Processing Deficits In Schizophrenia Research Articles

Meta-analysis on the association between genetic polymorphisms and prepulse inhibition of the acoustic startle response

Sensorimotor gating measured by prepulse inhibition (PPI) of the acoustic startle response (ASR) has been proposed as one of the most promising electrophysiological endophenotypes of schizophrenia. During the past decade, a number of publications have reported significant associations between genetic polymorphisms and PPI in samples of schizophrenia patients and healthy volunteers. However, an overall evaluation of the robustness of these results has not been published so far. Therefore, we performed the first meta-analysis of published and unpublished associations between gene polymorphisms and PPI of ASR. Unpublished associations between genetic polymorphisms and PPI were derived from three independent samples. In total, 120 single observations from 16 independent samples with 2660 study participants and 43 polymorphisms were included. After correction for multiple testing based on false discovery rate and considering the number of analyzed polymorphisms, significant associations were shown for four variants, even though none of these associations survived a genome-wide correction (P<5∗10−8). These results imply that PPI might be modulated by four genotypes – COMT rs4680 (primarily in males), GRIK3 rs1027599, TCF4 rs9960767, and PRODH rs385440 – indicating a role of these gene variations in the development of early information processing deficits in schizophrenia. However, the overall impact of single genes on PPI is still rather small suggesting that PPI is – like the disease phenotype – highly polygenic. Future genome-wide analyses studies with large sample sizes will enhance our understanding on the genetic architecture of PPI.

Clinical and Cognitive Significance of Auditory Sensory Processing Deficits in Schizophrenia.

Although patients with schizophrenia exhibit impaired suppression of the P50 event-related brain potential in response to the second of two identical auditory stimuli during a paired-stimulus paradigm, uncertainty remains over whether this deficit in inhibitory gating of auditory sensory processes has relevance for patients' clinical symptoms or cognitive performance. The authors examined associations between P50 suppression deficits and several core features of schizophrenia to address this gap. P50 was recorded from 52 patients with schizophrenia and 41 healthy comparison subjects during a standard auditory paired-stimulus task. Clinical symptoms were assessed with the Scale for the Assessment of Positive Symptoms and the Scale for the Assessment of Negative Symptoms. The MATRICS Consensus Cognitive Battery was utilized to measure cognitive performance in a subsample of 39 patients. Correlation and regression analyses were conducted to examine P50 suppression in relation to clinical symptom and cognitive performance measures. Schizophrenia patients demonstrated a deficit in P50 suppression when compared with healthy subjects, replicating prior research. Within the patient sample, impaired P50 suppression covaried reliably with greater difficulties in attention, poorer working memory, and reduced processing speed. Impaired suppression of auditory stimuli was associated with core pathological features of schizophrenia, increasing confidence that P50 inhibitory processing can inform the development of interventions that target cognitive impairments in this chronic and debilitating mental illness.

Developmental trajectory of mismatch negativity and visual event-related potentials in healthy controls: Implications for neurodevelopmental vs. neurodegenerative models of schizophrenia

Sensory processing deficits are core features of schizophrenia, reflected in impaired generation of event-related potential (ERP) measures such as auditory mismatch negativity (MMN) and visual P1. To understand the potential time course of development of deficits in schizophrenia, we obtained MMN to unattended duration, intensity and frequency deviants, and visual P1 to attended LSF stimuli, in 43 healthy individuals ages 6 to 25years (mean 17), and compared results to data from 30 adult schizophrenia patients (mean age 38). We analyzed “time-domain” measures of amplitude and latency, and event-related spectral perturbation (ERSP, “time-frequency”) to evaluate underlying neurophysiological mechanisms.Duration and intensity MMN amplitudes increased from childhood to late adolescence, while frequency MMN reached maximum amplitude during early development. As reported previously, in ERSP analyses, MMN activity corresponded primarily to theta-band (4–7Hz) activity, while responses to standards occurred primarily in alpha (8–12Hz) across age groups. Both deviant-induced theta and standard-induced alpha activity declined significantly with age for all deviant types. Likewise, visual P1 also showed an amplitude decline over development, reflecting a reduction in both evoked power and ITC.While MMN “difference” waveform ERP data suggest failure of maturation in schizophrenia, MMN ERSP analyses instead support a neurodegenerative process, as these isolate responses to deviants and standards, showing large low-frequency evoked power for both in children. Neurodegenerative processes are also supported by large visual P1 amplitudes and large low-frequency evoked power in children, in contrast with adult schizophrenia. Sensory processing deficits in schizophrenia may be related to accelerated synaptic pruning.

