Biomedical subjects

Kenneth M Heilman

Publications and source records attributed to Kenneth M Heilman.

At least 19 recordsLinked to original sources

PubMed2007

Asymmetrical alien hands in corticobasal degeneration.

There are several forms of alien limb, but alien limb in corticobasal degeneration (CBD) is not well understood. We studied a patient with CBD who demonstrated two different types of alien limb. With his right hand he demonstrated a tactile avoidance response with levitation. With his left hand, he demonstrated continuous tactile pursuit of the examiner's hand ("tactile mitgehen"). Mitgehen is often associated with frontal dysfunction, but avoidance response and levitation are often associated with parietal dysfunction.

Agnosia↗

PubMed2007

Carbidopa/levodopa-responsive myoclonus.

A 64-year-old right-handed woman's right hand and arm developed spontaneous jerks that eventually involved her trunk. As she had some features of parkinsonism, she was treated with carbidopa/levodopa and her myoclonus dramatically improved. The mechanism accounting for this improvement is unknown.

Antiparkinson Agents↗

PubMed2006

Ipsilateral motor activation during unimanual and bimanual motor tasks.

OBJECTIVE: To test for the presence and possible asymmetry of ipsilateral motor activation during unimanual and bimanual motor tasks. METHODS: Twelve right-handed healthy subjects underwent motor evoked potential (MEP) measurement of one hand (target-hand) while the other hand (task-hand) performed different motor tasks. The target-hand was either at rest (first experiment) or performed a Perdue PegBoard task (second experiment). The task-hand was either at rest, performed a simultaneous pegboard task, or rotated a coin (second experiment). RESULTS: In the first experiment, the motor task resulted in significant increase in MEP area in the target-hand, regardless which hand was the task-hand, with a greater increase when the left hand was the task-hand. In the second experiment, ipsilateral motor activation was not present for either hand, however, when the right hand was the task-hand, performance of continuous coin rotation by the right hand resulted in a significant decrease in the MEP area of the left hand. CONCLUSIONS: Hemispheric asymmetry and task-dependence of ipsilateral motor cortex activation supports the postulate that motor activity may start bilaterally with subsequent interhemispheric inhibition. Furthermore, in right-handers, the left motor cortex is either more active in ipsilateral hand movements or exerts more effective inhibitory control over the right motor cortex than vice versa. SIGNIFICANCE: We suggest that hemispheric asymmetry in ipsilateral motor control is a factor in determining motor dominance in right-handed individuals.

Adult↗

PubMed2006

Posture recognition in Alzheimer's disease.

BACKGROUND: Apraxia is neurologically induced deficit in the ability perform purposeful skilled movements. One of the most common forms is ideomotor apraxia (IMA) where spatial and temporal production errors are most prevalent. IMA can be associated Alzheimer's disease (AD), even early in its course, but is often not identified possibly because the evaluation of IMA by inexperienced judges using performance tests is unreliable. The purpose of this study, therefore, is to learn if the Postural Knowledge Test (PKT), a praxis discrimination test that assesses knowledge of transitive (PKT-T subtest) and intransitive (PKT-I subtest) postures and does not require extensive training, is as sensitive and specific as the praxis performance tests. METHODS: We studied 15 subjects with probable AD as well as 18 age-matched controls by having them perform transitive and intransitive gestures to command and imitation, as well as having them discriminate between correct and incorrect transitive and intransitive postures. RESULTS: Overall on all tests, the control subjects performed better than those with AD. In addition all subjects had more trouble with transitive than intransitive gestures. Using a stepwise discriminative analysis, 81.8% of the subjects could be classified according to Group (94.4% of Controls, 66.7% of AD subjects). In this analysis, the PKT-T (transitive posture subtest) was the only measure that contributed to the discrimination of subjects. CONCLUSION: We found that having subjects select the correct transitive hand postures in this "booklet test" was more sensitive than grading their praxis performances even when using judges with extensive training. This suggests that this discrimination test might be an excellent means for diagnosing and screening patients for AD. The reason why recognition of transitive postures is relatively more difficult for our AD subjects is not known. Two possibilities are that the representations for intransitive movements are stronger than those for transitive movements, and hence, more resistant to degradation, or that intransitive acts are stored in parts of the brain not affected by AD.

Aged↗

PubMed2006

Alterations in working memory as a function of leukoaraiosis in dementia.

