Context Processing Deficits Research Articles

Poster #9 REPEATED FORCED SWIMMING REDUCES GLUTAMATE UPTAKE IN HIPPOCAMPAL SLICES AND AFFECTS DIFFERENTLY THE RATS BEHAVIOR IN TWO MODELS RELATED TO COGNITIVE SYMPTOMS OF SCHIZOPHRENIA: NOVEL OBJECT RECOGNITION AND PRE-PULSE IHNIBITION

performance observed at the 0.32 mg/kg dose of Ketamine did not differ significantly from the saline control condition. However, the higher doses of Ketamine did. With increasing dosage, the monkey made more errors on the trial type in which schizophrenia patients tend to make more errors. This trial type requires intact context processing to perform correctly. Discussion: The current study demonstrates that Ketamine is able to replicate in a monkey the behavioral performance pattern on the DPX task seen in schizophrenia patients performing the AX-CPT and the DPX task. The monkey tended to make more errors on the trial type that requires intact context processing to perform indicating a drug induced context processing deficit. The results of this study, pending replication, lay the groundwork for establishing a non-primate model to better study and characterize the context processing deficit seen in the schizophrenia patient population.

The effect of emotional context on facial emotion ratings in schizophrenia

Individuals with schizophrenia show deficits both in facial emotion recognition and context processing (Kohler, C.G., Walker, J.B., Martin, E.A., Healey, K.M., Moberg, P.J., 2010. Facial emotion perception in schizophrenia: a meta-analytic review. Schizophr. Bull. 36, 1009–1019). Recent evidence suggests context information can affect facial emotion recognition (Aviezer, H., Bentin, S., Hassin, R.R., Meschino, W.S., Kennedy, J., Grewal, S., Esmail, S., Cohen, S., Moscovitch, M., 2009. Not on the face alone: perception of contextualized face expressions in Huntington's disease. Brain 132, 1633–1644). Thus, individuals with schizophrenia may have deficits in facial emotion processing, at least in part, due to impairments in processing context information (Green, M.J., Waldron, J.H., Coltheart, M., 2007. Emotional context processing is impaired in schizophrenia. Cogn. Neuropsychiatry 12, 259–280.). We used a novel experimental task, the Emotion Context Processing Task (ECPT) to examine the influences of emotional context (IAPS pictures) on the processing of subtle surprised faces in schizophrenia. One of the task conditions included a manipulation designed to determine whether enhancing attention to the context (by requiring a categorization judgment on the context pictures) would facilitate the influence of context on facial emotion processing in schizophrenia. In addition, we tested whether deficits on a non-social context processing would predict deficits in the influence of context on facial emotion processing in schizophrenia. We administered the Dot Probe Expectancy Task (a non-social context processing task) and the ECPT to individuals with schizophrenia (n = 35) and healthy controls (n = 32). Individuals with schizophrenia showed an intact influence of context information on facial emotion recognition. The manipulation designed to enhance attention to emotional context reduced the effect of context for both groups. In schizophrenia, better processing of non-social context was associated with a stronger influence of context on valence ratings of facial expressions in the negative context condition. These results suggest in schizophrenia, similar mechanisms may influence the processing of context for both social and non-social information.

Visual Context Processing Deficits in Schizophrenia: Effects of Deafness and Disorganization