Face-related visual search deficits in first-episode schizophrenia

Schizophrenia is considered a complex illness with multiple cognitive dysfunctions, including a deficit in visual processing. However, whether the deficiency of visual processing in schizophrenia is general across stimuli or stimulus-specific remains the subject of debate. In the current study, eighteen first-episode schizophrenic patients and eighteen healthy controls participated in three visual search tasks in which they were asked to search a specific target of a triangle, face identity or facial affect. The results showed that, compared to healthy controls, the accuracies for face identity and facial affect searches were significantly lower in schizophrenic patients, while the performance of the triangle search was the same. Furthermore, the accuracy of the facial affect search was negatively correlated to negative symptoms in schizophrenia. These results revealed a face-related deficit in schizophrenia and suggest that visual processing deficits in schizophrenia were stimuli-specific.

Temporal processing deficit leads to impaired multisensory binding in schizophrenia

ABSTRACTIntroduction: Schizophrenia has been characterised by neurodevelopmental dysconnectivity resulting in cognitive and perceptual dysmetria. Hence patients with schizophrenia may be impaired to detect the temporal relationship between stimuli in different sensory modalities. However, only a few studies described deficit in perception of temporally asynchronous multisensory stimuli in schizophrenia.Methods: We examined the perceptual bias and the processing time of synchronous and delayed sounds in the streaming–bouncing illusion in 16 patients with schizophrenia and a matched control group of 18 participants.Results: Equal for patients and controls, the synchronous sound biased the percept of two moving squares towards bouncing as opposed to the more frequent streaming percept in the condition without sound. In healthy controls, a delay of the sound presentation significantly reduced the bias and led to prolonged processing time whereas patients with schizophrenia did not differentiate between this condition and the condition with synchronous sound.Conclusion: Schizophrenia leads to a prolonged window of simultaneity for audiovisual stimuli. Therefore, temporal processing deficit in schizophrenia can lead to hyperintegration of temporally unmatched multisensory stimuli.

Probing the magnocellular and parvocellular visual pathways in facial emotion perception in schizophrenia

Schizophrenia patients have well-established deficits in facial emotion perception, which contribute to their poor social functioning. A number of studies have related these deficits to a differential dysfunction in the magnocellular (M) versus parvocellular (P) visual pathway. We assessed 35 schizophrenia patients and 35 healthy individuals on an emotion identification task, in which facial stimuli were either unaltered (broad spatial frequency, BSF) or manipulated to contain only high (HSF) or low (LSF) spatial frequencies, thereby respectively biasing the visual system toward the P- or M- pathways. As expected, patients were less accurate and slower in recognizing emotions across all conditions, relative to controls. Performance was best in the BSF condition followed by the HSF and finally the LSF condition, in both groups. A significant group by spatial frequency interaction reflected a smaller magnitude of impairment in the HSF condition, compared to the other two conditions that preferentially engage the M-system. These findings are consistent with studies showing a differential M-pathway abnormality in schizophrenia with a less pronounced impairment in P-function. The current study suggests that patients have less difficulty extracting emotional content from faces when LSFs are attenuated and supports the need to remediate basic visual processing deficits in schizophrenia.

