Biomedical subjects

K M Heilman

Publications and source records attributed to K M Heilman.

At least 19 recordsLinked to original sources

PubMed2006

Limb-kinetic apraxia in Parkinson disease.

To learn if limb-kinetic apraxia (LKA) is associated with Parkinson disease (PD), participants with PD (on medications) and control subjects performed finger tapping (FT), measuring movement speed, and performed coin rotation (CR), measuring precise coordinated but independent finger movements and speed. There were no group differences in FT, a measure of bradykinesia-rigidity, but CR rotation was impaired in PD. Thus, LKA, not related to bradykinesia-rigidity, is associated with PD.

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PubMed2006

What's inside the art? The influence of frontotemporal dementia in art production.

We evaluated the productions of an artist with frontotemporal lobar degeneration from before dementia onset until she was fully symptomatic. We noted an improvement of technique that might be related to sparing and disinhibition of the right posterior neocortex. There was a reduction of closure (completeness of the painting), possibly induced by impersistence and a decrease in evocative impact that might be explained by frontal and anterotemporal-limbic dysfunction.

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PubMed2006

Deafferentation-disconnection neglect induced by posterior cerebral artery infarction.

OBJECTIVE: To investigate patients with posterior cerebral artery (PCA) infarctions to learn whether hemispatial neglect is more frequent and severe after right than left PCA infarction; whether visual field defects (VFDs) influence the presence or severity of hemispatial neglect; and the anatomic loci of lesions that are associated with hemispatial neglect. METHODS: The authors recruited 45 patients with PCA infarction that involved only the occipital lobe or the occipital lobe plus other areas served by the PCA. All subjects received seven neglect tests within 2 months after onset. RESULTS: Overall, the frequency of hemispatial neglect was 42.2%. The frequency did not significantly differ between the right (48.0%) and left (35.0%) PCA groups, but the severity of hemispatial neglect was significantly greater in the right group. VFD alone did not influence the frequency or severity of neglect after controlling other variables. Isolated occipital lesions were rarely associated with hemispatial neglect, and it was only the occipital plus splenial lesion that significantly influenced the frequency and severity of neglect. CONCLUSIONS: This study suggests that after excluding such confounding factors as aphasia or hemiplegia, neglect frequency does not differ between the right and left posterior cerebral artery (PCA) groups, but the severity of neglect is greater after right PCA infarctions; even in the acute stage of PCA infarction; visual field defect from an isolated occipital lesion does not cause hemispatial neglect; and the injury to both the occipital lobe and the splenium of the corpus callosum is important for producing hemispatial neglect with PCA infarction.

Adult↗

PubMed2006

Incremental limb hypometria.

To find out if patients with right hemisphere strokes (RHD) demonstrate a form of progressive or incremental limb hypometria (ILH), 11 RHD patients and eight matched controls were tested by having them draw a series of horizontal lines while blindfolded. Unlike controls, six RHD patients displayed an incremental decrease in the length of lines they drew, a sign of ILH. ILH might be a common source of disability and hinder rehabilitation efforts.

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PubMed2005

Subcortical vascular dementia: integrating neuropsychological and neuroradiologic data.

BACKGROUND: Research criteria for subcortical vascular dementia are based on radiologic evidence of vascular pathology and greater impairment on tests of executive control than memory. The relationship(s) between neuroradiological evidence of subcortical vascular disease and neuropsychological impairments has not been specified. OBJECTIVE: To define these research criteria, the authors rated the severity of MRI white matter abnormalities (WMAs) and neuropsychological data from patients with dementia. METHODS: Sixty-nine outpatients who met the criteria for dementia were studied with neuropsychological tests that assessed executive (mental) control, declarative memory, visuoconstruction (clock drawing), and language (semantic category fluency). MRI-WMAs were rated using a leukoaraiosis (LA) scale (range 0 to 40). RESULTS: First, regression analyses demonstrated that neuropsychological measures accounted for 60.7% of the variance in WMA severity (47.3% of this variance attributable to executive/visuoconstructive test performance, 13.4% attributable to memory/language test performance). Second, patients were grouped according to the severity of WMAs (i.e., low, moderate, and severe white matter groups). Only patients with mild WMA (mean LA = 3.61 +/- 2.63, approximately 2.4 to 15.6% of the subcortical white matter) presented with greater impairment on memory/language tests vs executive control/visuoconstructive tests, a neuropsychological profile typically associated with Alzheimer disease. Patients with moderate WMA (mean LA = 12.76 +/- 2.49, approximately 25.6 to 38.1% of the subcortical white matter) presented with equal impairment on executive/visuoconstructional vs memory/language tests. Patients with severe WMA (mean LA = 21.76 +/- 2.97, approximately 46.9 to 62.4% of the subcortical white matter) displayed a profile of greater executive/visuoconstructional impairment relative to memory/language disabilities. CONCLUSION: A profile of equal impairment on tests of executive control and memory along with radiologic evidence involving about one-fourth of the cerebral white matter as measured by the Leukoaraiosis Scale may be sufficient for a diagnosis of subcortical vascular dementia.