Visual illusions allow for strong tests of perceptual functioning. Perceptual impairments can produce superior task performance on certain tasks (i.e., more veridical perception), thereby avoiding generalized deficit confounds while tapping mechanisms that are largely outside of conscious control. Using a task based on the Ebbinghaus illusion, a perceptual phenomenon where the perceived size of a central target object is affected by the size of surrounding inducers, we tested hypotheses related to visual integration in deaf (n = 31) and hearing (n = 34) patients with schizophrenia. In past studies, psychiatrically healthy samples displayed increased visual integration relative to schizophrenia samples and thus were less able to correctly judge target sizes. Deafness, and especially the use of sign language, leads to heightened sensitivity to peripheral visual cues and increased sensitivity to visual context. Therefore, relative to hearing subjects, deaf subjects were expected to display increased context sensitivity (ie, a more normal illusion effect as evidenced by a decreased ability to correctly judge central target sizes). Confirming the hypothesis, deaf signers were significantly more sensitive to the illusion than nonsigning hearing patients. Moreover, an earlier age of sign language acquisition, higher levels of linguistic ability, and shorter illness duration were significantly related to increased context sensitivity. As predicted, disorganization was associated with reduced context sensitivity for all subjects. The primary implications of these data are that perceptual organization impairment in schizophrenia is plastic and that it is related to a broader failure in coordinating cognitive activity.

Neural basis of semantic priming in schizophrenia during a lexical decision task: A magneto-encephalography study

Numerous behavioral and electrophysiological studies have provided evidence of abnormal semantic processing in schizophrenia. However, the neural basis of these deficits is poorly understood. We investigated magnetic cortical responses elicited by a word-pair lexical decision task in 20 patients with schizophrenia and 12 healthy control subjects. The task involved presentation of a prime word (200ms), followed by a blank (250ms), and then a target stimulus (1200ms); the subject had to decide whether the target was a real word or not. During this task, bilateral temporal and left prefrontal activations were observed in both groups. However, in contrast to controls, patients with schizophrenia did not show increased activation in the left temporal and anterior cingulate cortices between 200 and 450ms in response to semantic incongruity. These results suggested that schizophrenia was associated with a functional disturbance in some semantic regions that gave rise to the N400 component. Moreover, a significant modulation in the right temporal cortex was observed in patients, but not in controls. This suggested the existence of alternative processes in patients because both groups showed similar behavioral priming. Finally, we elucidated some functional abnormalities in the semantic network during prime word processing in patients, indicated by prolonged activation compared to healthy controls. Thus, in addition to context integration impairment, abnormal activations during the prime word provided new evidence of context processing deficits in schizophrenia.

INCREASED LIMBIC SYSTEM ACTIVITY ASSOCIATED WITH APPETITE DYSFUNCTION IN SCHIZOPHRENIC PATIENTS FOLLOWING AN OLANZAPINE TREATMENT

(DLPFC, BA10) to perform the context processing task, reflecting inefficiency. In patients there are frontal activity differences according to the genotype, with met carriers activating more DLPFC (left BA47, right BA 45) and anterior cingulate (BA32) than val carriers. Discussion: COMT genotype exerts little impact on neuropsychological functions. Differences in cognitive performance across groups are reliably measured by the MATRICS Consensus Cognitive battery, however this instrument seems to be not sensitive enough to capture COMT genotype effects. Specific cognitive domains (context processing) are more sensitive to COMT genotype effects. Although patients with schizophrenia spectrum disorder exhibit more prominent deficits in context processing, these deficits are also seen in their relatives. The DPX task, which assesses context processing, is sensitive to COMT genotype in patients. Val/val carriers exhibit more contex processing impairment than met/met carriers, probably due to less dopamine availability in the PFC. Prefrontal brain activity of context processing deficits in schizophrenia may be mediated by COMT genotype effects.

The Effect of Context Processing on Different Aspects of Social Cognition in Schizophrenia