Language context processing deficits in schizophrenia: The role of attentional engagement

Individuals with schizophrenia exhibit problems in language comprehension that are most evident during discourse processing. We hypothesized that deficits in cognitive control contribute to these comprehension deficits during discourse processing, and investigated the underlying cognitive-neural mechanisms using EEG (alpha power) and ERPs (N400). N400 amplitudes to globally supported or unsupported target words near the end of stories were used to index sensitivity to previous context. ERPs showed reduced sensitivity to context in patients versus controls. EEG alpha-band activity was used to index attentional engagement while participants listened to the stories. We found that context effects varied with attentional engagement in both groups, as well as with negative symptom severity in patients. Both groups demonstrated trial-to-trial fluctuations in alpha. Relatively high alpha power was associated with compromised discourse processing in participants with schizophrenia when it occurred during any early portion of the story. In contrast, discourse processing was only compromised in controls when alpha was relatively high for longer segments of the stories. Our results indicate that shifts in attention from the story context may be more detrimental to discourse processing for participants with schizophrenia than for controls, most likely due to an impaired ability to benefit from global context.

Effects of Acute Ketamine Infusion on Visual Working Memory: Event-Related Potentials

BackgroundWorking memory (WM) deficits are a core feature of schizophrenia. Electrophysiological studies suggest that impaired early visual processing may contribute to impaired WM in the visual domain. Abnormal N-methyl-D-aspartate (NMDA) receptor function has been implicated both in WM and in early visual processing deficits in schizophrenia. We investigated whether ketamine, a noncompetitive NMDA antagonist, would replicate in healthy volunteers the WM performance and early visual processing abnormalities we and others have reported in patients with schizophrenia. MethodsForty-four healthy volunteers were randomly assigned to receive intravenous ketamine or placebo. During infusion, the effects of ketamine were recorded using standardized psychiatric scales. Visual evoked potentials (P100 and P300 components) were recorded during performance of a delayed matching to sample task. ResultsKetamine induced mild psychosis-like symptoms and impaired WM performance. It also significantly increased the P100 amplitude, while P300 amplitude decreased in a load-dependent manner. Amplitudes of P100 during retrieval correlated with cognitive performance only in the placebo group. ConclusionsWe confirmed previous studies showing that ketamine reproduces the impairment of WM performance and smaller P300 amplitudes observed in schizophrenia. However, ketamine increased visual P100 amplitude in contrast to our observation of reduced P100 amplitudes in established schizophrenia. The effects of ketamine on WM and P300 are likely to involve impaired NMDA function, as these receptors are implicated in changes of synaptic strength underlying associative learning and memory. Increased P100 amplitude may reflect the secondary disinhibition of cortical glutamate release that occurs after NMDA blockade.

Anomalous Self-Experiences and positive symptoms are independently associated with emotion processing deficits in schizophrenia

Social-cognitive models posit a role of Anomalous Self-Experiences (ASEs), disturbances in the subjective experience of the self, in the development and maintenance of psychosis. Theorists have suggested that ASEs may underlie the social-cognitive deficits that are common in people with schizophrenia. Positive symptoms, negative symptoms, and ASEs may interfere with the ability to perceive, use, understand, and manage emotions. In the current study, 45 people with schizophrenia and 28 healthy controls completed the Inventory of Psychotic-Like Anomalous Self-Experiences (IPASE), the Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT), and were rated on the Positive and Negative Syndrome Scale (PANSS). Participants with schizophrenia had higher IPASE scores and lower MSCEIT scores than the comparison group. In a series of simultaneous regressions, ASEs, but not positive or negative symptoms, were associated with Total MSCEIT scores and the Using Emotions branch score. In contrast, positive symptoms, but not ASEs or negative symptoms were associated with Perceiving and Managing Emotions branches. Both ASEs and positive symptoms independently contributed to Emotional Experiencing scores. The severity of negative symptoms was not associated with deficits in any MSCEIT scores. These results suggest unique roles for ASEs and positive symptoms in emotion processing deficits in people with schizophrenia.

Reduced frontal theta oscillations indicate altered crossmodal prediction error processing in schizophrenia.

