Types Of Visual Information Research Articles

Role of the temporal domain for response selection and perceptual binding.

Most cognitive functions are based on highly parallel and distributed information processing by the brain. A paradigmatic example is provided by the vertebrate visual system where numerous cortical areas have been described which analyse different types of visual information. At present, it is unclear how information can be integrated and how coherent representational states can be established in such distributed systems. We suggest that this so-called 'binding problem' may be solved in the temporal domain. The hypothesis is that synchronization of neuronal discharges can serve for the integration of distributed neurons into cell assemblies and that this process may underlie the selection of perceptually and behaviourally relevant information. We review experimental results, mainly obtained in the visual system, which support this temporal binding hypothesis.

Visual Motion-Detection Circuits in Flies: Parallel Direction- and Non-Direction-Sensitive Pathways between the Medulla and Lobula Plate

The neural circuitry of motion processing in insects, as in primates, involves the segregation of different types of visual information into parallel retinotopic pathways that subsequently are reunited at higher levels. In insects, achromatic, motion-sensitive pathways to the lobula plate are separated from color-processing pathways to the lobula. Further parallel subdivisions of the retinotopic pathways to the lobula plate have been suggested from anatomical observations. Here, we provide direct physiological evidence that the two most prominent of these latter pathways are, indeed, functionally distinct: recordings from the retinotopic pathway defined by small-field bushy T-cells (T4) demonstrate only weak directional selectivity to motion, in striking contrast with previously demonstrated strong directional selectivity in the second, T5-cell, pathway. Additional intracellular recordings and anatomical descriptions have been obtained from other identified neurons that may be crucial in early motion detection and processing: a deep medulla amacrine cell that seems well suited to provide the lateral interactions among retinotopic elements required for motion detection; a unique class of Y-cells that provide small-field, directionally selective feedback from the lobula plate to the medulla; and a new heterolateral lobula plate tangential cell that collates directional, motion-sensitive inputs. These results add important new elements to the set of identified neurons that process motion information. The results suggest specific hypotheses regarding the neuronal substrates for motion-processing circuitry and corroborate behavioral studies in bees that predict distinct pathways for directional and nondirectional motion.

Object and spatial visual working memory activate separate neural systems in human cortex.

Human and nonhuman primate visual systems are divided into object and spatial information processing pathways. In the macaque, it has been shown that these pathways project to separate areas in the frontal lobe and that the ventral and dorsal frontal areas are, respectively, involved in working memory for objects and spatial locations. A positron emission tomography (PET) study was done to determine if a similar anatomical segregation exists in humans for object and spatial visual working memory. Face working memory demonstrated significant increases in regional cerebral blood flow (rCBF), relative to location working memory, in fusiform, parahippocampal, inferior frontal, and anterior cingulate cortices, and in right thalamus and midline cerebellum. Location working memory demonstrated significant increases in cRBF, relative to face working memory, in superior and inferior parietal cortex, and in the superior frontal sulcus. Our results show that the neural systems involved in working memory for faces and for spatial location are functionally segregated, with different areas recruited in both extrastriate and frontal cortices for processing the two types of visual information.

Qualitative and quantitative features of axons projecting from caudal to rostral inferior temporal cortex of squirrel monkeys.

On the basis of cortical and subcortical connections and architectonics, inferior temporal (IT) cortex of squirrel monkeys consists of a caudal region, ITC, with dorsal (ITCd) and ventral (ITCv) subdivisions; a rostral region, ITR; and possibly a third region intermediate to ITC and ITR, ITI (Weller & Steele, 1992; Steele & Weller, 1993). The present study qualitatively and quantitatively examined the terminal arborizations of 26 axons in ITR and ITI labeled by injections of biocytin or, in one case, horseradish peroxidase, in ITCv. The majority of axons gave rise to a single terminal arbor, with a small number branching into two overlapping or nearby arbors. Presumptive terminal specializations consisted of rounded, bead-like swellings, most often located en passant. All axons terminated in layer 4 of cortex, and most had additional terminations in layers 3 and 5. The total extent of each axon's terminal arbor was 125-750 microns dorsoventrally (mean = 360.6 microns) and 150-725 microns anteroposteriorly (mean = 328.1 microns; all values uncorrected for shrinkage). In most axons, especially those with larger terminal fields, boutons were not uniformly distributed, but formed 2-4 clumps (mean = 2.2), with a mean width of 149 microns, separated by narrower regions of fewer boutons. Based on a cluster analysis of characteristics of the 26 axons, axons projecting from caudal (ITCv) to rostral (ITR or ITI) IT cortex of squirrel monkeys comprised three groups that we called Type I, Type II, and Type III. Type I axons, the smallest in area extent of terminal arbor, terminated predominantly in dorsal ITR. Type III axons, largest in areal extent, and Type II axons, intermediate in areal extent, terminated in ventral ITR and throughout ITI. The three classes of axons may correspond to different types of visual information entering rostral IT cortex. The clumping of boutons suggests that individual axons terminate in limited patches within their terminal fields.

