Neuroscience
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What do animals hear? While it remains challenging to adequately assess sensory perception in animal models, it is important to determine perceptual abilities in model systems to understand how physiological processes and plasticity relate to perception, learning, and cognition. Here we discuss hearing in rodents, reviewing previous and recent behavioral experiments querying acoustic perception in rats and mice, and examining the relation between behavioral data and electrophysiological recordings from the central auditory system. We focus on measurements of critical bands, which are psychoacoustic phenomena that seem to have a neural basis in the functional organization of the cochlea and the inferior colliculus. We then discuss how behavioral training, brain stimulation, and neuropathology impact auditory processing and perception.
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Can the human brain itself serve as a model for a systems neuroscience approach to understanding the human brain? After all, how the brain is able to create the richness and complexity of human behavior is still largely mysterious. What better choice to study that complexity than to study it in humans? However, measurements of brain activity typically need to be made non-invasively which puts severe constraints on what can be learned about the internal workings of the brain. ⋯ Resting both on quantitative measurements and considerations of what is known through animal models, we concluded that weighting of sensory signals by the magnitude of their response is a neural mechanism for efficient selection of sensory signals and consequent improvements in behavioral performance with attention. While animal models have many technical advantages over studying the brain in humans, we believe that human systems neuroscience should endeavor to validate, replicate and extend basic knowledge learned from animal model systems and thus form a bridge to understanding how the brain creates the complex and rich cognitive capacities of humans.
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An animal's survival strongly depends on a nervous system that can rapidly process and integrate the changing quality of its environment and promote the most appropriate physiological responses. This is amply demonstrated in the nematode worm Caenorhabditis elegans, where its sensory system has been shown to impact multiple physiological traits that range from behavior and developmental plasticity to longevity. ⋯ Here we review our current understanding of how the C. elegans sensory system affects diverse physiological traits, whose coordination would be essential for survival under fluctuating environments. The knowledge we derive from the C. elegans studies should provide testable hypotheses in discovering similar mechanisms in higher animals.
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The study of motor control has long concerned itself with the origins of movement variability. Indeed, a common goal of many computational models of motor control is to predict the empirically observed patterns of movement variability. Competing models thus attempt to capture how the brain constrains variability that is detrimental and/or generates variability that might be beneficial. ⋯ Below we describe recent research in which we were able to determine an important source of movement variability using a non-human primate model: the rhesus macaque. The macaque, much like the human, can produce flexible yet highly precise behavior. For this reason, among others, the macaque was an ideal model for the study of movement variability.
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Image segmentation is a fundamental aspect of vision and a critical part of scene understanding. Our visual system rapidly and effortlessly segments scenes into component objects but the underlying neural basis is unknown. ⋯ We found that many neurons tuned to boundary curvature maintained their shape selectivity over a large range of occlusion levels as compared to neurons that are not tuned to boundary curvature. This lends support to the hypothesis that segmentation in the face of occlusion may be solved by contour grouping.