Our brain generates predictions about forthcoming stimuli and compares predicted with incoming input. Failures in predicting events might contribute to hallucinations and delusions in schizophrenia (SZ). When a stimulus violates prediction, neural activity that reflects prediction error (PE) processing is found. While PE processing deficits have been reported in unisensory paradigms, it is unknown whether SZ patients (SZP) show altered crossmodal PE processing. We measured high-density electroencephalography and applied source estimation approaches to investigate crossmodal PE processing generated by audiovisual speech. In SZP and healthy control participants (HC), we used an established paradigm in which high- and low-predictive visual syllables were paired with congruent or incongruent auditory syllables. We examined crossmodal PE processing in SZP and HC by comparing differences in event-related potentials and neural oscillations between incongruent and congruent high- and low-predictive audiovisual syllables. In both groups event-related potentials between 206 and 250 ms were larger in high- compared with low-predictive syllables, suggesting intact audiovisual incongruence detection in the auditory cortex of SZP. The analysis of oscillatory responses revealed theta-band (4-7 Hz) power enhancement in high- compared with low-predictive syllables between 230 and 370 ms in the frontal cortex of HC but not SZP. Thus aberrant frontal theta-band oscillations reflect crossmodal PE processing deficits in SZ. The present study suggests a top-down multisensory processing deficit and highlights the role of dysfunctional frontal oscillations for the SZ psychopathology.

Neural oscillatory deficits in schizophrenia predict behavioral and neurocognitive impairments.

Paying attention to visual stimuli is typically accompanied by event-related desynchronizations (ERD) of ongoing alpha (7–14 Hz) activity in visual cortex. The present study used time-frequency based analyses to investigate the role of impaired alpha ERD in visual processing deficits in schizophrenia (Sz). Subjects viewed sinusoidal gratings of high (HSF) and low (LSF) spatial frequency (SF) designed to test functioning of the parvo- vs. magnocellular pathways, respectively. Patients with Sz and healthy controls paid attention selectively to either the LSF or HSF gratings which were presented in random order. Event-related brain potentials (ERPs) were recorded to all stimuli. As in our previous study, it was found that Sz patients were selectively impaired at detecting LSF target stimuli and that ERP amplitudes to LSF stimuli were diminished, both for the early sensory-evoked components and for the attend minus unattend difference component (the Selection Negativity), which is generally regarded as a specific index of feature-selective attention. In the time-frequency domain, the differential ERP deficits to LSF stimuli were echoed in a virtually absent theta-band phase locked response to both unattended and attended LSF stimuli (along with relatively intact theta-band activity for HSF stimuli). In contrast to the theta-band evoked responses which were tightly stimulus locked, stimulus-induced desynchronizations of ongoing alpha activity were not tightly stimulus locked and were apparent only in induced power analyses. Sz patients were significantly impaired in the attention-related modulation of ongoing alpha activity for both HSF and LSF stimuli. These deficits correlated with patients’ behavioral deficits in visual information processing as well as with visually based neurocognitive deficits. These findings suggest an additional, pathway-independent, mechanism by which deficits in early visual processing contribute to overall cognitive impairment in Sz.

A study of the relationship between receptive and expressive language processing in schizophrenia