A review of the neurophysiology of the turtle retina: Photoreceptors

How the vertebrate retina encodes and analyses information concerning light New increment and decrement, form, colour and movement is not fully understood. Neurophysiological studies of turtle retina have provided insights into how different types of visual information are processed. In the visual system, distinct functional channels appear to operate in parallel, namely ON/OFF, colour opponent/non-colour opponent and transient/sustained channels. Using the turtle retina as a model, this three-part review shows how functional pathways emerge from interactions between retinal neurons. It discusses how distinctive receptive field properties of the various types of retinal neuron are generated, as well as their significance for visual processing. Photoreceptors, which convert light into an electrical signal, are the subject of Part I. The structure, connectivity and light responses of these highly specialised cells are discussed. Photoreceptors are unusual sensory receptors because they respond to light with membrane hyperpolarisation. This decreases the rate of release of their neurotransmitter, glutamate. The phototransmitter interacts with postsynaptic receptors on horizontal and bipolar cells. Part II focuses on these second order neurons. Part III concludes with a discussion of amacrine and ganglion cells of the inner retina.

Color character recognition method based on human perception

Color is one of the most powerful and important types of visual information in various fields such as image processing, electronic imaging, and robot vision technologies. A new color character recognition system, composed of a camera, optical filters, an image board, a neuro board, and a micro computer was constructed. Using typewriter characters and backgrounds in five colors, two kinds of experiments were performed. The first consisted of preliminary experiments testing the effectiveness ofthe modified opponent-colortheory ofthe human eye for use in machine character recognition. The second was an experiment in color character recognition, in which the system recognized both characters and their colors.

Videohistory: Focusing on the American Past

The technological revolution of the twentieth century has provided historians with new sources of documentation for their research. With the advent of video technology, the researcher has access to new types of visual information about people, places, objects, and interactions. Just as the development of audio recording technology in the 1940s stimulated the field of oral history, the ease and low cost of video technology in the 1970s offered new opportunities for the historian interested in using visual documentation. Self-conscious and structured historical documentation with video -often called videohistoryprovides an essential component of research for historians interested in material culture, the use of objects, and the relationships of people to one another and to their environments. Many historians have also found videohistory an excellent way to capture the history of people and communities who do not leave extensive written documentation. Visual information, then, supplements and complements documentary evidence, audiotaped oral histories, and artifacts. The historian who uses the video medium to study a person's environment (and ways of interacting with that environment) and material culture encounters a density of information rarely found in other forms of historical documentation. The words, background, objects, and movements each tell a separate story; when analyzed together, the subtle relationships between them provide an information total greater than the sum of the parts. Individual scholars and projects nationwide have created a wide range of videohistory materials that are now available for research use. Videohistory collections contain visual portraits of scientists, politicians, doctors, teachers, and artists. A video camera captured veterans discussing their Vietnam experience and a group of women scientists from Los Alamos recalling the first atomic bomb test. Videohistorians have recorded processes of traditional food preparation by southwestern native Americans, dairy farming by Minnesotans, and clockmaking by New Englanders to document rapidly changing life-styles. Videohistorians have preserved glimpses of life in the city and rural towns, in the laboratory and the slate quarry, on the farm and in the factory. Videohistory collections mirror the diversity of

