Research
I am a cognitive neuroscientist with a background in physics developing tools to study dynamic mechanisms of cognition and development. To understand the human brain, I study the cooperation between perceptual and motor systems in shaping our perception of the world. A focus is on the perception and production of temporal rhythms in music and language and potential therapeutic and educational applications of music. Rhythm provides a well-defined test case for the hypothesis that the motor system plays a causal role in auditory perception, and that the development of this system is important for learning to temporally guide attention. I approach research questions using behavior and EEG/MEG recording and analysis, including recordings of the complex auditory brainstem responses (cABR). I am also involved in the development of new algorithms to analyze multimodal EEG/MEG data, including the integration of motion capture data with EEG analysis, and new approaches to connectivity analysis. Below is a video from the INC Open House on 4/2/19, explaining my recent research.
Below are some of my projects (click on title to read more):
Research Support
COMPLETED
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07/01/2012 – 06/30/2013
2019 National Endowment for the Arts (NEA) Research Lab
4/1/19 - 3/31/23 University of California at San Diego -
La Jolla, CA -
$300,000, renewed
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UC San Diego PIs Drs. John Iversen, Tim Brown, and Terry Jernigan, in partnership with San Diego Children’s Choir and Vista Unified School District, will study the potential effects of musical interventions on early childhood development. They will conduct the Early Academic Readiness and Learning Intervention - longitudinal intervention trials of vocal music in pre-school aged children, testing if music has impact on school readiness, cognition, and emotion. Brain Mechanisms of Rhythm Perception
Testing the Impact of the Motor System on Auditory Perception 06/01/15 – 05/31/19 - National Science Foundation |
Impact of Music training on child brain and behavioral development
I direct the SIMPHONY project, a comprehensive longitudinal study of the impact of music training on child brain and behavioral development. While it is well known that adult musicians’ brains and abilities are different from non-musicians, longitudinal study is necessary to prove that the differences are not pre-existing. The study tests the hypothesis that music training will accelerate brain development. The study is the first of its kind to combine a five-year longitudinal design with a deep battery of brain and behavioral measures. It is made possible by collaborating with NIHfunded longitudinal research at UCSD Center for Human Development which aims to define developmental trajectories for brain growth. I added a musically-enriched subgroup into this study to enable the study of experience on development, as well as several additional tests, including measurements of the complex auditory brainstem response, funded by a REaCh pilot grant. To date, baseline data has been analyzed, showing structure/function links between motor system development and rhythmic skills, and showing how the development of specific brain circuits, not calendar age, is more predictive of performance. A notable finding is that the maturity of the motor system predicts auditory rhythm perception ability. The data are in the process of being thoroughly quality-controlled and reprocessed and funding will be sought to fully analyze it.
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EEG/MEG signal processing
I have published several novel analysis methodologies for fusing multimodal data and causal connectivity analysis. Leading implementer of MEG methods within EEGLAB. Currently work with Prof. Jorge Cortes of UCSD Mechanical and Aerospace Engineering aims to develop new quantitative formalisms for the analysis of brain networks, drawing on distributed network science and bilinear systems to propose solutions to several problems facing existing methods, including the learning of network structure from
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Brain Mechanisms of Temporal Perception
Humans have a unique mode of perceiving time by organizing events around a regular succession of beats. Beats are important moments in time most commonly encountered in music, but may also be important for language perception. Because of the links between hearing and moving, study of beat perception gives us a clear window into a fundamental form of sensorimotor integration, and is a rich stage for understanding network interactions among systems in the brain. A central focus of my ongoing work is to understand the brain network dynamics responsible for beat perception using techniques with high temporal resolution, such as magneto- and electroencephalography (MEG & EEG). While we have known from brain imaging that motor structures are active during beat perception, their dynamic role is unknown. Is motor activity merely suppressed movement, or does it play a more constitutive role in auditory perception? To address this quandary, I have developed the ‘beat shift’ paradigm, which has enabled, for the first time, the dissociation of brain activity related to the internally generated pulse from external sound-evoked activity, a critical distinction for understanding auditory and motor contributions that was conflated by past studies. Using this method, I have shown that the internal sense of pulse that we perceive when listening to rhythms modulates auditory responses to sound, as well as for the first time demonstrating that brain activity in premotor cortex dynamically represents the pulse, independent of sound. I pushed the boundaries of data analysis, introducing for the first time in the music cognition field advanced quantitative methods including independent component analysis (ICA) and causal connectivity metrics to begin to describe the dynamic neural circuits underlying rhythm perception. Building on these results, I co-developed the Action Simulation for Auditory Prediction (ASAP) hypothesis, which makes the strong, and novel, claim that the motor system is causally necessary for beat perception. Currently I am leading a project to test the ASAP hypothesis through connectivity measures of EEG and direct tests of the causal role of the motor system in perception using TMS to transiently suppress portions of the motor system in order to observe effects on auditory rhythm perception and activity. This work represents a unique approach within the field, and a new combination of methods to test what is perhaps the most clearly articulated mechanistic hypothesis regarding the interaction of motor and auditory systems during beat perception.
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Role of experience and modality in shaping temporal perception
Additional studies using purely behavioral methods to provide strong constraints on theorizing about neural mechanisms. For many years it has been thought that auditory-motor coupling was inherently more temporally precise than the other senses, and better able to drive rhythmic behavior, to the extent that some have argued that synchronization with visual stimuli must occur via internal recoding into auditory representations. My research has successfully challenged these ideas, providing the first evidence of accurate synchronization to visual stimuli.
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Universality, language, and rhythm
Work done earlier in my career continues to be relevant in the fields of music cognition and language development. Three studies in particular have stimulated extensive continuing research. In 2008, we were the first to show that basic rhythm perception was not universal, as had been thought for the last century, but was influenced by language experience. This bears on a core question of how infants are able to learn the syntactic structure of language from acoustic cues, and has inspired a number of follow-on studies. In 2009 we presented the first evidence that a non-human animal, a sulphur crested cockatoo named Snowball, could synchronize movement with rhythm. This discovery has since been replicated and has inspired an explosion of empirical and theoretical work on synchronization in animals and the evolutionary importance of synchronization. Finally, we developed a test of pure beat perception (the BAT, or beat alignment test) that has become an international standard in the field and is incorporated in multiple music cognition batteries, including a nationwide study with the BBC in the UK, which studied musicality in over 200,000 people.
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