Visual-spatial learning and memory in schizotypal personality disorder: continued evidence for the importance of working memory in the schizophrenia spectrum.

Verbal episodic memory deficits, a well-established feature of the schizophrenia spectrum, have also been found in individuals with schizotypal personality disorder (SPD), although visual-spatial episodic memory has proven harder to examine. To address this, we administered the Visual Object Learning Test (VOLT), a measure of visual-spatial learning and memory, as well as the California Verbal Learning Test (CVLT) and a verbal working memory test, to 50 individuals with SPD, 19 with other personality disorders (OPD), and 17 healthy volunteers. Compared to both other groups, individuals with SPD learned verbal and visual-spatial information at a reduced rate and recalled fewer words and objects after a long delay. Verbal working memory performance eliminated diagnostic differences in these episodic memory domains. These findings suggest that it is possible to detect both auditory and visual processing episodic memory abnormalities in the spectrum and that these deficits are uniformly a function of verbal working memory impairments.     

分裂型人格障碍大学生的社会认知功能

目的:探讨分裂型人格障碍者的社会认知功能特征。方法:应用分裂型人格问卷(schizotypal personality questionnaire,SPQ)从某大学2007年度入学的4461名大学生中筛选SPQ高分者(总分38分),应用DSM-IV轴II人格障碍用临床定式访谈版(Structured Clinical Interview for DSMIV Axis Ⅱ,SCIDⅡ)进行面谈,并据DSM-IV诊断标准确定分裂型人格障碍(schizotypal personality disorder,SPD)者。共41名SPD者、53名SPQ高分者(不符合任何人格障碍标准)和37名对照组学生(SPQ≤18的低分者)完成本研究。应用Ekman标准面孔库中的面孔生成刺激材料,研究受试的面孔不同程度性别识别(分低、中、高3等程度的男女识别)和面孔不同程度表情识别(分低、中、高3等程度的高兴、厌恶和恐惧情绪的识别)能力,分析其判断正确率。结果:(1)性别识别。总体正确率在3组之间差异无统计学意义(F=0.71,P=0.494);组别与性别程度之间有交互作用(F=3.83,P=0.016),后续分析发现仅在低程度男性面孔识别正确率方面3组之间存在差异(F=3.40,P=0.036),进一步两两比较显示,SPD组的判断正确率明显低于对照组[(21.13±20.86%)vs.(35.43±30.15%),P=0.010];(2)表情识别。总体正确率在3组之间差异有统计学意义(F=3.44,P=0.035),SPD组的正确率低于对照组[(45.14±18.21%)vs.(54.66±18.24%),P=0.039];组别与表情程度之间存在交互作用(F=3.04,P=0.044),在中等程度高兴和中等程度厌恶表情识别方面上,对照组正确率均高于其他2组[(73.64±28.64)vs.(71.34±20.34)、(57.46±31.96),(60.13±28.04)vs.(52.94±24.44)、(43.44±22.22);均P0.05]。结论:分裂型人格障碍患者的面孔表情识别能力受损,提示他们可能存在社会认知功能障碍。     

Neural substrates of manipulation in visuospatial working memory

The present study aimed to investigate in humans whether similar neuronal mechanisms underlie the manipulation and active processing of visual and visuospatial stimuli. Simultaneous and successive mental rotation and identity judgment of 2-D matrices and 3-D cube figures were contrasted using functional magnetic resonance imaging (fMRI). Results demonstrate that activation patterns during mental rotation with low working memory demands differ depending on stimulus type (2-D vs. 3-D). Comparison of simultaneous mental rotation of matrices and 3-D cubes resulted in activation of frontal as well as inferior and superior parietal cortices. The opposite contrast (mental rotation of 3-D cubes vs. 2-D matrices) yielded only frontal cortex activation. The findings also yield evidence for converging, overlapping activation patterns for 2-D and 3-D stimuli if working memory demands are increased. Results are discussed within the framework of current working memory models.     

Dual-task information processing in schizotypal personality disorder: evidence of impaired processing capacity

Working memory theories heavily rely on the concept of processing resources and the their efficient deployment. Some recent work with schizophrenia-spectrum patients has suggested that many associated cognitive impairments may be reduced to deficits in working memory, possibly related to reductions in information-processing capacity resources. In this study, 38 patients with schizotypal personality disorder (SPD), 22 patients with other personality disorders, and 14 healthy comparison participants performed a dual-task processing assessment that was designed specifically for use in this type of study. Participants recalled lists of digits at their predetermined maximum digit span and performed box-checking tests, first alone and then in a dual-task format. Instructions included equal prioritization of both tasks. SPD patients had significantly shorter digit spans, and they also showed more deterioration on both tasks. Performance operating characteristics curves indicated that SPD patients' reduced performance was not due to abnormal resource allocation strategies leading to strategic failures. The authors discuss the implications of these processing capacity limitations for understanding both the signature of cognitive impairment within the schizophrenia spectrum and general abnormalities in working memory.     