It is well known that individuals with schizophrenia have impaired social cognition. The construct of social cognition involves several components, including perception, interpretation, and the ability to integrate context (Adolphs R. The neurobiology of social cognition. Curr Opin Neurobiol. 2001;11:231-239; Brothers L. The social brain: a project for integrating primate behavior and neurophysiology in a new domain. Concepts Neurosci. 1990;1:27-61). Importantly, a number of studies have suggested that deficits in context processing underlie cognitive dysfunction in schizophrenia (Penn DL, Corrigan PW, Bentall RP, Racenstein JM, Newman L. Social cognition in schizophrenia. Psychol Bull. 1997;121(1):114-132; Green MF, Nuechterlein KH. Should schizophrenia be treated as a neurocognitive disorder? Schizophr Bull. 1999;25:309-319). Thus, the purpose of the current study was to investigate the relationship between context processing and different aspects of social cognition in schizophrenia. Individuals with schizophrenia (n = 41) and the healthy controls (n = 32) participated in this study. The participants completed 2 sections of The Awareness of Social Inference Test: (1) social inference minimal (SI-M) and (2) social inference enriched (SI-E). They also completed face and voice emotion discrimination tasks. In addition, we used the AX-Continuous Performance Test (AX-CPT) to measure context processing and the n-back task to measure working memory more generally. AX-CPT performance in schizophrenia was positively correlated with both SI-M and SI-E performance but not with either the face or the voice discrimination. Furthermore, the correlation between AX-CPT performance and SI-M/SI-E performance was significantly stronger in individuals with schizophrenia than in controls. These results suggest that impairments in context processing are related to inferential components of social cognition in schizophrenia but not to the ability to recognition facial or vocal emotion. As such, deficits in context processing may contribute to deficits in both "hot" and "cold" aspects of cognition in schizophrenia.

The dot pattern expectancy task: Reliability and replication of deficits in schizophrenia.

The dot pattern expectancy (DPX) task was created to efficiently assess context-processing deficits in patients with schizophrenia. Three studies investigated the characteristics of the DPX relevant for clinical applications. To answer questions regarding the psychometric properties of the task, performance on this task was studied in 2 healthy samples. Acceptable reliability and internal consistency and retest reliability were found for most measures of context processing, but not for a difficulty control condition. These characteristics were also found in a suggested brief version (DPX(brf)), which may be more practical for clinical purposes. In a 3rd study, schizophrenia patients showed a specific deficit in context processing, replicating previous findings. Findings of these studies indicated some promise for use of this task in measuring context processing and also identified characteristics of this task that need to be strengthened to increase reliability, feasibility, and single-subject interpretability.

The impact of context processing deficits on task-switching performance in schizophrenia

The prefrontal cortex (PFC) has been described as important for maintaining and implementing contextual information in the service of goal-oriented behavior. Accordingly, impairments in context processing are thought to underlie cognitive deficits associated with schizophrenia, a clinical disorder that has been linked to PFC dysfunction (Servan-Schreiber et al., 1996). However, task switching, a cognitive ability linked to PFC function, has not been consistently impaired in schizophrenia. In this experiment, we assessed whether task-switching performance would be selectively impaired for patients when context demands were high. In the rule-switching condition, a switch required the updating of the relevant task response rules whereas perceptual switching did not entail a switching of contextual information. Instead, a perceptual switch entailed a shift of visuospatial attention to the relevant feature. A second goal was to determine whether potential deficits in context switching would be observed in schizophrenia even in situations when these patients do not need to overcome a prepotent response. Studies of context processing have typically required patients with schizophrenia to use contextual rules to overcome prepotent response tendencies whereas our switching paradigm did not require the inhibition of a competing response. Patients were much slower to switch tasks than controls when contextual rules switched from one trial to the next whereas their performance was intact when the switch occurred between different feature sets and contextual demands were low. Our results demonstrate that context processing deficits are observable in schizophrenia even when there is no prepotent response tendency to inhibit. Moreover, our results suggest that PFC impairments influence performance primarily when patients are required to switch the application of one explicit rule to another.