Age Factors↗

PubMed2004

Aberrant auditory processing and atypical planum temporale in developmental stuttering.

OBJECTIVE: To learn if people with persistent developmental stuttering and atypical anatomy of their auditory temporal cortex have, when compared to control subjects, changes in fluency induced with delayed auditory feedback (DAF). BACKGROUND: DAF improves fluency in many individuals who stutter, and induces dysfluency in some normal people. The planum temporale (PT), a portion of auditory temporal cortex, is anatomically atypical in some adults who stutter and atypical anatomy might induce aberrant function. Thus, the people who demonstrate the paradoxical response to DAF might be those who have atypical anatomy. METHODS: Experimental subjects were adults with developmental stuttering (n = 14) and control subjects (n = 14) matched for age, sex, education, and handedness. Volumetric MRI scans of all subjects were obtained and the PT was measured in the right and left hemispheres. Based on these scans, subjects were classified as typical (leftward PT asymmetry) or atypical (rightward PT asymmetry). Prose passages were read at baseline, with non-altered feedback (NAF), and with DAF, and fluency was measured in these three conditions. RESULTS: At baseline the adults with developmental stuttering were significantly more dysfluent than controls (p < 0.0005). Controls' fluency did not significantly change with DAF, but DAF improved fluency in adults with developmental stuttering (p < 0.0005). In the stutter group enhanced fluency was associated with atypical (rightward) PT asymmetry, and the presence of typical (leftward) PT asymmetry was not associated with any significant change in fluency. The individuals with atypical PT asymmetry also had more severe stuttering at baseline compared to the experimental subjects with typical PT anatomy. CONCLUSIONS: In adults with persistent developmental stuttering and atypical PT anatomy, fluency is improved with DAF. These experimental subjects who showed improvement had more severe stuttering at baseline. Anomalous PT anatomy may be a neural risk for developmental stuttering in some individuals. Although a number of explanations are tenable, it may be that atypical rightward PT asymmetry may alter speech feedback, and treatment with DAF might allow these people to compensate.

Adult↗

PubMed2004

On-line anosognosia: unawareness for chorea in real time but not on videotape delay.

In hemiplegics, anosognosia (unawareness of deficit) rests on a mismatch between expected and actual movement: a feedback hypothesis emphasizes sensory deficits or neglect, a feedforward hypothesis postulates impaired intention to move. Anosognosia for other problems is less studied. The authors report a man without sensory deficits who was unaware of choreiform movements, except on videotape delay. The authors believe that a feed-forward mechanism underlies his "on-line" unawareness.

Agnosia↗

PubMed2004

Attentional bias induced by viewing actual or illusory movements.

OBJECTIVE: To learn to which portions of a line normal subjects would attend when watching this line actually moving or when perceiving movement even in the absence of actual movement, an illusory movement. METHODS: Twenty normal subjects watched a computer monitor on which either lines or dots moved to the right or left. They also watched stationary lines, which appeared to be moving to the left or right because the background was moving in the opposite direction. While watching these lines or dots, their eye movements were monitored to determine the position of fixation. RESULTS: Overall, subjects fixated on the side of the line that was in the direction of real or illusory movement. In the actual movement condition, leftward motion induced more of an attentional bias than rightward motion. In the illusory movement condition, however, rightward illusory movement condition induced more of an attentional bias than leftward movement. CONCLUSIONS: Objects moving leftward or rightward primarily activate the contralateral hemisphere. This hemispheric activation may induce a contralateral overt orienting response that is reflected by eccentric eye fixation. Treatments of neglect, such as caloric vestibular stimulation, may alter an attentional bias by inducing the illusion of movement.

