bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional magnetic resonance imaging and positron emission tomography studies of motion perception, eye movements, and reading
Authors: Greenlee Mark W. 
Published: April 2012

AbstractThis chapter addresses the recent findings from studies of visual motion processing, eye movements, and reading. It specifically outlines the brain-imaging studies that have studied cortical responses to visual motion. It then provides studies that explore the cortical control of reading and evidence for the involvement of cortical areas in reading disabilities. It assesses the current findings on functional imaging of human cortical responses to visual motion. In addition, it deals with the influences associated with stimulus properties. The results of many groups suggest that several cortical areas respond selectively to visual motion. Different visual areas also respond to complex optic flow fields. Moreover, the data indicate that changes in the subject's attention can modify the blood oxygen level-dependent (BOLD) response to visual stimulation. Attention to different aspects of moving stimuli can lead to differences in the response. The role of pursuit eye movements in motion perception and the resultant pattern of BOLD responses are also considered. The task-dependent effects of pro- and anti-saccades, variations in the amplitude and frequency of saccades, and the difference between saccadic eye movements and smooth pursuit are also explained. Finally, it describes the results linked to reading and disorders of reading.
Lesions in primate visual cortex leading to deficits of visual perception
Authors: Merigan William H. , Pasternak Tatiana 
Published: April 2012

AbstractThis chapter reports a selective, critical analysis of the contribution of lesions of visual neurons to understand the function of the visual pathways. The analysis highlights more recent studies that have examined the influences of striate and extrastriate lesions in the primate. It specifically discusses the deficits of visual perception caused by lesions in primate visual cortex, e.g., lesions caused by ablation experiments in monkeys, by relating the symptoms caused by the lesions to the physiology of the visual system. It is shown that V4 lesions seem to transiently disrupt colour discrimination learning and to slightly elevate chromatic contrast thresholds, but not to permanently disrupt discrimination of hue differences. A number of lesion studies have generated disruptions of more complex behaviours such as reaching, eye movements, and learning and attention. Moreover, many studies have shown a noteworthy degree of recovery after lesions in both the ventral and the dorsal pathways, although the recovery looks to be much more pronounced in the dorsal than in the ventral pathway.
Magnetic stimulation in studies of vision and attention
Authors: Ellison Amanda , Stewart Lauren , Cowey Alan , Walsh Vincent 
Published: April 2012

AbstractThis chapter shows that short lasting, reversible functional lesions can be safely produced in healthy humans, too, by means of transcranial magnetic stimulation (TMS). TMS thus establishes a novel method to associate animal studies with those on patients and to create a new discipline, experimental neuropsychology, in humans. The role of the parietal cortex in visual attention is a question of central concern. TMS has many uses in the vision sciences that demand the attention of researchers. The impact of learning and plasticity are good paradigms for studying cortical change and the potential for combining TMS with other neuroimaging techniques will widen the scope of its utility in the study of vision.
Unconscious perception: blindsight
Authors: Weiskrantz L. 
Published: April 2012

AbstractThis chapter shows that blindsight illustrates that at least a limited analysis of visual signals continues in some patients even in those parts of their visual field for which they are subjectively blind. It begins by presenting categories of residual visual capacities. There are two general approaches to indirect methods of testing for residual visual function that allow an inference without requiring the subject to guess ‘without seeing’: (1) reflexes to visual stimuli in the blind hemifield; (2) interactions between the intact and impaired hemifields. There can be no doubt that parallel extrastriate visual pathways can mediate visual discriminations, in humans as well as in other primates, but it is the dissociations that emerge, suggesting a segregation of functions, that we are only beginning to characterize.
Perception, memory, and agnosia
Authors: Farah Martha J. 
Published: April 2012

AbstractThis chapter outlines the evidence on perception, memory, and agnosia. It proposes a rapprochement among the different positions that have been taken on the issue. It concentrates on a form of agnosia called, by most authors, associative visual agnosia. The empirical evidence on memory and perception in associative agnosia is provided. At the early stages, the nature of the representations is influenced only minimally by learning and experience. At progressively later stages, learning plays a more significant role in identifying what is explicitly represented. The experience of having seen particular objects will shape what the later representations are most useful for representing.
Recovery and rehabilitation of cerebral visual disorders
Authors: Zihl Josef 
Published: April 2012

AbstractThis chapter presents a brief description of visual deficits after brain injury. It also discusses observations on spontaneous recovery of vision. In addition, the return of visual function using systematic practice and the improvement of visual efficiency by compensation strategies are described. There is evidence that visual deficits induced by acquired brain injury can spontaneously recover, at least to a certain degree. In addition, there is additional data that specific training can support functional recovery, although the underlying mechanisms are not exactly known. Furthermore, many of the described procedures still have an experimental character, but they represent a first step in developing more sophisticated procedures to decrease visual deficits or their consequences.
The role of similarity in natural categorization
Authors: Hampton James A. 
Published: April 2012

