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Biomedical subjects

K M Heilman

Publications and source records attributed to K M Heilman.

At least 91 records · Page 5Linked to original sources
PubMed1998

Attentional bias in normal subjects performing visual and tactile radial line bisections.

Misbisection of lines is thought to represent an attentional bias. When radial lines (intersection of the midsagittal and transverse planes) are presented below eye level, normal subjects are biased toward far peripersonal space in the visual modality and to near peripersonal space in the tactile modality. These errors may be related to a body centered, a retinotopic, or an object centered attentional bias. The purpose of this study was to contrast the body centered and retinotopic-objective centered hypotheses by having 12 normal subjects perform visual and tactile bisections of radial lines that are above and below eye level. The top of the page, which may be defined by retinotopic or object centered coordinates, contains the portion of the line that is most distant from our bodies when the page is below eye level. However, above eye level, the top of a radial line would be the portion of the page that is most proximal to our bodies. We observed that when stimuli are presented below eye level, normal subjects have a visual bias toward far peripersonal space or the top of the page or both, and have a tactile bias in the opposite direction. In the above eye position we found no overall bias in either modality. Because above eye level the body centered bias should have remained the same but the retinotopic or object centered bias should have reversed, our results suggest that the body and object centered or retinotopic biases, which are oriented in opposite directions, nullified each other.

Adult↗
PubMed1998

Treatment of a case of phonological alexia with agraphia using the Auditory Discrimination in Depth (ADD) program.

Phonological alexia and agraphia are acquired disorders characterized by an impaired ability to convert graphemes to phonemes (alexia) or phonemes to graphemes (agraphia). These disorders result in phonological errors typified by adding, omitting, shifting, or repeating phonemes in words during reading or graphemes when spelling. In developmental dyslexia, similar phonological errors are believed to result from deficient phonological awareness, an oral language skill that manifests itself in the ability to notice, think about, or manipulate the individual sounds in words. The Auditory Discrimination in Depth (ADD) program has been reported to train phonological awareness in developmental dyslexia and dysgraphia. We used a multiple-probe design to evaluate the ADD program's effectiveness with a patient with a mild phonological alexia and mixed agraphia following a left hemisphere infarction. Large gains in phonological awareness, reading and spelling nonwords, and reading and spelling real words were demonstrated. A follow-up reassessment, 2 months posttreatment, found the patient had maintained treatment gains in phonological awareness and reading, and attained additional improvement in real word reading.

Agraphia↗
PubMed1998

Left hemispheric specialization for learned, skilled, and purposeful action.

Three-dimensional motion analyses were performed on trajectories of repetitive "slicing" gestures by 4 participants with left-hemisphere lesions and limb apraxia, 6 participants with right-hemisphere lesions, and 7 neurologically intact participants. Left hemispheric lesioned participants with apraxia, but not right hemispheric lesioned participants showed impaired coupling of spatial and temporal aspects of wrist trajectories and deficits in interjoint coordination. Both groups of brain-lesioned participants differed from control participants in the 3-D plane of the wrist motion. The deficits of some right hemispheric lesioned participants in controlling the plane of wrist motion may be a consequence of left hemispatial neglect with rightward deviations. In contrast, the deficits of apraxic participants in controlling wrist trajectories and coordinating joint motions seem to reflect a deficit in these participants for the movement plan.

Aged↗
PubMed1998

Cortical influences in emotion.

