Biomedical subjects

K M Heilman

Publications and source records attributed to K M Heilman.

At least 73 records · Page 4Linked to original sources

PubMed1999

Apraxia in corticobasal degeneration.

Corticobasal degeneration (CBD) is a degenerative disease that often presents with an asymmetric progressive ideomotor limb apraxia. Some apraxic subjects may fail to perform skilled purposive movements on command because they have lost the memories or representations that specify how these movements should be performed (representational deficit). In contrast, other apraxic subjects may have the movement representations but are unable to utilize the information contained in them to execute skilled purposive movements (production-execution deficit). To learn if the apraxic deficit in CBD is induced by a representational or a production-execution deficit, we tested three nondemented subjects with CBD on tasks requiring production of meaningful or meaningless gestures to command, gesture imitation, gesture discrimination, and novel gesture learning. A fourth subject with incomplete data also is presented. The results suggest that the apraxia associated with CBD is initially induced by a production-execution defect with relative sparing of the movement representations.

Aged↗

PubMed1999

Frontal-opercular aphasia.

The standard nomenclature divides nonfluent aphasic syndromes with relatively spared comprehension into Broca's aphasia and transcortical motor aphasia. We report on a patient with a persistent nonfluent aphasia from a discrete, primarily cortical, frontal-opercular lesion who had impaired syntax but intact repetition and, therefore, did not conform to the traditional classification. Based on this patient's behavior and a review of other cases, we have divided the nonfluent aphasias with intact comprehension into five disorders. (1) Verbal akinesia-exhibiting diminished intention or drive to speak and associated with medial frontal lesions (supplementary motor area and cingulate gyrus) or with lesions damaging the efferent projections from these areas. (2) Disorders of syntax-telegraphic and agrammatic utterances that may be associated with dominant pars opercularis lesions. (3) Phonemic disintegration-a failure to correctly produce phonemes, which may be associated with injury to the opercular primary motor cortex or efferent projections from this area. (4) Defects of lexical access-patients who struggle to find words and are impaired at timed word-generation tasks. Defects of lexical access may be associated with lesions of the pars triangularis and adjacent prefrontal cortex. (5) Mixed defects. According to this model, the traditional patient with Broca's aphasia would exhibit disorders of syntax, phonemic disintegration, and defects of lexical access, whereas the traditional patient with transcortical motor aphasia would have verbal akinesia or defects of lexical access or both. Our patient had defects of lexical access and syntax, but only mild symptoms of phonemic disintegration, suggesting that his opercular primary motor cortex was relatively intact. Our patient's ability to repeat normally while his propositional speech remained telegraphic suggests that different neural mechanisms subserve these functions.

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PubMed1999

Adverse effect of dopamine agonist therapy in a patient with motor-intentional neglect.

Studies in animals and humans report dopamine agonists can improve neglect. Because dopamine deficit reduces intention to act, it has been suspected the dopamine agonist bromocriptine would improve deficient hemispatial intention. Thus, the effect of bromocriptine on line bisection was examined in a patient with neglect and failure of the action-intention system. The 58-year-old patient had left-sided neglect from a right cerebral infarction involving both cortical and subcortical (striatal) structures. It was determined that neglect on a line bisection task was attributable to a motor-intentional bias by testing under congruous and incongruous video monitoring. Testing sessions were held before starting bromocriptine, on 20 mg/d, and after stopping bromocriptine. The patient's ipsilesional bias increased on bromocriptine, and improved when bromocriptine was stopped. Bromocriptine may worsen neglect if putamenal receptors are damaged. Dopamine agonists may activate the normal hemisphere, increasing an intentional bias. Clinicians using dopaminergic pharmacotherapy should assess patients for this possible adverse effect.

Attention↗

PubMed1999

Crossed apraxia: implications for handedness.

Liepmann posited that right hand preference relates to left hemisphere dominance for learned skilled movements. Limb apraxia, impairment of skilled movement, typically occurs in individuals with left hemisphere (LH) lesions. The occurrence of apraxia in right-handed individuals following right-hemisphere lesions appears to refute Liepmann's hypothesis. We studied the apraxia of a right-handed man, RF, following a right frontal lesion to determine whether his apraxia paralleled the apraxia seen following LH lesions. Results of behavioral testing indicated that, like individuals with apraxia following left frontal lesions, RF was better at gesture recognition than gesture production which was significantly impaired across tasks. Kinematic motion analyses of movement linearity, planarity, and the coupling of temporospatial aspects of movements substantiated the parallel impairments in RF and patients with LH apraxia. The impairment seen in our patient with crossed apraxia provides evidence for the fractionation of systems underlying hand preference and skilled movement.

