Multi-level decoding of task sets in neurophysiological data during cognitive flexibility.

Cognitive flexibility is essential to achieve higher level goals. Cognitive theories assume that the activation/deactivation of goals and task rules is central to understand cognitive flexibility. However, how this activation/deactivation dynamic is implemented on a neurophysiological level is unclear. Using EEG-based multivariate pattern analysis (MVPA) methods, we show that activation of relevant information occurs parallel in time at multiple levels in the neurophysiological signal containing aspects of stimulus-related processing, response selection, and motor response execution, and relates to different brain regions. The intensity with which task sets are activated and processed dynamically decreases and increases. The temporal stability of these activations could, however, hardly explain behavioral performance. Instead, task set deactivation processes associated with left orbitofrontal regions and inferior parietal regions selectively acting on motor response task sets are relevant. The study shows how propositions from cognitive theories stressing the importance task set activation/deactivation during cognitive flexibility are implemented on a neurophysiological level.

Task Switching and the Role of Motor Reprogramming in Parietal Structures.

Human behaviour amazes with extraordinary flexibility and the underlying neural mechanisms have often been studied using task switching. Despite extensive research, the relative importance of "cognitive" and "motor" aspects during switching is unclear. In the current study we examine this question combining EEG analysis techniques and source localization to examine whether the selection of the response, or processes during the execution of the response, contribute most to switching effects. A clear dissociation was observed in the signal decomposition, since codes relating to motor aspects play a significant role in task switching and the scope of the switching costs. This was not the case for signals that denote reaction selection or decision processes that respond to selection or basic stimulus processing codes. On a functional neuroanatomical level, these modulations in motor processes showed a clear temporal sequence in that motor codes are processed primarily in superior parietal regions (Brodman area 7) and only then in premotor regions (Brodman area 6). The observed modulations may reflect motor reprogramming processes. The study shows how EEG signal analysis in combination with brain mapping methods can inform debates on theories of human cognitive flexibility.

Comprehensive Behavioral Intervention for Tics reduces perception-action binding during inhibitory control in Gilles de la Tourette syndrome.

Gilles de la Tourette Syndrome (GTS) is a developmental disorder. Empirical studies and an emerging cognitive framework on GTS suggest that GTS is a disorder of abnormally strong 'perception-action binding'. Theoretical considerations imply that the effectiveness of long-established behavioral interventions might be related to a normalization of increased binding in GTS. This has not been tested yet. We examined the effect of a standardized Comprehensive Behavior Intervention for Tics (CBIT) in N = 21 adolescent GTS patients and N = 21 healthy controls on perception-action binding in an inhibitory control paradigm. Prior to CBIT, GTS patients showed compromised performance compared to controls, specifically when inhibitory control was triggered by uni-modal visual compared to bi-modal stimuli. After CBIT intervention, GTS patient's performance was at the same level as healthy controls. This is supported by a Bayesian data analysis. CBIT specifically affected inhibitory control in a condition where reconfigurations of perception-action bindings are necessary to perform inhibitory control. A power of 95% was evident for these effects. CBIT reduces increased 'binding' between perception and action in GTS and thereby increases the ability to perform response inhibition. The results are the first to provide insights as to why CBIT is effective by relating elements of this intervention to overarching cognitive theoretical frameworks on perception-action bindings.

Numbers in action during cognitive flexibility - A neurophysiological approach on numerical operations underlying task switching.

Cognitive flexibility is a major competence to cope with daily life requirements and is usually investigated using task switching paradigms. Often, numerical stimuli are used to examine switching between task rules. Based upon functional neuroanatomical considerations we hypothesize that the ability to efficiently perform task switching varies depending on the cognitive operations performed with these numerical stimuli during task switching (magnitude vs parity judgments). We use a system-neurophysiological approach combining EEG and event-related potential (ERP) recordings with temporal data decomposition and source localization methods. We show that task switching processes are more demanding during parity judgments, compared to magnitude judgments. This, however, was only the case when task switching processes were triggered by external sensory stimuli, but not when memory-based processes had to be used during task switching. After accounting for intra-individual variability in the EEG data, the neurophysiological data showed that these effects were due to very specific subprocesses reflecting processes to update task sets and stimulus-response mappings during task switching. Source reconstructions show that left inferior and superior parietal areas (BA40 and BA7) were associated with these processes. The data show how different numerical operations differentially affect cognitive flexibility processes. Especially parity judgments exacerbate processes to update and reconfigure task sets during task switching in parietal areas. These findings are a valuable contribution to further reflections on the theories developed to date in task switching.

Perceived distress, personality characteristics, coping strategies and psychosocial impairments in a national German multicenter cohort of patients with Crohn's disease and ulcerative colitis.

BACKGROUND AND AIMS: This study examined differences in personality, psychological distress, and stress coping in inflammatory bowel disease (IBD) depending on type of disease and disease activity. We compared patients suffering from Crohn's disease (CD) and ulcerative colitis (UC) with controls. While the literature is replete with distinctive features of the pathogenesis of IBD, the specific differences in psychological impairments are not well studied. METHODS: In this German national multicenter study, participants were recruited from 32 centers. Two hundred ninety-seven questionnaires were included, delivering vast information on disease status and psychological well-being based on validated instruments with a total of 285 variables. RESULTS: CD patients were more affected by psychological impairments than patients suffering from UC or controls. Importantly, patients with active CD scored higher in neuroticism (p < 0.01), psychological distress (p < 0.001) and maladaptive stress coping (escape, p = 0.03; rumination, p < 0.03), but less need for social support (p = 0.001) than controls. In contrast, patients suffering from active UC showed psychological distress (p < 0.04) and maladaptive coping (avoidance, p < 0.03; escape, p = 0.01). Patients in remission seemed to be less affected. In particular, patients with UC in remission were not inflicted by psychological impairments. The group of CD patients in remission however, showed insecurity (p < 0.01) and paranoid ideation (p = 0.04). CONCLUSIONS: We identified specific aspects of psychological impairment in IBD depending on disease and disease activity. Our results underscore the need for psychological support and treatment particularly in active CD.

