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Biomedical subjects

D Bowers

Publications and source records attributed to D Bowers.

At least 19 recordsLinked to original sources
PubMed1995

Spontaneous gestures following right hemisphere infarct.

Neurobehavioral studies of gesturing have been largely limited to left hemisphere damaged (LHD) patients. We compared spontaneous gesturing in seven right hemisphere damaged (RHD) patients, seven LHD patients, and seven normal controls (NHD) during videotaped interviews. Two judges coded symbolic, expressive, grooming, and fidgeting gestures in 120 10-sec intervals of videotape per patient. We found that RHD patients made significantly more total gestures and grooming gestures with the hand ipsilateral to their lesion than did LHD patients. Furthermore, RHD patients made more total and grooming gestures with their right hand than NHD subjects did with either hand. There were no differences in gesture production between the right and left hands of NHD patients. These results suggest that RHD produces enhanced gesturing, particularly involving grooming behavior.

Aged↗
PubMed1995

Emotional facial imagery, perception, and expression in Parkinson's disease.

Patients with Parkinson's disease (PD) may be impaired at expressing emotional faces and perceiving emotional facial affect. We tested the hypothesis that patients with PD may be impaired at imaging emotional faces. We first compared 12 patients with PD and 30 control subjects on perceptual and imagery tasks. Patients were significantly impaired on a task of emotional facial imagery but not on a control task of object imagery. Patients were also impaired on a task of perceiving emotional faces. Subsequently, we found that PD patients were impaired relative to controls on making emotional faces. Performance on both the perceptual and motor tasks of facial expression significantly correlated with performance on the emotional facial imagery task. We suggest that the basal ganglia, together with the right hemisphere, are part of a neural network subserving emotional facial tasks.

Aged↗
PubMed1994

Apperceptive visual agnosia: a case study.

A man with an infarction of his inferior temporal and occipital association cortex bilaterally, which spared primary visual cortex, had impaired visual recognition of objects, faces, colors, words, and gestures. Analysis of visual function indicated that the recognition failures resulted from an agnosia, rather than elemental visual impairment. Whereas his impairment of gesture recognition appeared to be related to an associative agnosia, his inability to recognize objects was related to an apperceptive agnosia. There may be four subtypes of apperceptive agnosia: one where the internal object representations or structural descriptions are impaired, another where an adequate percept cannot be derived, a third where the internal referent and percept are dissociated, and a fourth where both levels are impaired. Our patient demonstrated a failure to relate individual elements to the whole, a failure to integrate multiple elements, and a reliance on global perception. He had normal object imagery. These results suggest that, whereas internal representations were intact, he was unable to form adequate perceptual representations.

Aged↗
PubMed1993

Right hemisphere facial expressivity during natural conversation.

Most studies of facial expressivity in patients with focal brain lesions have examined the ability to produce emotional expression in laboratory settings using various experimental paradigms. In this study, we compared facial expressivity in right hemisphere damaged patients (RHD), left hemisphere damaged patients (LHD), and normal controls (NHD) during videotaped semistructured interviews with the patient and spouse in their home. Three research assistants rated 120 10-sec segments of videotape per patient on a 7-point expressivity scale. We found that RHD patients showed reduced facial expressivity in comparison to both LHD and NHD subjects during spontaneous conversation. In particular, RHD patients demonstrated significantly less smiling and laughter than LHD patients and normal controls. These findings were not a general feature of communicative competence in RHD patients as discourse production equaled that of normal controls. These results support the hypothesis that the right hemisphere mediates facial expressivity during spontaneous social interaction.

Aged↗
PubMed1993

Case management in Alzheimer's disease.

Patients with a diagnosis of Alzheimer's disease and their families need the assistance of a case manager to deal with the issues of long-term care. The case manager assists with education, planning, linking to formal and informal resources, and addressing emotional needs in the family unit. This article discusses specific suggestions to address problems in the three stages of Alzheimer's disease from the time of medical diagnosis to the end of life.

Alzheimer Disease↗
PubMed1992

Peripheral ischaemia and gangrene presenting at birth.

