Ipsilesional 'where' with contralesional 'what' neglect

Whereas contralesional spatial neglect is usually caused by right temporo-parietal lesions, ipsilesional spatial neglect is induced primarily by right frontal lesions. This report describes a 73-year-old woman with a right inferior parietal lesion who on 'where' tasks (line bisection and midline pointing) demonstrated ipsilesional neglect, but on 'what' tests (gap vs. no-gap detection cancellation and clothing tape removal) demonstrated contralesional neglect. This 'what' and 'where' directional dissociation provides evidence for independent 'what' and 'where' attentional networks; however, the reason this parietal lesion causes this contralesional vs. ipsilesional spatial attentional 'what' and 'where' dichotomy remains to be determined.     

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.     

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.     

Ipsilesional versus contralesional neglect depends on attentional demands

Right hemisphere injuries often produce contralesional hemispatial neglect (CN). In contrast to CN, some patients with right hemisphere damage can also show so-called ipsilesional neglect (IN). Previous reports found that patients tend to show IN on line bisection tasks but CN on other tasks such as target cancellation. To learn why these two tasks induce different spatial biases in patients with right hemisphere injury, conventional (i.e. solid) line bisection was compared with two novel bisection tasks consisting of horizontally aligned strings of characters. The subjects' task was to mark a target character that was at or closest to the true midpoint of the simulated line. Four of the 5 patients showed a dissociation whereby IN occurred for solid lines while CN was observed on character lines. The two patients assessed with an antisaccade paradigm showed a "visual grasp" for leftward stimuli. The present results suggest that neglect on line bisection may reflect two opposing forces, an approach behavior or "visual grasp" toward left hemispace and an attentional bias toward right hemispace.     

Explicit and implicit perception of illusory contours in unilateral spatial neglect: behavioural and anatomical correlates of preattentive grouping mechanisms

Studies of hemispatial neglect suggest that some perceptual processes still operate on contralesional stimuli independent from spatial attention or awareness. Here we examined whether preattentive processing in extrastriate areas may group unconnected elements inducing illusory contours despite neglect. While it has been debated whether illusory contours arise from preattentive grouping or higher cognitive processes, neurophysiological studies show that neurones in secondary visual cortex (V2) can code for illusory contours. Twelve patients with right hemisphere damage and left neglect were tested for implicit and explicit detection of illusory contours using, respectively: (1) a bisection task where patients were not explicitly required to attend to lateral elements and judged the midpoint of Kanizsa illusory stimuli, as well as other physically connected or unconnected stimuli of the same length; (2) a matching task where patients had to overtly attend to lateral elements and made same/different judgements on pairs of illusory stimuli with identical or different inducers on the right or left side. In some patients, bisection judgements were consistently similar on Kanizsa stimuli with illusory contours and connected stimuli with real contours but different on unconnected gap figures, regardless of their length, suggesting implicit grouping of inducing elements prior to processing stages where a spatial attentional bias arose. Their lesions centred on the inferior parietal cortex or thalamus. Other patients did not show a systematic bisection pattern and had lesions extending posteriorly in the lateral occipital cortex. However, both groups of patients failed to detect left-side inducers in explicit matching judgements, even though errors often revealed unconscious processing, and they showed similar neglect severity on other standard tests. These findings suggest that grouping by illusory contours can occur preattentively and influence bisection independently from the ability to detect contralateral inducers explicitly, severity of inattention, and other forms of unconscious processing. Implicit grouping may depend on the sparing of lateral occipital areas involved in figure-ground segmentation at early stages of visual processing.     

The behavioural assessment of visual neglect

Abstract

Unilateral visual neglect is among the most striking consequences of right-sided brain damage and is characterised by the patient's failure to respond to stimuli on the side contralateral to the lesion. Visual neglect disrupts many aspects of daily living such as mobility, dressing, and reading, yet the underlying mechanisms remain poorly understood.

