Kenneth M. Heilman

Right hemisphere dominance for attention: The mechanism underlying hemispheric asymmetries of inattention (neglect)

Because hemiinattention is most commonly caused by right parietal lesions, it is possible that the left hemisphere attends to contralateral stimuli whereas the right attends to both contralateral and ipsilateral stimuli. We gave lateralized visual stimuli to 12 normal subjects and recorded the electroencephalograms. Desynchronization was determined by comparing the alpha power 1 second before and 1 second after a lateralized visual stimulus. Although the left parietal lobe desynchronized most after right-sided stimuli, the right parietal lobe desynchronized equally after right or left stimuli. These findings support the hypothesis that the right hemisphere is dominant for attention.

Predictors of Cognitive Dysfunction after Major Noncardiac Surgery

Background:The authors designed a prospective longitudinal study to investigate the hypothesis that advancing age is a risk factor for postoperative cognitive dysfunction (POCD) after major noncardiac surgery and the impact of POCD on mortality in the first year after surgery. Methods:One thousand sixty-four patients aged 18 yr or older completed neuropsychological tests before surgery, at hospital discharge, and 3 months after surgery. Patients were categorized as young (18–39 yr), middle-aged (40–59 yr), or elderly (60 yr or older). At 1 yr after surgery, patients were contacted to determine their survival status. Results:At hospital discharge, POCD was present in 117 (36.6%) young, 112 (30.4%) middle-aged, and 138 (41.4%) elderly patients. There was a significant difference between all age groups and the age-matched control subjects (P < 0.001). At 3 months after surgery, POCD was present in 16 (5.7%) young, 19 (5.6%) middle-aged, and 39 (12.7%) elderly patients. At this time point, the prevalence of cognitive dysfunction was similar between age-matched controls and young and middle-aged patients but significantly higher in elderly patients compared to elderly control subjects (P < 0.001). The independent risk factors for POCD at 3 months after surgery were increasing age, lower educational level, a history of previous cerebral vascular accident with no residual impairment, and POCD at hospital discharge. Patients with POCD at hospital discharge were more likely to die in the first 3 months after surgery (P = 0.02). Likewise, patients who had POCD at both hospital discharge and 3 months after surgery were more likely to die in the first year after surgery (P = 0.02). Conclusions:Cognitive dysfunction is common in adult patients of all ages at hospital discharge after major noncardiac surgery, but only the elderly (aged 60 yr or older) are at significant risk for long-term cognitive problems. Patients with POCD are at an increased risk of death in the first year after surgery.

Pseudoneglect: effects of hemispace on a tactile line bisection task.

Abstract The purpose of this study was to determine whether tactile laterality effects can be attributed to an anatomical pathway-transmission model or to some hemispheric mechanism involved in the perception and/or mediation of activities in the contralateral hemispatial field. Hemispace is not the same as the visual half field, but refers to the external space to the left or right of body midline. To differentiate between these two hypotheses, 24 normal dextrals performed a tactile line bisection task using the left or right hand in each of three spatial conditions: at midline, in left hemispace and right hemispace. The findings indicated that both hemisphere-hemispace mechanisms and hemisphere-hand connections contributed to laterality effects. Furthermore, a pseudoneglect phenomenon was observed.

Two forms of ideomotor apraxia

Destruction of parietal areas containing visuokinesthetic motor engrams, where motor acts may be programmed, should be distinguishable from apraxia induced by disconnection of these parietal areas from frontal motor areas. Destruction should result in inability to distinguish well-performed from poorly performed movements, whereas disconnection should not. We gave movement and act-discrimination tasks to apraxic and nonapraxic patients with anterior lesions or nonfluent aphasia, and to patients with posterior lesions or fluent aphasia. On both tasks, the performance of posterior/fluent patients was worse than that of all other patients. Our results suggest that there are two types of patients with ideomotor apraxia.

Auditory affective agnosia. Disturbed comprehension of affective speech.

Hughlings Jackson noted that, although some aphasic patients were unable to use propositional speech, affective speech appeared to be spared. The purpose of this experiment was to study patients with unilateral hemispheric disease in order to ascertain if there are hemispheric asymmetries in the comprehension of affective speech. Six subjects had right temporoparietal lesions (left unilateral neglect) and six subjects had left temporoparietal lesions (fluent aphasias). These subjects were presented with 32 tape recorded sentences. In 16 trials the patients were asked to judge the emotional mood of the speaker (happy, sad, angry, indifferent) and in 16 trials the patients were asked to judge the content. Line drawings containing facial expressions of the four emotions or line drawings corresponding with the four basic contents were displayed with each sentence and the patient responded by pointing. All 12 subjects made perfect scores on the content portion of the test. On the emotional portion the right hemispheric patients scored a mean of 4-17 and the left hemispheric group scored a mean 10-17. The difference between these means is significantly (P less than 0-01) and suggests that patients with right hemispheric dysfunction and neglect have a defect in the comprehension of affective speech.