AbstractThe intuitive idea that one puts things into categories because one finds them similar appears to be non-controversial, if not circular. Cars are clearly more similar to other cars than they are to trees, and trees more similar to other trees than they are to cars. However, a number of theorists have recently questioned the degree to which the notion of similarity is sufficiently clearly defined and constrained to serve as an explanation of the categorization. This chapter discusses the arguments for and against basing categorization on a notion of similarity, and concludes that, construed broadly, similarity may yet be the best explanation of how most of our conceptual categories function. It proposes a distinction between concepts viewed as a cultural phenomenon and concepts at the psychological level, and suggests a naive model of conceptual development that starts with concepts as similarity clusters.
Induction and inherent similarity
Authors: Ellison T. Mark 
Published: April 2012

AbstractThis chapter explores a new account of the difference between logical compatibility and inductive confirmation. No amount of past evidence ensures any conclusion about the future. Nevertheless, certain potential generalizations are reliable adopted, and others ignored with conflicting predictions. This selection and its lack of basis in logic is well recognized in philosophy, where it is termed the problem of induction. However, the problem of induction is of concern not only for philosophers, but also for psychologists and cognitive scientists. In any scientific account of human inductive behaviour, reliable experimental results should be deducible from the experimental conditions.
Categorization by simplicity: a minimum description length approach to unsupervised clustering
Authors: Pothos Emmanuel M. , Chater Nick 
Published: April 2012

AbstractThere is a strong intuition that one important factor in determining psychological categories is that they should group similar items together — that categories should be seen as running along default lines in a psychological similarity space. To make this idea precise requires finding some ‘objective’ criterion for determining a ‘good’ classification, given a set of similarity data. This chapter provides such a criterion, based on an application of a simplicity principle, that can be viewed as a general criterion for cognition. To illustrate the approach, it addresses the specific illustrative problem of dividing a set of items into groups, on the basis of data consisting of pairwise similarities between the items. A simplicity principle is used to assess the relative goodness of different clusterings on the same data set: a particular classification is good to the extent that it provides a short encoding of the similarity information.
Issues in case-based reasoning
Authors: Rodríguez Abraham Rodríguez 
Published: April 2012

AbstractThis chapter provides an introduction to the paradigm of case-based reasoning, an approach to the design of knowledge-based systems which implements the idea that classification and problem-solving depend crucially on remembering similar past episodes. At the heart of any case-based system is a standard sequence of steps that has been described in detail, summarized as ‘retrieve, reuse, revise, and retain’. As a field, CBR has rapidly reached maturity, as evidenced by the number of commercial applications in use, as well as the existence of numerous development tools and methodologies. The current technological level in the field allows rapid development of help-desk-like applications, which are characterized by the simplicity of their representational structures and similarity function. However, limitations of current technology become apparent with more complex tasks.
Background knowledge and models of categorization
Authors: Heit Evan 
Published: April 2012

AbstractThis chapter focuses on the integration model of categorization, which is one similarity-based model that has already been applied to a series of experiments on background knowledge effects. This chapter addresses the generality of the integration model by applying it to a set of experiments designed by other researchers. How far can a similarity-based model of categorization go, applying ordinary assumptions about categorization and without making any special claims about other kinds of theoretical processing? The integration model is an exemplar model of categorization that has been extended to apply to situations in which previous knowledge has an influence.
Spatial neglect
Authors: Heilman Kenneth M. , Watson Robert T. , Valenstein Edward 
Published: April 2012

AbstractThis chapter provides a discussion of the history and mechanisms underlying spatial neglect. It also describes several neuropsychological mechanisms that have been hypothesized to account for hemispatial deficit, including deficits in attention, intention, and representation. It is shown that the mesencephalic-diencephalic reticular system mediates arousal, and unilateral attentional neglect follows unilateral mesencephalic reticular activating system lesions because the mesencephalic reticular formation does not prepare the cortex for sensory processing and/or because it no longer inhibits the ipsilateral nucleus reticularis, which then inhibits thalamic transmission of sensory input to the cortex. The action-intention hypothesis of spatial neglect states that while patients may be aware of stimuli in contralateral hemispace, they fail to act on these stimuli. In general, studies have revealed that patients with neglect are less likely to live independently than even patients with severe aphasia and a right hemiparesis.
Functional Anatomy of Attention and Neglect
Authors: Mesulam Marsel 
Published: April 2012