Adult↗

PubMed2004

The Character-line Bisection Task: a new test for hemispatial neglect.

A failure to report or respond to stimuli presented in a portion of space is termed hemispatial neglect. Line bisection and line cancellation are two of the tests used most commonly to assess for neglect. Perhaps, because neglect can be induced by a variety of deficits, neither of these tests used alone is as sensitive as both used together. Hence, the primary purpose of this study was to assess the sensitivity, reliability and validity of a new test called the Character-line Bisection Task (CLBT) that combines features of both the bisection and cancellation tests. Since local attention and language are primarily mediated by and activate the left hemisphere, our second goal was to learn if the CLBT and especially the letter version induce a greater rightward bias than the solid-line bisection task. Eighty patients with acute right hemisphere stroke and 81 controls performed the CLBT that consists of two subtests, the Letter-line and Star-line Bisection tasks. All subjects also completed four conventional tests for neglect (Standard solid-line bisection, line cancellation, Star Cancellation, and figure copying). In the bisection tasks both patients and controls bisected to the right with the CLBT than with the solid-line bisection task, suggesting the CLBT induces asymmetrical hemispheric activation. This enhanced rightward deviation with the CLBT was the same for the Letter-line and Star-line Bisection tasks. In regard to sensitivity, we defined the presence of neglect syndrome based on a total score derived from performance of controls on all six tests. This total score detected 55 (68.8%) patients with neglect. Within this group, the Letter-line and Star-line tasks diagnosed neglect in 50 and 48 patients, respectively, resulting in the highest sensitivities (90.9, 87.3%) of the six tests. Thus, the CLBTs demonstrated higher sensitivities than the other commonly used neglect tests and these new tests can be useful for the detection and quantification of unilateral neglect.

Adult↗

PubMed2004

Just thinking about targets can aggravate neglect on cancellation tests.

While many studies investigate how the visual features of targets influence cancellation performance in neglect, few, if any, even consider that thought processes, such as the use of an algorithm to identify targets, might similarly aggravate neglect. This single-case study of a patient with chronic neglect compared cancellation performance after manipulating (1) ease of visual target identification, (2) the use of an algorithm to identify targets, and (3) the material-specific nature of target cancellation. Neglect severity was defined by the number and location of target omissions. While each manipulation had a differential impact on neglect severity, the novel and interesting finding occurred during the second condition, when a math algorithm was used to identify targets. In this condition, target omissions increased relative to other tests and target cancellations were confined to the right half of the page. This is the first report, to our knowledge, that neglect on cancellation tests can be aggravated by an internal thought process, a math algorithm, as opposed to external manipulations of visual stimuli and procedural characteristics of cancellation tests. An important characteristic of the algorithm used in this study is that it appeared to activate the intact left cerebral hemisphere.

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PubMed2004

A rodent model for investigating the neurobiology of contralateral neglect.

BACKGROUND: Contralateral neglect is a common and disabling sequela of right hemisphere strokes. Neglect involves attentional and cognitive deficits, including distortions of contralateral spatial and personal awareness. There are no established successful therapies for neglect, and treatment is often complicated by anosognosia. The disturbances associated with neglect are debilitating to patients and their families, and presence of neglect is a strong predictor of poor prognosis for recovery. OBJECTIVE: The present report reviews findings from 20 years of research using a rat model of neglect. In the rat, 2 cortical areas that are linked by corticocortical connections have been identified as having a major role in neglect, and these correspond to frontal and parietal fields in primates. These 2 cortical areas also have convergent projections to the dorsocentral striatum, which has been implicated as a crucial subcortical component of the cortical-striatal-thalamic circuitry involved in directed attention and neglect. We discuss the role of the dorsocentral striatum in neglect and recovery and present evidence that induced axonal sprouting may promote functional recovery following cortical lesions that produce neglect. CONCLUSIONS: The rodent model of neglect captures some of the essential behavioral and anatomic features of neglect in humans. This model has helped reveal the pathophysiology of neglect, has suggested a crucial role of the striatum in recovery from neglect, and is being used to investigate potential therapeutic approaches.