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PubMed1999

Apraxia and motor-skill acquisition in Alzheimer's disease are dissociable.

Many patients with Alzheimer's disease (AD) are apraxic and the apraxia has been posited to be related to a loss of movement representations. Whereas patients with Alzheimer's disease have been reported to demonstrate normal motor learning on a rotor pursuit skill acquisition task, it is unknown whether AD subjects who are apraxic demonstrate normal skill-learning. We tested subjects with probable AD and normal controls on a rotor pursuit task. We also tested the AD subjects for ideomotor apraxia. Subjects with AD who were apraxic had normal motor learning. In addition, praxis score did not correlate with performance on the skill-acquisition task. The results suggest that ideomotor praxis and motor learning are at least partly dissociable.

Aged↗

PubMed1999

Developmental stuttering and Parkinson's disease: the effects of levodopa treatment.

The effects of dopamine on developmental stuttering was studied in a 44 year old man with developmental stuttering and Parkinson's disease during three levodopa "on" periods and three "off" periods. When compared with the "off" periods, during the "on"' periods he demonstrated an increase of speech dysfluencies. These findings lend support to the dopamine hypothesis of developmental stuttering.

Adult↗

PubMed1999

Ipsilesional neglect: behavioural and anatomical features.

OBJECTIVE: To learn more about the behavioural and anatomical features of ipsilesional neglect. METHODS: Thirty consecutive patients with spatial neglect were tested on cancellation and line bisection tasks. To learn if patients with ipsilesional neglect demonstrate the sensory-attentional or motor-intentional type of neglect, a video apparatus was used that dissociates these determinants. RESULTS: Five patients showed evidence of ipsilesional neglect. This phenomenon was seen only on the line bisection task. All patients with ipsilesional neglect had lesions involving frontal-subcortical regions. Although ipsilesional neglect evolved from early in three of five cases, the other patients displayed ipsilesional neglect without initial contralateral neglect, suggesting that ipsilesional neglect cannot be fully attributed to a compensatory strategy. The results of the tests that used the video apparatus indicate that right sided frontal or subcortical injury may induce contralateral attentional or intentional "approach" behaviours. CONCLUSIONS: Ipsilesional neglect is most often associated with frontal-subcortical lesions, cannot be entirely attributed to a compensatory strategy, and may be induced by an attentional bias, an intentional bias, or both.

Adult↗

PubMed1999

Pupillographic findings in neglect.

OBJECTIVES: Unilateral sensory neglect has been attributed to various defects, including a hemispatial attention-arousal deficit. However, support for this hypothesis has only been indirect. Therefore, the purpose of this study was to further test the hemispatial attentional-arousal hypothesis by measuring pupillary response as an index of arousal. METHODS: There were two experimental subjects with neglect and six matched controls. Stimuli (Arabic numbers) were presented on the right, left, and centre of a screen. The subjects were asked to look at the number in the centre, on the right, or left of the screen while their pupil diameter was measured. RESULTS: Unlike the control subjects, the subjects with neglect, who were aware of the left sided stimuli, did not show a pupillary dilatation when they looked at the stimulus on the left. CONCLUSIONS: Although this study provides support for the hemispatial attention-arousal hypotheses of neglect, it does not preclude the possibility that other mechanisms may also be important.

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PubMed1999

Spared comprehension of emotional prosody in a patient with global aphasia.

BACKGROUND: Several studies have demonstrated that patients with right hemisphere damage, when compared with left-hemisphere damaged controls, are impaired at comprehending emotional prosody. Critics of these studies, however, note that selection may have been biased because left-hemisphere-damaged subjects had good verbal comprehension. OBJECTIVE: To learn whether a subject with a large left hemisphere stroke and global aphasia could comprehend emotional prosody in spoken material. METHOD: The authors formally tested speech and language with the Western Aphasia Battery and comprehension of emotional prosody and emotional facial expression with the Florida Affect Battery. RESULTS: The patient could not perform verbally mediated tests but demonstrated spared ability to match emotional prosody to emotional facial expressions under a variety of conditions. CONCLUSIONS: These observations further support the idea that verbal and emotional communication systems are independent and mediated by different hemispheres.

Adult↗

PubMed1999

Articulatory processes and phonologic dyslexia.

