The speed of thought: information processing in the cerebral cortex

This book deals with information processing in the primate temporal visual cortex, one of the higher visual association areas, which is believed to be important for the representation of complex stimuli and may also play a role in visual memory. Here, the need for rapid information processing shapes the functional architecture of all sensory systems, acting to reduce, where possible, wiring length and the number of synapses, to allow faster processing.</p

An introduction to the visual system [2nd ed.]

Building on the successful formula of the first edition, Martin Tovee offers a concise but detailed account of how the visual system is organised and functions to produce visual perception. He takes his readers from first principles; the structure and function of the eye and what happens when light enters, to how we see and process images, recognise patterns and faces, and through to the most recent discoveries in molecular genetics and brain imaging, and how they have uncovered a host of new advances in our understanding of how visual information is processed within the brain. Incorporating new material throughout, including almost 50 new images, every chapter has been updated to include the latest research, and culminates in helpful key points, which summarise the lessons learnt. This book is an invaluable course text for students within the fields of psychology, neuroscience, biology and physiology.</p

An introduction to the visual system [2nd ed.]

Building on the successful formula of the first edition, Martin Tovee offers a concise but detailed account of how the visual system is organised and functions to produce visual perception. He takes his readers from first principles; the structure and function of the eye and what happens when light enters, to how we see and process images, recognise patterns and faces, and through to the most recent discoveries in molecular genetics and brain imaging, and how they have uncovered a host of new advances in our understanding of how visual information is processed within the brain. Incorporating new material throughout, including almost 50 new images, every chapter has been updated to include the latest research, and culminates in helpful key points, which summarise the lessons learnt. This book is an invaluable course text for students within the fields of psychology, neuroscience, biology and physiology.</p

Is face processing special?

Are faces processed differently from other complex visual stimuli? For this to be the case, three main criteria would have to be fulfilled: (1) face recognition would exhibit functional characteristics not found in the recognition of other visual stimuli, (2) the neural machinery that mediates face recognition would be anatomically separate from the neurons mediating general object recognition, and (3) faces would be represented differently from other visual stimuli at the neural level. This paper assesses the data bearing on these criteria and discusses whether they do indeed constitute evidence for a special face processing system.</p

The molecular genetics and evolution of primate colour vision

Until recently, the genetic basis of colour vision could only be inferred from measuring the colour vision of family groups. However, in the past few years the sites of the genes for visual pigments have been located and sequenced. The genes that specify the opsins for the rod and short-wavelength cone pigments are located on the third and seventh chromosomes, respectively. In Old World primates the genes for the middle- and long-wavelength pigments are located on the q arm of the X chromosome in a head-to-tail array. The close sequence similarity of the two genes on the X chromosome leads to a high frequency of unequal inter- and intragenic recombination leading to gene deletion or the creation of hybrid genes. In New World primates there is only a single locus on the X chromosome for a middle- to long-wavelength cone pigment. However, three alleles can occur at this locus and each codes for a slightly different cone pigment. As a result there are three types of male dichromat and three types of female dichromat and trichromat in each species. Colour vision in New World primates might be an intermediate stage between the uniform dichromacy of non-primate mammals and the uniform trichromacy of Old World primates. Alternatively, colour vision in New World primates might be an adaptation to allow a wide variety of colour-vision types within a single family group. © 1994.</p

Face cells

It has been known since the 1970s that there are neurons in the monkey visual system that are sensitiveto faces. These face cells have been studied in most detail in the anterior inferior temporal (IT)cortex and the upper bank of the superior temporal sulcus (STS), but they also occur in other areas suchas the amygdala and the inferior convexity of the prefrontal cortex (Figure 1).Characteristically, the optimal stimuli of face cells cannot be deconstructed into simpler componentshapes (Wang et al., 1996). In general, these cells show virtually no response to any other stimulustested (such as textures, gratings, bars, and the edges of various colors), but respond strongly to avariety of faces, including real ones, plastic models, and video display unit images of human andmonkey faces. The responses of many face cells are invariant to size and position; the cell’s responseis maintained when there is a change in the size of the face, or if the position of the facewithin the cell’s receptive field is altered. Face cells do not respond well to images of faces that havehad the components rearranged, even though all the components are still present and the outline isunchanged (e.g., Perrett et al., 1992). Face cells are even sensitive to the relative position of featureswithin the face; particularly important is inter-eye distance, distance from eyes to mouth, and theamount and style of hair on the forehead (e.g., Young and Yamane, 1992)</p

An introduction to the visual system

In recent years there has been a host of new advances in our understanding of how we see. From molecular genetics come details of the photopigments and the molecular causes of disorders like colour blindness. In-depth analysis has shown how a cell converts light into a neural signal using the photopigments. Traditional techniques of microelectrode recording along with new techniques of functional imaging - such as PET scans - have made it possible to understand how visual information is processed in the brain. This processing results in the single coherent perception of the world we see in our 'mind's eye'. An Introduction to the Visual System provides a concise, but detailed, overview of this field. It is clearly written, and each chapter ends with a helpful 'key points' section. It is ideal for anyone studying visual perception, from the second year of an undergraduate course onwards.</p

An introduction to the visual system

In recent years there has been a host of new advances in our understanding of how we see. From molecular genetics come details of the photopigments and the molecular causes of disorders like colour blindness. In-depth analysis has shown how a cell converts light into a neural signal using the photopigments. Traditional techniques of microelectrode recording along with new techniques of functional imaging - such as PET scans - have made it possible to understand how visual information is processed in the brain. This processing results in the single coherent perception of the world we see in our 'mind's eye'. An Introduction to the Visual System provides a concise, but detailed, overview of this field. It is clearly written, and each chapter ends with a helpful 'key points' section. It is ideal for anyone studying visual perception, from the second year of an undergraduate course onwards.</p

The speed of thought: information processing in the cerebral cortex

This book deals with information processing in the primate temporal visual cortex, one of the higher visual association areas, which is believed to be important for the representation of complex stimuli and may also play a role in visual memory. Here, the need for rapid information processing shapes the functional architecture of all sensory systems, acting to reduce, where possible, wiring length and the number of synapses, to allow faster processing.</p

The molecular genetics and evolution of primate colour vision

Until recently, the genetic basis of colour vision could only be inferred from measuring the colour vision of family groups. However, in the past few years the sites of the genes for visual pigments have been located and sequenced. The genes that specify the opsins for the rod and short-wavelength cone pigments are located on the third and seventh chromosomes, respectively. In Old World primates the genes for the middle- and long-wavelength pigments are located on the q arm of the X chromosome in a head-to-tail array. The close sequence similarity of the two genes on the X chromosome leads to a high frequency of unequal inter- and intragenic recombination leading to gene deletion or the creation of hybrid genes. In New World primates there is only a single locus on the X chromosome for a middle- to long-wavelength cone pigment. However, three alleles can occur at this locus and each codes for a slightly different cone pigment. As a result there are three types of male dichromat and three types of female dichromat and trichromat in each species. Colour vision in New World primates might be an intermediate stage between the uniform dichromacy of non-primate mammals and the uniform trichromacy of Old World primates. Alternatively, colour vision in New World primates might be an adaptation to allow a wide variety of colour-vision types within a single family group.</p