Task-merging for finer separation of functional brain networks in working memory.

Background: In task-state functional magnetic resonance imaging (fMRI), hemodynamic response (HDR) shapes help identify cognitive process(es) supported by a brain network. However, when distinguishable networks have similar time courses, the low temporal resolution of the HDRs may result in spatial and temporal blurring of these networks. The present study demonstrated how task-merging and multivariate analysis allows data-driven separation of working memory (WM) processes.

Alternation between different types of evidence attenuates judgments of severity.

Most real-world judgments and decisions require the consideration of multiple types of evidence. For example, judging the severity of environmental damage, medical illness, or negative economic trends often involves tracking and integrating evidence from multiple sources (i.e.

Left-dominant temporal-frontal hypercoupling in schizophrenia patients with hallucinations during speech perception.

Background: Task-based functional neuroimaging studies of schizophrenia have not yet replicated the increased coordinated hyperactivity in speech-related brain regions that is reported with symptom-capture and resting-state studies of hallucinations. This may be due to suboptimal selection of cognitive tasks.

Methods: In the current study, we used a task that allowed experimental manipulation of control over verbal material and compared brain activity between 23 schizophrenia patients (10 hallucinators, 13 nonhallucinators), 22 psychiatric (bipolar), and 27 healthy controls.

Patterns of Cortical Oscillations Organize Neural Activity into Whole-Brain Functional Networks Evident in the fMRI BOLD Signal.

Recent findings from electrophysiology and multimodal neuroimaging have elucidated the relationship between patterns of cortical oscillations evident in EEG/MEG and the functional brain networks evident in the BOLD signal. Much of the existing literature emphasized how high-frequency cortical oscillations are thought to coordinate neural activity locally, while low-frequency oscillations play a role in coordinating activity between more distant brain regions. However, the assignment of different frequencies to different spatial scales is an oversimplification.

Functional connectivity in a frontoparietal network involving the dorsal anterior cingulate cortex underlies decisions to accept a hypothesis.

Optimally interpreting our situations and experiences frequently requires comparing the evidence supporting conflicting hypotheses and deciding which to accept. This decision is comparable to an "Aha!" moment reached during insightful problem solving. We used a probabilistic reasoning task to investigate the neural activity underlying these processes.

Bias in favour of self-selected hypotheses is associated with delusion severity in schizophrenia.

Introduction: Delusions are typically characterised by idiosyncratic, self-generated explanations used to interpret events, as opposed to the culturally normative interpretations. Thus, a bias in favour of one's own hypotheses may be a fundamental aspect of delusions.

Methods: We tested this possibility in the current study by comparing judgements of self-selected hypotheses to judgements of externally selected ones in a probabilistic reasoning task.

Hyperintensity of functional networks involving voice-selective cortical regions during silent thought in schizophrenia.

An important aspect of schizophrenia symptomatology is inner-outer confusion, or blurring of ego boundaries, which is linked to symptoms such as hallucinations and Schneiderian delusions. Dysfunction in the cognitive processes involved in the generation of private thoughts may contribute to blurring of the ego boundaries through increased activation in functional networks including speech- and voice-selective cortical regions. In the present study, the neural underpinnings of silent verbal thought generation and speech perception were investigated using functional magnetic resonance imaging (fMRI).

Action and outcome activity state patterns in the anterior cingulate cortex.

Although there are numerous theories regarding anterior cingulate cortex (ACC) function, most suggest that it is involved in some form of action or outcome processing. The present study characterized the dominant patterns of ACC activity on a task in which actions and outcomes could vary independently. Patterns of activity were detected using a modified form of principal component analysis (PCA), termed constrained PCA in which a regression procedure was applied prior to PCA to eliminate the contribution of nontask-related activity.

The bivalency effect in task switching: event-related potentials.

During task switching, if we occasionally encounter stimuli that cue more than one task (i.e., bivalent stimuli), response slowing is observed on all univalent trials within that block, even when no features overlap with the bivalent stimuli.

A phase I dose-escalation study of clofarabine in combination with fractionated gemtuzumab ozogamicin in patients with refractory or relapsed acute myeloid leukemia.

Clofarabine and gemtuzumab ozogamicin (GO) are active agents against acute myeloid leukemia (AML), but have not previously been tested in combination. We conducted a phase I study to determine the maximum tolerated dose (MTD) and dose limiting toxicities (DLTs) of clofarabine when combined with GO in adult patients with relapsed or refractory AML. Twenty patients received clofarabine (10, 20 or 30 mg/m(2)) on days 1-5, with GO 3 mg/m(2)/day on days 1, 4 and 7.

Evidence affects hypothesis judgments more if accumulated gradually than if presented instantaneously.

