Biomedical subjects

C M Butter

Publications and source records attributed to C M Butter.

At least 19 recordsLinked to original sources

PubMed1998

Spatial characteristics of cerebral polyopia: a case study.

A 41-year-old woman showed bilateral monocular polyopia and an incomplete, right-sided homonymous hemianopia following bilateral cerebral strokes confirmed by neuroimaging. She was tested with briefly-presented visual stimuli to determine whether her polyopic images varied with visual field position of stimuli which evoked them. Stimuli close to her scotoma elicited polyopic images at shorter latency and higher probability than did stimuli more distant from it. RS could maintain stable fixation on small stimuli, suggesting that eye movements were not responsible for her polyopia. We discuss the possibility that cerebral polyopia is due to recoding of visual receptive fields in primary visual cortex and that bilateral occipital lesions are a causative factor in the genesis of the disorder.

Adult↗

PubMed1997

Field-specific deficits in visual imagery following hemianopia due to unilateral occipital infarcts.

Patients with stable, homonymous hemianopia due to unilateral occipital infarcts and control subjects performed a task in which they judged whether or not an arrow was pointing at one of the dots in a pattern of dots they had recently seen in free vision, but was no longer visible. This task, as shown in prior studies as well as in the present one, involves the use of visual imagery. The patients made more errors when the arrow pointed to the side ipsilateral to their hemianopia than they did when the arrow pointed to the side contralateral to their hemianopia. The patients' performance in control tasks indicated that this impairment was not due to deficits in several non-imaginal processes required to perform the imagery task, namely scanning the dots and perceiving their spatial positions, memory for their position and encoding arrow direction. These findings support the view that visual imagery involves topographically organized visual areas of the occipital lobe.

Adult↗

PubMed1996

Effects of stimulus source and intensity on covert orientation to auditory stimuli.

Normal subjects showed costs and benefits of informative auditory spatial cues with auditory targets in RT tasks when stimulus intensity was low, or when the stimuli were presented monaurally through headphones. These findings imply that attention to auditory stimuli, like attention to visual or tactile stimuli, can be shifted spatially in detection tasks, and that covert orienting to auditory stimuli occurs in conditions favoring the intention to orient the head to a sound source. According to this view, orienting of attention to auditory stimuli, as well as to visual and tactile stimuli, is linked functionally to mechanisms controlling overt orienting movements that increase stimulus identification.

Adolescent↗

PubMed1996

Tactile rod bisection: hemispheric activation and sex differences.

Blindfolded subjects estimated with either hand the center of rods positioned in either left or right hemispace. In one condition, they also performed a concurrent verbal task. Bias and variability of bisection settings were the dependent variables. Bisections performed in left hemispace were biased to the left of true center, more so when the left hand was used. In contrast, bisections performed in right hemispace were biased rightward, more so when the right hand was used. There were no significant differences in variability of bisections in any condition. Interactions of hand with hemispace in which the task was performed differed for the two sexes. Moreover, the secondary verbal task had no effect on either measure. We conclude that of several factors that may underlie bisection biases, attention was the most relevant.

Adult↗

PubMed1996

Visual-spatial deficits expalin visual symptoms in Alzheimer's disease.

PURPOSE: To determine whether the visual symptoms of patients with Alzheimer's disease are related to visual-spatial dysfunction. METHODS: We administered a test battery modified from existing neuropsychometric materials that taxed visual-spatial skills, form identification, color vision, and visual memory. We tested 14 patients with Alzheimer's disease who had visual symptoms prominent enough to prompt ophthalmologic consultation, 11 patients with Alzheimer's disease who lacked such visual symptoms, and a control group of 53 subjects without Alzheimer's disease. The groups with Alzheimer's disease were matched for Wechsler Adult Intelligence Scale-Revised scores. RESULTS: Patients with Alzheimer's disease who had prominent visual symptoms differed significantly from those without prominent visual symptoms only in their relatively poor visual-spatial test scores. CONCLUSIONS: Visual symptoms in Alzheimer's disease are related primarily to visual-spatial deficits. These findings are consistent with previous evidence that patients with Alzheimer's disease who have prominent visual symptoms have accentuated histologic and metabolic abnormalities in the parieto-occipital regions known to process visual-spatial information. The findings support the view that pathways mediating visual-spatial and form identification are at least partially segregated in the brain, and emphasize that tests used to screen visually symptomatic patients with Alzheimer's disease will be more effective if they prominently assess visual-spatial skills.

