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Biomedical subjects

K M Heilman

Publications and source records attributed to K M Heilman.

At least 55 records · Page 3Linked to original sources
PubMed2000

Cognitive and vestibulo-proprioceptive components of spatial ability in Parkinson's disease.

Visual-spatial deficits are often associated with Parkinson's Disease (PD). Recent theories suggest that frontal-basal ganglionic dysfunction affects cognition in PD. Although this hypothesis does not entirely explain spatial deficits in PD, the inappropriate utilization of cues associated with executive dysfunction may induce spatial deficits. Alternatively, the vestibular system is also involved in spatial cognition, and vestibular dysfunction may affect visual-spatial ability in PD. To test these hypotheses, we administered the Water Jar Test, while perturbing vestibulo-proprioceptive input. Non-demented PD patients were significantly less accurate than controls in judging horizontal, and appeared to inappropriately utilize cues. No group effect was found for head tilt. These findings suggest the visual-spatial difficulties seen in PD are related to executive dysfunction that is associated with a disruption of the frontal-basal ganglionic and frontal-parietal systems.

Basal Ganglia↗
PubMed2000

Attentional grasp in far extrapersonal space after thalamic infarction.

Studies of animals and humans with focal brain damage suggest that attention in near and far extrapersonal space may be mediated by anatomically separate systems. Thalamic lesions have been associated with spatial neglect, but whether asymmetric attention specific to near or far space occur after thalamic damage has not been explored. It is also unclear if thalamic injury can induce contralesional defective response inhibition. We tested a woman with a left thalamic infarction who reported that, when driving, she had a tendency to veer towards people or objects on the right side of the road. Our patient and four controls performed a line bisection task with a laser pointer in near and far extrapersonal space. The experimenter marked each bisection either from the right of the presented line (right-distractor, RD) or the left (left-distractor, LD). RD and LD trials were pseudo-randomized. Our patient performed similarly to controls (mean -0.7 mm, controls -0.6 mm) on the line bisection task in near space. In far space she erred significantly rightward compared to her performance in near space (p<0.001). Controls performed similarly in near and far space. The experimenter position did not affect our patient's performance on near line bisections, nor did controls demonstrate a distractor effect for the near condition. In the far condition, however, our patient showed a significant distractor effect (LD -3.3 mm, RD 35.3 mm, p<0.001). Controls also demonstrated a distractor effect in the far condition (LD -6.4 mm, RD 0.7 mm, p<0.01), though of much smaller magnitude. Our results suggest that frontal-thalamic systems regulating visual attention may be disrupted by thalamic infarction. Such damage may produce an attentional grasp specific to far extrapersonal space.

Attention↗
PubMed2000

Digitizing the moving face during dynamic displays of emotion.

Humans typically decode facial signals during dynamic interactions in which the face moves. In this study, we digitized real time video signals in order to examine movement asymmetries across the face during emotional and nonemotional expressions. Forty dextral males were tested. For each expression, a 400 ms video segment was analyzed for changes in signal value (pixel intensity) over consecutive frames. The upper and lower face regions were examined separately due to differences in the cortical enervation of facial muscles in the upper (bilateral) vs lower face (contralateral). Results revealed distinctly different movement asymmetries over the lower and upper hemiface. In the upper face, more movement occurred over the right side for most facial expressions, regardless of emotionality. The latter finding questions the assumption that muscles of the upper face are symmetrical and/or bilaterally enervated in a symmetrical manner. In the lower face, negative expressions linked to fight-flight emotions (i.e. fear, anger) were associated with greater left sided movement, whereas happiness tended to be associated with more right sided movement. No consistent pattern of movement asymmetry occurred for nonemotional expressions. Although the valence-related movement asymmetries in the lower face are consistent with neuropsychological models of emotional expressivity, it remains unclear whether they reflect activation or inhibitory hemispheric mechanisms. Taken together, these data suggest that multiple factors may contribute to expressive movement asymmetries of the face.

Adolescent↗
PubMed2000

Arousal response with aging: pupillographic study.

