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PubMedDate not supplied

On-chip visual perception of motion: a bio-inspired connectionist model on FPGA.

Visual motion provides useful information to understand the dynamics of a scene to allow intelligent systems interact with their environment. Motion computation is usually restricted by real time requirements that need the design and implementation of specific hardware architectures. In this paper, the design of hardware architecture for a bio-inspired neural model for motion estimation is presented. The motion estimation is based on a strongly localized bio-inspired connectionist model with a particular adaptation of spatio-temporal Gabor-like filtering. The architecture is constituted by three main modules that perform spatial, temporal, and excitatory-inhibitory connectionist processing. The biomimetic architecture is modeled, simulated and validated in VHDL. The synthesis results on a Field Programmable Gate Array (FPGA) device show the potential achievement of real-time performance at an affordable silicon area.

Models, Neurological↗
PubMed2002

Enhancement of visual perception by crossmodal visuo-auditory interaction.

Neurophysiological studies have shown in animals that a sudden sound enhanced perceptual processing of subsequent visual stimuli. In the present study, we explored the possibility that such enhancement also exists in humans and can be explained through crossmodal integration effects, whereby the interaction occurs at the level of bimodal neurons. Subjects were required to detect visual stimuli in a unimodal visual condition or in crossmodal audio-visual conditions. The spatial and the temporal proximity of multisensory stimuli were systematically varied. An enhancement of the perceptual sensitivity (d') for luminance detection was found when the audiovisual stimuli followed a rather clear spatial and temporal rule, governing multisensory integration at the neuronal level.

Adult↗
PubMed1987

[Modification of visual perception by vision training].

The course of the visual pathway as far as the sulcus temporalis superior is described and the change in the shape of the receptive fields is pointed out. The transformation of action potentials into conscious perception is interpreted as it was by Eccles. A connection is made between the problem of learning and the plasticity of the spine synapses, the capacity of which can be considerably increased. In conclusion, it is pointed out that in cases of macular disease it is possible to stimulate peripheral areas of the visual field by special training and thus to help the visual field by special training and thus to help the patient.

Aged↗
PubMed1993

Conscious visual perception without V1.

We used the technique of PET to determine whether visual signals reach visual area V5, specialized for visual motion, when a human patient, blinded by a lesion in area V1, discriminates the direction of motion of visual stimuli and shows, through his verbal reports, that he is consciously aware of both the nature of the visual stimulus and its direction of motion. The results showed that area V5 was active without a parallel activation of area V1, implying that the visual input can reach V5 without passing first through V1 and that such an input is sufficient for both the discrimination and the conscious awareness of the visual stimulus.

Adult↗
PubMed1997

Visuelle Welt: a Windows program for demonstrating visual-perception phenomena.

The Windows program Visuelle Welt allows the demonstration of various visual phenomena such as geometrical-optical illusions, subjective contours, apparent movement, and Gestalt principles. One of the program's most interesting features is that the illusion-inducing context can be switched off, and in addition for many phenomena parameters can be varied interactively.

Computer Terminals↗
PubMed2005

Pre- and poststimulus alpha rhythms are related to conscious visual perception: a high-resolution EEG study.

Conscious and unconscious visuospatial processes have been related to parietooccipital cortical activation as revealed by late visual-evoked potentials. Here the working hypothesis was that a specific pattern of pre- and poststimulus theta (about 4-6 Hz) and alpha (about 6-12 Hz) rhythms is differently represented during conscious compared with unconscious visuospatial processes. Electroencephalographic (EEG) data (128 channels) were recorded in normal adults during a visuospatial task. A cue stimulus appeared at the right or left (equal probability) monitor side for a "threshold time" inducing about 50% of correct recognitions. It was followed (2 s) by visual go stimuli at spatially congruent or incongruent position with reference to the cue location. Left (right) mouse button was clicked if the go stimulus appeared at the left (right) monitor side. Then, subjects said "seen" if they had detected the cue stimulus or "not seen" if missed (self-report). Sources of theta and alpha rhythms during seen and not seen EEG epochs were estimated by low-resolution electromagnetic brain topography software. Results showed that the prestimulus "low-band" (about 6-10 Hz) alpha rhythms in frontal, parietal, and occipital areas were stronger in power in the seen than in the not seen trials. After the visual stimulation, the power of the "high-band" (about 10-12 Hz) alpha rhythms in parietal and occipital areas decreased more in the seen than in the not seen trials. The present results suggest that visuospatial consciousness covary--presumably with a facilitatory effect--with the power of both pre- and poststimulus alpha rhythms.

Adult↗
PubMed2002

Laser projection versus a CRT display in the visual perception of aircraft aspect.

High-resolution visual displays have been designed for flight simulation so that observers may judge the aspect angle of aircraft at far distances. The present experiment compares two display devices as untrained observers judge the spatial orientation of two target aircraft: F-15 and F-16 jets. The display devices are a prototype direct-write microlaser projector and an SXGA-format CRT display. Observers' accuracy of aircraft identification is better with the laser projector, and recognition response times are faster. A simple rule was found to fit the observers' response times; it is expressed in terms of a statistic on the autocorrelation of black-and-white silhouette images of aircraft. Observers' estimates of aspect are biased by the laser projector, whereas observers' estimates of aspect are accurate on average with the SXGA display. This bias in estimation of aspect may be attributable to variations in line brightness introduced by the laser projector. Actual or potential applications of this research include the evaluation of high-resolution visual displays for the training of basic fighter maneuvers with military jet pilots.

Aircraft↗
PubMed1996

Cortical mechanisms for visual perception of object motion and position in space.

The present review is aimed at analyzing and discussing some of the cortical mechanisms possibly involved in the perception of object motion and object localization in the visual field. A comprehensive approach to these topics would be beyond the scope of this work. The highest priority, therefore, will be given to the cortical machinery involved in these processes, while very little (or nothing at all) will be said on the possible role played by subcortical structures such as the lateral geniculate nucleus and the superior colliculus which, albeit not directly involved in perception, might contribute to it.

Animals↗
PubMed1988

Visual perception of moving parts.

There are countless three-dimensional interpretations of a set of points moving in a two-dimensional image. A unique visual interpretation of motion thus requires assumptions about the types of structure likely to be found in the three-dimensional world. We propose that the human visual system favors articulated structures in its interpretations. An articulated structure is a rigid body with moving parts that themselves are rigid and rotate in fixed planes with respect to the body. (A bicycle is an example.) We claim that an image consisting of just two moving points is seen as an articulated structure (when their motion is consistent with one), even though countless other interpretations are possible, including a rigid one of a rod moving in space. An experiment is presented in support of our claim, and a well-known display from an old experiment is reinterpreted as a special case of an articulated structure.

Humans↗