Improving prefrontal cortex function in schizophrenia through focused training of cognitive control

Altered Cognitive Control Activations after Moderate-to-Severe Traumatic Brain Injury and Their Relationship to Injury Severity and Everyday-Life Function

This study investigated how the neuronal underpinnings of both adaptive and stable cognitive control processes are affected by traumatic brain injury (TBI). Functional magnetic resonance imaging (fMRI) was undertaken in 62 survivors of moderate-to-severe TBI (>1 year after injury) and 68 healthy controls during performance of a continuous performance test adapted for use in a mixed block- and event-related design. Survivors of TBI demonstrated increased reliance on adaptive task control processes within an a priori core region for cognitive control in the medial frontal cortex. TBI survivors also had increased activations related to time-on-task effects during stable task-set maintenance in right inferior parietal and prefrontal cortices. Increased brain activations in TBI survivors had a dose-dependent linear positive relationship to injury severity and were negatively correlated with self-reported cognitive control problems in everyday-life situations. Results were adjusted for age, education, and fMRI task performance. In conclusion, evidence was provided that the neural underpinnings of adaptive and stable control processes are differently affected by TBI. Moreover, it was demonstrated that increased brain activations typically observed in survivors of TBI might represent injury-specific compensatory adaptations also utilized in everyday-life situations.

On the relationship between anxiety and error monitoring: a meta-analysis and conceptual framework

Research involving event-related brain potentials has revealed that anxiety is associated with enhanced error monitoring, as reflected in increased amplitude of the error-related negativity (ERN). The nature of the relationship between anxiety and error monitoring is unclear, however. Through meta-analysis and a critical review of the literature, we argue that anxious apprehension/worry is the dimension of anxiety most closely associated with error monitoring. Although, overall, anxiety demonstrated a robust, “small-to-medium” relationship with enhanced ERN (r = −0.25), studies employing measures of anxious apprehension show a threefold greater effect size estimate (r = −0.35) than those utilizing other measures of anxiety (r = −0.09). Our conceptual framework helps explain this more specific relationship between anxiety and enhanced ERN and delineates the unique roles of worry, conflict processing, and modes of cognitive control. Collectively, our analysis suggests that enhanced ERN in anxiety results from the interplay of a decrease in processes supporting active goal maintenance and a compensatory increase in processes dedicated to transient reactivation of task goals on an as-needed basis when salient events (i.e., errors) occur.

Spared and impaired aspects of motivated cognitive control in schizophrenia

The ability to upregulate cognitive control in motivationally salient situations was examined in individuals with schizophrenia (patients) and healthy controls. Fifty-four patients and 39 healthy controls were recruited. A computerized monetary response conflict task required participants to identity a picture, over which was printed a matching (congruent), neutral, or incongruent word. This baseline condition was followed by an incentive condition, in which participants were given the opportunity to win money on reward-cued trials. These reward-cued trials were interleaved with nonreward cued trials. Reaction times (RT) were examined for both incentive context effects (difference in RT between baseline and nonreward cue trials in the incentive condition) and incentive cue effects (difference in RT between nonreward and reward cue trials in the incentive condition). Compared with baseline, controls showed a speeding of responses during both the nonreward (incentive context effect) and reward cued (incentive cue effect) trials during the incentive condition, but with a larger incentive context than incentive cue effect, suggesting a reliance on proactive control strategies. Although patients also showed a speeding of responses to both nonreward and reward cued trials, they showed a significantly smaller incentive context effect than controls, suggesting a reduction in the use of proactive control and a greater reliance on the use of "just-in-time," reactive control strategies. These results are discussed in light of the relationship between motivation and cognitive impairments in schizophrenia, and the potential role of impairments in prefrontally mediated active maintenance mechanisms.