The aetiology of non-iatrogenic causes of peripheral ischaemia and gangrene presenting either at birth or within a few hours of delivery is unknown in the majority of 56 confirmed cases. In this review of 47 cases occurring since 1941 the aetiology was clear in only 6, four due to compression by the encircling umbilical cord. There was no clear association with gestational age, birth weight, maternal age or type of delivery. Seven were infants of poorly controlled diabetic mothers and these may constitute a subgroup due to altered haemostatic mechanisms. Pregnancy hypertension was an association in 7 cases, oligohydramnios in 6. There is only limited support for birth trauma, sepsis, and thrombo-emboli from the ductus arteriosus as causes. There is indirect evidence that thrombo-emboli can migrate from the placental bed to the fetus. In recent years death from this condition has been rare with surgical thrombectomy increasingly successful in late presenting cases. When gangrene is established at birth surgical amputation, autoamputation, or some loss of function is usual. Peripheral ischaemic insults presenting at birth may be part of a wider spectrum of disorders, both prenatal and perinatal, attributable to occlusive vascular disruption.

Extremities↗
PubMed1992

Amnesia following a discrete basal forebrain lesion.

Destructive lesions of the basal forebrain are associated with memory impairment in both humans and experimental animals. The basal forebrain is thought to contribute to memory function by providing cholinergic innervation to critical memory structures such as the hippocampus and amygdala. In previously reported clinical cases of basal forebrain amnesia, multiple neuroanatomical regions have been damaged, preventing identification of the minimal critical lesion necessary to produce an amnestic syndrome. We describe a patient who developed persistent, global anterograde and retrograde amnesia following resection of a low-grade glioma. Post-surgical magnetic resonance imaging studies revealed a small discrete lesion, centred in the right diagonal band of Broca, that included the preoptic area, the anterior hypothalamus, the lamina terminalis and the paraterminal gyrus. The septal nuclei and the cell bodies of the nucleus basalis of Meynert appeared to have been spared, as were other structures in the medial temporal lobe and diencephalon. Our case provides critical support for the independent contribution of the basal forebrain, in particular the diagonal band nuclei, in memory function. We propose that our patient's amnesia resulted from disconnection of pathways between the diagonal band nuclei and the hippocampal region, depriving the hippocampus of cholinergic innervation.

Amnesia↗
PubMed1991

Frontal verbal amnesia. Phonological amnesia.

Although aphasic patients with frontal lobe damage may demonstrate impaired retention of verbal material, significant anterograde memory disturbances have not, to our knowledge, been reported with a minor Broca's aphasia. We describe a patient with minor Broca's aphasia who exhibited an unusual and profound anterograde memory disturbance, especially for phonologically specified stimuli. We suggest that this disturbance is attributable to an impairment in the volitional, controlled search of stored phonological information.

Amnesia↗
PubMed1991

Autonomic and behavioral evidence of "implicit" memory in amnesia.

A profoundly amnesic patient with a left retrosplenial-fornix lesion was tested on a recognition task that evaluated both verbal and electrodermal aspects of new learning. In addition, "implicit memory" tasks (mirror reading and perceptual identification) were given. The patient displayed strong evidence of learning on all tasks although the results of this learning were not represented in explicit recall or recognition. These findings suggest that autonomic as well as behavioral evidence can index spared memory functions in amnesia. The specific meaning of electrodermal recognition and its possible place in the distinction between implicit and explicit memory is discussed.

Adult↗
PubMed1991

Autobiographical memory: influence of right hemisphere damage on emotionality and specificity.

This study investigated the ability of right hemisphere damaged (RHD) patients to recall autobiographical material in response to emotional versus nonemotional cues. A modified Crovitz paradigm was used in which patients were asked to recall a specific episode from their own life that related to a cue word. These episodes were rated for emotionality and specificity by independent raters. Patients also rated the emotionality of their own episodes. Independent raters judged the reports of the RHD patients as less specific and less emotional than those of matched nonneurologic control subjects. This was true for episodes in response to emotional as well as nonemotional cue words. RHD patients' own ratings of these episodes, however, did not differ from those of controls. These findings are discussed in terms of RHD patients' overall difficulties in processing emotional material and in terms of the nature of autobiographical memory.

Aged↗
PubMed1991

The role of the right hemisphere in emotional communication.

