Neuroscience
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Editorial Comment
Potential of Mirror Rehabilitation Therapy in Stroke Outcome.
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The world is richly structured on multiple spatiotemporal scales. In order to represent spatial structure, many machine-learning models repeat a set of basic operations at each layer of a hierarchical architecture. ⋯ Because our brains also process temporal information that is rich and occurs across multiple time scales, might the brain employ an analogous set of operations for temporal information processing? Here we define a candidate set of temporal operations, and we review evidence that they are implemented in the mammalian cerebral cortex in a hierarchical manner. We conclude that multiple consecutive stages of cortical processing can be understood to perform temporal pooling, temporal normalization and temporal pattern completion.
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Age-related changes in auditory and visual perception have an impact on the quality of life. It has been debated how perceptual organization is influenced by advancing age. From the neurochemical perspective, we investigated age effects on auditory and visual bistability. ⋯ However, no correlation was found in the prefrontal cortex and anterior cingulate cortex. In addition, effective volitional control was reduced with advancing age. Our results suggest that sequential scene analysis in auditory and visual domains is influenced by both age-related and neurochemical factors.
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Music is a curious example of a temporally patterned acoustic stimulus, and a compelling pan-cultural phenomenon. This review strives to bring some insights from decades of music psychology and sensorimotor synchronization (SMS) literature into the mainstream auditory domain, arguing that musical rhythm perception is shaped in important ways by temporal processing mechanisms in the brain. The feature that unites these disparate disciplines is an appreciation of the central importance of timing, sequencing, and anticipation. ⋯ We then move away from music to explore the perceptual effects of rhythmic timing in pattern detection, auditory scene analysis, and speech perception. Finally, we review the neurophysiology of general timing processes that may underlie aspects of the perception of rhythmic patterns. We conclude with a brief summary and outlook for future research.
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Review
Automatic frequency-shift detection in the auditory system: A review of psychophysical findings.
The human brain has the task of binding successive sounds produced by the same acoustic source into a coherent perceptual stream, and binding must be selective when several sources are concurrently active. Binding appears to obey a principle of spectral proximity: pure tones close in frequency are more likely to be bound than pure tones with remote frequencies. It has been hypothesized that the binding process is realized by automatic "frequency-shift detectors" (FSDs), comparable to the detectors of spatial motion in the visual system. ⋯ A number of variants of this study have been performed since 2005, in order to confirm the existence of FSDs, to characterize their properties, and to clarify as far as possible their neural underpinnings. The results obtained up to now suggest that the working of the FSDs exploits an implicit sensory memory which is powerful with respect to both capacity and retention time. Tones within chords can be perceptually enhanced by small frequency shifts, in a manner suggesting that the FSDs can serve in auditory scene analysis not only as binding tools but also, to a limited extent, as segregation tools.