The goal of this project is to elucidate the neural mechanisms of visual attention and working memory. Carrying out even the most mundane tasks requires that relevant sensory information be selectively processed and remembered. Attention and working memory are two fundamental and related mental operations that are frequently called upon during goal-directed behavior. The neural basis of these two forms of cognition is largely unknown; much of what is known consists of localized neurophysiological correlates within the human and nonhuman primate brain. These correlates indicate, for example, that individual neurons within the frontal lobe exhibit persistent activation in relation to the maintenance of task information during working-memory tasks. These persistent signals are also associated with the preparation of eye movements, suggesting that motor preparation per se, and the neural circuits underlying motor preparation, may provide the mechanism for visual attention and working memory. In the current project, the PI will examine the causal role of persistent, eye-movement-related activity in frontal cortex in driving visual attention and visual working memory. To achieve this, the PI will employ state-of-the-art neurophysiological, neuropharmacological and psychophysical methods in behaving nonhuman primates. This project is crucial for understanding how sensory information is regulated during complex, adaptive behavior by the primate brain, and is pivotal for establishing a neurophysiological basis of cognition. This research project also involves an effort to develop an optimal undergraduate and graduate curriculum in integrative neuroscience, a field that necessarily involves a broad spectrum of disciplines. The project also includes an aggressive effort to recruit talented underrepresented minority undergraduates from other institutions to participate in summer research activities and to apply for graduate studies in the neurosciences.
Our ability to selectively process important sensory information at the expense of extraneous, or potentially distracting, information is provided by the faculty of attention. The ability to pay attention is among the most fundamental of human cognitive functions. That our nervous system is able to selectively filter out irrelevant information for the benefit of relevant information is evident to any human observer. Moreover, the ability to filter sensory information is critical for normal goal-directed behavior. Even the most basic goal-directed human behavior would constantly be derailed if sensory input, and the movements it drives, could not be willfully regulated. Selective attention is the fundamental cognitive capacity that permits such regulation. Impairments of attention in humans, such as in attention-deficit/hyperactivity disorder (ADHD), which affects ~5% of the world’s population, indeed can pose major behavioral obstacles for individuals. The goal of the completed project was to understand how networks of nerve cells (neurons) within the human brain selectively process behaviorally relevant stimuli and how this mechanism relates to working memory. During the project period we discovered that within primate frontal cortex, neurons involved in the preparation of eye movements also control the selection of relevant visual information (visual attention) within visual cortex. We also discovered that the control of visual cortical signals by frontal cortex involves dopamine D1 receptors which is known to be involved working memory.These are important discoveries as they not only demonstrate a causal basis for visuospatial attention and reveal how this fundamental cognitive function relates to working memory at the cellular and molecular level, but it also establishes a link between the suspected involvement of frontal cortical dopamine in attention and the effects of attention on the processing of visual information within visual cortex.