This paper describes the development, standardisation and validation of a test battery designed to identify a wide variety of visual neglect behaviours observed in clinical practice. The Behavioural Inattention Test (B.I.T.), which was standardised on a large stroke population (n = 80), is described. Unlike existing studies of visual neglect, the B.I.T. relates test results to functional assessment and rehabilitation. Using the test battery and normative data from 50 age-matched controls, 30 patients (37.5%) were classified as demonstrating neglect. Neglect is more frequent and severe following right-rather than left-sided lesions. Inter-rater, test-retest, and parallel forms of the test show the neglect battery to be a reliable measure of patient performance. Correlations with ‘conventional’ and clinical judgements demonstrate the underlying validity of the battery.

The B.I.T. thus provides a conceptual framework within which to investigate and characterise visual neglect in a manner that is useful to rehabilitation.     

Near and far space neglect: task sensitivity and anatomical substrates

Most group studies which have investigated neglect for near and far space have found an increased severity of symptoms in far space compared to near space. However, the majority of these studies used relatively small samples and based their findings almost exclusively on line bisection performance. The aim of the present study was, therefore, to explore the occurrence of neglect for near and far space in a larger group of unselected right brain damaged patients and to evaluate whether neglect specific to near and far space is a task-related deficit or generalises across distance irrespective of task. In addition, a lesion overlap analysis was carried out to identify critical lesion sites associated with distance specific neglect deficits. Thirty-eight right hemisphere damaged patients carried out a line bisection and a cancellation task by using a pen in near space (40 cm) and a laser pointer in far space (320 cm). The results showed that both the number of left-sided omissions and rightward bisection errors were significantly increased in near compared to far space. Distance specific dissociations, albeit less common, were more frequently observed for cancellation than line bisection. These results suggest that space representation in neglect is more severely impaired in near than in far space. In addition, distance related dissociations in neglect may depend on task demands. Although the anatomical findings were broadly consistent with a dorsal and ventral stream dichotomy for near and far space processing, they also suggest the involvement of intermediate structures in distance related neglect phenomena.     

Impact of alertness training on spatial neglect: a behavioural and fMRI study

The effects of a 3-week computerised alertness training on chronic (>3 months) visuospatial hemineglect were investigated prospectively in seven patients by means of neuropsychological tests and functional magnetic resonance imaging (fMRI). Following the alertness training, the group showed improved alertness and a significant improvement in the performance of a neglect test battery over and above any improvement during a 3-week baseline phase. Improvements in the neglect tasks were accompanied by an increase of right hemisphere neural activity in frontal cortex, anterior cingulate cortex, precuneus, cuneus and angular gyrus. These areas have previously been associated with alertness and spatial attention. A similar pattern of increased neural activity was found for the left hemisphere. Four weeks after the end of the training, the patients' neglect test performance had mostly returned to baseline, while the increases in neural activity bilaterally in frontal areas, in the right anterior cingulate cortex, the right angular gyrus and the left temporoparietal cortex remained. The data show that a 3-week computerised alertness training can improve performance both in alertness and neglect tests and that these behavioural improvements are associated with reactivation in areas associated with alerting and visuospatial attention. The limited stability of these effects over time suggests that a 3-week alertness training alone does not result in long lasting improvements in every patient, but refining the treatment protocol may lead to a more stable amelioration of neglect symptoms.     

Haloperidol treatment reverses behavioural and anatomical changes in cocaine-dependent mice

Abnormal dopamine (DA) transmission occurs in many pathological conditions, including drug addiction. Previously, we showed DA D2 receptor (D2R) activation results in pruning of the axonal arbour of DA neurones that innervate the dorsal striatum. Thus, we hypothesised that long-term D2R stimulation through drugs of addiction should cause arbour pruning of neurones that innervate the ventral striatum and thus reduce DA release and contribute to craving. If so, D2R blockade should return these arbours to normal size and may overcome craving. We show that long-term treatment with a D2R antagonist (haloperidol) reverses behavioural and anatomical effects of cocaine dependence in mice, including relapse. This change in arbour size reflects new synapse formation and our data suggest this must occur in the presence of increased DA activity to reverse cocaine-seeking behaviour. These findings hold significant implications for the understanding and treatment of cocaine addiction.     