Dominance of Objects over Context in a Mediotemporal Lobe Model of Schizophrenia

BackgroundA large body of evidence suggests impaired context processing in schizophrenia. Here we propose that this impairment arises from defective integration of mediotemporal ‘what’ and ‘where’ routes, carrying object and spatial information to the hippocampus.Methodology and FindingsWe have previously shown, in a mediotemporal lobe (MTL) model, that the abnormal connectivity between MTL regions observed in schizophrenia can explain the episodic memory deficits associated with the disorder. Here we show that the same neuropathology leads to several context processing deficits observed in patients with schizophrenia: 1) failure to choose subordinate stimuli over dominant ones when the former fit the context, 2) decreased contextual constraints in memory retrieval, as reflected in increased false alarm rates and 3) impaired retrieval of contextual information in source monitoring. Model analyses show that these deficits occur because the ‘schizophrenic MTL’ forms fragmented episodic representations, in which objects are overrepresented at the expense of spatial contextual information.Conclusions and SignificanceThese findings highlight the importance of MTL neuropathology in schizophrenia, demonstrating that it may underlie a broad spectrum of deficits, including context processing and memory impairments. It is argued that these processing deficits may contribute to central schizophrenia symptoms such as contextually inappropriate behavior, associative abnormalities, conversational drift, concreteness and delusions.

Spatio-temporal EEG waves in first episode schizophrenia

Schizophrenia is characterized by a deficit in context processing, with physiological correlates of hypofrontality and reduced amplitude P3b event-related potentials. We hypothesized an additional physiological correlate: differences in the spatio-temporal dynamics of cortical activity along the anterior-posterior axis of the scalp. This study assessed latency topographies of spatio-temporal waves under task conditions that elicit the P3b. EEG was recorded during separate auditory and visual tasks. Event-related spatio-temporal waves were quantified from scalp EEG of subjects with first episode schizophrenia (FES) and matched controls. The P3b-related task conditions elicited a peak in spatio-temporal waves in the delta band at a similar latency to the P3b event-related potential. Subjects with FES had fewer episodes of anterior to posterior waves in the 2-4 Hz band compared to controls. Within the FES group, a tendency for fewer episodes of anterior to posterior waves was associated with high Psychomotor Poverty symptom factor scores. Subjects with FES had altered global EEG dynamics along the anterior-posterior axis during task conditions involving context update. The directional nature of this finding and its association with Psychomotor Poverty suggest this result is related to findings of hypofrontality in schizophrenia.

Context processing in schizotypal personality disorder: Evidence of specificity of impairment to the schizophrenia spectrum.

Working memory abnormalities, which are particularly pronounced on context processing tasks, appear relatively specific to schizophrenia spectrum illnesses compared with other psychotic disorders. However, the specificity of context processing deficits to schizotypal personality disorder (SPD), a prototype of schizophrenia, has not been studied. The authors administered 3 versions of the modified AX Continuous Performance Test and an N-back working memory test to 63 individuals with SPD and 25 with other personality disorders, as well as 42 healthy controls. For the AX Continuous Performance Test standard and degraded versions, there was a significant Trial Type x Delay x Group interaction, as SPDs made significantly more errors reflecting poor maintenance of context and fewer errors reflecting good maintenance of context. SPDs also demonstrated poor performance on the N-back, especially at the 2-back condition. Context processing errors and N-back accuracy scores were related to disorganization symptoms. These findings, which are quite similar to those previously reported in patients with schizophrenia, suggest that context processing deficits are specific to the schizophrenia spectrum and are not a reflection of overall psychopathology.