The performance of cognitive behaviors requires an activated, aroused cerebral cortex. Although studies have shown that there are decrements of cognitive functions in the elderly, changes in arousal with aging have not been fully studied. Our objective was to learn if there are attention-arousal changes associated with aging. Visual stimuli were presented to induce orienting responses or arousal reactions. Because changes in pupil size reflect changes in arousal, we recorded and compared pupillary responses of young and older normal participants using infared pupillography. During the 1 s that we recorded pupillary changes, we found major phases: a brief initial constriction (C1), then a maximal dilation (D1)--an arousal response, followed by constriction (C2), a habituation response. Although amplitude of these 3 phases was not different between the 2 groups, the interval between the D1 and C2 response was prolonged in the older group. Although the arousal response is not dramatically altered with aging, habituation appears to be delayed.

Adult↗
PubMed2000

Limb and hemispatial hypometria.

In a previous study, we demonstrated that unilateral cerebral lesions produce hypometric limb movements of the contralateral arm and hemispatial (i.e., directional) hypometria for movements towards contralateral hemispace. In the present study, we investigated 10 patients with right cerebral lesions and 25 healthy controls using a task to uncouple deficits in sensory perceptual systems and motor-action output systems on directional hypometria. This task required participants, with their eyes closed, to reproduce lateral and medial horizontal displacements (15-27 cm) with each arm. Each participant was seated at a waist high table and had their hand placed at an origin point aligned with the axillary fold on the same side. Their hand was moved by the investigator from the origin point to a target point and brought back to the point of origin (input displacement). The participant was then asked to return their hand to either the same target point or to an equidistant target point in the opposite direction. Healthy dextral participants were significantly more hypometric with their right arm, but patients with right cerebral lesions exhibited an opposite pattern with overall left arm hypometria. In addition, patients were significantly more hypometric for movements when output displacements were toward left hemispace. No effect was found for direction of sensory input. The results suggest that the directional hypometria is predominantly produced by hemispatial output deficits.

Adolescent↗
PubMed2000

Conceptual apraxia in probable Alzheimer's disease as demonstrated by the Florida Action Recall Test.

Patients with probable Alzheimer's disease (AD) often have difficulties associated with semantic knowledge. Therefore, conceptual apraxia, a defect of action semantics and mechanical knowledge, may be an early sign of this disease. The Florida Action Recall Test (FLART), developed to assess conceptual apraxia, consists of 45 line drawings of objects or scenes. The subject must imagine the proper tool to apply to each pictured object or scene and then pantomime its use. Twelve participants with Alzheimer's disease (NINCDS-ADRDA criteria) and 21 age- and education-matched controls were tested. Nine Alzheimer's disease participants scored below a 2-standard-deviation cutoff on conceptual accuracy, and the three who scored above the cutoff were beyond a 2-standard-deviation cutoff on completion time. The FLART appears to be a sensitive measure of conceptual apraxia in the early stages of Alzheimer's disease.

Aged↗
PubMed2000

Horizontal line bisections in upper and lower body space.

Whereas the ventral cortical visual stream is important in object recognition, the dorsal stream is specialized for spatial localization. In humans there are also right and left hemisphere asymmetries in visual processing: the left hemisphere being more important in object recognition and the right in specifying spatial locations. Based on these dorsal-ventral and right-left where-what dichotomies, one would expect that the dorsal right hemisphere systems would be most activated during spatial localization tasks, and this activation may induce a leftward spatial bias in lower space. To determine if visual stimuli in upper and lower body space evoke different hemispheric activation, we had 12 normal participants bisect horizontal lines above and below eye level. Participants erred leftward in lower body space relative to upper body space (M = 1.3345 mm and 0.4225 mm, respectively; p = .011). In upper body space, bisection errors did not differ from zero, but in lower body space, errors tended to deviate leftward (M = 1.3345 mm, differs from null hypotheses at p = .0755). Our results are consistent with dorsal stream/right hemisphere activation when performing a spatial localization task in lower versus upper body space.

