Description of Research Expertise

KEY WORDS:
Electrophysiology; threshold psychophysics; vision; perceptual decisions

RESEARCH INTERESTS
How the brain forms decisions about sensory stimuli: What are the underlying neural computations? Where are the circuits that perform these computations? How are these circuits shaped by experience?

RESEARCH TECHNIQUES
Single and multiple electrode recordings in awake, behaving monkeys; threshold psychophysics; computational modeling.

RESEARCH SUMMARY
Recent advances in neuroscience have begun to shed light on how the brain represents sensory information and issues motor commands. My interest is in how the two are linked: How does the brain interpret sensory information to guide behavior? To study this link, which is central to perception, decision-making and other aspects of higher brain function, we conduct electrophysiological experiments on monkeys trained to perform demanding visual-discrimination tasks. The goals of these experiments are to identify the neural circuits involved in forming these perceptual decisions, to expose the underlying computations and to address how these computations are shaped by experience.

One task that we use extensively requires the monkey to discriminate the direction of random-dot motion and to indicate its direction decision with an eye movement to one of two choice targets. By varying the strength of motion, we can manipulate the ease or difficulty of the task and induce the monkeys to work near psychophysical threshold. This manipulation draws out the decision process and introduces errors, which allows us to examine the perceptual decision as it evolves over time and to dissociate the monkey's behavioral response from the sensory processing.

In previous experiments, decisions linked to specific eye movements were shown to be evident in the circuits that prepare the eye-movement response. We are building on these results with two new lines of inquiry. First, we are investigating whether principles of sensory-motor integration that we have learned using the direction-discrimination task can be generalized to more abstract decisions (that is, decisions not linked to specific actions). Second, we will forge new connections to the study of plasticity and learning by studying how experience shapes the neural computations responsible for forming these perceptual decisions.