Emotions may be classified into two major divisions: experience and behavior. Because the brain is critical for mediating emotional experience and behavior, diseases of the brain may induce changes in emotional behavior and experience. Disorders of almost all portions of the cerebral hemisphere, including the cortex, limbic system, and basal ganglia, have been associated with changes of emotional experience and behavior. Dysfunction of the cerebral cortex may be associated with disorders of emotional communication. Whereas deficits of the left hemisphere appear to impair the comprehension and expression of propositional language, deficits of the right hemisphere may be associated with an impaired ability to comprehend and express emotional gestures such as facial expression and emotional prosody. Some patients have either prosodic or facial emotional deficits. Some have only expressive or receptive deficits. However, others may be globally impaired, either within or across modalities. The posterior portions of the neocortex appear to be important for comprehension and the anterior for expression of both emotional prosody and faces. Injury and dysfunction of the limbic system may also alter emotional communication and experience. For example, damage to the amygdala may be associated with an impaired ability to recognized emotional faces and a reduction of affect, especially anger, rage, and fear. In contrast, lesions of the septal region may be associated with increased ragelike behaviors. Seizures frequently emanate from the limbic system, and seizures that start in the amygdala can induce fear and perhaps even rage. Disorders of the basal ganglia may also be associated with defects of emotional communication and experience. Patients with Parkinson's disease not only may be impaired at communicating emotions with both expressive and receptive deficits but also are often depressed and anxious. Patients with Huntington's disease may have emotional comprehension deficits with an impaired ability to recognize emotional faces and prosody. Patients with Huntington's disease may have mood changes even before motor dysfunction becomes manifest. Many of the defects in emotional experience may be related to the associated changes in neurotransmitter systems. Unfortunately, how alteration of neurotransmitters induce mood changes remains unknown. In this chapter we review the feedback and central theories of emotional experience. Although we argue against the postulates that feedback is critical to the experience of emotions, we do suspect that feedback may influence emotions. Emotions may be conditioned and may use thalamic-limbic circuits, as proposed by LeDoux. However, most emotional behaviors and experiences are induced by complex stimuli that an isolated thalamus could not interpret. The cerebral cortex of humans has complex modular systems that analyze stimuli, develop percepts, and interpret meaning. We discuss the proposal that the experience of emotions is dimensional. Almost all primary emotions can be described with two or three factors, including valence, arousal, and motor activation.

Arousal↗
PubMed1998

Dissociation of sensory-attentional from motor-intentional neglect.

OBJECTIVES: Spatial neglect may result from disruption of sensory-attentional systems that spatially allocate perceptual resources and the motor-intentional systems that direct exploration and action. Previous studies have suggested that the line bisection task is more sensitive to sensory-attentional disorders and the cancellation task to motor-intentional disorders. A new technique was developed that allows the dissociation of sensory-attentional and motor-intentional deficits in both tasks and thereby allows comparison of these tasks. METHODS: Ten patients with right hemispheric injury and hemispatial neglect performed line bisection and cancellation tasks while viewing stimuli on closed circuit TV. Direct view of the exploring hand and the target was precluded; the TV monitor guided performance. The direct condition made the direction of hand movement on the table (workspace) congruent with that on the monitor. Inverting the camera produced the indirect condition wherein the lateral movement in the workspace occurred in the opposite direction on the monitor. RESULTS: On the cancellation task, five patients marked targets in the right workspace in the direct condition but the left workspace in the indirect condition, indicating sensory-attentional neglect. However, four other patients cancelled targets only in the right workspace in both conditions, failing to explore the left workspace, suggesting motor-intentional neglect. A patient who performed ambiguously may have elements of both types of neglect. Only two out of five patients designated as sensory-attentional in cancellation tasks showed sensory neglect on line bisection. The other three patients, as well as patients defined as motor-intentional by cancellation performance, exhibited motor-intentional neglect on line bisection. CONCLUSION: The designation of sensory-attentional versus motor-intentional neglect therefore, in part, depends on task specific demands.

Adult↗
PubMed1998

Molecular approach to find target(s) for oligoclonal bands in multiple sclerosis.

