右利手右大脑半球卒中患者的镜像书写研究

目的探讨右利手患者右大脑半球卒中时的镜像书写发生情况及其发生机制。方法对经ＣＴ确诊的右利手右大脑半球卒中患者按《汉语失语症检查法（草案）》进行检查，其中１３例左侧轻瘫者进行左手书写检查，并检查了左右定向力和视空间能力。结果１３例左手书写的患者中，６例出现镜像书写，占４６．１％，２例为中度，４例为轻度。２例中度镜像书写者左右定向差，６例患者均无视空间障碍。间隔２周以上复查，均有明显恢复或消失。结论①非优势半球病变可引起镜像书写，其发生率与优势半球卒中相仿；②认为右半球卒中阻断了左侧书写运动－图式对右侧镜像书写运动－图式的抑制及对右侧运动区书写运动的主导作用而产生镜像书写，提出镜像书写运动联系通路理论。左右定向障碍对镜像书写的发生也有一定作用；③视空间障碍与镜像书写似无明显关系。     

Differential right hemispheric memory storage of emotional and non-emotional faces

Seventy-two female subjects memorized two photographed faces and subsequently discriminated these “target” faces from two “non-target” faces. The faces were presented unilaterally for 150 msec, and manual reaction times for the discriminations served as the dependent variable. The face stimuli were either “neutral” or “emotional” in facial expression, these attributes having been shown, by a preliminary study, to be highly reliable. Faster reaction times were obtained for left visual field than for right visual presentation. Subjects (N = 36) who memorized emotional faces showed significantly faster discrimination of faces presented in the left than in the right visual field (25·7 msec); subjects (N = 36) who memorized faces lacking emotional expression also showed significant left visual field superiority (11·6 msec), but this left field superiority was significantly smaller than that of subjects memorizing emotional faces. Results are consistent with previous tachistoscopic evidence of right hemisphere superiority in face recognition speed and with diverse non-tachistoscopic evidence of preferential memory storage of affective material. The pattern of latencies for the different visual field-response hand conditions supported a model of lateral specialization in which the specialized hemisphere normally processes both directly-received and interhemispherically- transferred stimuli.     

Parallel-serial processing and hemispheric function.

In one experiment 14 subjects made same-different responses to geometric forms varying in number from two to four, and presented randomly in the left or right visual hemifields. In a second experiment two different groups of subjects (N₁ = N₂ = 6) responded to letters, varying in number from two to four which could be matched on either nominal or physical identity. In both experiments reaction times were faster for stimuli directed to the right hemisphere and in no condition did reaction times increase with increasing number of stimuli. Implications for a relationship between mode of processing and hemispheric function were discussed.     

Visuospatial stimulus-bound automatic writing behavior: a right hemispheric stroke syndrome

Three cases of visuospatial stimulus-bound automatic writing behavior were identified among 80 patients (4%) with acute right cerebral hemispheric stroke. All cases had similar clinical characteristics and writing behavior, and visuospatial stimulus-bound automatic writing was related to visually perceived letters. This syndrome might be specific for right hemispheric stroke and might be included among other hypergraphic syndromes attributable to right hemispheric damage.     

The effects of emotional valence on hemispheric processing of metaphoric word pairs

Recent theories of metaphor comprehension discuss the cognitive substrates involved in processing metaphors. However, the role of valence perception during metaphor comprehension has received little attention. The present study aims to examine the effect of emotional valence on metaphor processing, as well as the interaction between this effect and hemispheric differences. Metaphoric, literal, and meaningless word pairs were presented to 43 participants who performed a semantic judgment task. Results showed that processing of metaphors with negative valence was faster when done in the right hemisphere as compared with the left hemisphere. These findings indicate that emotional valence interacts with cognitive processes of metaphor comprehension. We discuss valence with respect to the class inclusion model and the fine versus coarse semantic coding model of metaphor processing.     

Semantic paralexia: A release of right hemispheric function from left hemispheric control?

In an unselected group of aphasics those patients who produced semantic paralexias had significantly larger lesions than those without semantic paralexias. The possible mechanisms of the release of “alternative” right hemisphere reading from left hemisphere control are discussed.     

Global-local processing in schizophrenia: hemispheric asymmetry and symptom-specific interference.