Proactive and reactive cognitive control and dorsolateral prefrontal cortex dysfunction in first episode schizophrenia

Cognitive control deficits have been consistently documented in patients with schizophrenia. Recent work in cognitive neuroscience has hypothesized a distinction between two theoretically separable modes of cognitive control—reactive and proactive. However, it remains unclear the extent to which these processes are uniquely associated with dysfunctional neural recruitment in individuals with schizophrenia. This functional magnetic resonance imaging (fMRI) study utilized the color word Stroop task and AX Continuous Performance Task (AX-CPT) to tap reactive and proactive control processes, respectively, in a sample of 54 healthy controls and 43 patients with first episode schizophrenia. Healthy controls demonstrated robust dorsolateral prefrontal, anterior cingulate, and parietal cortex activity on both tasks. In contrast, patients with schizophrenia did not show any significant activation during proactive control, while showing activation similar to control subjects during reactive control. Critically, an interaction analysis showed that the degree to which prefrontal activity was reduced in patients versus controls depended on the type of control process engaged. Controls showed increased dorsolateral prefrontal cortex (DLPFC) and parietal activity in the proactive compared to the reactive control task, whereas patients with schizophrenia did not demonstrate this increase. Additionally, patients' DLPFC activity and performance during proactive control was associated with disorganization symptoms, while no reactive control measures showed this association. Proactive control processes and concomitant dysfunctional recruitment of DLPFC represent robust features of schizophrenia that are also directly associated with symptoms of disorganization.

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Cognitive control and fronto-parietal recruitment are disrupted in schizophrenia.

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Schizophrenia patients show hypoactivation during proactive not reactive control.

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DLPFC activity was associated with disorganization only in proactive control.

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Proactive control deficits may reflect a more robust marker of disease pathology.

Temporal dynamics of motivation-cognitive control interactions revealed by high-resolution pupillometry

Motivational manipulations, such as the presence of performance-contingent reward incentives, can have substantial influences on cognitive control. Previous evidence suggests that reward incentives may enhance cognitive performance specifically through increased preparatory, or proactive, control processes. The present study examined reward influences on cognitive control dynamics in the AX-Continuous Performance Task (AX-CPT), using high-resolution pupillometry. In the AX-CPT, contextual cues must be actively maintained over a delay in order to appropriately respond to ambiguous target probes. A key feature of the task is that it permits dissociable characterization of preparatory, proactive control processes (i.e., utilization of context) and reactive control processes (i.e., target-evoked interference resolution). Task performance profiles suggested that reward incentives enhanced proactive control (context utilization). Critically, pupil dilation was also increased on reward incentive trials during context maintenance periods, suggesting trial-specific shifts in proactive control, particularly when context cues indicated the need to overcome the dominant target response bias. Reward incentives had both transient (i.e., trial-by-trial) and sustained (i.e., block-based) effects on pupil dilation, which may reflect distinct underlying processes. The transient pupillary effects were present even when comparing against trials matched in task performance, suggesting a unique motivational influence of reward incentives. These results suggest that pupillometry may be a useful technique for investigating reward motivational signals and their dynamic influence on cognitive control.

Neural activity during emotion recognition after combined cognitive plus social cognitive training in schizophrenia

Cognitive remediation training has been shown to improve both cognitive and social cognitive deficits in people with schizophrenia, but the mechanisms that support this behavioral improvement are largely unknown. One hypothesis is that intensive behavioral training in cognition and/or social cognition restores the underlying neural mechanisms that support targeted skills. However, there is little research on the neural effects of cognitive remediation training. This study investigated whether a 50 h (10-week) remediation intervention which included both cognitive and social cognitive training would influence neural function in regions that support social cognition. Twenty-two stable, outpatient schizophrenia participants were randomized to a treatment condition consisting of auditory-based cognitive training (AT) [Brain Fitness Program/auditory module ~60 min/day] plus social cognition training (SCT) which was focused on emotion recognition [~5-15 min per day] or a placebo condition of non-specific computer games (CG) for an equal amount of time. Pre and post intervention assessments included an fMRI task of positive and negative facial emotion recognition, and standard behavioral assessments of cognition, emotion processing, and functional outcome. There were no significant intervention-related improvements in general cognition or functional outcome. fMRI results showed the predicted group-by-time interaction. Specifically, in comparison to CG, AT+SCT participants had a greater pre-to-post intervention increase in postcentral gyrus activity during emotion recognition of both positive and negative emotions. Furthermore, among all participants, the increase in postcentral gyrus activity predicted behavioral improvement on a standardized test of emotion processing (MSCEIT: Perceiving Emotions). Results indicate that combined cognition and social cognition training impacts neural mechanisms that support social cognition skills.