Previous research has established that patients with right hemisphere damage (RHD) are impaired in the comprehension of emotional prosody and facial expression. There are several explanations for this impairment. It may reflect defective acoustic and visuospatial analysis, disruption of nonverbal communicative representations, or a disturbance in the comprehension of emotional meaning. In order to examine these hypotheses, we asked RHD patients, left hemisphere damaged patients (LHD) and normal controls (NC) to judge the emotional content of sentences describing nonverbal expressions, and sentences describing emotional situations. We found that RHD subjects performed normally in their ability to infer the emotion conveyed by sentences describing situations. However, RHD patients were impaired in relation to both LHD and NC in the capacity to judge the emotional content of sentences depicting facial, prosodic, and gestural expressions, suggesting a disruption of nonverbal communicative representations.

Cerebrovascular Disorders↗
PubMed1991

Differential impact of right and left hemisphere lesions on facial emotion and object imagery.

Thirty-six patients with unilateral hemispheric lesions of the right hemisphere (RHD), left hemisphere (LHD), or no neurologic disease were evaluated on two tasks of visual imagery: one involved imagery for facial emotions and the other involved imagery for common objects. As a group, the RHD patients were more impaired on the emotional than the object imagery task, whereas the LHD patients showed the opposite pattern. Individual case analyses suggested that the RHD group consisted of different behavioural subtypes. One patient with a right inferior occipito-temporal lesion had a facial emotion imagery generation defect, other RHD patients displayed a facial affect agnosia (being impaired on emotional imagery and emotional perceptual tasks), while other RHD patients had perceptual defects with sparing of imagery performance. A final RHD group was globally impaired across all imagery and perceptual tasks. These findings support the hypothesis that the right hemisphere may contain a 'lexicon' of facial emotions. Furthermore, these findings argue against current views that it is exclusively the left or right hemisphere that mediates visual imagery. Rather, hemispheric asymmetries in imagery performance are to some extent material-representation specific and may arise when (a) the representations of objects/events to be imaged are differentially represented in the hemispheres, and/or (b) when the operations acting on these imaged events are differentially lateralized.

Aged↗
PubMed1990

Frontal hypermetabolism and thalamic hypometabolism in a patient with abnormal orienting and retrosplenial amnesia.

A patient with verbal amnesia and a propensity to direct his attention to the right following a retrosplenial area lesion was studied with positron emission tomography using [F-18] fluorodeoxyglucose. These studies showed that the left thalamus was hypometabolic, and the anterior 2/3 of the left hemisphere was hypermetabolic when compared with the right. There were no significant differences seen in the medial temporal lobes. Based on this study, it is posited that interruption of hippocampal input into the anterior thalamus was responsible for the amnesia, and the left frontal hyperactivity was associated with the propensity to attend contralaterally.

Adult↗
PubMed1990

The contribution of an imagery code to verbal memory.

Free recall for auditorially presented spatial information was examined in a patient with a large right cerebral infarction. Despite normal verbal memory at immediate and 30-minute conditions, the patient exhibited a significant loss in verbal recall at 24 hours and a more severe deficit in the recall of the spatial components of prose passages across all delayed recall conditions. These results suggest that although the verbal code is important early in the learning process, spatial imagery exerts an increasing influence over time. Thus, reliance upon a left hemispheric mediated verbal encoding process may only allow for partial integration of linguistic and visuospatial properties.

Adult↗
PubMed1990

Peripersonal and vertical neglect.

When bisecting radial lines visually, normal subjects err towards distant peripersonal space, and when bisecting vertical lines visually, they err towards upper vertical space. In contrast, when bisecting lines under tactile-proprioceptive guidance, subjects err towards near peripersonal space, suggesting that normally attention is preferentially distributed away from the body during visual exploration but distributed towards the body during tactile exploration. A patient with ischaemic lesions, however, involving both inferior temporal lobes neglected far peripersonal and upper vertical space. He also demonstrated a motor bias away from the neglected space. These findings suggest that in man attention is spatially directed in three orthogonal axes (horizontal, vertical and radial), that attention may normally be unequally distributed in each of these axes, and that neglect may occur in not only the horizontal axis but also in the radial and vertical axes.

Adult↗