Agnosia↗

PubMed2003

Atypical cerebral laterality in adults with persistent developmental stuttering.

BACKGROUND: Two of the most consistent anatomic asymmetries found in the human brain are a larger right than left prefrontal and left than right occipital lobe. Reduced or reversed asymmetries of these regions are considered markers of atypical cerebral laterality, and atypical cerebral laterality has been proposed to increase neural risk for developmental stuttering. OBJECTIVE: S: To learn if atypical prefrontal and occipital lobe asymmetries are more common in adults who stutter vs fluent control subjects and to determine whether lobar size or asymmetry patterns are associated with stuttering severity or language abilities. METHODS: Adults with persistent developmental stuttering (n = 16) and matched control subjects (n = 16) had language and stuttering assessments. Subjects were also studied with volumetric MRI scans. Total hemisphere, prefrontal, and occipital lobe regions were measured, and volumes were calculated proportionally to hemisphere volume. RESULTS: Hemisphere and total brain volumes did not differ between the groups. Control subjects had the expected larger right than left prefrontal and larger left than right occipital lobe volume. In contrast, the adults who stutter did not have these asymmetries. Stuttering severity was not associated with specific anatomic configurations, whereas language-processing deficits in adults who stutter were associated with prefrontal and occipital volume reduction. CONCLUSIONS: Developmental stuttering is associated with atypical prefrontal and occipital lobe asymmetries. In addition, deficits in language processing were associated with some anatomic measures in the adults who stutter.

Adult↗

PubMed2003

Ecological implications of ideomotor apraxia: evidence from physical activities of daily living.

OBJECTIVE: To learn if ideomotor apraxia (IMA) adversely influences skilled acts in the environment and interferes with independent functioning after stroke. METHODS: The relationship between IMA severity, based on scores from a verbal gesture-to-command (pantomime) task, and the dependency score, as defined by increased caregiver assistance on the Physical Self-Maintenance Scale (PSMS), was investigated in 10 unilateral left hemisphere-damaged stroke patients and 10 matched control subjects. RESULTS: There was a significant relationship between apraxia severity and dependency in physical functioning (PSMS). Impairment on the PSMS in the patients with IMA could not be accounted for based on overall cognitive impairment, poststroke depression, content-conceptual errors, elementary motor impairment, lesion size, or stroke-test interval. Analysis of categories composing the PSMS revealed that the patients with apraxia had increased dependency in grooming, bathing, and toileting relative to age-matched control subjects. CONCLUSIONS: These findings emphasize the ecological implications of apraxia and the need for rehabilitation strategies to improve the execution and efficiency of coordinated skilled movements in stroke patients with left hemisphere damage.

Activities of Daily Living↗

PubMed2002

Influence of final search direction on tactile line bisection in normal subjects.

BACKGROUND: Many variables influence the tactile bisection performance of normal subjects. Of these, studies that investigated the starting point effect have reported inconsistent results. OBJECTIVE: To determine if the final search direction rather than the initial search direction (starting point) may have an effect on tactile bisection performance, especially when subjects are making multiple searches. METHODS: The authors divided the experiment into single- and multiple-search tasks. Thirty-two blindfolded normal subjects were asked to indicate the midpoint of a rod after a one-way search (single-search task) or after two or more one-way searches (multiple-search task). In each task, the subject started on either end of the horizontally placed rods. The same procedure was also conducted with rods oriented vertically or radially. Therefore, there were six conditions (two starting points x three orientations). RESULTS: In the single-search task, there was a significant effect of starting point or movement direction in all six conditions, with biases occurring toward the starting point from the true midpoint (this is termed the "overshoot phenomenon"). In the multiple-search task, however, there was no significant effect of the starting point in all six conditions. Rather, biases depended on the final movement direction in five of the six conditions, occurring toward the starting point of the final search. CONCLUSION: Future research is needed to understand the mechanism of the overshoot phenomenon in tactile bisection by normal subjects and how the overshoot phenomenon influences patients with neglect.

Adult↗

PubMed2002

The Gerstmann syndrome in Alzheimer's disease.