Functional connectivity and infant spatial working memory: a frequency band analysis

The limited research on the functional meaning of infant EEG frequency bands has used measures of EEG power. The purpose of this study was to examine task‐related changes in frontal EEG coherence measures for three infant EEG frequency bands (2–5 Hz, 6–9 Hz, 10–13 Hz) during a spatial working memory task. Eight‐month‐olds exhibited baseline‐to‐task changes in frontal EEG coherence for all infant frequency bands. Both the 2–5 Hz and the 10–13 Hz bands differentiated frontal functional connectivity during the distinct processing stages, but each band provided unique information. The 10–13 Hz band, however, was the only frequency band to distinguish frontal EEG coherence values during correct and incorrect responses. These data reveal valuable information concerning frontal functional connectivity and the functional meaning of three different infant EEG frequency bands during working memory processing.     

Event-related potential correlates of impaired visuospatial working memory in schizophrenia

Previous studies have reported that patients with schizophrenia demonstrate impaired performance during working memory (WM) tasks. The current study aimed to determine whether WM impairments in schizophrenia are accompanied by reduced slow wave (SW) activity during on-line maintenance of mnemonic information. Event-related potentials were obtained from patients with schizophrenia and well controls as they performed a visuospatial delayed response task. On 50% of trials, a distractor stimulus was introduced during the delay. Compared with controls, patients with schizophrenia produced less SW memory negativity, particularly over the right hemisphere, together with reduced frontal enhancement of SW memory negativity in response to distraction. The results indicate that patients with schizophrenia generate less maintenance phase neuronal activity during WM performance, especially under conditions of distraction.     

Processing sentence context in women with schizotypal personality disorder: an ERP study

Accumulating evidence suggests that schizophrenic patients do not use context efficiently. Also, studies suggest similarities in clinical and cognitive profiles between schizophrenic and schizotypal personality disorder (SPD) individuals, and epidemiological studies point to a genetic link between the two disorders. This study examined electrophysiological correlates of processing sentence context in a group of SPD women in a classical N400 sentence paradigm. The study assessed if the dysfunction in context use found previously in schizophrenia and male SPD also exists in female SPD. We tested 17 SPD and 16 matched normal control women. The results suggest the presence of abnormality in context use in female SPD similar to that previously reported for male schizophrenic and SPD individuals, but of lesser degree of severity. In SPD women, relative to their comparison group, a more negative N400 was found only to auditory congruent sentences.     

Visuospatial and verbal working memory load: effects on visuospatial vigilance

In this study, we examined the impact of concurrent verbal and visuospatial working memory demands on performance of a visuospatial successive target detection task. Three hundred and four participants performed a visuospatial vigilance task while simultaneously performing either a spatial or verbal working memory task that either required a memory load during the vigil or did not require a memory load during the vigil. Perceptual sensitivity A′ to vigilance target stimuli was reduced by concurrent memory load, both verbal and visuospatial. The decline in perceptual sensitivity to vigilance targets, the vigilance decrement, was steeper for a visuospatial memory task than a verbal memory task, regardless of concurrent memory load. Memory performance after vigilance detection trials was much lower for visuospatial than verbal items, even though memory performance before vigilance detection trials was higher for visuospatial than verbal items. Together, this indicates increased interference when a visuospatial vigilance task is paired with a visuospatial memory task, than when paired with a verbal memory task. Overall, the visuospatial and verbal working memory loads both impacted vigilance target detection, suggesting utilization of common executive resources. There may, however, be domain specific interference, and this may be exacerbated for two visuospatial tasks.     