OBJECTIVES: Oligoclonal bands are a characteristic finding in the CSF of patients with multiple sclerosis, yet their target antigen(s) remain unknown. The objective was to determine whether a filamentous phage peptide library could be employed to allow the oligoclonal bands to select their own target epitopes. METHODS: CSF IgG antibody from 14 patients with multiple sclerosis and 14 controls was used to select individual phage clones from a bacteriophage library containing approximately 4 x 10(7) different hexamers expressed on its surface pIII protein. The amino acid sequence selected was deduced by sequencing the DNA of the genetically engineered insert. RESULTS: In general, after three rounds of selection, CSF from both patients with multiple sclerosis and controls selected one to two consistent peptide motifs. Five out of 14 patients with multiple sclerosis, and one control, selected the amino acid sequence motif, RRPFF. Given 20 possible amino acids per position, the likelihood of five patients selecting the same linear five amino acid sequence is at most 1.6 x 10(-3), corrected for the number of clones sequenced. A GenBank computer search showed that this sequence is found in the Epstein-Barr Virus nuclear antigen (EBNA-1), and a heat shock protein alphaB crystallin. Human serum antibodies to a synthetic peptide containing RRPFF were virtually exclusively found in patients with prior infection by Epstein-Barr virus. Other studies have suggested a relation between Epstein-Barr virus infection and multiple sclerosis, including nearly 100% Epstein-Barr virus seropositivity among patients with multiple sclerosis and increased concentrations of antibody to EBNA in CSF of patients with multiple sclerosis. By antigen specific immunoblotting, antibodies to the RRPFF motif in the CSF were shown to correspond to a subset of oligoclonal bands in the CSF from the same patient. CONCLUSION: This study shows that phage epitope display libraries may be used to select amino acid motifs which are potentially relevant to the pathogenesis of multiple sclerosis.

Amino Acid Sequence↗
PubMed1998

Diagonal spatial neglect.

OBJECTIVE: To determine whether stroke patients with diagonal neglect on cancellation may show diagonal neglect on line bisection, and hence to indicate whether diagonal neglect may be related solely to the type of test used or whether instead it may reflect a fundamental spatial disorder. METHODS: Nine patients with subacute right hemispheric stroke who neglected targets primarily in the near left direction on line cancellation bisected diagonal lines of two opposing orientations: near left to far right and far left to near right. The errors were assessed to determine whether line orientation significantly affected bisection error. RESULTS: Eight patients had significant bisection errors. One of these showed no effect of line orientation on error, consistent with lateral neglect. The remaining seven patients had a line orientation effect, indicating a net diagonal spatial bias. For the group, cancellation errors were significantly correlated with the line orientation effect on bisection errors. CONCLUSIONS: A significant diagonal bias on two tests of spatial attention may appear in stroke patients, although the directions of the biases may differ within individual patients. None the less, diagonal neglect may be a fundamental spatial attentional disturbance of right hemispheric stroke. Greater severity of stroke deficit as indicated by cancellation error score may be associated with a greater degree of diagonal neglect on line bisection.

Aged↗
PubMed1998

The effect of semantic and emotional context on written recall for verbal language in high functioning adults with autism spectrum disorder.

OBJECTIVE: Several deficits have been proposed to account for cognitive impairment in autism including an inability to comprehend the perspectives of others ("theory of mind"), an inability to process emotional information, and difficulty drawing together diverse information in context ("central coherence"). Because context (central coherence) and emotion can influence memory, a study was designed to show if autism spectrum disorder was associated with impaired utilisation of context and emotion in recall; and if impairments in theory of mind processing would influence recall in autism spectrum disorder. METHODS: Ten high functioning subjects with autism spectrum disorder and 13 age and IQ matched controls were tested using recall tests. In the first coherence memory test, subjects listened to a series of word lists that were in varying degrees of syntactic and semantic (coherent) order and were asked to recall the words. In the second coherence memory test, subjects listened to stories consisting of sentences that were, or were not, in logical (coherent) order. In the emotional memory test, the subjects listened to sentences that were highly emotional or non-emotional. In the theory of mind test, the subjects listened to stories requiring varying levels of understanding of the perspectives of others. RESULTS: There were no significant differences between groups in recall of coherent versus incoherent word lists, nor was there a significant difference between groups in recall of coherent versus incoherent stories. However, the control subjects recalled more of the emotional than non-emotional sentences, whereas the autism spectrum disorder group did not show such a difference. No significant difference existed in recall of stories requiring varying levels of understanding of the perspectives of others among subjects with autism spectrum disorder, and subjects with autism spectrum disorder did not differ from control subjects in the influence of theory of mind content on story recall. CONCLUSION: The study shows that memory in high functioning adults with autism spectrum disorder is facilitated by emotional content to a lesser degree than it is facilitated by coherence. Therefore, impairments in emotional processing cannot be considered as simply an effect of the "weak central coherence" theory in autism spectrum disorder. Whereas the reasons for this emotional deficit are unknown, evidence of abnormalities of the limbic structures in autism spectrum disorder may provide an anatomical explanation.