Event Abstract Back to Event A study of the relationship between receptive and expressive language processing in schizophrenia Eric Tan1*, Gregory Yelland2 and Susan Rossell3, 4 1 Monash University, Monash-Alfred Psychiatry Research Centre, Australia 2 Monash University, Australia 3 Swinburne University of Technology, Brain and Psychological Sciences research centre, Australia 4 Monash-Alfred Psychiatry Research Centre, Australia Background: Traditional language models propose a relationship between the two components of language processing: receptive/comprehension and expressive/production. Dysfunction of language production has been recognised in schizophrenia, notably in the aberrant speech patterns termed formal thought disorder (TD). Presently, language production in schizophrenia is better characterised than language comprehension. This study thus aimed to expand on current understanding of language comprehension in schizophrenia, and examine its relationship to individual TD symptoms. Two aspects were studied: word/lexical recognition, and meaning attribution for words and sentences. Method: Fifty-seven schizophrenia/schizoaffective disorder patients and 48 healthy controls completed a clinical assessment and three language tasks assessing word recognition, synonym identification and sentence comprehension. Poorer patient performance was expected on the latter two tasks. Results: Results indicated that recognition of word form was not impaired in schizophrenia, indicating intact lexical processing. While single word synonym identification was not significantly impaired, there was a tendency to attribute word meanings based on phonological similarity, which increased with severity of some TD symptoms. Importantly, there was a significant sentence comprehension deficit for processing deep structure, which correlated with severity of selective TD symptoms. Conclusions: Sentence comprehension appears to be impaired here, which supports the case for some receptive language processing deficits in schizophrenia. There is also evidence for a relationship between aspects of language comprehension and speech production, which suggests a role for the former in TD aetiology, which differs between individual symptom types (i.e. derailment and circumstantiality). The remediation of language comprehension problems may thus be an avenue to pursue in alleviating TD symptomatology. Keywords: Language, Schizophrenia, syntax, Language comprehension, Language production, formal thought disorder, lexical-semantics Conference: XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014. Presentation Type: Poster Topic: Language Citation: Tan E, Yelland G and Rossell S (2015). A study of the relationship between receptive and expressive language processing in schizophrenia. Conference Abstract: XII International Conference on Cognitive Neuroscience (ICON-XII). doi: 10.3389/conf.fnhum.2015.217.00404 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Feb 2015; Published Online: 24 Apr 2015. * Correspondence: Mr. Eric Tan, Monash University, Monash-Alfred Psychiatry Research Centre, Melbourne, Australia, Eric.Tan@monash.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Eric Tan Gregory Yelland Susan Rossell Google Eric Tan Gregory Yelland Susan Rossell Google Scholar Eric Tan Gregory Yelland Susan Rossell PubMed Eric Tan Gregory Yelland Susan Rossell Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Facial affect processing deficits in schizophrenia: a meta-analysis of antipsychotic treatment effects.

Social cognition, including emotion processing, is a recognised deficit observed in patients with schizophrenia. It is one cognitive domain which has been emphasised as requiring further investigation, with the efficacy of antipsychotic treatment on this deficit remaining unclear. Nine studies met our criteria for entry into a meta-analysis of the effects of medication on facial affect processing, including data from 1162 patients and six antipsychotics. Overall we found a small, positive effect (Hedge’s g = 0.13, 95% CI 0.05 to 0.21, p = 0.002). In a subgroup analysis this was statistically significant for atypical, but not typical, antipsychotics. It should be noted that the pooled sample size of the typical subgroup was significantly lower than the atypical. Meta-regression analyses revealed that age, gender and changes in symptom severity were not moderating factors. For the small, positive effect on facial affect processing, the clinical significance is questionable in terms of treating deficits in emotion identification in schizophrenia. We show that antipsychotic medications are poor at improving facial affect processing compared to reducing symptoms. This highlights the need for further investigation into the neuropharmacological mechanisms associated with accurate emotion processing, to inform treatment options for these deficits in schizophrenia.

Pre-pulse inhibition and antisaccade performance indicate impaired attention modulation of cognitive inhibition in 22q11.2 deletion syndrome (22q11DS).

Background22q11.2 deletion syndrome (22q11DS) is associated with a number of physical anomalies and neuropsychological deficits including impairments in executive and sensorimotor function. It is estimated that 25% of children with 22q11DS will develop schizophrenia and other psychotic disorders later in life. Evidence of genetic transmission of information processing deficits in schizophrenia suggests performance in 22q11DS individuals will enhance understanding of the neurobiological and genetic substrates associated with information processing. In this report, we examine information processing in 22q11DS using measures of startle eyeblink modification and antisaccade inhibition to explore similarities with schizophrenia and associations with neurocognitive performance.MethodsStartle modification (passive and active tasks; 120- and 480-ms pre-pulse intervals) and antisaccade inhibition were measured in 25 individuals with genetically confirmed 22q11DS and 30 healthy control subjects.ResultsIndividuals with 22q11DS exhibited increased antisaccade error as well as some evidence (trend-level effect) of impaired sensorimotor gating during the active condition, suggesting a dysfunction in controlled attentional processing, rather than a pre-attentive dysfunction using this paradigm.ConclusionsThe findings from the present study show similarities with previous studies in clinical populations associated with 22q11DS such as schizophrenia that may indicate shared dysfunction of inhibition pathways in these groups.