Adult↗
PubMed2000

Neglect and related disorders.

Neglect is a failure to report, respond, or orient to contralateral stimuli that is not caused by an elemental sensorimotor deficit. Subtypes of neglect are distinguished by input (attentional) or output (intentional) demands, the distribution (personal, spatial, and representational), and the means of eliciting the signs (unilateral or bilateral stimuli). In this article we discuss how to assess patients for neglect, the pathophysiology of neglect, and the treatment of neglect.

Attention↗
PubMed2000

Dissociation of anosognosia and phantom movement during the Wada test.

OBJECTIVE: Patients who misperceive that they are moving their paralysed arm (phantom movements) may not recognise its weakness. Therefore, the relation between phantom limb movements and anosognosia for hemiplegia during selective right hemispheric anaesthesia (the Wada test) was examined. METHODS: Nine patients with intractable epilepsy underwent the Wada test. During the right hemispheric injection, after the onset of hemiparesis, anosognosia was assessed by asking patients if they were weak. The patient's vision was limited such that they could not see the position of their limbs. Phantom movements were tested for by asking patients to attempt to lift their left upper limb, and to demonstrate their left limb's position by placing their right limb in the same position as their left. Proprioception was tested by lifting the patient's paretic upper limb and having patients demonstrate this position by lifting their right limb to the same position. RESULTS: Three patients experienced left phantom limb movements, and five were anosognosic for their hemiplegia. However, phantom movement occurred in only one patient with anosognosia. The other two patients with phantom movement were without anosognosia. The patient with phantom movement and anosognosia had impaired proprioception. The two patients with phantom movement but without anosognosia had intact proprioception. CONCLUSIONS: Phantom movement in the presence of a proprioceptive deficit could contribute to anosognosia. However, anosognosia and phantom movement are dissociable; therefore phantom movement cannot alone account for anosognosia. Because phantom movement occurred with and without proprioceptive deficits, proprioceptive loss is not a prerequisite for phantom movement.

Adult↗
PubMed2000

Alterations in the functional anatomy of reading induced by rehabilitation of an alexic patient.

OBJECTIVE: The goal of the study was to measure regional cerebral blood flow (CBF) in a stroke patient with acquired phonologic alexia before and after therapy using the Auditory Discrimination in Depth (ADD) program. BACKGROUND: After rehabilitation of acquired language disorders, functional imaging can detect activity in brain structures that do not mediate language during normal conditions. However, the anatomic correlates of recovery or rehabilitation from acquired reading disorders are largely undescribed. METHODS: Cerebral SPECT scans were obtained before and after the intervention with Auditory Discrimination in Depth. The first and last activation tasks necessitated that the patient read nonwords during radionuclide uptake. Another (control) scan was acquired during performance of a nonlinguistic task shortly before the end of the ADD program. RESULTS: Before therapy, the right hemisphere was inactive during nonword reading relative to the nonlinguistic task. After treatment, nonword reading increased cerebral blood flow in the posterior right perisylvian cortices homologous to the dominant hemisphere areas engaged by reading. Brain activity also increased in Broca's area of both hemispheres. CONCLUSIONS: Dyslexia rehabilitation may facilitate right-hemisphere cortical networks in the reading process and increase engagement of phonologic articulatory motor representations in Broca's area.

Dyslexia↗
PubMed1999

Ipsilesional intentional neglect and the effect of cueing.

BACKGROUND: Contralesional hemispatial neglect may be induced by an attentional deficit where patients are inattentive to or unaware of stimuli in contralesional hemispace, an intentional deficit where patients are unable to act in or towards contralesional hemispace, or both. The deficits associated with ipsilesional neglect have not been as well characterized. Because cueing may be used as a rehabilitative assistive device, we wanted to learn whether the efficacy of an attentional or intentional cue was related to the type of bias. METHODS: We studied a patient with a right frontotemporal stroke who had ipsilesional neglect by using a video apparatus that dissociates sensory-attentional and motor-intentional systems. We also performed a cueing experiment with primarily sensory-attentional cues (i.e., read the letter at the end of the line) and primarily motor-intentional cues (i.e., touch the end of the line). RESULTS AND CONCLUSIONS: Ipsilesional neglect was primarily a motor-intentional deficit with a motor-action bias to the left and a secondary sensory-attentional bias for stimuli to the right. With cueing we found a double dissociation: the rightwards motor-intentional cue improved the primary left-sided intentional bias and the leftwards sensory-attentional cue improved the secondary right-sided attentional bias. Effective rehabilitation strategies need to address both sensory-attentional and motor-intentional deficits in patients with neglect.