A quantitative genetic analysis of schizotypal personality traits

BACKGROUND: Previous twin studies investigating the heritability of schizotypy have often had limited power and have failed to measure the disorganization/social anxiety component. METHOD: Seven hundred and thirty-three female twin pairs, drawn from the Institute of Psychiatry Volunteer Twin Register, completed the Oxford-Liverpool Inventory of Feelings and Experiences and the Peters et al. Delusions Inventory. Structural equation modelling was carried out on scores for MZ and DZ twin pairs. RESULTS: The best fitting models for all scales comprised additive genetic and unique environmental effects. Heritability was estimated at approximately 50% for most scales, although it was lower at 37% for the PDI scale. Multivariate structural equation model fitting revealed a best-fitting model in which additive genetic and unique environmental influences act through a single common pathway for Cognitive Disorganization, Unusual Experiences and the PDI, and through a separate common pathway for Cognitive Disorganization and Introvertive Anhedonia. CONCLUSIONS: The various components of schizotypy are moderately heritable. Multivariate model fitting indicates that at least two latent factor structures are required to account for the covariation between the various components of schizotypy. The positive and negative components of schizotypy are relatively genetically independent, although each in turn may be related to Cognitive Disorganization.     

Functional MRI correlates of the recall of unresolved life events in borderline personality disorder

BACKGROUND: Patients with borderline personality disorder (BPD) frequently report unresolved life events but it is still poorly understood, how these experiences are represented in the brain. Using functional magnetic resonance imaging (fMRI), the present study aimed at investigating the neural correlates of the recall of unresolved life events in patients with BPD and healthy controls. METHOD: Twenty female BPD patients and 21 healthy control subjects underwent fMRI. During measurement subjects recalled unresolved and resolved negative life events. Individual cue words were used to stimulate autobiographical memory. After scanning, subjects rated their emotional states during the recall of both types of memories. RESULTS: When contrasting unresolved and resolved life events, patients showed significant bilateral activation of frontotemporal areas including the insula, amygdala, and the anterior cingulate cortex, the left posterior cingulate cortex, right occipital cortex, the bilateral cerebellum and the midbrain. In healthy subjects, no differential brain activation was related to these conditions. The 2 x 2 factorial analysis (DeltaBPD - Deltacontrols) revealed similar results with bilateral activation of the frontal cortex including parts of the insula and of the orbitofrontal cortex, temporal activation including the amygdala, activation of the right occipital cortex, and parts of the cerebellum. Patients but not controls reported higher levels of anxiety and helplessness during the unresolved versus resolved memory condition. CONCLUSIONS: The activation of both, the amygdala and prefrontal areas, might reflect an increased effortful but insufficient attempt to control intensive emotions during the recall of unresolved life events in patients with BPD.     

Emotion-induced memory dysfunction in borderline personality disorder

Introduction. Although emotional dysregulation is a core problem in borderline personality disorder (BPD), few neuropsychological studies have evaluated the impact of emotion. The present study aimed at the comprehensive investigation of verbal memory functions with and without emotionally relevant interference in BPD. BPD patients were expected to perform as well as healthy subjects in standard memory tasks but to show fewer capacities to control for emotionally negative interference.

Methods. 47 patients with BPD and 70 healthy control subjects participated. An experimental task assessed verbal memory with respect to standard and emotionally relevant and neutral interference learning conditions. Applied standard tests covered working memory, delayed memory, and word fluency.

Results. Memory performances of BPD patients were impaired when negatively valenced interference was conducted but normal in all other conditions. These results remained stable after controlling for comorbid major depression and posttraumatic stress disorder.

Discussion. The present findings suggest no general impairment of verbal memory functions in BPD but control and inhibition of interference by emotionally significant material seem to be disturbed.     

Object working memory and visuospatial processing: functional neuroanatomy analyzed by event-related fMRI

We report an event-related functional magnetic-resonance-imaging (fMRI) experiment that investigates the relationship of transient visual object memory, visuospatial orienting, and object recognition. Delayed object matching and visuospatial orienting involved a highly overlapping network of brain areas. Common areas were the frontal eye fields (FEF), the pre-supplementary motor area (pre-SMA)/SMA complex, the precentral gyri, and the horizontal and descending branches of the intraparietal sulcus (IPS). Selective delay activation was observed anterior to the FEF and in the ascending part of the IPS. Right dorsolateral prefrontal cortex was involved in goal-directed visual search, but showed no delay activity.     