AbstractThis chapter attempts to illustrate that parietal lobe, frontal lobes, cingulate gyrus, striatum and thalamus constitute a large-scale network subserving spatial attention, that hemispatial neglect is a syndrome of the network as a whole, and that the complexity of this network is commensurate with the clinical heterogeneity of the neglect syndrome. It is noted that components of the ascending reticular activating system, such as the intralaminar thalamic nuclei, the brainstem raphe nuclei, the nucleus locus ceruleus, the ventral tegmental area-substantia nigra, and the nucleus basalis project to each cortical component of the attentional network. The reviewed data has resulted in the hypothesis that spatial attention is organized at the level of a distributed large-scale network revolving around three cortical components, each of which supports a slightly different neural representation of the extrapersonal space. Each of these components serves a dual purpose: it provides a local network for regional neural computations and also a nodal point for the linkage of distributed information. Moreover, the components of the attentional network can collectively specify whether and how an event in extrapersonal space will attract covert attentional shifts, orientation, foveation, manual grasp, and overt search behaviors.
Neglect in Monkeys
Authors: Wardak Claire , Olivier Etienne , Duhamel Jean-René 
Published: April 2012

AbstractThis chapter outlines results from permanent and reversible lesion experiments in monkeys. It also describes these in the light of current knowledge of the anatomical and functional organization of the parietal and frontal cortices. It first briefly establishes the current anatomical and functional background with respect to which monkey lesion experiments have to be interpreted. Cortical ablation studies in monkeys have demonstrated that neglect can occur following lesions of either the periarcuate frontal or the inferior parietal regions. In addition, it has been shown that the inactivation of distinct parietal and frontal subregions can generate selective deficits in visual attention and in target and movement selection, largely confirming the functional role originally postulated for these areas on the basis of single-cell recording studies.
Posterior parietal networks encoding visual space
Authors: Galletti Claudio , Fattori Patrizia 
Published: April 2012

AbstractThis chapter outlines the cellular mechanisms that are probably involved in the encoding process of visual space in physiological conditions. It is noted that gaze-dependent visual cells are not able to continually inform about what happens in the same spatial location of the visual field, regardless of eye movements. The real-position behavior could be the result of the work of many strongly modulated gaze-dependent visual cells. Two mechanisms possibly encoding the visual space have been proposed in the posterior parietal cortex (PPC). One is distributed, retinotopically organized, and based on the activity of gaze-dependent visual cells, and the other is direct, nonretinotopically organized, and based on the activity of the so-called real-position cells. It is proposed that the interaction between visual and oculomotor signals, as they occur in gaze-dependent visual cells, represents the first step in the analysis of visual space occurring in almost all areas of the dorsal visual stream. Real-position cells have not been yet detected in the dorsal PPC (areas V6A and ventral intraparietal area [VIP]) and in the ventral premotor cortex, i.e., in regions of the dorsal visual stream that are probably implicated in the visual guidance of actions.
Cortical substrates of visuospatial awareness outside the classical dorsal stream of visual processing
Authors: Thier Peter , Haarmeier Thomas , Chakraborty Subhojit , Lindner Axel , Tikhonov Alexander 
Published: April 2012

Abstract
This chapter presents work that addresses cortical substrates of visuospatial awareness outside the classical dorsal stream of visual processing. It is shown that the visual posterior sylvian area (VPS) may be a major player in a network of visual areas, underlying visual space perception and the subjective sense of visuospatial stability. This statement is based on experiments, which the authors have conducted in order to find an answer to the question of how the brain is able to construct a stable representation of the visual world, despite the confounding effects that movement of the subject has on the visual stimuli impinging on the retinas. The work clearly confirms the notion that the perception of visual motion is based on an inferential mechanism involving a nonretinal reference signal capturing the visual consequences of the eye movement. Furthermore, it illustrates that this inferential mechanism resides in rather ‘late’ parts of the cortical hierarchy of motion processing, sparing the early stages up to cortical area middle temporal (MT), and that disturbances of this mechanism may give rise to severe disturbances of vision and spatial orientation as exemplified by RW.
The exploration of space and objects in neglect
Authors: Niemeier Matthias , Karnath Hans-Otto 
Published: April 2012

AbstractThis chapter deals with the exploration of space and objects in spatial neglect. The studies demonstrate that both segmentation and rotation of stimuli have an impact on neglect symptoms which can be described in object-centered coordinates. In addition, it outlines experimental data reported on the spatial distribution of neglect patients' spontaneous exploratory behavior and then contrasts these results with the predictions of the enhancement and the normalization models. Moreover, an alternative concept, referred to as integrated space-object map (ISO-map), that prevents the presented problems by combining the enhancement model with a normalization model, is proposed. It is noted that the simulations indicate that both types of coordinates are simultaneously disturbed, suggesting that both coordinate systems might be closely connected in the brain. Finally, it answers how and where the ISO-map might be enforced in the brain.
Visual peripersonal space in humans
Authors: Làdavas Elisabetta 
Published: April 2012

