Vocal control and sensorimotor learning in songbirds
(Publications)

Sucessfully producing complex behavior requires that neurons in the brain produce a pattern of muscular activation that in turn results in the desired behavioral output. My current work on songbirds investigates the relationship between these very different levels of description - neural activity, muscular activation, and task performance - by using range of techniques to describe how neural circuits in the songbird brain drive vocal output and are modified by sensory experience. This work, conducted in the laboratory of Dr. Michael Brainard at UCSF, combines neurophysiological recordings, behavioral manipulations, and computational approaches to describe the interplay between sensory feedback, motor production, and neural plasticity.

Motor psychophysics and reach modelling
(Publications)

When planning goal-directed movements, the brain must integrate sensory information from many different sources.  In the case of reaching movements to visual targets, subjects must integrate visual target information with visual as well as proprioceptive information about the arm.  My doctoral research in the laboratory of Dr. Philip Sabes focused on how vision and proprioception are combined to estimate the arm's position during motor planning.  To address this question, we used a virtual reality environment to alter the visual feedback that subjects receive from the arm prior to reach onset, thereby dissociating the visual and proprioceptive signals used in the planning process.  By performing quantitative, model-based analyses of the errors caused by such manipulations, we inferred the mixture of visual and proprioceptive information used at different stages of motor planning and described how sensory integration is affected by sensory noise and by the computational demands of the task being performed.
Recovery of function and cortical network modelling
(Publications)

Damage to the cerebral cortex (such as that caused by stroke) can lead to profound behavioral and cognitive impairments.  Equally dramatic, however, is the recovery sometimes seen in the weeks and months following such damage.  I have worked on several projects modelling the acute changes in cortical information processing that follow the destruction of a small portion of the cortical network.  The goal of these studies was to understand the impact of focal lesions on sensory receptive fields and to use these data both to understand the perceptual deficits that follow some strokes and to explore possible neurorehabilitative strategies.