Aged↗

PubMed1995

Effect of lateralized kinetic visual cues on visual search in patients with unilateral spatial neglect.

Patients with left neglect following right cerebral infarcts and normal control subjects searched for a single target letter among distractor letters presented on a display screen while kinetic visual cues were continuously presented on the left side or the center of the display screen. Kinetic visual cues presented on the left side enhanced patients' detection of left-sided targets but did not reduce the time that they required to search for left-sided targets. In contrast, the same cues did not alter the patients' detection or rate of search for left-sided targets when they were presented in the center of the display screen. Analysis of these and previous results suggest that kinetic visual cues may be more suitable than other forms of cueing for rehabilitation of neglect and may be particularly effective with neglect patients whose attention is strongly biased to the unneglected side.

Aged↗

PubMed1994

Integrative agnosia following progressive multifocal leukoencephalopathy.

A 43 year-old man with presumed progressive multifocal leukoencephalopathy developed difficulty recognizing objects and faces in the presence of adequate visual acuity and visual fields. His copying and matching of line drawings was intact, suggesting that his agnosia was associative. However, he had difficulty perceiving overlapping forms and drawings of single objects as integrated wholes. Unlike control subjects, he made fewer errors identifying silhouettes compared to line drawings with internal details. These alterations, together with his feature-by-feature descriptions of objects and copying, suggest that his agnosia was due to a disturbance in integrating local form features, as described by Riddoch and Humphreys (1987). This interpretation is supported by the findings that his tactile recognition and semantic and structural knowledge of the objects he could not identify visually were intact. Furthermore, his deficient performance in categorical matching of photographs to objects was dependent upon the perceptual complexity of the photographs. Similar deficits in early form processing described by other investigators are discussed.

AIDS Dementia Complex↗

PubMed1993

A screening test for integrative visual dysfunction in Alzheimer's disease.

OBJECTIVE: To develop a screening test to help ophthalmologists detect visually symptomatic patients with as yet undiagnosed Alzheimer's disease. DESIGN: Administration of a battery of tests consisting of items modified from existing psychometric materials to decrease examination time and increase ease of scoring. PARTICIPANTS: Fourteen patients with Alzheimer's disease and prominent visual symptoms; 53 control subjects matched to the patients with Alzheimer's disease for age, sex, and educational level; and 22 patients with subnormal visual acuity or visual fields who did not have Alzheimer's disease. RESULTS: The novel battery of tests distinguished all 14 visually symptomatic patients with Alzheimer's disease from patients without Alzheimer's disease and control subjects. CONCLUSION: This battery of tests should enhance the ophthalmologic detection of Alzheimer's disease.

Aged↗

PubMed1993

Pleasantness of a sweet taste during hunger and satiety: effects of gender and "sweet tooth".

Hungry or sated adult female (N = 29) and male subjects (N = 28), classified according to whether they had eaten or not within 2 h, rated four concentrations of sucrose in a lime drink for their sweetness intensity and pleasantness. Subjects also rated their attitude towards sweets in general (self-reported sweet tooth). Female subjects rated the solutions as less pleasant when tasted soon after a meal. Male subjects showed a non-significant trend in the same direction. Female subjects also rated the solutions as more intense than the male subjects did. Moreover, subjects who reported having a "sweet tooth" (regardless of gender) showed a significant alliesthesia effect (i.e., enhancement of pleasantness of sweet tastes by hunger), whereas those with "no sweet tooth" did not. We conclude that both gender and the degree of individual "sweet tooth" influence alliesthesia.