Dementia research suggests executive dysfunction is best understood within the context of disease-specific neuropathology. Leukoaraiosis (LA) results in executive dysfunction yet little is known about its impact on specific aspects of working memory (WM). This study aimed to investigate the relationship between MRI LA severity and WM in dementia. A visual rating scale was used to assign patients with dementia into groups with minimal-mild LA (Low LA; n=34) and moderate-severe LA (High LA; n=32). A modified Digit Span Backward Task consisting of 3-, 4-, and 5-span trials measured specific components of WM. Short-term storage and rehearsal in WM were assessed by the total number of digits reported regardless of recall order (ANY-ORDER; e.g., 47981 recalled '18943', score=4). Mental manipulation in the form of disengagement and temporal re-ordering was assessed by the total number of digits recalled in correct position (SERIAL-ORDER; e.g., 47981 recalled '18943', score=3). There was no difference between LA groups on ANY-ORDER comparisons. The High LA group obtained lower SERIAL-ORDER scores than the Low LA group. Stepwise regression analyses were conducted that first entered MMSE scores then composite z-scores reflecting executive functioning, language and memory. ANY-ORDER performance variance was explained solely by dementia severity. SERIAL-ORDER performance variance was further explained by executive dysfunction. Results suggest that high degrees of LA do not interfere with immediate (digit) recall but do interfere with disengagement and temporal re-ordering. LA may disconnect the frontal lobes from subcortical and cortical structures that form the neuronal networks critical for these WM functions.

Aged↗

PubMed2006

Lewy body dementia and creativity: case report.

BACKGROUND: We studied a visual artist with Lewy body dementia (LBD) to learn how this disease influenced his paintings during the course of the disease. METHODS: Study 1 evaluated two paintings of the same subject matter, one that the patient painted before his illness and the other after the onset of this disease. Study 2 evaluated a collection of his paintings from the time before he was ill (1994) until the time he stopped painting when he was suffering with LBD (2002). To learn how the onset and progression of LBD affected his paintings we had judges score the following qualities: aesthetic-beauty, closure completeness, evocative impact, novelty, technique and representational quality. RESULTS: In Study 1 we found that the representational ratings for the picture he painted when he had LBD was significantly lower than the picture he painted before he developed LBD. In Study 2, we found that all the artistic qualities measures temporally declined except novelty. We also found that the paintings that were judges as having the highest quality representations were significantly more novel than those that had poorer representations. In addition, we conducted a forward stepwise regression analysis using quality measures as predictor of year. This analysis revealed that only representational quality significantly predicted painting year. CONCLUSIONS: Our results suggest that as LBD progresses, except for novelty there is a gradual degradation of the ability to visually express artistic subject matter. It possible that the preserved ability to paint novel picture is related to relative preservation of frontal lobe function, but the degradation of other artistic qualities might be related to deterioration of the parietal lobes which either impairs the brain's iconic representations or the knowledge needed to portray these representations.

Adult↗

PubMed2006

Effect of vagus nerve stimulation on creativity and cognitive flexibility.

OBJECTIVE: The purpose of this study was to determine whether vagus nerve stimulation influences cognitive flexibility and creativity. METHODS: Ten subjects, in whom vagus nerve stimulators had been implanted for the treatment of intractable seizures, performed tasks that assessed cognitive flexibility (solving anagrams), creativity (Torrance Test), and memory (Hopkins Verbal Learning Test) during actual and sham vagus nerve stimulation. RESULTS: Vagus nerve stimulation impaired cognitive flexibility and creativity, but these results could not be explained by the induction of a general encephalopathy because VNS did not impair learning and improved retention. CONCLUSIONS: The means by which vagus nerve stimulation impairs cognitive flexibility and creative thinking is probably related to increased activity of the locus coeruleus-central adrenergic system that increases the signal-to-noise ratio and improves the brain's ability to attend to sensory input, but decreases its ability to recruit large-scale networks.

Adult↗

PubMed2006

Orthographic directionality and thematic role illustration in English and Arabic.

This study tested the hypotheses that people had a bias for drawing agents on the left of a picture when given a verb stimulus targeting an active or passive event (e.g., "kicked" or "is kicked") and that orthographic directionality would influence the way events were illustrated. Monolingual English speakers, who read and write left-to-right, and Arabic speakers, who read and write right-to-left, drew agents and patients in response to verb stimuli. We found no significant orthographic directionality effects and no preference for positioning agents on the left of pictures in either group or sentence type. Instead, participants drew agents on the right regardless of language or sentence type, and this was exaggerated in English speakers illustrating passive verbs. These findings support the existence of a preference for placing agents in the right hemispace that may result from asymmetrical hemispheric (i.e., left>right) activation induced by language processing. Our results are consistent with findings that people prefer pictures in which focus is on the right, a preference strongest in pictures with no implicit directionality of movement. This suggests that the methodology of the current study encouraged a static rather than dynamic interpretation of the verb in most participants.

Adult↗

PubMed2006

Verbal dichotic listening in right and left-handed adults: laterality effects of directed attention.