Sensitivity of clinical and behavioural tests of spatial neglect after right hemisphere stroke

OBJECTIVES: The lack of agreement regarding assessment methods is responsible for the variability in the reported rate of occurrence of spatial neglect after stroke. The aim of this study was to assess the sensitivity of different tests of neglect after right hemisphere stroke. METHODS: Two hundred and six subacute right hemisphere stroke patients were given a test battery including a preliminary assessment of anosognosia and of visual extinction, a clinical assessment of gaze orientation and of personal neglect, and paper and pencil tests of spatial neglect in the peripersonal space. Patients were compared with a previously reported control group. A subgroup of patients (n=69) received a behavioural assessment of neglect in daily life situations. RESULTS: The most sensitive paper and pencil measure was the starting point in the cancellation task. The whole battery was more sensitive than any single test alone. About 85% of patients presented some degree of neglect on at least one measure. An important finding was that behavioural assessment of neglect in daily life was more sensitive than any other single measure of neglect. Behavioural neglect was considered as moderate to severe in 36% of cases. A factorial analysis revealed that paper and pencil tests were related to two underlying factors. Dissociations were found between extrapersonal neglect, personal neglect, anosognosia, and extinction. Anatomical analyses showed that neglect was more common and severe when the posterior association cortex was damaged. CONCLUSIONS: The automatic rightward orientation bias is the most sensitive clinical measure of neglect. Behavioural assessment is more sensitive than any single paper and pencil test. The results also support the assumption that neglect is a heterogeneous disorder.     

Spinal cord softenings of identifiable cause: anatomical and clinical features

To complete our bibliographic review of spinal cord softenings, we now discuss the clinical and pathological findings in the cases of known or probable cause. Comparison of the diagnostic groups yields some differences in respect of sex, age and mode of onset, survival and extent of the anatomical lesion. Further differences, especially in age at onset, clinical pattern and lesion site, emerge from a comparison of these cases of known or probable cause with those whose cause is not apparent.

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Sommario A completamento di una precedente rassegna bibliografica, gli autori espongono i dati clinici e anatomopatologici dei casi di rammollimento midollare riferibili a una determinata causa eziologica. Il confronto tra i gruppi diagnostici permette di riconoscere alcune differenze riguardo all'incidenza del rammollimento midollare tra i due sessi, all'età e alle modalità di insorgenza, alla sopravvivenza dei pazienti, nonché all'estensione della lesione anatomica. Ulteriori differenze (specie per l'età di insorgenza, il quadro clinico e la sede della lesione) vengono evidenziate dal confronto tra i casi di rammollimento da causa eziologica probabile e quelli senza causa evidente.

     

Opioid-induced epileptogenic phenomena: anatomical, behavioral, and electroencephalographic features

Recent animal studies have indicated a possible role of opioids in epilepsy. Intraventricular opioid administration induces a prolonged nonconvulsive stuporous state characterized by epileptiform electroencephalographic patterns, and reversed by naloxone. In high doses, naloxone itself causes generalized clonic convulsions. We compared opioid-induced and naloxone-induced epileptogenic phenomena using quantitative 2-deoxyglucose autoradiography in order to define the anatomical structures involved in these two different seizure types. When opioid-induced seizures occurred, limbic structures were preferentially activated, but when naloxone-induced clonic convulsions occurred, pyramidal and extrapyramidal motor areas and some limbic structures were activated. Based on the present experiments and currently available evidence, we speculate that opioid-mediated epileptogenic phenomena are similar to those occurring during the postictal state of a fully kindled seizure, whereas naloxone-induced epileptogenic phenomena are similar to the ictal state. Therefore, simple pharmacological manipulation of endogenous opioid systems may allow selective study of ictal and postictal phenomena.     

