push the listener toward new biosonic perceptual, cognitive, emotional, and motor experiences, driving novel patterns of brain activity and engagement: from low-level sensory cortex through to tertiary, transmodal, and prefrontal cortex; from subcortical emotion-evoking limbic structures and reward circuits to higher order cognitive and reflective intellectual systems. Music created in a neuroscientifically informed way might be able to expand the listener's experience both viscerally and cerebrally. That is the hope.

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Warning: Listening to Motor Overflow may induce involuntary movements of the digits, extremities, and limbs and has been known to cause near-dance experiences.