A cognitive neuropsychological model of limb praxis

Abstract This paper is devoted to the development of a composite model of limb praxis processing that is supported by a series of dissociations noted in the performance of apraxic patients. These dissociations include die separability of praxis production from praxis reception, the selectivity of input modalities, an “assembled” route of praxis imitation, and the possible fragmentation of semantics into an action and a nonaction system.

Hypoarousal in patients with the neglect syndrome and emotional indifference

Physiologic theories of emotion suggest that activation is important in the experience of emotion; patients exhibiting “neglect” as a consequence of right parietotemporal dysfunction show flattened affect. We studied arousalin patients with lesions of the right hemisphere who also exhibited emotional indifference, in aphasic patients with lesions of the left hemisphere, and in non-brain-damaged controls, by stimulating the forearm ipsilateral to the side of the brain lesion while recording galvanic skin responses (GSRs) from the fingers on the same side. The group exhibiting neglect had lower GSRs than aphasic patients or non-brain-damaged controls. Aphasic patients had higher GSRs than non-brain-damaged controls. These results suggest that neglect is associated with disturbances in bilateral arousal and that this disorder of arousal may be responsible in part for flattened affect. The heightened GSR in aphasic patients may reflect disinhibition, which might be partly responsible for increased emotionality in these patients.

Frontal lobe neglect in man

“My hypothesis is that the frontal lobes are the seat of coordination and fusion of the incoming and outgoing products of the several sensory and motor areas of the cortex.” Bianchi (1895)’ made this hypothesis after excising the frontal lobes in animals and observing rotary movements t o the side of the lesion and a visual disturbance that appeared as a contralateral hemianopia. Kennard’ showed that there was also a loss of cutaneous sensitivity in these animals, and Kennard and Ectors3 proposed that the visual defect was more a hemianopia in which an object is disregarded than a true hemianopia. Welch and Stuteville4 found that with lesions of the posterior part of the superior limb of the arcuate sulcus, their monkeys had unilateral neglect t o all sensory modalities tested. Although many investigators have produced and described frontal neglect in monkeys, unilateral frontal neglect has not been described in man other than in the two cases of pseudohemianopia described by Halstead’ and ThiebauL6 The purpose of this study was t o assess patients with frontal lobe lesions to establish the p r e s e n c e of unilateral neglect hemispatial agnosia, inattention, and extinction t o simultaneous stimuli -and to relate these findings t o other known phenomena attributed t o frontal lobe disease. Patients admitted t o the University of Florida Teaching Hospital o r Boston City Hospital during 1969 and 1970 who demonstrated lesions confined to the frontal lobes, as demonstrated by brain scan or postmortem examination, were included in this series. Six cases of unilateral neglect were uncovered (see table). The anatomic loci of the lesions were determined by pathological exami-

Discrimination and evocation of affectively intoned speech in patients with right parietal disease

Patients with right parietal disease have disturbed comprehension of affective speech. Ability to discriminate affective speech (make same/different discriminations) and ability to repeat emotionally bland sentences with affective tones were tested in three groups of subjects—patients with right parietal dysfunction and neglect, conduction aphasics with left hemispheric lesions, and patients without intracranial disease. Patients with right parietal dysfunction performed significantly poorer than did aphasic controls on both a recognition and discrimination task. Patients with right parietal dysfunction also scored poorer on the evocative task than the nonaphasic controls.

Relative frequencies of Alzheimer disease, Lewy body, vascular and frontotemporal dementia, and hippocampal sclerosis in the State of Florida Brain Bank

Alzheimer disease (AD) is the most common dementing illness in the elderly, but there is equivocal evidence regarding the frequency of other disorders such as Lewy body disease (LBD), vascular dementia (VaD), frontotemporal dementia (FTD), and hippocampal sclerosis (HS). This ambiguity may be related to factors such as the age and gender of subjects with dementia. Therefore, the objective of this study was to calculate the relative frequencies of AD, LBD, VaD, FTD, and HS among 382 subjects with dementia from the State of Florida Brain Bank and to study the effect of age and gender on these frequencies. AD was the most frequent pathologic finding (77%), followed by LBD (26%), VaD (18%), HS (13%), and FTD (5%). Mixed pathology was common: Concomitant AD was present in 66% of LBD patients, 77% of VaD patients, and 66% of HS patients. The relative frequency of VaD increased with age, whereas the relative frequencies of FTD and LBD declined with age. Males were overrepresented among those with LBD, whereas females were overrepresented among AD subjects with onset age over 70 years. These estimates of the a priori probabilities of dementing disorders have implications for clinicians and researchers.