Context, complexity, and cognitive processing in schizophrenia

Background. Cohen et al.'s (1990, 1999) concept of context has been employed to explain various schizophrenic cognitive deficits. Braver et al.'s (2001) modified definition allows us to link context to cognitive complexity and explain a range of our experimental findings. Method. Saccadic and manual responses to experimental paradigms involving familiar and unfamiliar versions of tasks varying in stimulus–response compatibility, response familiarity, and temporal factors were used. These include comparison of acoustic and visually driven saccades and antisaccades, manual and saccadic pattern reproduction, and colour (cognitively guided) saccades with two delay intervals. Results. In one experiment, schizophrenic participants, unlike controls, made fewer errors on the auditory compared to the visual antisaccade task, suggesting that prepotent responses are more easily inhibited when stimulus–response compatibility is reduced. In a second experiment in which a left–right response sequence is reproduced manually or saccadically, schizophrenic performance is impaired when the novel and thus more complex saccadic response is required. In the third experiment, a colour signal is interpreted to determine the correct direction of a saccade. With two different blocked delay intervals, shortening the delay results in schizophrenic performance decline, suggesting difficulty adjusting to temporal context changes. Conclusion. These results, together with our previous findings (Schooler et al., 1997a; Zahn et al., 1998) suggest schizophrenic context processing deficits become increasingly evident as contexts become more complex. These results may be due to microgaps in schizophrenic individuals’ maintenance of context.

Prefrontal Cortex Function in Nonpsychotic Siblings of Individuals with Schizophrenia

Cognitive dysfunction is a hallmark feature of schizophrenia. In recent years, it has been proposed that impairments in attention, working memory and executive function may all reflect an underlying deficit in context processing. In individuals with schizophrenia, deficits in context processing have been associated with functional impairments of the dorsolateral prefrontal cortex (DLPFC). We used a variation of the continuous performance task, the AX-CPT, to test the hypothesis that genetic high-risk individuals (full siblings of individuals with schizophrenia) have deficits in context processing and abnormal activation of the DLPFC as compared to community controls. Siblings of individuals with schizophrenia made significantly more B-X errors on the AX-CPT, indicative of a deficit in context processing. They also showed task-related hyper-activation in a number of brain regions, including the DLPFC. Inefficient hyper-activation of the DLPFC may underlie deficits in context processing and contribute to the genetic vulnerability for developing schizophrenia.

Context processing performance in bipolar disorder patients

Context processing is the adaptive control of current behavior through the use of prior context information. It has been found to be impaired in schizophrenia. Some studies have indicated that, compared with patients with schizophrenia, those with bipolar disorder (BPD) display a similar but less severe neuropsychological pattern of impairment. However, this cognitive dimension has not yet been examined in BPD patients in the existing literature. An expectancy version of the AX continuous performance test (AX-CPT) was administered to 15 bipolar outpatients and 26 healthy controls. Patients with schizophrenia, in which context processing deficits are known to occur, were used as a reference group. Bipolar patients showed a context processing deficit relative to healthy controls, although this was less severe and generalized than in schizophrenia patients. These findings suggest there are milder impairments in context processing in BPD compared with schizophrenia. However, the severity of possible context processing deficits in BPD may have been underestimated in our sample of mostly euthymic outpatients.

Accounting for Cognitive Aging: Context Processing, Inhibition or Processing Speed?

ABSTRACT Age-related deficits in context processing were examined in relationship to two predominant theories of cognitive aging (the Inhibitory Deficit and Processing Speed Models). Older and younger adults completed a measure of context processing (AX Continuous Performance Test (CPT) task) as well as a computerized battery of inhibitory tasks: Stroop, garden path sentences, go no-go, and the stop-signal paradigm. Participants also completed a simple processing speed task. After controlling for baseline differences in processing speed, age effects were detected on the AX-CPT. Smaller, but significant age effects were noted on the Stroop and stop-signal tasks, but no significant age effects were found on the garden path sentence and go no-go tasks. Intertask correlations were weak, providing little evidence for a homogenous or uniform construct of inhibition. The sensitivity of the AX-CPT to cognitive aging is discussed in the context of existing theories of cognitive aging. The authors suggest that deficits in context processing and utilization may underlie cognitive aging phenomena.