BACKGROUND/OBJECTIVE: Grapheme-to-phoneme conversion (GPC) allows the pronunciation of nonword letter strings and of real words with which the literate reader has no previous experience. Although cross-modal association between visual (orthographic) and auditory (phonemic-input) representations may contribute to GPC, many cases of deep or phonologic alexia result from injury to anterior perisylvian regions. Thus, GPC may rely upon associations between orthographic and articulatory (phonemic-output) representations. METHOD/RESULTS/CONCLUSION: Detailed analysis of a patient with phonologic alexia suggests that defective knowledge of the position and motion of the articulatory apparatus might contribute to impaired transcoding from letters to sounds.

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PubMed1999

Dissociation between autonomic responding and verbal report in right and left hemisphere brain damage during anticipatory anxiety.

OBJECTIVE: To study the relationship between peripheral autonomic arousal and emotional experience. BACKGROUND: Several theories of emotional experience suggest that this experience is, at least in part, related to feedback from the viscera and the autonomic nervous system. METHOD: To partially test this hypothesis and to learn if there are hemispheric asymmetries of emotional experience, we studied skin conductance responses (SCR) and verbal report in patients with right hemisphere damage (RHD), patients with left hemisphere damage (LHD), and normal control subjects during the anticipation of electric shocks. RESULTS: During the shock condition, RHD and LHD subjects had smaller SCRs than did normal control subjects. Verbal report measures, however, revealed that subjects reported feeling less pleasant, more aroused, and less in control during the shock condition compared to the no-shock condition. Unlike the SCR results, the verbal report of emotional experience did not differ between the patients with RHD, patients with LHD, and normal control subjects. CONCLUSIONS: Emotional experience is not dependent upon activation of and feedback from the autonomic nervous system.

Aged↗

PubMed1999

Ideomotor apraxia in Alzheimer disease and left hemisphere stroke: limb transitive and intransitive movements.

OBJECTIVE: Ideomotor apraxia was studied in patients with Alzheimer disease (AD) and unilateral left hemispheric damaged (LHD) stroke to determine whether these groups differed. BACKGROUND: Given that the neuropathology of AD is bilateral and more diffuse than the localized involvement in patients after an LHD stroke, and given that the cognitive deficits in AD are more widespread than in LHD stroke, the authors predicted that patients with these disorders would differ in response to an auditory command task administered to evaluate ideomotor apraxia, and that the two patient groups would be significantly more impaired than healthy matched control subjects. METHODS: Twenty-one persons were studied, including equal numbers of patients with AD, patients with unilateral LHD stroke, and control subjects. An auditory command test of limb apraxia was administered and videotaped to score performance and to code spatial-temporal or content errors. RESULTS: The patients with AD and LHD stroke were significantly more impaired than healthy control subjects. Whereas the patients with AD and LHD stroke were equally apraxic and did not differ in their performance of transitive limb movements, the patients with AD were significantly more impaired than the patients with stroke when performing intransitive limb movements. A positive correlation was found between severity of dementia and severity of apraxia in the patients with AD. The patients with LHD stroke were as likely to make spatial-temporal as content errors when performing intransitive limb movements, whereas the patients with AD made content errors only. Error types produced with transitive limb movements did not differ between groups; spatial-temporal errors were the most common errors made both by patients with AD and patients with LHD stroke. CONCLUSIONS: As predicted, patients with AD and with LHD stroke were impaired when producing limb movements after auditory command, and both patient groups were significantly more impaired than the healthy adults. Patients with AD were significantly more impaired than patients with stroke when performing intransitive limb movements, and error types differed by group. Patients with AD and patients with stroke were equally impaired when performing transitive movements, and error types did not differ by group. Patients with ideomotor apraxia are often degraded in their production of transitive and intransitive movements, and the observation that performance may differ depending on the type of limb movement suggests that movement representations for transitive and intransitive movements may be at least partially independent.

Aged↗

PubMed1998

Possible mechanisms of anosognosia: a defect in self-awareness.

Anosognosia of hemiplegia is of interest for both pragmatic and theoretical reasons. We discuss several neuropsychological theories that have been proposed to explain this deficit. Although for psychological reasons people might deny deficits, the denial hypothesis cannot account for the hemispheric asymmetries associated with this disorder and cannot explain why some patients might deny one deficit and recognize another equally disabling deficit. There is some evidence that faulty feedback from sensory deficits, spatial neglect and asomatognosia might be responsible for anosognosia in some patients. However, these feedback hypotheses cannot account for anosognosia in all patients. Although the hemispheric disconnection hypothesis is appealing, disconnection is probably only a rare cause of this disorder. The feedforward intentional theory of anosognosia suggests that the discovery of weakness is dependent on attempted action and some patients might have anosognosia because they do not attempt to move. We present evidence that supports this theory. The presence of one mechanism of anosognosia, however, does not preclude the possibility that other mechanisms might also be working to produce this disorder. Although a large population study needs to be performed, we suspect that anosognosia might be caused by several of the mechanisms that we have discussed. On the basis of the studies of impaired corporeal self-awareness that we have reviewed, we can infer that normal self-awareness is dependent on several parallel processes. One must have sensory feedback and the ability to attend to both one's body and the space where parts of the body may be positioned or acting. One must develop a representation of the body, and this representation must be continuously modified by expectations (feedforward) and knowledge of results (feedback).

