Visual field defects after frontal eye-field lesions in monkeys

Latto, Richard; Cowey, Alan

doi:10.1016/0006-8993(71)90002-3

Cited by 185 publications

(51 citation statements)

References 29 publications

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“…This pattern was apparent for both hemifields, and indeed the impact of right FEF TMS upon ␣ (the TVA parameter corresponding to top-down control) did not differ between hemifields. On the other hand, there was a spatial tendency for right FEF TMS to enhance report of ipsilateral right targets and to impair report of left targets in those displays that presented two targets in opposite hemifields [analogous to the extinction that has been reported to reveal spatial deficits after FEF damage in monkeys (Latto and Cowey, 1971)]. …”

Section: Discussionmentioning

confidence: 99%

Visual Selection and the Human Frontal Eye Fields: Effects of Frontal Transcranial Magnetic Stimulation on Partial Report Analyzed by Bundesen's Theory of Visual Attention

Hung

Driver²,

Walsh³

2011

J. Neurosci.

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Section: Discussionmentioning

confidence: 99%

Visual Selection and the Human Frontal Eye Fields: Effects of Frontal Transcranial Magnetic Stimulation on Partial Report Analyzed by Bundesen's Theory of Visual Attention

Hung

Driver²,

Walsh³

2011

J. Neurosci.

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“…It is clear, for example, that non-V1 cortical areas play an essential role because removal of all cortex except V1 in primates renders them visually unresponsive (24). It is also the case that lesions of the frontal eye field (FEF; the anatomical limits of which remain unsharp) in the monkey in some ways simulate that of visual cortex damage itself because the animal appears to be unresponsive to visual events, and the effects of different subtotal lesions can be mapped specifically in a "monkey perimeter" (25). It is striking that the foci active in awareness in a blindsight subject led to the identification of frontal area 46 (14) with reported awareness, which itself has strong connections with FEF.…”

Section: Discussionmentioning

confidence: 99%

Consciousness of the first order in blindsight

Sahraie

Hibbard

Trevethan³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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At suprathreshold levels, detection and awareness of visual stimuli are typically synonymous in nonclinical populations. But following postgeniculate lesions, some patients may perform above chance in forced-choice detection paradigms, while reporting not to see the visual events presented within their blind field. This phenomenon, termed "blindsight," is intriguing because it demonstrates a dissociation between detection and perception. It is possible, however, for a blindsight patient to have some "feeling" of the occurrence of an event without seeing per se. This is termed blindsight type II to distinguish it from the type I, defined as discrimination capability in the total absence of any acknowledged awareness. Here we report on a well-studied patient, D.B., whose blindsight capabilities have been previously documented. We have found that D.B. is capable of detecting visual patterns defined by changes in luminance (first-order gratings) and those defined by contrast modulation of textured patterns (textured gratings; second-order stimuli) while being aware of the former but reporting no awareness of the latter. We have systematically investigated the parameters that could lead to visual awareness of the patterns and show that mechanisms underlying the subjective reports of visual awareness rely primarily on low spatial frequency, first-order spatial components of the image.S ince the early reports in the 1970s of brain-damaged human subjects who are able to discriminate visual events in the absence of self-reported conscious awareness (1, 2), an obvious but difficult question has arisen as to what stimulus properties would drive visual awareness. In nonclinical populations, a number of paradigms have been developed to examine the prerequisites. For example, in attentional-blink paradigms (3), rapid serial visual presentation demonstrates that letters or words presented within a short temporal window following a task-relevant target may be degraded. As is well known, manipulating the functional significance of targets by using the participant's name (4) or emotional stimuli (5) modulates reported perception and discrimination of stimuli. More recently, the flash suppression technique in binocular rivalry, where one eye is presented with a rapid random sequence of abstract shapes while a specific stimulus is presented to the other eye (6), has been used to demonstrate that some classes of stimuli can break through and elicit awareness (7,8). Common among tasks presented to nonclinical subjects is the assumption that awareness of the stimuli and their discrimination, if not identical, cannot be dissociated from each other.The blindsight phenomenon in human subjects is unique: following visual cortical lesions, the detection and discrimination of stimulus features can occur in the absence of subjective awareness. For this reason, the research relies on "heroic" approaches such as forced-choice guessing (9). The reported awareness is then recorded using a commentary key paradigm on either a binary (10) or a mult...

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“…Although the simple coding of saccades may not be equivalent to the analysis of far space, some authors have pointed to the possibility that an area involved in eye movement programming might contribute to far space representation. Therefore, based on the physiological properties of area 8 neurons and on ablation studies showing that lesions of monkeys' frontal eye-fields causes inattention for stimuli presented contralateral to the brain damage (Latto & Cowey, 1971) especially in the far space (Rizzolatti, Gentilucci, & Matelli, 1985), Rizzolatti and Gallese (1988) proposed that area 8 is involved in far space representation. Furthermore, Colby, Duhamel, and Goldberg (1996) showed that neurons in area LIP (that is richly connected with, and physiologically similar to, area 8) might be another neural substrate for the representation of far space in monkeys.…”

Section: Introductionmentioning

confidence: 99%

When Far Becomes Near: Remapping of Space by Tool Use

Berti

Frassinetti

2000

Journal of Cognitive Neuroscience

630

398

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Abstract& Far (extrapersonal) and near (peripersonal) spaces are behaviorally defined as the space outside the hand-reaching distance and the space within the hand-reaching distance. Animal and human studies have confirmed this distinction, showing that space is not homogeneously represented in the brain. In this paper we demonstrate that the coding of space as ''far'' and ''near'' is not only determined by the hand-reaching distance, but it is also dependent on how the brain represents the extension of the body space. We will show that when the cerebral representation of body space is extended to include objects or tools used by the subject, space previously mapped as far can be remapped as near. Patient P.P., after a right hemisphere stroke, showed a dissociation between near and far spaces in the manifestation of neglect. Indeed, in a line bisection task, neglect was apparent in near space, but not in far space when bisection in the far space was performed with a projection lightpen. However, when in the far space bisection was performed with a stick, used by the patient to reach the line, neglect appeared and was as severe as neglect in the near space. An artificial extension of the patient's body (the stick) caused a remapping of far space as near space. &

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Visual field defects after frontal eye-field lesions in monkeys

Cited by 185 publications

References 29 publications

Visual Selection and the Human Frontal Eye Fields: Effects of Frontal Transcranial Magnetic Stimulation on Partial Report Analyzed by Bundesen's Theory of Visual Attention

Visual Selection and the Human Frontal Eye Fields: Effects of Frontal Transcranial Magnetic Stimulation on Partial Report Analyzed by Bundesen's Theory of Visual Attention

Consciousness of the first order in blindsight

When Far Becomes Near: Remapping of Space by Tool Use

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