Dichotic listening performance of consonant vowel stimuli was studied in 51 adult right- and left-handers in three attention conditions: non-directed and directed to either the right or left ear. In the non-directed condition, a significant right-ear advantage was found in both handedness groups with a stronger asymmetry in right-handers. There are at least three explanations for this ear bias. The classic or structural hypothesis suggests that to the right ear projects more strongly to the language dominant left hemisphere. The callosal relay hypothesis is based on the influence of inhibitory connections via the corpus callosum. The attentional hypothesis suggests that each hemisphere primarily directs attention to contralateral space and because the left hemisphere is dominant for language in both groups, and is aroused by speech stimuli, attention is primarily directed to the right ear. Neither hypothesis can explain why greater than 95% of right-handers have left hemisphere language dominance, but only 70-80% have a right ear bias. Our results demonstrate that in the directed attention conditions both groups increased their lateral biases when directed to either the right or left. The classic or structural hypothesis cannot account for these changes, thereby providing support for the attentional hypothesis. In addition, the right-handed subjects exhibited a greater shift of bias than did the left-handed subjects, when directing their attention leftward. This finding suggests that right-handed people are better able to shift their attention than left-handed people.

Adult↗

PubMed2006

The right arm likes to be close.

A prior study revealed that the left (vs. right) hemisphere has a visual attentional bias toward the body, a finding that is consistent with the observation that most of the visual cognitive activities performed by the left hemisphere (e.g., reading) take place in proximal (peripersonal) space. In addition, when right-handed people perform bimanual motor tasks their right hand is often held more proximal to the body than their left hand. In this study, we wanted to test the hypothesis that the right hand is also more biased toward the body than is the left hand. Thus, we had blindfolded right-handed subjects attempt to draw straight horizontal lines (at the junction of the transverse and coronal planes), with their left and right hands, on sheets of paper placed in front of them and then measured their deviation from the coronal plane. We found that these subjects' right hands deviated closer to their body than did their left hands. These results support the postulate that in addition to an attentional bias, the left hemisphere-right hand has a proximal motor bias. This bias might account for means by which right-handed people position their hands when using both hands on tools and implements.

Adult↗

PubMed2006

Effects of gesture+verbal treatment for noun and verb retrieval in aphasia.

Links between verbs and gesture knowledge suggest that verb retrieval may be particularly amenable to gesture+verbal training (GVT) in aphasia compared to noun retrieval. This study examines effects of GVT for noun and verb retrieval in nine individuals with aphasia subsequent to left hemisphere stroke. Participants presented an array of noun and verb retrieval deficits, including impairments of semantic and/or phonologic processing. In a single-participant experimental design, we investigated effects of GVT for noun and verb retrieval in two counterbalanced treatment phases. Effects were evaluated in spoken naming and gesture production to pictured objects and actions. Spoken naming improvements associated with large effect sizes were noted for trained nouns (5/9) and verbs (5/9); no improvements were evident for untrained words. Gesture production improved for trained nouns (8/9) and verbs (6/9), and for untrained nouns (2/9) and verbs (2/9). No significant differences were evident between nouns and verbs in spoken naming or gesture production. Improvements were evident across individuals with varied sources of word retrieval impairments. GVT has the potential to improve communication by increasing spoken word retrieval of trained nouns and verbs and by promoting use of gesture as a means to communicate when word retrieval fails.

Aged↗

PubMed2006

Defective comprehension of emotional faces and prosody as a result of right hemisphere stroke: modality versus emotion-type specificity.

Studies of patients with brain damage, as well as studies with normal subjects have revealed that the right hemisphere is important for recognizing emotions expressed by faces and prosody. It is unclear, however, if the knowledge needed to perform recognition of emotional stimuli is organized by modality or by the type of emotion. Thus, the purpose of this study is to assess these alternative a priori hypotheses. The participants of this study were 30 stroke patients with right hemisphere damage (RHD) and 31 normal controls (NC). Subjects were assessed with the Polish adaptation of the Right Hemisphere Language Battery of Bryan and the Facial Affect Recognition Test based on work of Ekman and Friesen. RHD participants were significantly impaired on both emotional tasks. Whereas on the visual-faces task the RHD subjects recognized happiness better than anger or sadness, the reverse dissociation was found in the auditory-prosody test. These results confirm prior studies demonstrating the role of the right hemisphere in understanding facial and prosodic emotional expressions. These results also suggest that the representations needed to recognize these emotional stimuli are organized by modality (prosodic-echoic and facial-eidetic) and that some modality specific features are more impaired than others.

Acoustic Stimulation↗

PubMed2006

Visual selective attention in Parkinson's disease: dissociation of exogenous and endogenous inhibition.

