Friday, September 3rd, 2010

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Research


My ongoing research direction can be described in terms of several intersecting research questions:


1.) What are the stages of mental and neural computation that constitute our ability to speak, and exactly when and how are they implemented in the human brain?

  • My goal is to contribute toward a fine-scale model of language production, at the mechanistic level.
  • Measuring the precise timing, and physiological basis, of neural computation stages poses many challenges, and the ICE method is well suited to meeting these challenges.

2.) How, specifically, does the brain represent grammar and grammatical processing?

  • Grammar is arguably the brain’s central talent that separates language from communication systems of other animals.
  • It can be described by the implicit rules that turn the relationships among words (and word parts) into meaning, thus allowing us to express an infinite range of thoughts with a finite menu of words.
  • It is NOT the explicit rules that teachers in school may have plagued you with, such as “Don’t split your infinitives”.
  • My research combines ICE and fMRI methods, and uses morphosyntax (word endings) as a model system to study grammar.
  • While people produce words in the grammatically correct forms for simplified sentences, I record and chronicle active cell populations, and patterns of synchronous firing among them, to ask what the fundamental units of neuronal processing are for grammar.

3.) How can we best characterize Broca’s area?

  • Broca’s area, a region in the frontal left hemisphere of the human brain, has been implicated in language function since Dr. Paul Broca’s insight (in 1861) that the mind is divisible into faculties, such as speech, and these are controlled by divisions of the brain, in this case what became known as Broca’s area.
  • The role(s) assigned to Broca’s area have changed several times, as a product of much scientific debate. Text books often still teach that Broca’s area underlies speaking, and another area (Wernicke’s) underlies comprehending, although this model (encapsulated in the “Wernicke-Geschwind” model) is decades out of date. Some results from my research have helped push beyond the model, though much remains to be done.
  • It has long been clear that Broca’s area has more than one function (unsurprising given it contains ~100 million cells and ~1 trillion synapses), but decomposing the region into functional subcomponents (anatomically or otherwise) has been notoriously difficult.
  • I aim to characterize the computational entities within Broca’s area in terms of time, space, and physiology – and relate them to the mental functions they produce.

4.) What are the functions, and origins, of neural synchrony in the adult cortex?

  • I am investigating this in terms of how language-related brain circuits that are far apart and/or compute different aspects of language may communicate to exchange information. However, the data may drive me in new directions.
  • Synchrony is when cells in different parts of the brain fire or become synaptically active in the same patterns.
  • Episodes of synchrony may allow information to be transferred among the brain’s expertise entities, or may even represent the information processing itself, so it is important to characterize the nature and computational importance of transient episodes of neuronal synchrony during real-time mental processes.