Theory of mind and perceptual context‐processing in schizophrenia

Introduction. A series of studies have suggested that schizophrenia patients are deficient in theory of mind (ToM). However, the cognitive mechanisms underlying ToM deficits in schizophrenia are largely unknown. The present study examined the hypothesis that impaired ToM in schizophrenia can be understood as a deficit in context processing. Methods. Disorganised schizophrenia patients (N = 12), nondisorganised schizophrenia patients (N = 36), and nonpsychotic psychiatric patients (N = 26) were tested on three ToM tasks and a visual size perception task, a measure of perceptual context processing. In addition, statistical analyses were carried out which compared chronic, treatment‐refractory schizophrenia patients (N = 28) to those with an episodic course of illness (N = 20). Results. Overall, ToM performance was linked to deficits in context processing in schizophrenia patients. Statistical comparisons showed that disorganised as well as chronic schizophrenia patients were more impaired in ToM but more accurate in a visual size perception task where perceptual context is misleading. Conclusions. This pattern of results is interpreted as indicating a possible link between deficits in ToM and perceptual context processing, which together with deficits in perceptual grouping, are part of a broader dysfunction in cognitive coordination in schizophrenia.

When a schizophrenic deficit becomes a reasoning advantage

A deficit in context processing has been proposed to be one of the major deficiencies in schizophrenia. A demanding reasoning task, known to promote a very reproducible bias (i.e., a reasoning error) in healthy subjects, triggered by a misleading context, was administered in 26 schizophrenic patients and 26 healthy participants. Responses at random were checked by including an additional group of 11 schizophrenic patients who performed a control version of the task. We showed that patients presented a surprising imperviousness to the reasoning bias and had significantly better logical performances than their paired healthy participants. This finding demonstrates that there are some problem solving situations where disregarding contextual information, a cognitive deficit that usually impairs schizophrenic patients gives them a cognitive advantage over healthy controls.

The influence of aging and frontal function on the neural correlates of regulative and evaluative aspects of cognitive control.

The influence of aging and frontal function on the neural correlates of regulative and evaluative control was examined by means of event-related brain potentials (ERPs). The behavioral data indicated that interference was greater for older than for younger adults and that this difference was mediated by frontal function. The ERP data revealed effects of aging on the neural correlates of both regulative and evaluative control. Prestimulus neural activity was correlated with response time and frontal function, and these relationships were moderated by the response-to-stimulus interval (RSI); the poststimulus data also revealed age-related differences in the neural correlates of evaluative control that interacted with RSI. These data support predictions derived from the context processing deficit theory of aging.

Scale for the evaluation of communication disorders in patients with schizophrenia: A validation study

Objective A scale for the evaluation of communication disorders in patients with schizophrenia (Schizophrenia Communication Disorder Scale-SCD) is proposed based on studies showing that cognitive disorders specific to the disorganization seen in schizophrenia consist of context processing deficits and problems in the attribution of mental states. Thus the focus of this scale is on the cognitive difficulties revealed in conversation during a structured interview. Method Fifty-six patients with schizophrenia, depression or mania were evaluated. Results and conclusion Significantly elevated scores on the SCD were present in patients with schizophrenia compared to all other groups. Thus, this scale adds to the tools available for evaluating the language of patients with schizophrenia and helps focus on characteristics that are specific to this psychotic diagnosis.

Prefrontal functioning during context processing in schizophrenia and major depression: An event-related fMRI study

Patients with schizophrenia frequently demonstrate hypofrontality in tasks that require executive processing; however questions still remain as to whether prefrontal cortex dysfunctions are specific to schizophrenia, or a general feature of major psychopathology. Context processing is conceptualized as an executive function associated with attention and working memory processes. Impairment in the ability of patients with schizophrenia to represent and maintain context information has been previously reported in a number of studies. To examine the question of the specificity of a context processing deficit to schizophrenia, we used functional MRI and an expectancy AX continuous performance task designed to assess context processing in a group of healthy controls ( n = 9), depressed patient controls ( n = 10), and patients with schizophrenia ( n = 7). The behavioral performance was consistent with a context processing deficit in patients with schizophrenia, but not those with depression. The imaging data replicate previous results in showing abnormal activity in the right middle frontal gyrus (BA9) in schizophrenia patients related to context processing.