Attention↗
PubMed1999

Cerebral lateralization: relationship of language and ideomotor praxis.

OBJECTIVE: To determine the relationship of language lateralization and hand preference to praxis performance following left and right hemispheric amobarbital-induced inactivations. BACKGROUND: Patients who are aphasic from left cerebral dysfunction also frequently exhibit ideomotor apraxia in which they make temporal, spatial, and postural errors of learned skilled movements. However, hemispheric lateralization of the systems mediating ideomotor praxis in patients with atypical cerebral language dominance (i.e., bilateral or right hemispheric language function) remains uncertain. METHODS: Subjects included 90 patients with intractable seizures who were undergoing the intracarotid amobarbital procedure (IAP) as part of their preoperative evaluation for epilepsy surgery. Hand preference was determined by the Benton Handedness Questionnaire. Praxis was assessed by the subject's performance when pantomiming the use of four pictured tools. RESULTS: During left IAP, patients with typical language dominance made more ideomotor apraxic errors than did patients with atypical language dominance. During right IAP, patients with atypical language dominance made more ideomotor apraxic errors than did patients with typical language dominance. Overall, patients with atypical language dominance made fewer ideomotor apraxic errors than did patients with typical language dominance. These relationships were present irrespective of hand preference. CONCLUSIONS: Language dominance is more closely associated with the laterality of temporal and spatial movement representations (i.e., ideomotor praxis dominance) than is hand preference. Patients with atypical language dominance exhibit more bilateral cerebral distribution of both language and praxis function.

Adult↗
PubMed1999

Conduction aphasia and the arcuate fasciculus: A reexamination of the Wernicke-Geschwind model.

Wernicke, and later Geschwind, posited that the critical lesion in conduction aphasia is in the dominant hemisphere's arcuate fasciculus. This white matter pathway was thought to connect the anterior language production areas with the posterior language areas that contain auditory memories of words (a phonological lexicon). Alternatively, conduction aphasia might be induced by cortical dysfunction, which impairs the phonological output lexicon. We observed an epileptic patient who, during cortical stimulation of her posterior superior temporal gyrus, demonstrated frequent phonemic paraphasias, decreased repetition of words, and yet had intact semantic knowledge, a pattern consistent with conduction aphasia. These findings suggest that cortical dysfunction alone may induce conduction aphasia.

Aphasia, Conduction↗
PubMed1999

Noradrenergic modulation of cognitive flexibility in problem solving.

Stress causes impaired performance on tests of creativity. Drugs that block beta-adrenergic receptors improve test performance in patients with test anxiety. Furthermore, catecholamine precursors (L-DOPA) reduce the flexibility of semantic networks. Our study investigated the effect of noradrenergic system modulation on cognitive flexibility in problem solving. Eighteen normal subjects undertook three problem solving tasks (number series, shape manipulation and anagrams) 45 min after propranolol, placebo and ephedrine. On the task that appeared to rely most heavily on cognitive flexibility (anagrams), subjects who were most able to solve these problems demonstrated significantly shorter solution times (logarithmic scores) after propranolol than after ephedrine. This suggested that the noradrenergic system exerts a modulatory effect on cognitive flexibility in problem solving.

Adolescent↗
PubMed1999

Effects of left frontal transcranial magnetic stimulation on depressed mood, cognition, and corticomotor threshold.

