Neuroscience
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In the ascending auditory pathway, the central nucleus of the inferior colliculus (IC) receives and integrates excitatory and inhibitory inputs from many bilateral lower auditory nuclei, intrinsic projections within the IC, contralateral IC through the commissure of the IC and from the auditory cortex. All these presynaptic excitatory and inhibitory inputs dynamically shape and modulate the auditory response properties of individual IC neurons. For this reason, acoustic response properties vary among individual IC neurons due to different activity pattern of presynaptic inputs. ⋯ Additionally, 30-minute short-term ESDNLL alone produces variation in the best frequency (BF) and minimum threshold (MT) of modulated IC neurons. These varied response parameters recover in different manner and time course among individual modulated IC neurons. Possible pathways and neural mechanisms underlying these findings are discussed.
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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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The perception of fine textures relies on highly precise and repeatable spiking patterns evoked in tactile afferents. These patterns have been shown to depend not only on the surface microstructure and material but also on the speed at which it moves across the skin. ⋯ In the present study, we measure the signals evoked in tactile afferents of macaques to a diverse set of textures scanned across the skin at two different contact forces and find that responses are largely independent of contact force over the range tested. We conclude that the force invariance of texture perception reflects the force independence of texture representations in the nerve.
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Comparative Study
Multisensory integration in short-term memory: Musicians do rock.
Demonstrated interactions between seeing and hearing led us to assess the link between music training and short-term memory for auditory, visual and audiovisual sequences of rapidly presented, quasi-random components. Visual sequences' components varied in luminance; auditory sequences' components varied in frequency. Concurrent components in audiovisual sequences were either congruent (the frequency of an auditory item increased monotonically with the luminance of the visual item it accompanied), or incongruent (an item's frequency was uncorrelated with luminance of the item it accompanied). ⋯ Subjects with prior instrumental training significantly outperformed their untrained counterparts, with both auditory and visual sequences, and with sequences of correlated auditory and visual items. Reverse correlation showed that the presence of a correlated, concurrent auditory stream altered subjects' reliance on particular visual items in a sequence. Moreover, congruence between auditory and visual items produced performance above what would be predicted from simple summation of information from the two modalities, a result that might reflect a contribution from special-purpose, multimodal neural mechanisms.