Spatial Selectivity
Mostrando 13-24 de 40 artigos, teses e dissertações.
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13. Spatial and temporal frequency selectivity of neurones in visual cortical areas V1 and V2 of the macaque monkey.
The spatial and temporal frequency selectivity of 148 neurones in the striate cortex, V1, and of 122 neurones in the second visual cortical area, V2, of the macaque monkey were studied using sine-wave gratings of suprathreshold contrast drifting over the receptive field at the preferred orientation and direction. Neurones in V1 and V2 were selective for diff
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14. The development of spatial-frequency selectivity in kitten striate cortex.
1. Single units were recorded in the striate cortex of kittens aged between 2 and 12 weeks. Contrast sensitivity measurements made using moving sinusoidal gratings were used to construct spatial-frequency tuning curves. 2. In young kittens cells had low sensitivities, responded only to low spatial frequencies and were unselective for spatial frequency. In ad
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15. Spatial and temporal frequency selectivity of cells in area 21a of the cat.
1. The spatial and temporal response properties of single cells in area 21a of the anaesthetized cat were assessed using drifting sinusoidal gratings presented at the optimum orientation for each cell. 2. Responses to sinusoidal gratings were dominated by an elevation of the mean discharge, with a relatively small modulated component at the temporal frequenc
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16. Critical bands in cat spatial vision.
1. The ability of cats to detect sinusoidal grating patterns superimposed on one-dimensional visual noise was assessed using behavioural methods. 2. The magnitude of elevation in contrast threshold due to noise increased monotonically within limits with increasing noise contrast. 3. Visual noise was filtered using various techniques (band-reject, low-pass, h
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17. Formation of receptive fields in realistic visual environments according to the Bienenstock, Cooper, and Munro (BCM) theory.
The Bienenstock, Cooper, and Munro (BCM) theory of synaptic plasticity has successfully reproduced the development of orientation selectivity and ocular dominance in kitten visual cortex in normal, as well as deprived, visual environments. To better compare the consequences of this theory with experiment, previous abstractions of the visual environment are r
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18. A neuronal network model of macaque primary visual cortex (V1): Orientation selectivity and dynamics in the input layer 4Cα
In this paper, we offer an explanation for how selectivity for orientation could be produced by a model with circuitry that is based on the anatomy of V1 cortex. It is a network model of layer 4Cα in macaque primary visual cortex (area V1). The model consists of a large number of integrate-and-fire conductance-based point neurons, both excitatory and i
The National Academy of Sciences.
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19. The velocity dependence of direction selectivity of visual cortical neurones in the cat.
1. The range of velocities, yielding direction-selective responses, was investigated in a total of 167 direction-selective cells from areas 17 and 18 of the cat, using a high-contrast light bar moving at velocities ranging from 0.6 to 900 deg s-1. 2. 11% of the cells were direction selective over the full range of velocities tested. Most cells (66%) gave onl
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20. Spatial vision of the achromat: spatial frequency and orientation-specific adaptation.
1. The psychophysical technique of selective adaptation to stationary sine-wave gratings of varying spatial frequency and orientation was used to investigate the central processing of spatial information in the visual system of the complete achromat. 2. For adapting spatial frequencies of 1 and 2 cycles/deg, the spatial frequency and orientation selectivity
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21. Auditory Spatial Tuning at the Crossroads of the Midbrain and Forebrain
The barn owl's midbrain and forebrain contain neurons tuned to sound direction. The spatial receptive fields of these neurons result from sensitivity to combinations of interaural time (ITD) and level (ILD) differences over a broad frequency range. While a map of auditory space has been described in the midbrain, no similar topographic representation has bee
American Physiological Society.
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22. Mechanisms and streams for processing of “what” and “where” in auditory cortex
The functional specialization and hierarchical organization of multiple areas in rhesus monkey auditory cortex were examined with various types of complex sounds. Neurons in the lateral belt areas of the superior temporal gyrus were tuned to the best center frequency and bandwidth of band-passed noise bursts. They were also selective for the rate and di
The National Academy of Sciences.
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23. Spatial frequency and orientation tuning dynamics in area V1
Spatial frequency (SF) and orientation tuning are intrinsic properties of neurons in primary visual cortex (area V1). To investigate the neural mechanisms mediating selectivity in the awake animal, we measured the temporal dynamics of SF and orientation tuning. We adapted a high-speed reverse-correlation method previously used to characterize orientation tun
The National Academy of Sciences.
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24. Visual attention to surfaces in three-dimensional space.
Although attention plays a significant role in vision, its spatial deployment and spread in the third dimension is not well understood. In visual search experiments we show that we cannot easily focus attention across isodepth loci unless they are part of a well-formed surface with locally coplanar elements. Yet we can easily spread our attention selectively