Adult↗
PubMed1998

Progressive ventral posterior cortical degeneration presenting as alexia for music and words.

Patients with posterior cortical atrophy may have dorsal visual system (occipital-parietal) dysfunction (optic ataxia, visuospatial disorientation, and simultanagnosia), ventral visual system (occipital-temporal) dysfunction (pure alexia, prosopagnosia, visual anomia, and agnosia), or both. We report a professional musician with ventral system dysfunction whose first symptom was alexia for music. Subsequently, she developed pure alexia for words but had preserved sorting of words. These observations suggest that the ventral visual system is important in music and word reading. However, sorting of words may be mediated by the dorsal visual system.

Aged↗
PubMed1998

Ipsilateral neglect during intracarotid amobarbital test.

Neglect usually occurs in the space contralateral to brain injury. Recent studies describe ipsilateral neglect (IN) whereby patients with right hemisphere injury misbisect lines to the left of midpoint. IN usually develops after contralateral neglect (CN) resolves. We observed whether IN occurs during intracarotid amobarbital infusion. After clinical testing but before resolution of barbiturate effect, 20 right-handed subjects bisected lines until baseline performance returned. More than half (12 of 20) showed transient CN. IN occurred in 40% (8 of 20) of patients, always during the recovery stage of anesthesia, and most frequently followed initial CN.

Adolescent↗
PubMed1998

Facilitory paratonia and frontal lobe functioning.

OBJECTIVE: To learn if paratonia predicts frontal cognitive impairments. BACKGROUND: Paratonia, an alteration of tone to passive movement, can be divided into oppositional paratonia ("gegenhalten," "paratonic rigidity") and facilitory paratonia. Although paratonia has been thought to be induced by frontal lobe dysfunction, previous studies suggest that paratonia does not correlate with cognitive impairment. However, only oppositional paratonia has been studied in this manner, and in these studies only the presence or absence of paratonia was assessed instead of a quantitative scale. Facilitory paratonia has not been studied for its relation to cognitive function. METHODS: Twenty-five patients evaluated for degenerative dementia were assessed on semiquantitative 5-point scales for paratonia by two independent raters. A quantifiable test--the modified Kral procedure--which assesses continued movement by the patient after cessation of passive movement was also administered for comparison with facilitory paratonia. To assess frontal lobe function, subjects were tested for echopraxia, distractibility, and word fluency. To screen for other cognitive defects, subjects were given the Mini-Mental State Examination (MMSE). RESULTS: The modified Kral procedure strongly correlated with subjective rating of facilitory paratonia. This correlation was significantly stronger than the correlation with oppositional paratonia. The modified Kral procedure was also highly predictive of echopraxia, but was less predictive of other frontal lobe tests. Facilitory paratonia, oppositional paratonia, and the modified Kral procedure each strongly predicted scores on the MMSE. CONCLUSIONS: Both facilitory and oppositional paratonia strongly predict general cognitive performance. The modified Kral procedure is a reliable indicator of facilitory paratonia and a predictor of impaired performance on frontal lobe tests.

Aged↗
PubMed1998

Neglect after right hemisphere stroke: a smaller floodlight for distributed attention.

OBJECTIVE: To learn whether there was a defect in an attentional floodlight. We used a line decision task for which subjects had to decide if two line segments separated by a gap were one line or two parallel lines. We varied the area of the gap and, therefore, the area over which subjects needed to spread attention to perform the task correctly. BACKGROUND: Visual tasks requiring focused attention use an attentional spotlight. Other visual tasks requiring spatially distributed attention may require a floodlight. Neglect after right hemisphere stroke can be associated with a defect in the attentional spotlight. RESULTS AND CONCLUSIONS: Two patients with neglect after right hemisphere stroke performed more poorly than normal control subjects and left hemisphere-damaged control subjects as the area of spread in the gap increased. Right hemisphere-damaged patients did not differ from control subjects' performance on another visuospatial parameter--the degree of discontinuity between the line segments. These results support a defective attentional floodlight in neglect.