Cortical substrates and functional correlates of auditory deviance processing deficits in schizophrenia.

Although sensory processing abnormalities contribute to widespread cognitive and psychosocial impairments in schizophrenia (SZ) patients, scalp-channel measures of averaged event-related potentials (ERPs) mix contributions from distinct cortical source-area generators, diluting the functional relevance of channel-based ERP measures. SZ patients (n = 42) and non-psychiatric comparison subjects (n = 47) participated in a passive auditory duration oddball paradigm, eliciting a triphasic (Deviant−Standard) tone ERP difference complex, here termed the auditory deviance response (ADR), comprised of a mid-frontal mismatch negativity (MMN), P3a positivity, and re-orienting negativity (RON) peak sequence. To identify its cortical sources and to assess possible relationships between their response contributions and clinical SZ measures, we applied independent component analysis to the continuous 68-channel EEG data and clustered the resulting independent components (ICs) across subjects on spectral, ERP, and topographic similarities. Six IC clusters centered in right superior temporal, right inferior frontal, ventral mid-cingulate, anterior cingulate, medial orbitofrontal, and dorsal mid-cingulate cortex each made triphasic response contributions. Although correlations between measures of SZ clinical, cognitive, and psychosocial functioning and standard (Fz) scalp-channel ADR peak measures were weak or absent, for at least four IC clusters one or more significant correlations emerged. In particular, differences in MMN peak amplitude in the right superior temporal IC cluster accounted for 48% of the variance in SZ-subject performance on tasks necessary for real-world functioning and medial orbitofrontal cluster P3a amplitude accounted for 40%/54% of SZ-subject variance in positive/negative symptoms. Thus, source-resolved auditory deviance response measures including MMN may be highly sensitive to SZ clinical, cognitive, and functional characteristics.

Sequential processing deficits in schizophrenia: Relationship to neuropsychology and genetics

Utilizing a combination of neuropsychological and cognitive neuroscience approaches may be essential for characterizing cognitive deficits in schizophrenia and eventually assessing cognitive outcomes. This study was designed to compare the stability of select exemplars for these approaches and their correlations in schizophrenia patients with stable treatment and clinical profiles. Reliability estimates for serial order processing were comparable to neuropsychological measures and indicate that experimental serial order processing measures may be less susceptible to practice effects than traditional neuropsychological measures. Correlations were moderate and consistent with a global cognitive factor. Exploratory analyses indicated a potentially critical role of the Met allele of the Catechol-O-methyltransferase (COMT) Val158Met polymorphism in externally paced sequential recall. Experimental measures of serial order processing may reflect frontostriatal dysfunction and be a useful supplement to large neuropsychological batteries.

Automatic Auditory Processing Deficits in Schizophrenia and Clinical High-Risk Patients: Forecasting Psychosis Risk with Mismatch Negativity

Only about one third of patients at high risk for psychosis based on current clinical criteria convert to a psychotic disorder within a 2.5-year follow-up period. Targeting clinical high-risk (CHR) individuals for preventive interventions could expose many to unnecessary treatments, underscoring the need to enhance predictive accuracy with nonclinical measures. Candidate measures include event-related potential components with established sensitivity to schizophrenia. Here, we examined the mismatch negativity (MMN) component of the event-related potential elicited automatically by auditory deviance in CHR and early illness schizophrenia (ESZ) patients. We also examined whether MMN predicted subsequent conversion to psychosis in CHR patients. Mismatch negativity to auditory deviants (duration, frequency, and duration + frequency double deviant) was assessed in 44 healthy control subjects, 19 ESZ, and 38 CHR patients. Within CHR patients, 15 converters to psychosis were compared with 16 nonconverters with at least 12 months of clinical follow-up. Hierarchical Cox regression examined the ability of MMN to predict time to psychosis onset in CHR patients. Irrespective of deviant type, MMN was significantly reduced in ESZ and CHR patients relative to healthy control subjects and in CHR converters relative to nonconverters. Mismatch negativity did not significantly differentiate ESZ and CHR patients. The duration + frequency double deviant MMN, but not the single deviant MMNs, significantly predicted the time to psychosis onset in CHR patients. Neurophysiological mechanisms underlying automatic processing of auditory deviance, as reflected by the duration + frequency double deviant MMN, are compromised before psychosis onset and can enhance the prediction of psychosis risk among CHR patients.