Impairment in the inhibitory mechanism of visual selective attention in patients with Parkinson's disease (PD) is controversial. The present study sought to understand disparate findings in a manner analogous to the relative preservation of exogenously evoked movement and impairment of endogenously evoked movement. The authors examined inhibition of return (i.e., exogenously evoked inhibition; IOR) and negative priming (i.e., endogenously evoked inhibition; NP) in a group of 14 patients with PD and 14 healthy controls (HC). Unlike the HC, who demonstrated significant inhibition in both tasks, the group with PD demonstrated intact inhibition only in the IOR task. Dopamine replacement therapy did not affect performance. The findings are discussed within the context of a model that differentiates the essential involvement of the basal ganglia for endogenously evoked spatial inhibition.

Aged↗

PubMed2006

Naming concepts: evidence of two routes.

This study examines a parallel distributed processing (PDP) model (partly based on the Wernicke-Lichtheim information processing model) that posits two routes for naming concepts, whole word and phonological. To test the two naming route hypothesis of this model, we performed confrontation naming tests that were either uncued, semantically cued, or phonologically cued in a patient with naming impairment due to Broca's aphasia. In spoken language and in uncued naming to confrontation, word retrieval was severely impaired and marked by semantic but no phonemic paraphasic errors. With semantic cues, naming behavior was unchanged; however, with phonological cues, naming success was enhanced but frequent phonemic paraphasias were produced. These results suggest that the patient spontaneously engaged the whole word naming route, but when given phonological cues, he engaged an alternative phonological naming route that incorporated phonological sequence knowledge.

Adaptation, Psychological↗

PubMed2006

Ipsilesional attentional-approach neglect or crossover effect.

Patients with ipsilateral neglect (IN) bisect lines toward contralesional space. It has been posited that IN might be induced by an attempt at compensation, as part of the crossover effect, where patients with an ipsilesional bias when bisecting long lines, cross over and develop a contralesional bias on short lines or as a release of an approach (grasp) behavior that might be attentional or intentional. To test these alternative hypotheses we had a patient with IN from a right medial frontal lesion bisect lines that contained no cue, a left-sided cue, a right-sided cue, and bilateral cues. If this patient had ipsilateral neglect (IN) because of a crossover effect or compensation, right-sided cues should have influenced bisection more than left-sided cues. We, however, found that only left-sided cues induced a significant change (left-sided deviation) providing support for the attentional-approach (grasp) hypothesis. Further support of this contralesional attentional grasp hypothesis comes from the observation that this patient also had ipsilesional extinction to simultaneous stimuli.

Attention↗

PubMed2006

Progressive oculo-orofacial-speech apraxia (POOSA).

A loss of speech can be related to disorders of the motor units (paresis), language deficits (aphasia), or speech programming deficits (apraxia of speech). Although apraxia of speech has been reported to be associated with degenerative diseases, we observed a patient with a unique constellation of signs that included apraxia of speech, oculo-orofacial apraxia and a supranuclear ophthalmoplegia in the absence of extrapyramidal (Parkinsonian) signs. Post-mortem examination revealed a loss of neurons in the frontal and temporal regions, but there was also a marked loss of neurons and astrogliosis in the caudate, claustrum, globus pallidus, substantia nigra, and loss of axons in the anterior cerebral peduncles. This patient's clinical presentation and the pathological correlates suggest that he might have suffered with a distinct disorder we call progressive oculo-orofacial-speech apraxia or POOSA.

Apraxias↗

PubMed2006

Callosal neglect in hydrocephalus.

A functional disconnection of the corpus callosum (CC) can induce a form of spatial neglect where each hand (e.g., left) when attempting to bisect lines in the opposite (e.g., right) hemispace deviates toward its own (e.g., left) hemispace. Patients with hydrocephalus often show thinning of the CC but callosal neglect has not been reported in this condition. Two right-handed patients with hydrocephalus and thinning of the CC, as well as six matched controls, were assessed for neglect by performing the line bisection task in left, right and center space with their right and left hands. When compared to controls neither patient, using either their right or left hands, demonstrated a bias in the center or left space conditions, but with lines in right space both subjects' left hand deviated significantly to the left. Thus, patients with hydrocephalic interhemispheric functional disconnection might show a form of callosal neglect. This hemispatial-hand asymmetry of deviation, however, also might be related to the disinhibition of the attentionally dominant right hemisphere.

Aged↗

PubMed2006

Alzheimer's "other dementia".

A short history of Alzheimer disease and vascular dementia is presented. The socio-medical events that led to the dominance of Alzheimer disease are discussed. Alzheimer's contributions to our current understanding of vascular dementia are reviewed.

Alzheimer Disease↗