The hypothesis of atypical functional hemispheric asymmetry in schizophrenia is tested using the directed global-local paradigm, a lateralizing measure of visual perception. Results indicate low error rates (< 2%) for schizophrenia and normal control groups, but longer response times for the schizophrenia group. In the normal group, detection speed of global and local forms did not differ. In contrast, the schizophrenia group responded significantly faster to local relative to global forms, which supports the asymmetry hypotheses of left hemisphere overactivity-right hemisphere underactivity in schizophrenia. The normal group exhibited a global interference effect (slowed response latency to the local target in the presence of a dissimilar global distractor). When the schizophrenia group was examined according to symptom type and severity, high positive symptom severity was associated with local interference (slowed response latency to the global target in the presence of dissimilar local distractors). Negative symptoms were not associated with interference from the competing local or global forms. Patients with a combination of high positive and low negative symptoms showed significantly greater local interference than patients with high negative and low positive symptoms. Interconnected temporal and frontal systems are postulated to contribute to this pattern of perceptual processing efficiency and distractibility in schizophrenia.     

Comprehension of emotional prosody following unilateral hemispheric lesions: processing defect versus distraction defect

Two studies were conducted in order to determine whether the poor performance of RHD patients on emotional prosody tasks could be attributed to a defect in perceiving/categorizing emotional prosody (processing defect) or to a problem in being distracted by the semantic content of affectively intoned sentences (distraction defect). In one study, patients with RHD, LHD or NHD listened to affectively intoned sentences in which the semantic content was congruent or incongruent with the emotional prosody. In a second study, the patients listened to affectively intoned sentences that had been speech filtered or unfiltered. Findings from these studies indicate that both processing and distraction defects are present in RHD patients.     

Looking at human eyes affects contralesional stimulus processing after right hemispheric stroke

Human eyes are a powerful social cue that may automatically attract the attention of an observer. Here we tested whether looking toward open human eyes, as often arises in standard clinical "confrontation" tests, may affect contralesional errors in a group of right brain-damaged patients showing visual extinction. Patients were requested to discriminate peripheral shape-targets presented on the left, right, or bilaterally. On each trial they also saw a central task-irrelevant stimulus, comprising an image of the eye sector of a human face, with those seen eyes open or closed. The conditions with central eye stimuli open (vs closed) induced more errors for contralesional peripheral targets, particularly for bilateral trials. These results suggest that seeing open eyes in central vision may attract attentional resources there, reducing attention to the periphery, particularly for the affected contralesional side. The seen gaze of the examiner may thus need to be considered during confrontation testing and may contribute to the effectiveness of that clinical procedure.     

The effect of right and left hemispheric lesions on effortful and automatic memory tasks

The effect of lateralised cerebral damage on two memory tasks-free recall of words and memory of their temporal order-was investigated under intentional, incidental, and 'true incidental' learning conditions. Ten Right Brain Damaged patients (RBD), 10 Left Brain Damaged patients (LBD), as well as 15 age-matched and 15 younger control individuals, participated in this study. It was hypothesised that effortful and automatic memory processes involve predominantly the left and right cerebral hemispheres, respectively. Automaticity was defined either by the learning conditions (i.e. incidental-automatic and intentional-effortful) or by the type of task (i.e. temporal-order-automatic and free-recall-effortful) regardless of the learning conditions. In the free recall task the RBD group outperformed the LBD group under all learning conditions. In the temporal order task, the RBD group performed worse than normal controls under all learning conditions while the LBD group performed more poorly than matched controls in the intentional and incidental but not in the 'true incidental' learning condition. The results are discussed in terms of the relationship between effortful and automatic memory processes and cerebral lateralisation.     

Attentional load affects automatic emotional processing: evidence from event-related potentials

One open question on the relation between attention and emotion concerns the automatic processing of emotional visual stimuli outside the focus of attention. This study examined to what extent the emotional processing at unattended locations is modulated by the processing load at attended locations. Event-related potentials were measured to task-irrelevant unpleasant and neutral pictures briefly presented at peripheral locations while participants performed a visual central task varying in load (low and high load). Unpleasant pictures elicited larger amplitudes of N1-P2 at parietoccipital and occipital sites than that of neutral pictures. This effect was only significant in the low-load condition. Data suggest that brain responses to affective value of task-irrelevant peripheral pictures are modulated by attentional load at fixation.     