The Simple Copy Task: Detecting Higher Order Visual Processing Deficits in Schizophrenia, Dementia, and Movement Disorder Groups

The Simple Copy Task (SCT) is a figure copying test with inherent appeal due to its short administration time, graded task difficulty, varied stimuli, and potential to eliminate floor effects. Despite this, there is a lack of data regarding its construct validity and diagnostic utility. The present study compared SCT performance of schizophrenia (n = 29), dementia (n = 64), and movement disorder (n = 12) groups with that of unmatched healthy control participants (n = 49). Movement disorder patients committed a high degree of misplacement errors, whereas dementia patients tended to omit items, add extraneous detail, and perseverate. The schizophrenia group was most similar to the dementia group in their performance on the SCT, committing primarily omission and perseveration errors. The SCT was most closely related to the Rey Complex Figure Task (r = 0.68, p < .01) and the Block Design Task (r = 0.62, p < .01). Age (r = −0.14, p < .01) and education (r = 0.35, p < .01) effects were present; however, there was no impact of gender and handedness. Taken together, these findings provide support for the utility of the task and directions for clinical interpretation.

The Influence of Semantic Processing on Odor Identification Ability in Schizophrenia

Despite the well-documented observation of odor identification deficits in schizophrenia, less is known about where the disruption in the process of correctly identifying an odor occurs. This study aimed to determine the potential moderating effects of semantic processing on the observed olfactory dysfunction in schizophrenia. Schizophrenia patients and healthy comparison subjects completed two versions of the University of Pennsylvania Smell Identification Test (UPSIT): an uncued free-response version and the standard multiple-choice paradigm, as well as three semantic measures: The Boston Naming Test, Animal Naming, and Pyramids and Palm Tree Test. Schizophrenia patients yielded significantly lower scores than the comparison group on the standard UPSIT and on semantic measures. No relationship was observed between olfactory and semantic task performance in patients. These data suggest that odor identification deficits may not be primarily due to semantic processing deficits in schizophrenia.

Windows to the soul: vision science as a tool for studying biological mechanisms of information processing deficits in schizophrenia

Cognitive and information processing deficits are core features and important sources of disability in schizophrenia. Our understanding of the neural substrates of these deficits remains incomplete, in large part because the complexity of impairments in schizophrenia makes the identification of specific deficits very challenging. Vision science presents unique opportunities in this regard: many years of basic research have led to detailed characterization of relationships between structure and function in the early visual system and have produced sophisticated methods to quantify visual perception and characterize its neural substrates. We present a selective review of research that illustrates the opportunities for discovery provided by visual studies in schizophrenia. We highlight work that has been particularly effective in applying vision science methods to identify specific neural abnormalities underlying information processing deficits in schizophrenia. In addition, we describe studies that have utilized psychophysical experimental designs that mitigate generalized deficit confounds, thereby revealing specific visual impairments in schizophrenia. These studies contribute to accumulating evidence that early visual cortex is a useful experimental system for the study of local cortical circuit abnormalities in schizophrenia. The high degree of similarity across neocortical areas of neuronal subtypes and their patterns of connectivity suggests that insights obtained from the study of early visual cortex may be applicable to other brain regions. We conclude with a discussion of future studies that combine vision science and neuroimaging methods. These studies have the potential to address pressing questions in schizophrenia, including the dissociation of local circuit deficits vs. impairments in feedback modulation by cognitive processes such as spatial attention and working memory, and the relative contributions of glutamatergic and GABAergic deficits.