In a hypothesis comparison task involving quantifiable evidence, we investigated whether judgments of relative probability were affected by gradual evidence accumulation and by making a series of revised ratings, rather than a single final one. Each trial of our task required participants to rate the probability that a focal hypothesis, rather than its alternative, was correct. We manipulated (1) the strength of evidence supporting the focal hypothesis, (2) the strength of evidence supporting its alternative, and (3) whether that evidence was presented in three sequential portions (gradually accumulated evidence condition) or, instead, was all presented instantaneously (control condition).

Decreased efficiency of task-positive and task-negative networks during working memory in schizophrenia.

Working memory (WM) is one of the most impaired cognitive processes in schizophrenia. Functional magnetic resonance imaging (fMRI) studies in this area have typically found a reduction in information processing efficiency but have focused on the dorsolateral prefrontal cortex. In the current study using the Sternberg Item Recognition Test, we consider networks of regions supporting WM and measure the activation of functionally connected neural networks over different WM load conditions.

The contribution of hypersalience to the "jumping to conclusions" bias associated with delusions in schizophrenia.

Background: Previous schizophrenia research involving the "beads task" has suggested an association between delusions and 2 reasoning biases: (1) "jumping to conclusions" (JTC), whereby early, resolute decisions are formed on the basis of little evidence and (2) over-adjustment of probability estimates following a single instance of disconfirmatory evidence. In the current study, we used a novel JTC-style paradigm to provide new information about a cognitive operation common to these 2 reasoning biases.

Methods: Using a task that required participants to rate the likelihood that a fisherman was catching a series of black or white fish from Lake A and not Lake B, and vice versa, we compared the responses of 4 groups (healthy, bipolar, nondelusional schizophrenia and delusional schizophrenia) when we manipulated 2 elements of the Bayesian formula: incoming data and prior odds.

Inhibition of return in the covert deployment of attention: evidence from human electrophysiology.

People are slow to react to objects that appear at recently attended locations. This delay-known as inhibition of return (IOR)-is believed to aid search of the visual environment by discouraging inspection of recently inspected objects. However, after two decades of research, there is no evidence that IOR reflects an inhibition in the covert deployment of attention.

Source monitoring biases and auditory hallucinations.

Introduction: Previous source monitoring studies on schizophrenia reported an association between external source misattribution and hallucinations, but this is often not replicated. This inconsistency may be attributable to a failure in accounting for guessing parameters when computing source monitoring biases.

Methods: Fifty-one patients and 20 healthy controls were required to recall the source of items originating from external (computer and experimenter) or internal (the subject) sources.

Increased hindsight bias in schizophrenia.

An underlying theme common to prominent theoretical accounts of cognition in schizophrenia is that information processing is disproportionately influenced by recently/currently encountered information relative to the influence of previously learned information. In this study, the authors tested this account by using the hindsight bias or knew-it-all-along (KIA) paradigm, which demonstrates that newly acquired knowledge influences recall of past events. In line with the account that patients with schizophrenia display a disproportionately strong influence of recently encountered information relative to the influence of previously learned information, patients displayed a KIA effect that was significantly greater than in controls.

The contribution of a cognitive bias against disconfirmatory evidence (BADE) to delusions in schizophrenia.

A neuropsychological paradigm is introduced that provides a measure of a bias against disconfirmatory evidence (BADE), and its correspondence with delusions in people with schizophrenia and schizoaffective disorder was investigated. Fifty-two patients diagnosed with schizophrenia or schizoaffective disorder (36 were acutely delusional) and 24 healthy control participants were presented with delusion-neutral pictures in each trial, and were asked to rate the plausibility of four written interpretations of the scenario depicted by that picture. Subsequently, new pictures that provided background information about the depicted scenario were successively presented, and participants were requested to adjust their ratings, taking into account this new information.

Visual search irregularities in schizophrenia depend on display size switching.

Introduction: In past research it has been demonstrated that when performing a visual search task with either one or multiple (4, 7 or 10) stimuli displayed, patients with schizophrenia demonstrate slow response times (RTs) in the display size of one, target-absent (one-absent) condition. The goals of the present investigation were to replicate this effect, and to gain an understanding of the underlying cognitive operations by comparing display-size switch to display-size repeat trials.

Methods: In two experiments, patients and controls performed a visual search task with either one or four stimuli displayed.

Confidence in errors as a possible basis for delusions in schizophrenia.

In two previous studies, it was observed that schizophrenic patients display increased confidence in memory errors compared with controls. The patient group displayed an increased proportion of errors in their knowledge system, quantified as the percentage of high-confident responses that are errors. The latter phenomenon has been termed knowledge corruption and is put forward as a risk factor for the emergence of delusions.

False memories in schizophrenia.

In prior studies, it was observed that patients with schizophrenia show abnormally high knowledge corruption (i.e., high-confident errors expressed as a percentage of all high-confident responses were increased for schizophrenic patients relative to controls).