The neural basis of visual priming

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The ability of the human brain to continuously change and update with experience is one of the fundamental properties that distinguishes it from artificially constructed devices. One manifestation of experience-dependent changes in the human brain is visual priming, in which performance on repeated objects is improved compared to performance on new stimuli (responses are both faster and more accurate). Despite the rich knowledge on the behavioral aspects of visual priming, much less is known about the underlying neural mechanisms. Recent advances in brain imaging have allowed Dr. Kalanit Grill-Spector to examine the brain changes that occur with stimulus repetition. For example, she and her colleagues have found that repeating object images reduces the brain activity in object-selective areas in the human visual cortex. However, it is counterintuitive why reduced cortical activity would be associated with improved behavioral performance? With NSF funding, the goal of Dr. Grill-Spector's project is to understand the neural mechanisms underlying visual priming and to understand how these mechanisms produce changes in cortical activity in object-selective areas in the human brain. These experiments are designed to distinguish between alternative theories explaining visual priming and to rule out non-specific processes, such as changes in the overall attention level. To do so, Dr. Grill-Spector will combine brain imaging experiments and behavioral measurements. By manipulating repetition parameters, top-down attention and stimulus strength, and measuring the effect of these factors on both behavior and brain activation, she will determine which mechanism is more relevant. The results of this project will be critical for understanding the neural basis of experience-dependent changes in the visual system and will have a large impact on the fields of perceptual learning, implicit memory and visual cognition. These experiments will have an important contribution in understanding the physiological basis of a fundamental and intensively studied cognitive process: visual priming. Elucidating the cognitive and neural bases of visual priming will impact understanding of perceptual learning and plasticity of object representations in high-level visual areas, which in turn will affect a range of fields from clinical aspects of implicit memory to AI models of object recognition. For example, better understanding of the neural basis of perceptual learning or skill learning will facilitate better rehabilitation programs for patients who experienced strokes or other localized brain damage to sensory cortical areas. Furthermore, the proposed work will provide substantial novel insights into the neural processes associated with visual memory, which has important implications for the acquisition of novel object recognition skills. This type of skill is an important aspect of many forms of scientific and medical training (e.g., understanding radiological photos or learning to visually distinguish between chromosomes). In sum, by providing a greater understanding of neural plasticity, this work will inform our understanding of experience-dependent changes in the visual system as well as a wide range of learning and memory phenomena.