Emotional language is all right: Emotional prosody reduces hemispheric asymmetry for linguistic processing

ABSTRACT

In an influential paper, Bryden and MacRae [(1989). Dichotic laterality effects obtained with emotional words. Neuropsychiatry, Neuropsychology, and Behavioral Neurology, 1, 171–176] introduced a dichotic listening task that allowed for the assessment of linguistic and prosodic processing asymmetries using the same stimuli. The task produces a robust right ear advantage (REA) for linguistic processing (identifying a target word), and a left ear advantage for emotional processing (identifying a target prosody). Here, we adapted this paradigm to determine whether and how the presence of emotional prosody might modulate hemispheric asymmetry for linguistic processing. Participants monitored for a target word among dichotic stimuli consisting of two different words, but spoken in the same emotional prosody—neutral, angry, happy, sad, or fearful. A strong REA was observed when the words were spoken in neutral prosody, which was attenuated for all the emotional prosodies. There were no differences in the ear advantage as a function of valence or discrete emotion, indicating that all emotions had similar effects. Findings are consistent with the hypothesis that the right hemisphere is better able to process speech when it carries emotional prosody. Implications for understanding of right hemisphere language functions are discussed.     

Increased reliance on a right hemispheric mechanism during idiom processing in adults with dyslexia

Previous studies on adults with dyslexia (DYS) have indicated difficulties in the comprehension of figurative language. Using the divided visual field paradigm, the present study investigated the hemispheric processing of idioms among 22 adults with DYS and 21 regular reader (RR) adults. Participants performed a lexical decision task for a target word related to either a literal or a figurative interpretation of an idiom. The results show that whereas the RR group demonstrated a bilateral pattern of hemispheric processing of idiomatic meanings, the DYS group showed a right hemisphere (RH) advantage. Furthermore, both groups demonstrated the typical RH advantage in processing the literal meanings of idioms. Our findings indicate increased recruitment of the RH in dyslexia, probably due to differences in cerebral language areas or weaker LH semantic processing.     

Dashcam-captured moment of right hemispheric stroke

A bus driver presented with neurological abnormalities following a driving mishap. He was diagnosed cardioembolic stroke. The bus was equipped with a dashboard camera that recorded the moment when the patient suffered the stroke. We reported the first case dashcam-captured images at the first sign of a right hemispheric stroke.     

Childhood emotional invalidation and right hemispheric mu suppression during a pain empathy task: An EEG study

Empathy is a critical aspect of social behavior, and impairment in empathic processing is linked to hindered social interactions and several disorders. Despite much interest in this topic, our understanding of the developmental and neural involvement for empathic processing is limited. Recent evidence suggests the Mirror Neuron System (MNS) may play a role in this behavior, and that mu rhythm suppression found over the sensorimotor cortices may be a proxy for the MNS. Therefore, we aimed to measure mu rhythm oscillations in response to empathic processing during observation of painful action-based situations using electroencephalogram (EEG). Our second goal was to examine how perceived parental emotional invalidation (EI) during childhood may relate to empathy and influence mu suppression. Our results showed that mu rhythm suppression was strongest over the right hemisphere. EI had a significant influence on this suppression between painful and non-painful images, and was negatively correlated with behavioral measures of empathy. Our findings suggest that perceived childhood EI may decrease empathizing abilities and influence neural responses to the painful experiences of others. Implications from this study could entail clinical intervention targeted at emotional invalidation to foster the healthy development of empathy.     

Vocal reaction times to unilaterally presented concrete and abstract words: towards a theory of differential right hemispheric semantic processing

Previous studies investigating hemispheric organization for processing concrete and abstract nouns have provided conflicting results. Using manual reaction time tasks some studies have shown that the right hemisphere is capable of analyzing concrete words but not abstract. Others, however, have inferred that the left hemisphere is the sole analyzer of both types of lexicon. The present study tested these issues further by measuring vocal reaction times of normal subjects to unilaterally presented concrete and abstract items. Results were consistent with a model of functional localization which suggests that the minor hemisphere is capable of differentially processing both types of lexicon in the presence of a dominant left hemisphere.     

The automatic updating of egocentric spatial relationships and its impairment due to right posterior cortical lesions

The non-visual updating of body-centred spatial relationships was investigated in an experiment in which blindfolded patients had to point to previously seen targets after a body rotation in the absence of vision. Patients with lesions to the right dorsal (RD) area were impaired at updating their positions relative to non-RD patients and normal subjects: they tended to underestimate systematically the angle through which they had turned. The results are interpreted in terms of impoverished locomotor input and/or systematically biased processing or locomotor proprioception in the RD patients, which prevented accurate tracking of changes in egocentric spatial relationships.     

Cerebral hemispheric lateralization of cognitive deficits due to alcoholism.

Twenty chronic alcoholics and a group of matched control subjects were tested on verbal and visuospatial memory tasks in order to test directly the hypothesis that alcoholism disturbs cognitive functions subserved by the right hemisphere more than those subserved by the left hemisphere. The results provide some support for the hypothesis and indicate that information may be lost by pooling together test results from alcoholics which come from a mixture of verbal and nonverbal tasks.