Altered perception-action binding modulates inhibitory control in Gilles de la Tourette syndrome.

BACKGROUND: Gilles de la Tourette Syndrome (GTS) is a multifaceted neuropsychiatric developmental disorder with onset in childhood or adolescence and frequent remissions in early adulthood. A rather new emerging concept of this syndrome suggests that it is a disorder of purposeful actions, in which sensory processes and their relation to motor responses (actions) play a particularly important role. Thus, this syndrome might be conceived as a condition of altered 'perception-action binding'. In the current study, we test this novel concept in the context of inhibitory control. METHODS: We examined N = 35 adolescent GTS patients and N = 39 healthy controls in a Go/Nogo-task manipulating the complexity of sensory information triggering identical actions; i.e. to inhibit a motor response. This was combined with event-related potential recordings, EEG data decomposition and source localization. RESULTS: GTS patients showed worse performance compared to controls and larger performance differences when inhibitory control had to be exerted using unimodal visual compared to bimodal auditory-visual stimuli. This suggests increased binding between bimodal stimuli and responses leading to increased costs of switching between responses instructed by bimodal and those instructed by unimodal stimuli. The neurophysiological data showed that this was related to mechanisms mediating between stimulus evaluation and response selection; i.e. perception-action binding processes in the right inferior parietal cortex (BA40). CONCLUSIONS: Stimulus-action inhibition binding is stronger in GTS patients than healthy controls and affects inhibitory control corroborating the concept suggesting that GTS might be a condition of altered perception-action integration (binding); i.e. a disorder of purposeful actions.

On the role of the prefrontal cortex in fatigue effects on cognitive flexibility - a system neurophysiological approach.

Demanding tasks like cognitive flexibility show time-related deterioration of performance (i.e. fatigability effects). Fatigability has been associated with structural and functional properties of the prefrontal cortex. However, the electrophysiological underpinnings of these processes are not well understood. We examined n = 34 healthy participants with a task switching paradigm in which switches were either signaled by cues or needed to be maintained by working memory processes. We analyzed event-related potentials (ERPs) and performed residue iteration decomposition (RIDE) to account for effects of fatigue on intra-individual variability of neurophysiological data. This was combined with source localization methods. We show that task switching is affected by time on task (TOT) effects mostly when working memory processes are needed. On a neurophysiological level, this effect could not be observed in standard ERPs, but only after accounting for intra-individual variability using RIDE. The RIDE data suggests that during task switching, fatigability specifically affects response recoding processes that are associated with functions of the middle frontal gyrus (MFG; BA10). The results underline propositions of the 'opportunity cost model', which states that fatigability effects of executive functions depend on the degree to which tasks engage similar prefrontal regions - in this case working memory and task switching mechanisms.

Specific neurophysiological mechanisms underlie cognitive inflexibility in inflammatory bowel disease.

Inflammatory bowel disease (IBD) is highly prevalent. While the pathophysiological mechanisms of IBD are increasingly understood, there is a lack of knowledge concerning cognitive dysfunctions in IBD. This is all the more the case concerning the underlying neurophysiological mechanisms. In the current study we focus on possible dysfunctions of cognitive flexibility (task switching) processes in IBD patients using a system neurophysiological approach combining event-related potential (ERP) recordings with source localization analyses. We show that there are task switching deficits (i.e. increased switch costs) in IBD patients. The neurophysiological data show that even though the pathophysiology of IBD is diverse and wide-spread, only specific cognitive subprocesses are altered: There was a selective dysfunction at the response selection level (N2 ERP) associated with functional alterations in the anterior cingulate cortex and the right inferior frontal gyrus. Attentional selection processes (N1 ERP), perceptual categorization processes (P1 ERP), or mechanisms related to the flexible implementation of task sets and related working memory processes (P3 ERP) do not contribute to cognitive inflexibility in IBD patients and were unchanged. It seems that pathophysiological processes in IBD strongly compromise cognitive-neurophysiological subprocesses related to fronto-striatal networks. These circuits may become overstrained in IBD when cognitive flexibility is required.

A systems neurophysiology approach to voluntary event coding.

Mechanisms responsible for the integration of perceptual events and appropriate actions (sensorimotor processes) have been subject to intense research. Different theoretical frameworks have been put forward with the "Theory of Event Coding (TEC)" being one of the most influential. In the current study, we focus on the concept of 'event files' within TEC and examine what sub-processes being dissociable by means of cognitive-neurophysiological methods are involved in voluntary event coding. This was combined with EEG source localization. We also introduce reward manipulations to delineate the neurophysiological sub-processes most relevant for performance variations during event coding. The results show that processes involved in voluntary event coding included predominantly stimulus categorization, feature unbinding and response selection, which were reflected by distinct neurophysiological processes (the P1, N2 and P3 ERPs). On a system's neurophysiological level, voluntary event-file coding is thus related to widely distributed parietal-medial frontal networks. Attentional selection processes (N1 ERP) turned out to be less important. Reward modulated stimulus categorization in parietal regions likely reflecting aspects of perceptual decision making but not in other processes. The perceptual categorization stage appears central for voluntary event-file coding.