The variable nature of cognitive control: a dual mechanisms framework

A core component of cognitive control - the ability to regulate thoughts and actions in accordance with internally represented behavioral goals - might be its intrinsic variability. In this article, I describe the dual mechanisms of control (DMC) framework, which postulates that this variability might arise from qualitative distinctions in temporal dynamics between proactive and reactive modes of control. Proactive control reflects the sustained and anticipatory maintenance of goal-relevant information within lateral prefrontal cortex (PFC) to enable optimal cognitive performance, whereas reactive control reflects transient stimulus-driven goal reactivation that recruits lateral PFC (plus a wider brain network) based on interference demands or episodic associations. I summarize recent research that demonstrates how the DMC framework provides a coherent explanation of three sources of cognitive control variation - intra-individual, inter-individual and between-groups - in terms of proactive versus reactive control biases.

CNTRICS imaging biomarker selections: Executive control paradigms

In this article, we describe results of the 5th Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia meeting which identified candidate imaging biomarkers for used in measuring neural activity associated with specific component processes of cognition that are targeted for treatment development in schizophrenia and other disorders. This manuscript describes the process by which measures related to executive control were selected, along with the specific measures recommended for further development. Two paradigms were recommended for measurement of the cognitive and neural mechanisms underlying 2 core component processes of executive control, rule generation and selection, and dynamic adjustments of Control. The 2 paradigms are the AX continuous performance task task (letter and dot forms), implemented as an functional magnetic resonance imaging (fMRI) paradigm to engage neural systems supporting rule generation and selection, and the switching Stroop task, implemented as either fMRI or electroencephalography that may be used as a measure of both rule generation and selection as well as dynamic adjustment in control. A detailed description of each paradigm, together with a review of the relevant literature related to their cognitive and neural validity and measurement properties is provided. These 2 paradigms are recommended for further development, including further validation at the cognitive and neural level and optimization with respect to subject tolerability, psychometric, and neurometric features.

Cognition in schizophrenia: core psychological and neural mechanisms

The challenge in understanding cognitive impairment in schizophrenia is that people with this illness have deficits in an array of domains. Here, we briefly review evidence regarding the pattern of deficits within three domains: context processing, working memory and episodic memory. We suggest that there may be a common mechanism driving deficits in these domains - an impairment in the ability to actively represent goal information in working memory to guide behavior, a function we refer to as proactive control. We suggest that such deficits in proactive control reflect impairments in dorsolateral prefrontal cortex, its interactions with other brain regions, such as parietal cortex, thalamus and striatum, and the influence of neurotransmitter systems, such as dopamine, GABA and glutamate.

Model-based dynamical analysis of functional disconnection in schizophrenia

Schizophrenia is shown to be associated with impaired interactions in functional macro-networks of the brain. The focus of our study was if there is an impairment of cognitive control of learning during schizophrenia. To investigate this question, we collected fMRI data from a group of stable schizophrenia patients and controls performing an object-location associative learning task in which the learning performance of the patient group was significantly worse. We applied Dynamic Causal Modeling to analyze the fMRI data. A set of causal models of BOLD signal generation was defined to evaluate connections between five regions material to the task (Primary Visual Cortex, Superior Parietal and Inferior Temporal Cortex, Hippocampus and Dorsal Prefrontal Cortex). Bayesian model selection was used to investigate hypotheses on differences in model architecture across groups, and indicated fundamental differences in model architecture in patients compared to controls. Models lacking connections related to cognitive control were more probable in the patient group. Hypotheses on differences in effective connectivity between groups were tested by comparing estimates of neural coupling parameters in winning model structures. This analysis indicated reduced fronto-hippocampal and hippocampo-inferior temporal coupling in patients, and reduced excitatory modulation of these pathways by learning. These findings may account for the documented reductions in learning performance of schizophrenia patients.