Awareness↗

PubMed1998

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Brain Diseases↗

PubMed1998

Analysis of primary and secondary influences on spatial neglect.

When attempting to determine the middle of a line, patients with neglect deviate from true center. Deviation may be induced by perceptual-attentional bias, premotor-intentional bias, or both. Using a video-based apparatus, we decoupled perceptual from premotor influences on line bisection performance in patients with hemispatial neglect to examine (a) the relationship between primary and secondary bias and (b) the relationship of bias type to lesion location. The same video-based procedure was applied to target cancellation to determine if neglect type varied as a function of task. Primary attentional-perceptual bias was found using line bisection in 14/26 subjects, most of whom had lesions involving the posterior hemisphere. Primary premotor-intentional bias on line bisection was more often associated with lesions of frontal-subcortical structures. The neglect type determined by the bisection task agreed with the results of target cancellation in most cases. Secondary bias was determined based upon whether decoupling decreased the magnitude of bisection error (concordant), increased error (discordant), or produced no significant change. Most patients showed a secondary bias, with 12/26 in the discordant group and 11/26 in the concordant group. Discordant secondary bias was more common in premotor-intentional neglect (10/12) than in perceptual-attentional neglect (2/14), whereas concordant bias was more common in the latter group (10/14) compared to the former (1/12). The nonrandom relationship between primary and secondary bias may provide a more detailed description of ways in which anatomically separate components of a cortical network contribute to spatial processing under conditions of perceptuomotor incongruity.

Brain↗

PubMed1998

Object and action naming in Alzheimer's disease.

We administered measures of object naming and action naming to matched groups of ten patients with Alzheimer's disease (AD) and ten normal control subjects. AD patients were impaired in both object and action naming, with object naming impaired to a significantly greater extent than action naming. This difference remained after controlling for the effects of word frequency. We propose that the pattern of pathological changes in AD impairs both conceptual and lexical retrieval systems for objects but only conceptual systems for actions. The similar patterns of error during the two tasks suggest quantitative rather than qualitative differences in the breakdown of the two abilities.

Aged↗

PubMed1998

Ipsilateral neglect: reversal of bias or exaggerated cross-over phenomenon?

When right brain injury produces contralesional neglect (CN), patients typically misbisect lines to the right. However, others demonstrate so-called "ipsilateral neglect" (IN) with misbisection to the left of midpoint. Paradoxically, most patients with CN also demonstrate a 'cross-over' phenomenon whereby they misbisect short lines to the left. It is not known whether patients with IN actually have a contralesional bias opposite the ipsilesional bias observed with CN, or if their performance reflects an exaggerated cross-over. These alternatives can be distinguished by power function analysis which evaluates the relationship between magnitude of perception and stimulus magnitude. Using line bisection tasks to derive a power function, an IN patient showed a reduced exponent (beta = 0.841), falling outside 95% confidence intervals (CI) for controls but within the CI for CN patients. The IN patient showed a greatly increased constant (K = 7.82), extending outside the CI for both controls and CN patients. The results suggest that the anomalous leftward misbisection with IN is associated with an exaggerated cross-over point and not simply reversal of spatial bias.

Adult↗

PubMed1998

Lateral asymmetries of pupillary responses.

We wanted to learn if pupillary changes induced by looking and attending to stimuli on the right and left are asymmetrical. In humans, there are hemispheric asymmetries in the control of attention-arousal systems. Because attention and arousal may influence pupil size, asymmetric pupillary responses may be seen when looking and attending in different directions. Twelve right-handed, healthy volunteers served as subjects. Using infrared pupillography, we recorded changes of pupillary diameter while subjects were looking and attending to the stimuli on the right and left sides of space. For the one second following a saccade, there are three phasic pupillary responses, an initial constriction (C1) then a dilation (D1), followed by constriction (C2). Evaluation of these three responses revealed right-left asymmetries with more pupil dilation (D1) when looking to the stimulus on the right. Our results suggest that subjects are more aroused when looking to the right than when looking to the left.

Adult↗