The lumbar roots and pedicles: a morphometric analysis and anatomical features

The objective of this study was to conduct a morphometric analysis of the lumbar nerve roots and surrounding structures. In this investigation, the lumbar roots were studied in 14 cadavers (70 lumbar vertebrae). Lumbar pedicle heights and widths were measured at every level of the lumbar vertebrae. The largest mean root diameter was 5.6 mm (L5 root) and the smallest 3.5 mm (L1 root). With regard to the root-dura exit angle, the widest was measured at L1 as 26.2+/-1.6 degrees and the narrowest at L5 as 16.3+/-2.4 degrees. The widest lumbar pedicle was measured at L5 as 17.1+/-4.2 mm and the narrowest at L1 as 8.4+/-1.8 mm. The longest lumbar pedicle was measured at L2 as 15.3+/-2.2 mm and the shortest at L4 as 13.8+/-2.3 mm. Quantitative measurements of lumbar root diameters, their exit angles from the dura, and lumbar pedicle heights and widths in anatomical dissection models may help us to gain a deeper understanding of the pathologies of this region and positively influence the success of surgical interventions.     

Review: Neuropathology and behavioural features of transgenic murine models of Alzheimer's disease

Our understanding of the underlying biology of Alzheimer's disease (AD) has been steadily progressing; however, this is yet to translate into a successful treatment in humans. The use of transgenic mouse models has helped to develop our understanding of AD, not only in terms of disease pathology, but also with the associated cognitive impairments typical of AD. Plaques and neurofibrillary tangles are often among the last pathological changes in AD mouse models, after neuronal loss and gliosis. There is a general consensus that successful treatments need to be applied before the onset of these pathologies and associated cognitive symptoms. This review discusses the different types of AD mouse models in terms of the temporal progression of the disease, how well they replicate the pathological changes seen in human AD and their cognitive defects. We provide a critical assessment of the behavioural tests used with AD mice to assess cognitive changes and decline, and discuss how successfully they correlate with cognitive impairments in humans with AD. This information is an important tool for AD researchers when deciding on appropriate mouse models, and when selecting measures to assess behavioural and cognitive change.     

Searching for anatomical correlates of olfactory lateralization in the honeybee antennal lobes: a morphological and behavioural study

The honeybee, Apis mellifera L. (Hymenoptera: Apidae), has recently become a model for studying brain asymmetry among invertebrates. A strong lateralization favouring the right antenna was discovered in odour learning and short-term memory recall experiments, and a lateral shift favouring the left antenna for long-term memory recall. Corresponding morphological asymmetries have been found in the distribution of olfactory sensilla between the antennae and confirmed by electrophysiological odour response measurements in isolated right and left antennae. The aim of this study was to investigate whether a morphological asymmetry can be observed in the volume of the primary olfactory centres of the central nervous system, the antennal lobes (ALs). Precise volume measurements of a subset of their functional units, the glomeruli, were performed in both sides of the brain, exploiting the advantages of two-photon microscopy. This novel method allowed minimal invasive acquisition of volume images of the ALs, avoiding artefacts from brain extraction and dehydration. The study was completed by a series of behavioural experiments in which response asymmetry in odour recall following proboscis extension reflex conditioning was assessed for odours, chosen to stimulate strong activity in the same glomeruli as in the morphological study. The volumetric measurements found no evidence of lateralization in the investigated glomeruli within the experimental limits. Instead, in the behavioural experiments, a striking odour dependence of the lateralization was observed. The results are discussed on the basis of recent neurophysiological and ethological experiments in A. mellifera.     

鞍区肿瘤的临床特征与术中解剖研究

目的 探讨鞍区解剖特点及垂体瘤、颅咽管瘤、Rathke囊肿、鞍结节脑膜瘤的临床特征.方法 分析115例鞍区肿瘤手术治疗的病例资料,观察不同肿瘤的临床特点及术中鞍区解剖.结果 垂体瘤为鞍内或鞍上肿瘤,发病率居于鞍区第1位,主要表现为垂体前叶功能障碍、肿瘤部分囊性变;颅咽管瘤发病年龄较小,肿瘤主体在鞍上,多表现为钙化或囊变;Rathke囊肿为主体在鞍内的圆形或椭圆形肿物,边界清楚,肿瘤大小1 cm左右,与周围垂体组织存在较明显边界;鞍结节脑膜瘤以视力障碍为首发症状,鞍结节及其附近蝶骨平台骨质结节状增生为特征.结论 鞍区肿瘤的临床特征各具有特异性,熟悉鞍区解剖结构对鞍区肿瘤切除具有重要意义.     