Adult↗

PubMed1992

Effect of stimuli in right hemispace on left-sided neglect in a line cancellation task.

Twenty-seven patients with right cerebral infarcts resulting in left-sided neglect in a line cancellation task were also tested for line cancellation when the lines were confined to the left half of sheets. All but one patient (whose neglect in the former condition was minimal) were still impaired in the latter condition, a finding that indicates that hyperattraction to test stimuli in the unneglected (right) hemispace was not the crucial factor preventing them from completing the standard version of the cancellation task, although it may have played some role. The results are consistent with the conclusion that hyperattention to stimuli in the unneglected hemifield, and possibly to stimuli in the unneglected hemispace, together with other factors, could account for the patients' impairment in line cancellation.

Aged↗

PubMed1992

Combined and separate effects of eye patching and visual stimulation on unilateral neglect following stroke.

In Experiment 1, 11 of 13 stroke patients with left-sided neglect benefitted from monocular patching in at least one (of five) tests of neglect. This beneficial effect in most cases was limited to the period when the patch was worn. In Experiment 2, another group of stroke patients (n = 18) with left-sided neglect were tested in a line-bisection task with monocular patching and/or lateralized visual stimulation--a procedure previously shown to reduce neglect. Each procedure resulted in substantial benefits; the two procedures combined resulted in significantly larger benefits than either alone. As in Experiment 1, the degree of benefit of patching (alone or in combination with stimulation) was not related to several demographic factors. These findings suggest that monocular patching, together with lateralized visual stimulation, may significantly reduce neglect in daily activities and may be more beneficial than procedures requiring patients to be aware of their disorder and to use strategies for scanning the neglected side.

Aged↗

PubMed1989

Spatial attentional shifts: further evidence for the role of polysensory mechanisms using visual and tactile stimuli.

Normal subjects performed simple reaction time responses to lateralized visual target stimuli (Experiment 1) and lateralized tactile target stimuli (Experiment 2). In each experiment, the lateralized targets were preceded at one of four intervals by a visual or tactile cue located on the same (valid cue), or opposite (invalid cue) side, or on both sides (neutral cue). The validity of the visual and tactile cues influenced the speed of response to either target stimulus. These findings, together with those previously reported (Buchtel and Butter, Neuropsychologia 26, 499-509, 1988), are consistent with the view that intra- and inter-modal spatial cueing is effective with modalities that are linked to orienting systems in which movements of the sensory array serve to improve sensory analysis.

Adult↗

PubMed1989

Altitudinal neglect following traumatic brain injury: a case report.

We present an analysis of altitudinal neglect in a patient who following traumatic brain injury showed extinction to a visual stimulus presented in the lower field when another stimulus was simultaneously presented in the upper field. When estimating the midpoint of vertically-oriented rods presented below eye level using visual cues, tactile/kinesthetic cues or a combination of these cues, she consistently pointed higher than control subjects did. She showed less severe impairments when the rods were presented at or above eye level. When estimating the midpoint between two clicks presented above and below her head, she pointed higher than did control subjects. These deficits cannot be accounted for by sensory or motor disorders and appear to be due to a disorder in attending to stimuli in the lower half to space.

Adult↗

PubMed1988

Spatial attentional shifts: implications for the role of polysensory mechanisms.

Simple reaction times to lateralized visual (Experiment 1) or auditory (Experiment 2) targets were studied in normal subjects. The targets were preceded by a visual or auditory cue located on the same (valid cue), or opposite (invalid cue) side as the subsequent target, or on both sides (neutral cue), with one of four cue target intervals. The validity of visual and auditory cues influenced the speed of response to the visual target but not to the auditory target. It is hypothesized that cross-modal cueing of spatial position works only with modalities for which a movement (e.g. saccade) leads to improved sensory analysis.