Anatomical segregation of two cortical visual pathways in the macaque monkey

A number of lines of evidence suggest that, in the macaque monkey, inferior parietal and inferotemporal cortices process different types of visual information. It has been suggested that visual information reaching these two subdivisions follows separate pathways from the striate cortex through the prestriate cortex. We examined directly this possibility by placing injections of the retrograde fluorescent tracers, fast blue and diamidino yellow, in inferior parietal and inferotemporal cortex and examining the spatial pattern of cortical areas containing labeled cells in two-dimensional reconstructions of the cortex. The results of injections in inferotemporal cortex show that TEO receives afferents from areas V2, ventral V3, V3A, central V4, V4t, and DPL in prestriate cortex and from areas IPa, PGa, and FST in the superior temporal sulcus (STS). Area TEp receives afferents only from V4 in prestriate cortex and from IPa, PGa, and FST in the anterior STS. Area TEa receives no prestriate input and is innervated by IPa, PGa, FST, and TPO in the anterior STS. The results of injections in inferior parietal cortex demonstrate that POa receives afferents from dorsal V3, V3A, peripheral V4, DPL, and PO in prestriate cortex, from MST and *VIP and from IPa, PGa, TPO, and FST in anterior STS. Area PGc (corresponding to 7a) is innervated by PO, MST, and by TPO in the anterior STS. Examination of the two-dimensional reconstructions of the pattern of labeling after combined injections of fast blue and diamidino yellow in areas POa and TEO revealed that these areas are principally innervated by different prestriate areas. Only a small region, centered on area V3A and extending into V4 and DPL, contained cells labeled by either injection as well as a small number of double-labeled cells. In contrast, areas POa and TEO receive afferents from extensive common regions in the anterior STS corresponding to areas IPa, PGa, and FST. These results directly demonstrate that visual information from the striate cortex reaches inferior parietal and inferotemporal cortices through largely separate prestriate cortical pathways. On the other hand, both parietal and inferotemporal cortices receive common inputs from extensive regions in the anterior STS which map play a role in linking the processing occurring in these two cortical subdivisions of the visual system.

Mast cells in newly formed lining tissue during acute inflammation: a six day air pouch model in the mouse.

Connective tissue mast cells were topographically and quantitatively studied in the newly formed lining tissue of six day old air pouches induced in the dorsal surface of mice. The results showed that the number of mast cells in the cavities innermost lining increased after injection of carrageenan into the cavity. Degranulation of mast cells was also observed. Variations in mast cell numbers in the lining seemed to correlate with the histamine content. These findings suggest that mast cells not only participate in the initiation of the early phase of acute inflammation but also appear to play an important part in regulating and prolonging more chronic inflammatory reactions.

The span of the effective stimulus during a fixation in reading

A computer-based eye-movement controlled, display system was developed for the study of perceptual processes in reading. A study was conducted to identify the region from which skilled readers pick up various types of visual information during a fixation while reading. This study involved making display changes, based on eye position, in the text pattern as the subject was in the act of reading from it, and then examining the effects these changes produced on eye behavior. The results indicated that the subjects acquired word-length pattern information at least 12 to 15 character positions to the right of the fixation point, and that this information primarily influenced saccade lengths. Specific letter- and word-shape information were acquired no further than 10 character positions to the right of the fixation point.

The perceptual span and peripheral cues in reading

Skilled readers read passages that were displayed on a Cathode Ray Tube controlled by a computer. The readers' eye movements were monitored and certain critical words were changed by the computer as the eye was in motion. The experimental technique utilized in the study provided data on how wide the area is from which a reader acquires information during a fixation in silent reading. The results also delineate different types of visual information that are acquired from various areas within the perceptual span. It was found that a reader was able to make a semantic interpretation of a word that began 1–6 character spaces from his fixation point. When he fixated 7–12 character spaces prior to a word, he was able to pick up such gross visual characteristics as word shape and initial and final letters. It was concluded that the skilled reader is able to take advantage of information in the periphery. However, the size of the area from which he does is rather small.

A developmental comparison of the processing of two types of visual information

Simple geometric forms and spatial position markers were tachistoscopically presented to Ss from four age groups (ranging from five years to adult) who responded by recreating the visual array with magnetic tokens. The basic findings were: (a) Ss remembered item positions better than identities; (b) no asymptote of position recall was reached by any age group when up to five position markers were presented; (c) when required to process identity information, position memory suffered, younger Ss showing the greatest decrement; (d) with unlimited viewing time, the pattern of results relating identity and spatial recall was not altered; (e) recall was better for the locations of position markers than for locations of geometric items. The results supported an hypothesis of separate processing mechanisms for spatial location and identity information. Improvement with age seems to result from an increasing ability to integrate the functioning of these separate mechanisms.