Time and neglect: abnormal temporal dynamics in unilateral spatial neglect

Temporality enters our immediate experience as passage and becoming: the role time plays in the construction of a world of enduring entities tends to go unnoticed. This paper examines the relation between time and ontology in the context of unilateral neglect, a neuropsychological syndrome in which patients fail to perceive or respond to stimuli in the contralateral hemifield, behaving as if that half of space does not exist. Traditional models characterize neglect exclusively in spatial terms. Based on recent investigations suggesting abnormal temporal dynamics, here we highlight the impact of time factors on the presentation of the disorder. Neglect patients do not simply miss the presence of stimuli on the left: they also ignore the past as well as the future of neglected stimuli. We claim that, if this occurs, it is because time, and not only space, is impaired.     

Ipsilesional and contralesional sensorimotor function after hemispherectomy: differences between distal and proximal function

Previous studies have reported mainly on contralesional somatosensory and motor function after hemispherectomy. So far, ipsilesional impairments have received little attention even though these have been reported in patients with less extensive lesions. In the current study we assessed ipsilesional and contralesional sensorimotor function in a group of 12 patients with hemispherectomy. In addition, we focused on differences between distal and proximal function and investigated several factors that may have contributed to individual differences between patients. The tests included tapping, force production, tactile double simultaneous stimulation, pressure sensitivity, passive joint movement sense and sensitivity to hot and cold. Ipsilesional impairments were found on all tests, except passive joint movement sense. Unexpectedly, no significant ipsilateral distal-proximal gradient was found for any of the measures. Both the removal of the diseased cerebral hemisphere and possible changes to the remaining brain structures may have affected ipsilesional sensorimotor function. Contralesional performance was impaired on all tests except for passive joint movement in the shoulder. The contralesional impairments were characterized by a distal-proximal gradient measured on all tests, except that of sensitivity to hot and cold. Distal function was always most impaired. The difference between distal and proximal motor function is in agreement with the established concepts of the motor pathways, with the motoneurons innervating proximal muscles receiving bilateral cortical and subcortical input. Age at onset of original brain damage correlated significantly with passive joint movement sense. Patients with known abnormalities to the remaining brain structures performed inferior on the tapping test only. No effect was found of the hemispheric side of removal.     

The neglect of child neglect: a meta-analytic review of the prevalence of neglect

Purpose

The aim of the current meta-analysis was to provide an estimate of the prevalence of physical and emotional neglect by integrating prevalence figures from the body of research reporting on neglect. An attempt was also made to unravel the substantial variation in prevalence figures reported in primary studies by analyzing the effects of procedural factors and sample characteristics on combined prevalence rates.

Methods

Studies providing prevalence rates of child neglect were searched using electronic databases, exploring specialized journals, and by searching references of publications for other relevant studies. Data were extracted using a coding system. Intercoder reliability was satisfactory. A comprehensive meta-analysis was conducted.

Results

Child physical neglect prevalence rates were found for 13 independent samples with a total of 59,406 participants, and child emotional neglect prevalence rates were found for 16 independent samples with a total of 59,655 participants. The overall estimated prevalence was 163/1,000 for physical neglect, and 184/1,000 for emotional neglect, with no apparent gender differences. The influence of research design factors on the prevalence of physical neglect was more pronounced than on the prevalence of emotional neglect. Studies on physical neglect in ‘low-resource’ countries were conspicuously absent.

Conclusions

Child neglect is a problem of considerable extent, but seems to be a neglected type of maltreatment in scientific research. This is illustrated by the deplorable dearth of studies on child neglect, especially in low-resource countries. Recommendations for the design of future prevalence studies are proposed.