Adult↗
PubMed1998

Hand preference and magnetic resonance imaging asymmetries of the central sulcus.

Hand preference is perhaps the most evident behavioral asymmetry observed in humans. Anatomic brain asymmetries that may be associated with hand preference have not been extensively studied, and no clear relationship between asymmetries of the motor system and hand preference have been established. Therefore, using volumetric magnetic resonance imaging methodologies, the surface area of the hand representation was measured along the length of the central sulcus in 15 consistent right- and 15 left-handers matched for age and gender. There was a significant leftward asymmetry of the motor hand area of the precentral gyrus in the right-handers, but no directional asymmetry was found in the left-handers. When asymmetry quotients were computed to determine the distribution of interhemispheric asymmetries, the left motor bank was greater than the right motor bank in 9 of 15 right-handers, the right motor bank was greater than the left motor bank in 3 of 15 right-handers, and the motor banks were equal in 3 of 15 right-handers. In contrast, among left-handers, the left motor bank was greater than the right motor bank in 5 of 15, the right motor bank was greater than the left motor bank in 5 of 15, and the motor banks were equal in 5 of 15. Although no direct measure of motor dexterity and skill was performed, these data suggest that anatomic asymmetries of the motor hand area may be related to hand preference because of the differences in right-handers and left-handers. Furthermore, the predominant leftward asymmetry in right-handers and the random distribution of asymmetries in the left-handers support Annett's right-shift theory. It is unclear, however, whether these asymmetries are the result of preferential hand use or are a reflection of a biologic preference to use one limb over the other.

Adult↗
PubMed1998

The effects of rotation on spatial attention.

Unilateral spatial neglect can be reduced by cold water caloric stimulation of the contralesional ear. Three hypotheses may account for this response. Caloric stimulation may increase the arousal of the damaged hypoaroused hemisphere. Moving stimuli to ipsilesional space improves the performance of patients with neglect. Caloric stimulation may move viewer-centered spatial maps in an ipsilesional direction. Unilateral neglect may be related to a spatial attentional bias. Vestibular stimulation may temporarily influence this bias. To learn if vestibular stimulation may induce an attentional spatial bias, the authors studied eight normal subjects by having these subjects attempt to bisect lines before and during vestibular stimulation. If caloric stimulation alters neglect because it changes the attentional spatial bias, the authors should be able to induce neglect in normal subjects by pertubating the vestibular system. Vestibular stimulation was induced by spinning a chair and then abruptly stopping the spinning chair. The authors found that after normal subjects were rotated to the left, they misbisected lines to the left but did not misbisect lines after they were rotated to the right. Although these results support the postulate that vestibular stimulation can induce an attentional spatial bias, the authors' results also suggest that there are intrinsic attentional asymmetries.

Adult↗
PubMed1998

Functional imaging: heterogeneity in task strategy and functional anatomy and the case for individual analysis.

To learn more about the functional anatomy of language, the authors used [99mTc]HMPAO single photon emission computed tomography (SPECT) functional imaging to study nonword rhyming, lexical-semantics and syntax. The authors did not find any task-related differences in cerebral blood flow using region-by-region analysis of variance. This led them to examine individual subject's task-related patterns of cerebral blood flow. This analysis revealed regions of interest with little or no change but also regions with changes as great as 30%. There was marked subject-to-subject variability in the pattern of blood flow, which precluded statistically significant results using analysis of variance. An alternative analytic strategy based on numbers of subjects exceeding a minimum threshold task-related change in cerebral blood flow was tested and shows promise in identifying commonalities and differences in individual task-related blood flow patterns. The authors conclude that the complex and difficult to interpret pattern of blood flow changes observed in this study reflect in considerable part the combined effects of variability in task strategy, owing in part to insufficiently constrained task performance, and variability in functional anatomy. The authors also tested the differences in results achieved with simple normalization and analysis of covariance approaches and found them to be insignificant.

Adult↗