BACKGROUND: The pathophysiology of depression may include synaptic hypoactivity of left prefrontal cortex. Several groups of investigators have described improved mood associated with rapid transcranial magnetic stimulation (rTMS) but have not looked for possible cognitive side effects associated with left prefrontal magnetic stimulation. METHODS: We measured the effects of left prefrontal rTMS on mood, cognition, and motor evoked potential threshold in 10 patients with medication-resistant major depression. RESULTS: In a 2-week open trial of left prefrontal rTMS off antidepressant medications, scores on the Hamilton Rating Scale for Depression and the Beck Depression Inventory decreased by 41% and 40%, respectively. After resuming pre-rTMS antidepressant medication, improvement in mood was still significant at 1 and 3 months later. rTMS had no adverse effects on neuropsychological performance. rTMS treatments were associated with significant decreases in motor evoked potential threshold in the 9 of 10 patients who remained off psychotropic medications during the 2-week treatment period. CONCLUSIONS: These preliminary data suggest that left prefrontal rTMS is safe and improves mood in patients with medication-resistant major depression. Changes in motor evoked potential threshold suggest that prefrontal rTMS may alter brain activity at sites remote from the stimulation. Double-blind, sham-controlled studies are needed.

Adult↗
PubMed1999

Motor perseverative behavior on a line cancellation task.

OBJECTIVES: To study the behavioral and neuroanatomic characteristics of perseverative behavior encountered on a target cancellation task in patients with neglect. METHODS: Motor perseverative behavior during line cancellation task was evaluated retrospectively in 60 patients with left hemispatial neglect from right hemispheric stroke. RESULTS: More than 30% of the patients (21 of 60) showed perseveration, manifested as either repetitive cancellation of the same target (18/21) or cancelling extra lines created by the patients themselves (3/21). Neglect severity correlated positively with the frequency of perseverative errors. Perseveration was most prominent in the rightmost portion of the array. Anterior lesions or massive lesions involving anterior and posterior regions were more likely to be associated with motor perseveration than were lesions restricted to posterior areas. CONCLUSIONS: Although the mechanism of motor perseveration remains to be elucidated, our findings suggest that the combination of aberrant approach behaviors associated with frontal lobe injury and an attentional or intentional bias toward the rightsided targets might explain the behavior.

Adolescent↗
PubMed1999

Apraxia differs in corticobasal degeneration and left-parietal stroke: A case study.

Corticobasal degeneration (CBD) is a progressive disorder characterized by both cortical and basal ganglia dysfunction such as asymmetrical apraxia, and akinetic rigidity, involuntary movements, and cortical sensory loss. Although apraxia is a key finding for the differential diagnosis of CBD, it has not been determined whether the features of apraxia seen in subjects with CBD are similar to those features exhibited by subjects with left-hemisphere damage from stroke. Therefore, for both clinical purposes and in order to better understand the brain mechanisms that lead to apraxia in CBD, we studied praxis in a patient with CBD and compared him to patients who are apraxic from left-parietal strokes. We used three-dimensional movement analyses to compare the features of apraxic movement. This subject with CBD was a dentist whose initial complaint had been that he "forgot" how to use his tools in the mouths of his patients. Analyses were performed on the trajectories made when using a knife to actually slice bread, and when repetitively gesturing slicing made to verbal command. Movements of the left hand, wrist, elbow, and shoulder were digitized in 3-D space. Although the CBD subject was clearly apraxic, the features of his apraxia differed markedly from those of the subjects with lesions in the left parietal lobe. For movements to command, the CBD subject showed joint coordination deficits, but his wrist trajectories were produced in the appropriate spatial plane, were correctly restricted to a single plane, and, like control subjects, were linear in path shape. However, when he was actually manipulating the tool and object, all of these aspects of his trajectories became impaired. In contrast, the deficits of the apraxic subjects with left-parietal damage were most pronounced to verbal command with their movements improving slightly although remaining impaired during actual tool and object manipulation. Unlike patients with parietal strokes, patients with CBD have degeneration in several systems and perhaps deficits in these other areas may account for the differences in praxic behavior.

Aged↗