AbstractThis chapter outlines evidence of the existence of a visual peripersonal space in humans that seems to be codified by an integrated visuotactile system. It describes the evidence of the existence of the peripersonal space centered on the hand and on the face. It also examines the functional properties of this space. It then considers the dynamic aspect of the peripersonal space, i.e., whether this space is fixed or whether it can be expanded or reduced depending on the action performed in space. The data shows the existence of an integrated system controlling both visual and tactile inputs within peripersonal space around the face and the hand and demonstrates how this system is functionally separated from that controlling visual information in the extrapersonal space. Moreover, evidence indicates that the visual experience of the body can somehow ‘boost’ the signal strength to neuronal circuits associated with the feel-touch experience. Furthermore, results illustrate that sight of the body part improves perception of visual stimuli presented in the peripersonal space.
The contribution of retinotopic and multimodal coding of space to horizontal space misrepresentation in neglect and hemianopia
Authors: Doricchi Fabrizio 
Published: April 2012

AbstractThis chapter addresses some apparently paradoxical phenomena concerning horizontal space misperception and misrepresentation in patients with left unilateral neglect. It concentrates on some empirical findings considered relevant for the understanding of ‘misrepresenting behaviors’ in neglect patients. A series of studies run by the author with several colleagues are described and the findings are related to those of investigations performed by other researchers in the field. In addition, the problem of space misrepresentation in hemianopia is addressed, and readers are briefly reminded about phenomena of size misperception due to dysmetropsia. On the basis of the empirical findings and the arguments summarized, misperception or misrepresentation of horizontal space, as determined in distance and size reproduction tasks explicitly requiring orienting toward the contralesional space, cannot be considered as the fundamental dysfunction explaining the rich, varied, and complex symptomatology that can be observed in neglect patients. Rather, horizontal space misrepresentation in neglect patients appears to be the result of concomitant disruption of visual retinotopic and specific multimodal non retinotopic representations of space (probably head centered).
Mapping spatial attention with reaction time in neglect patients
Authors: Marzi Carlo A. , Natale Elina , Anderson Britt 
Published: April 2012

AbstractThis chapter describes two attempts to cast light on an attentional model of neglect by trying to specify two important aspects. First, it examines whether the attentional impairment concerns exogenous stimulus-driven attention or endogenous controlled attention. Second, it fits the reaction time (RT) data to the saliency map model of neglect proposed by Anderson, which is a formal model of neglect inspired by clinical data (line bisection). The overall rationale of the approach depends on the idea that speed of RT (and detection performance) at various locations in the visual field depends on both retinal and attentional factors. The RT approach used in the study of the distribution of spatial attention across the visual field in neglect patients without hemianopia has provided evidence in broad agreement with hemispatial theories of neglect. In addition, a clear-cut hemifield difference in performance is shown. Moreover, fitting the RT data to the mathematical model of neglect proposed by Anderson has proved to be a fruitful exercise.
Primary sensory deficits after right brain damage—an attentional disorder by any other name?
Authors: Halligan Peter W. , Marshall John C. 
Published: April 2012

AbstractThis chapter provides a review of primary sensory deficits after right brain damage. It begins by presenting the historical basis for the conceptual divide between ‘primary’ and ‘high-level’ deficits. A number of converging studies have demonstrated that impairments such as visual field deficits, somatosensory disorders, and motor disorders, traditionally conceived as primary deficits, involve impairments of higher-order cognitive processes. The mere clinical fact that some patients show deficits on one set of tasks whereas others show deficits on other tasks does not in itself provide sufficient reason to justify a qualitative distinction between visual field deficit (VFD) and visual-spatial neglect (VSN).
Spatial, Temporal, and Form-Binding Effects in Vision
Authors: Riddoch M. Jane , Humphreys Glyn W. 
Published: April 2012

AbstractThis chapter addresses the nature of the processes which allow form elements to be bound into contours, contours to be bound into shapes, and the conjunctions of surface features such as color and form to be bound together. It then reports the case for several different forms of binding in visual processing; some are the function of the ventral visual system, while others may come about through the involvement of the dorsal visual pathway. In addition, it offers neuropsychological data suggesting that binding may be based on the common temporal onset of visual stimuli. Damage to early visual processing within the ventral visual stream can disrupt the binding of contours into shapes, although the binding of form elements into contours can still operate. Furthermore, the function of transient binding may be to provide the visual system with a rapid representation of the world.