Optimal allocation of attention is key to achieving peak behavioral performance. A detailed understanding of
the neuronal mechanisms that control attention will be essential for any comprehensive strategies to reduce
attention lapses or treat attention disorders. Moreover, better understanding of attention is likely to provide
valuable new insights into sensory processing and perception. The visual system is an ideal subject for the study
of attention. Peak visual performance is required for many human activities, and our relatively advanced
understanding of the functional organization of the visual system makes it choice for deploying state-of-the-art
techniques in well-described and well-differentiated brain regions.
The experiments proposed here will advance our understanding of attention by providing a comprehensive
characterization of the role of the locus coeruleus in visual attention. The locus coeruleus has long been
associated with attention and arousal. However, the specificity of its contributions to attention has received
relatively little investigation, despite many findings that suggest it has substantial functional specialization.
Recent work in our lab has been directed at identifying distinct component of visual attention. We have shown
that different brain structures make distinct contributions to changes in attention associated with behavioral
sensitivity, selectivity, and perceptual criterion. Recently, we have used optogenetic stimulation of the locus
coeruleus in monkeys and found that it can produce a robust and selective enhancement in behavioral sensitivity.
This result emphasizes that the locus coeruleus is a potent factor in controlling visual attention, and highlights
how little we know about the role it plays in controlling the various components that make up visual attention.
We will optogenetically activate locus coeruleus neurons to measure their influence on visual sensitivity,
selectivity and perceptual criterion, measuring both the magnitude and the dynamics of attention-related
behavioral enhancements that it mediates. To reveal how it enhances visual performance, we will record visual
responses from key visual structures – area V4, the frontal eye fields and the superior colliculus – during locus
coeruleus stimulation to directly assess how it contributes to the quality of central representations of behaviorally-
relevant visual stimuli. We will also record neuronal responses from the locus coeruleus itself while monkeys do
tasks that modulate specific components of visual attention. The results from these recordings will provide a
direct, detailed appraisal of the extent of specialization that exists within the locus coeruleus.
The locus coeruleus plays a major role in behavioral performance, yet its role has been largely overlooked
in efforts to understand the neurophysiology of visual attention. The proposed experiments will provide a precise,
comprehensive assessment of the place of the locus coeruleus in attention and will substantially advance our
understanding of the interaction of different brain structures in mediating visual behaviors.