BACKGROUND: It remains unclear from lesion studies whether the four signs of the Gerstmann syndrome (finger agnosia, acalculia, agraphia, and right-left confusion) cluster because the neuronal nets that mediate these activities have anatomical proximity, or because these four functions share a common network. If there is a common network, with degeneration, as may occur in Alzheimer's disease, each of the signs associated with Gerstmann's syndrome should correlate with the other three signs more closely than they correlate with other cognitive deficits. METHODS: Thirty eight patients with probable Alzheimer's disease were included in a retrospective analysis of neuropsychological functions. RESULTS: The four Gerstmann's syndrome signs did not cluster together. Finger naming and calculations were not significantly correlated. Right-left knowledge and calculations also did not correlate. CONCLUSIONS: The four cognitive functions impaired in Gerstmann's syndrome do not share a common neuronal network, and their co-occurrence with dominant parietal lobe injuries may be related to the anatomical proximity of the different networks mediating these functions.

Adult↗

PubMed2002

Lateralised motor control: hemispheric damage and the loss of deftness.

OBJECTIVE: To learn if the left compared with the right hemisphere of right handed subjects exerts bilateral compared with contralateral motor control when performing precise and coordinated finger movements. METHODS: The study investigated intertask differences of manual motor asymmetries such as speed, precision, and independent finger movements, in patients with unilateral lesions of the left (LHD) or right hemisphere (RHD) and normal controls (C). RESULTS: Normal subjects showed the greatest right hand preference on a task that required rapid coordinated and precise independent finger movements (coin rotation). Both hemisphere damaged groups revealed contralateral motor deficits, but the magnitudes of asymmetries were found to be significantly different (RHD>C>LHD) with contralateral and ipsilateral deficits for LHD subjects. The greatest ipsilateral deficits for the LHD subjects were on those tasks that require precision (grooved pegboard and coin rotation). CONCLUSIONS: The degree of hemispheric specialisation is, in part, dependent upon the nature of the motor task, with left hemisphere motor control necessary for tasks that require precision and coordinated independent finger movements.

Adult↗

PubMed2001

Anomalous anatomy of speech-language areas in adults with persistent developmental stuttering.

OBJECTIVE: The major aim of this study was to determine whether adults with persistent developmental stuttering (PDS) have anomalous anatomy in cortical speech-language areas. The major postulate was that anomalous cerebral dominance, reflected by anomalous cortical anatomy in various regions, may put an individual at increased risk for the development of stuttering. METHODS: Adults with PDS (n = 16) and controls (n = 16) matched for age, sex, hand preference, and education were studied. Volumetric MRI scans were completed. Frontal (pars triangularis, pars opercularis) and temporo-parietal areas (planum temporale, posterior ascending ramus) were measured in the left and right hemispheres and interhemispheric asymmetries were computed. Gyral variants were assessed within these perisylvian cortical speech-language areas. RESULTS: The right and left planum temporale were significantly larger in the adults with PDS (p = 0.045), and the magnitude of the planar asymmetry was reduced (p = 0.003). Some gyral variants were unique to the adults with PDS, including a second diagonal sulcus and extra gyri along the superior bank of the sylvian fossa. In addition, anatomic subgroups emerged based on sex and hand preference. Overall, the adults with PDS had significantly more gyral variants (mean = 4.19) than controls (mean = 1.31, p < 0.0005). CONCLUSIONS: These results provide strong evidence that adults with PDS have anomalous anatomy in perisylvian speech and language areas. No one anatomic feature distinguished the groups, but multiple loci within a widely distributed neural network differed between groups. These results provide the first evidence that anatomic anomalies within perisylvian speech-language areas may put an individual at risk for the development of stuttering.

Adult↗

PubMed2001

Extinction, working memory, and line bisection in spatial neglect.

The authors studied four patients with spatial neglect, using a task in which lines contain an off-centered bisection mark and a task in which the right and left segments of these bisected lines are presented independently and sequentially. In the prebisected line task, subjects reported the position of the bisection. In the segments task, subjects compared the length of the segments. Accuracy was greater with the sequential presentation of line segments, suggesting that an extinction-like phenomenon plays a role in line bisection bias.

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