Adult↗

PubMed1988

Changes in sensory inattention, directional motor neglect and "release" of the fixation reflex following a unilateral frontal lesion: a case report.

We recorded eye movements to and away from visual stimuli from a patient with left-sided neglect following a right frontal infarct in order to determine (a) whether and to what extent his neglect was due to sensory inattention and directional motor neglect and (b) whether he had difficulty suppressing inappropriate eye movements to visual stimuli ("release" of visual grasp) as his sensory inattention declined. In the first testing session, conducted 5 days following his stroke, he often failed to move his eyes when a stimulus on the left required a rightward eye movement, but he consistently moved his eyes to a stimulus on the right. Thus, he showed contralateral but not ipsilateral sensory inattention. Initially, he also was impaired in making leftward eye movements when right stimuli were presented. Thus, he also showed a directional motor neglect. In subsequent tests, his left-sided sensory inattention as defined above decreased, and was no longer present three weeks following his stroke, nor in a follow-up test conducted almost 6 months following this stroke. In contrast, his directional motor neglect, as defined above, was still present in the follow-up test. As his left-sided sensory inattention declined, his tendency to move his eyes incorrectly to stimuli on the left side (the side contralateral to his lesion) when these stimuli required eye movements to the right became stronger ("release" of visual grasp); he continued to show this strong tendency in the test conducted almost 6 months following his stroke.

Attention↗

PubMed1988

An experimental analysis of factors underlying neglect in line bisection.

The finding that patients with neglect make larger errors when bisecting longer lines could be due to failure to disengage attention from a segment of the line on the ipsilesional side, or to a reduced ability to direct attention and/or action contralaterally. The findings are reported from a patient with left-sided neglect who set the midpoint further away from the right end of lines as their length increased, a finding consistent with the latter interpretation. His errors were significantly related to length and lateral extent of lines presented in left hemispace, but only to length of lines presented in right hemispace.

Aged↗

PubMed1987

Comparison of the effects of superior colliculus and pulvinar lesions on visual search and tachistoscopic pattern discrimination in monkeys.

In order to investigate whether pulvinar lesions produce behavioral impairments similar to those that follow superior colliculus lesions, monkeys were tested on a visual search task before and after receiving radiofrequency lesions of either the superior colliculus or pulvinar. The animals searched for a small target pattern within an array of varying numbers of irrelevant patterns. After receiving colliculus lesions, the animals showed marked post-operative increases in either search time, percent errors, or both. By contrast, pulvinar lesions had little or no effect on visual search performance. Similarly, in learning to search for a target they had not previously seen, animals with colliculus lesions were impaired relative to unoperated controls, whereas pulvinar-lesioned animals did not differ from controls. In an attempt to confirm the finding that pulvinar lesions impair tachistoscopic pattern discrimination, we determined exposure-duration thresholds of pulvinar- and colliculus-lesioned monkeys for performance of a pattern discrimination. The thresholds of the colliculus-lesioned monkeys were elevated 20-fold relative to controls. By contrast, thresholds of the pulvinar-lesioned monkeys were normal. We conclude that the pulvinar is not critical for the attentional processes in which the superior colliculus participates.

Animals↗

PubMed1986

Impairments in orienting to visual stimuli in monkeys following unilateral lesions of the superior sulcal polysensory cortex.

Monkeys were tested for head and eye orientation to illuminated lamps in a hemisphere before and after serial, unilateral lesions of the polysensory superior temporal cortex (STS) or control lesions. Following STS lesions they were impaired in orienting to contralateral lamps; this impairment was more severe and persistent when a ipsilateral stimulus in the mirror-image position was simultaneously presented. These findings, together with deficits in manual reaching and grasping observed following STS lesions, support the view that the STS is part of a polysensory system controlling attention and exploratory movements.

Animals↗