Contrast dependence of perceptual grouping in brain-damaged patients with visual extinction

Spatial Vision
Marina PavlovskayaNachum Soroker

Abstract

Extinction is manifested in conditions of bilateral simultaneous stimulation, as a failure to detect the stimulus contra-lateral to the side of a cerebral lesion, while the same stimulus is correctly detected there when presented in isolation. The phenomenon is usually interpreted in terms of impaired mobilization of attention from an attended to an unattended object. We have recently shown, using pairs of Gabor patches as stimuli, that pair detection is maximally improved in conditions where the two stimuli presented simultaneously to the two halves of the visual field are co-oriented and co-axial and their location is not too eccentric. Here we add new information by showing that contrast isotropy of the stimulus pair is important in producing this orientation-similarity gain. The further advantage of co-oriented co-linear stimuli over co-oriented parallel (vertical) stimuli was shown exclusively with iso-contrast stimulus pairs, and was significantly enhanced when the contrast level of the stimulus pair was low. Stimulus properties producing reduced extinction seem to correlate with the selectivity pattern and contrast dependence of (a) spatial lateral facilitation observed in psychophysical studies with normal observers, an...Continue Reading

Citations

Jul 9, 2013·Experimental Brain Research·Kathleen VancleefGlyn W Humphreys
Feb 18, 2005·Neuropsychologia·Joseph L BrooksLynn C Robertson
Dec 1, 2005·Brain : a Journal of Neurology·Jacqueline C Snow, Jason B Mattingley

❮ Previous
Next ❯

Related Concepts

Trending Feeds

COVID-19

Coronaviruses encompass a large family of viruses that cause the common cold as well as more serious diseases, such as the ongoing outbreak of coronavirus disease 2019 (COVID-19; formally known as 2019-nCoV). Coronaviruses can spread from animals to humans; symptoms include fever, cough, shortness of breath, and breathing difficulties; in more severe cases, infection can lead to death. This feed covers recent research on COVID-19.

Blastomycosis

Blastomycosis fungal infections spread through inhaling Blastomyces dermatitidis spores. Discover the latest research on blastomycosis fungal infections here.

Nuclear Pore Complex in ALS/FTD

Alterations in nucleocytoplasmic transport, controlled by the nuclear pore complex, may be involved in the pathomechanism underlying multiple neurodegenerative diseases including Amyotrophic Lateral Sclerosis and Frontotemporal Dementia. Here is the latest research on the nuclear pore complex in ALS and FTD.

Applications of Molecular Barcoding

The concept of molecular barcoding is that each original DNA or RNA molecule is attached to a unique sequence barcode. Sequence reads having different barcodes represent different original molecules, while sequence reads having the same barcode are results of PCR duplication from one original molecule. Discover the latest research on molecular barcoding here.

Chronic Fatigue Syndrome

Chronic fatigue syndrome is a disease characterized by unexplained disabling fatigue; the pathology of which is incompletely understood. Discover the latest research on chronic fatigue syndrome here.

Evolution of Pluripotency

Pluripotency refers to the ability of a cell to develop into three primary germ cell layers of the embryo. This feed focuses on the mechanisms that underlie the evolution of pluripotency. Here is the latest research.

Position Effect Variegation

Position Effect Variagation occurs when a gene is inactivated due to its positioning near heterochromatic regions within a chromosome. Discover the latest research on Position Effect Variagation here.

STING Receptor Agonists

Stimulator of IFN genes (STING) are a group of transmembrane proteins that are involved in the induction of type I interferon that is important in the innate immune response. The stimulation of STING has been an active area of research in the treatment of cancer and infectious diseases. Here is the latest research on STING receptor agonists.

Microbicide

Microbicides are products that can be applied to vaginal or rectal mucosal surfaces with the goal of preventing, or at least significantly reducing, the transmission of sexually transmitted infections. Here is the latest research on microbicides.