Socioeconomic background and the developmental course of schizotypal and borderline personality disorder symptoms

Low socioeconomic status (SES) background has been identified as a risk for several mental disorders. However evidence regarding SES and the developmental course of personality disorder (PD) has not been addressed. Nor is it clear whether an SES relationship to PD symptom course may be attributable to known associated risks. Further, specificity of such relationships to a particular PD diagnostic pattern independent of comorbidity with other PD or with depression has not been investigated. Data are from a general population studied longitudinally between ages 10 and 36 in four assessment waves. Effects of SES-associated risks on the level of symptoms of schizotypal and borderline disorders are estimated and compared to effects on depressive symptoms. Low family SES had robust modest independent effects on both PDs over the entire age span despite substantial cumulative effects of trauma history, stressful recent life events, IQ, poor parenting, and comorbid symptoms. SES effects on depressive symptoms were generally absent, but a small "protective" effect of low SES appeared when comorbidity with PD symptoms was taken into account. Cumulatively, these risks account for developmental failures of substantial magnitude and consequence, marking the importance of understanding the remaining mechanisms of SES effects and programmatic implications for minimizing associated risk.     

Autobiographical memory and dissociation in borderline personality disorder

BACKGROUND: This study investigated whether individuals with borderline personality disorder (BPD) tend to be overgeneral in their autobiographical recall and whether the extent of their overgeneral recall covaries with their susceptibilities to dissociative experiences, as expected on theoretical grounds. METHODS: Twenty-three patients with BPD and 23 matched controls completed the Autobiographical Memory Test (AMT) and self-report measures of depression, anxiety, trait anger and dissociative experiences. RESULTS: Participants with BPD scored significantly higher than the control group on the measures of depression, anxiety, trait anger, and dissociative experiences and also retrieved significantly more general memories on the AMT. The number of general memories retrieved by the BPD group correlated significantly with their dissociation scores but not with their scores on mood measures. CONCLUSIONS: Patients with BPD have difficulties in recalling specific autobiographical memories. These difficulties are related to their tendency to dissociate and may help them to avoid episodic information that would evoke acutely negative affect.     

Parallel visuospatial and audiospatial working memory processes in the monkey dorsolateral prefrontal cortex

The dorsolateral area of the prefrontal cortex (PFC) in primates is involved in visuospatial working memory, but the cellular basis of spatial working memory for auditory information is poorly understood. Here we examined dorsolateral PFC neurons using visual and auditory oculomotor delayed-response tasks. We found that the dorsolateral PFC contains two groups of neurons, each showing directional delay-period activity depending on the location of the visual or auditory cue, suggesting that parallel neuronal processes for visual and auditory spatial working memory occur in the dorsolateral PFC.     

Functional neuroimaging of working memory in schizophrenia: task performance as a moderating variable

Functional neuroimaging studies in schizophrenia have demonstrated abnormal activation of dorsolateral prefrontal cortex (DLPFC) during working memory (WM) performance. However, findings of increased and decreased activity have been reported. The authors used meta-analysis to investigate whether diverging results arise as a function of differential WM task performance between patients and control participants. Results indicate that the magnitude of the group difference in WM performance is a moderator of DLPFC activation differences, and concepts such as hypo- or hyperfrontality do not universally characterize WM findings in schizophrenia. Thus, the variability in the WM activation findings between participants with schizophrenia and control participants reflects the specific conditions under which WM functions are evaluated, not just the WM construct per se.     

Neurophysiological correlates of increased verbal working memory in high-dissociative participants: a functional MRI study

BACKGROUND: Dissociation, defined as a disruption in usually integrated mental functions, is found not only in DSM-IV dissociative disorders, but also in post-traumatic stress disorder and eating disorders. Dissociative phenomena are also common in the general population, and may reflect a constitutionally determined cognitive style rather than a pathological trait acquired through experiencing adverse life events. In pathological dissociation, evidence has been presented for episodic memory dysfunction. In contrast, in high-dissociative subjects increased performance has been found for episodic memory and dual task performance. These findings have been linked to changes in working memory capacity. METHOD: In the present study, the authors sought to extend these findings by using functional magnetic resonance imaging during performance of two parametric working memory tasks. We tested 21 healthy low- and high-dissociative participants. RESULTS: High-dissociative participants performed slightly better during both tasks. Imaging data showed that both groups activated similar networks for both tasks, i.e. (bilateral) dorsolateral (DL) and ventrolateral prefrontal cortex (PFC), parietal cortex, and supplementary motor area. Group x task interactions were found in the high-dissociative group in L DLPFC and L parietal cortex; in the low-dissociative group in R fusiform gyrus. The differences in the high-dissociative group were independent from performance differences, implying that high-dissociative subjects generally recruit this network to a greater extent. CONCLUSIONS: These results confirm earlier findings using a verbal WM task in high-dissociative participants, and are compatible with the conceptualization of non-pathological dissociation as an information-processing style, characterized by distinct attentional and mnemonic abilities.