An attempt to derive a comprehensive theory of attention from both neurobiological and psychological data.

Humans and many other species attend to only a small portion of available visual information at any given moment. They enhance perception of the attended stimulus either overtly, making an eye or head movement to orient toward it, or covertly, without any such movements. The neural circuits that underlie these two types of attention behaviors, and the relationship between them, remain unclear. To investigate the interdependence of them we trained monkeys on a task that behaviorally dissociated the location of covert attention from the location of a saccade target. Recordings in extrastriate visual cortical area V4 surprisingly revealed that enhanced firing rates and other modulations of neural activity accompanied both covert attention and saccade preparation. These results suggested a hypothesis about the circuits that could mediate the control of both behaviors. We recorded neurons in the frontal eye field, an area involved in controlling both behaviors, and found evidence contradicting our hypothesis. Separately, we examined the circuit underlying the integration of attention-related feedback signals with visual information in visual cortex by recording from distinct neuron populations, defined by laminar depth, within V4 during the covert attention task. We found that all neuron populations were modulated indistinguishably during attention. Finally, we constructed a large-scale model of FEF and V4 on neuromorphic hardware and used it to investigate a novel hypothesis about the way feedback from FEF influences V4, namely, via NMDA synapses. This model makes predictions for future experiments that could help uncover the mechanism of attention-related modulation of visual cortex. Taken together, these results have helped to elucidate our understanding of the circuits within and between frontal and visual cortical areas underlying attention.

This is at once a review and a summary of the tremendous advances that have been made in recent years on the effect of attention on visual perception. This broad-ranging volume will appeal to vision scientists as well as to those involved in using visual processes in computer animations, display design or the sensory systems of machines. Physiologists and neuroscientists interested in any aspect of sensory or motor processes will also find it very useful.

This volume is not an attempt to give a comprehensive treatment of the many facets of intelligence. Rather, the intention is to present multiple approaches to interesting and novel ways of looking at old problems. The focus is on the visual and some of the conceptual intelligences. Vision is man's primary cognitive contact with the world around him, and we are vividly reminded of this by Roman Jakobson's autobiographical note, "The Evasive Initial" with which this volume begins. That we see the world as well as we do is something of a miracle. Looking out through our eyes, our brains give us reliable knowledge about the world around us in all it beauty of form, color and movement. The chapters in the first section look at how this may come about from various perspectives. How from the intensity array which the world casts on the eye's retina does the brain achieve recognition? What may be some of the processes involved in seeing? We see shapes, textures and colors, and subsequently, at the more cognitive levels, recognize them as objects which we can manipulate: we inspect them to discover what to use them for. The objects are tools or food; they are things, beautiful, lovable or frightening. They are things to remember and to talk about to our friends, or to ask someone for. We can ask for many or just a few. They are important to us or trivial.

LaBerge explores how we are able to restrict the input of extraneous and confusing information, or prepare to process a future stimulus, in order to take effective action. As well as describing the pathways in the cortex presumed to be involved in attentional processing, he examines the hypothesis that two subcortical structures, the superior colliculus and the thalamus, contain circuit mechanisms that embody an algorithm of attention. In addition, he takes us through various ways of posing the problem, from an information-processing description of how attention works to a consideration of some of the cognitive and behavioral consequences of the brain's computations, such as desiring, judging, imaging, and remembering.

Proceedings of the Fifth International School on Neural Networks "E.R. Caianiello" on Visual Attention MechaProceedings of the Fifth International School on Neural Networks "E.R. Caianiello" on Visual Attention Mechanisms, held 23-28 October 2000 in Vietri sul Mare, Italy.nisms, held 23-28 October 2000 in Vietri sul Mare, Italy. The book covers a number of broad themes relevant to visual attention, ranging from computer vision to psychology and physiology of vision. The main theme of the book is the attention processes of vision systems and it aims to point out the analogies and the divergences of biological vision with the frameworks introduced by computer scientists in artificial vision.

The Neural Theory of Visual Attention of Bundesen, Habekost, and Kyllingsbæk (2005) was proposed as a neural interpretation of Bundesen’s (1990) theory of visual attention (TVA). In NTVA, visual attention functions via two mechanisms: by dynamic remapping of receptive fields of cortical cells such that more cells are devoted to behaviorally important objects than to less important ones (filtering) and by multiplicative scaling of the level of activation in cells coding for particular features (pigeonholing). NTVA accounts for a wide range of known attentional effects in human performance and a wide range of effects observed in firing rates of single cells in the primate visual system and thus provides a mathematical framework to unify the 2 fields of research. In this Research Topic of Frontiers in Psychology, some of the leading theories of visual attention at both the cognitive, neuropsychological, and neurophysiological levels are presented and evaluated. In addition, the Research Topic encompasses application of the framework of NTVA to various patient populations and to neuroimaging as well as genetic and psychopharmacological studies.