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?
Single and multiple electrode recordings in awake, behaving monkeys;
threshold psychophysics; computational modeling.
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.
KEY WORDS: Electrophysiology; threshold psychophysics; vision;
perceptual decisions.
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Gold JI, Shadlen MN (2000). Representation of a perceptual decision in developing oculomotor commands. Nature 404:390-394.
Gold JI, Knudsen EI (2001). Auditory experience-induced adjustment of neural connectivity in the barn owl's inferior colliculus revealed by focal pharmacological inactivation. J Neurophysiol, 85(4): 1575-1584.
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Neuron 36:299–308.
Gold JI, Shadlen MN (2003). The influence of behavioral context on the representation of a perceptual decision in developing oculomotor commands J Neurosci 23: 632–651.
