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.
Attention deficit hyperactivity disorder (ADHD) affects about 5% of adults [1] and children [2] in the United States, reducing their quality of life and imposing a substantial burden on the economy [3]. Better understanding of basic neuronal mechanisms related to attention and their interaction with sensory signals is needed for enhancing human performance and for guiding assessment, diagnosis and treatment of deficits of attention. The proposed research will investigate how attention affects visual processing in the nervous system, and in particular how distinct control signals related to attention are distributed to different regions of the visual system.
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