Whether a stimulus is perceived is suggested to depend on the amount or strength of the sensory signal. This idea has received support from a recent study which found that, when neural activation in the frontal eye fields was boosted by magnetic stimulation, the observers' detection performance on a visual task improved.

Performance in most visual discrimination tasks is better along the horizontal than the vertical meridian (Horizontal-Vertical Anisotropy, HVA), and along the lower than the upper vertical meridian (Vertical Meridian Asymmetry, VMA), with intermediate performance at intercardinal locations. As these inhomogeneities are prevalent throughout visual tasks, it is important to understand the percept...

THOSE who are substantially and permanently handicapped by defective vision resulting from illness, injury, or congenital deformity may be described as partially sighted. The following criteria are suggested as a general guide in estimating " substantial handicap": (1) Visual acuity 3/60 to 6/60, with full visual fields. (2) Visual acuity up to 6/24, with moderate contraction of the visual fiel...

Static automated visual field testing is now an integral part of the detection and monitoring of primary open angle glaucoma. However, although many aspects of testing are automated, interpretation of the large amounts of data produced by these instruments is not. Two major challenges facing the practitioner are differentiating between the visual fields of a patient with early glaucoma and thos...

Nearly 40 years ago, in the pages of this journal, Hubel and Wiesel provided the first description of receptive fields in the primary visual cortex of higher mammals. They defined two classes of cortical cells, "simple" and "complex", based on neural responses to simple visual stimuli. The notion of a hierarchy of receptive fields, where increasingly intricate receptive fields are constructed f...

By using information theory to reduce the state space of sensor arrays, such as receptive fields, for AI decision making we offer an adaptive algorithm without classical biases of hand coded approaches. This paper presents a way to build an acyclic directed graph to organise the sensor inputs of a visual receptive field. The Information Distance Metric is used to repeatedly select two sensors, ...

This case report describes the development of asymptomatic visual field defects (VFDs) in a psychiatric patient with bipolar disorder receiving adjunctive tiagabine treatment. These defects were apparently reversible upon the discontinuation of tiagabine. Controlled clinical trials are indicated to determine if this finding is indicative of a class effect for all GABAergic antiepileptic drugs (...

Several factors that influence the evolution of the unusual head morphology of hammerhead sharks (family Sphyrnidae) are proposed but few are empirically tested. In this study we tested the 'enhanced binocular field' hypothesis (that proposes enhanced frontal binocularity) by comparison of the visual fields of three hammerhead species: the bonnethead shark, Sphyrna tiburo, the scalloped hammerh...

PURPOSE Blindness in glaucoma is difficult to assess with merely the use of the current World Health Organization (WHO) definition (a visual field restricted to 10° in a radius around central fixation), as this criterion does not cover other types of visual field loss that are encountered in clinical practice and also depict blindness. In this study, a 5-point ordinal scale was developed for th...

Asymmetries in the response to visual patterns in the upper and lower visual fields (above and below the centre of gaze) have been associated with ecological factors relating to the structure of typical visual environments. Here, we investigated whether the content of the upper and lower visual field representations in low-level regions of human visual cortex are specialised for visual patterns...