Perceptual training strongly improves visual motion perception in schizophrenia

Schizophrenia patients exhibit perceptual and cognitive deficits, including in visual motion processing. Given that cognitive systems depend upon perceptual inputs, improving patients' perceptual abilities may be an effective means of cognitive intervention. In healthy people, motion perception can be enhanced through perceptual learning, but it is unknown whether this perceptual plasticity remains in schizophrenia patients. The present study examined the degree to which patients' performance on visual motion discrimination can be improved, using a perceptual learning procedure. While both schizophrenia patients and healthy controls showed decreased direction discrimination thresholds (improved performance) with training, the magnitude of the improvement was greater in patients (47% improvement) than in controls (21% improvement). Both groups also improved moderately but non-significantly on an untrained task-speed discrimination. The large perceptual training effect in patients on the trained task suggests that perceptual plasticity is robust in schizophrenia and can be applied to develop bottom-up behavioral interventions.

Functional Brain Network Characterization and Adaptivity during Task Practice in Healthy Volunteers and People with Schizophrenia

Cognitive remediation involves task practice and may improve deficits in people suffering from schizophrenia, but little is known about underlying neurophysiological mechanisms. In people with schizophrenia and controls, we used magnetoencephalography (MEG) to examine accuracy and practice-related changes in parameters indexing neural network structure and activity, to determine whether these might be useful assays of the efficacy of cognitive remediation. Two MEG recordings were acquired during performance of a tone discrimination task used to improve the acuity of auditory processing, before and after ∼2.5 h of task practice. Accuracy before practice was negatively correlated with beta-band cost efficiency, a graph theoretical measure of network organization. Synthetic aperture magnetometry was used to localize brain oscillations with high spatial accuracy; results demonstrated sound and sensorimotor modulations of the beta band in temporo-parietal regions and the sensorimotor cortex respectively. High-gamma activity also correlated with sensorimotor processing during the task, with activation of auditory regions following sound stimulation, and activation of the left sensorimotor cortex preceding the button press. High-gamma power in the left frontal cortex was also found to correlate with accuracy. Following practice, sound-induced broad-band power in the left angular gyri increased. Accuracy improved and was found to correlate with increased mutual information (MI) between sensors in temporal-parietal regions in the beta band but not global cost efficiency. Based on these results, we conclude that hours of task practice can induce meso-scale changes such as increased power in relevant brain regions as well as changes in MI that correlate with improved accuracy.

Genetics of eating behavior: established and emerging concepts

Understanding why we eat and the motivational factors driving food choices is important for addressing the epidemics of obesity, diabetes, and cardiovascular disease. Eating behavior is a complex interplay of physiological, psychological, social, and genetic factors that influence meal timing, quantity of food intake, and food preference. Reviewed here is the current and emerging knowledge of the genetic influences on eating behavior and how these relate to obesity; particular emphasis is placed on the genetics of taste, meal size, and selection, and the emerging use of functional magnetic resonance imaging to study neural reactions in response to food stimuli in normal, overweight, and obese individuals.

Goal representations and motivational drive in schizophrenia: the role of prefrontal-striatal interactions

The past several years have seen a resurgence of interest in understanding the psychological and neural bases of what are often referred to as "negative symptoms" in schizophrenia. These aspects of schizophrenia include constructs such as asociality, avolition (a reduction in the motivation to initiate or persist in goal-directed behavior), and anhedonia (a reduction in the ability to experience pleasure). We believe that these dimensions of impairment in individuals with schizophrenia reflect difficulties using internal representations of emotional experiences, previous rewards, and motivational goals to drive current and future behavior in a way that would allow them to obtain desired outcomes, a deficit that has major clinical significance in terms of functional capacity. In this article, we review the major components of the systems that link experienced and anticipated rewards with motivated behavior that could potentially be impaired in schizophrenia. We conclude that the existing evidence suggests relatively intact hedonics in schizophrenia, but impairments in some aspects of reinforcement learning, reward prediction, and prediction error processing, consistent with an impairment in "wanting." As of yet, there is only indirect evidence of impairment in anterior cingulate and orbital frontal function that may support value and effort computations. However, there are intriguing hints that individuals with schizophrenia may not be able to use reward information to modulate cognitive control and dorsolateral prefrontal cortex function, suggesting a potentially important role for cortical-striatal interactions in mediating impairment in motivated and goal-directed behavior in schizophrenia.