Rapid modulation of sensory processing induced by stimulus conflict

Humans are constantly confronted with environmental stimuli that conflict with task goals and can interfere with successful behavior. Prevailing theories propose the existence of cognitive control mechanisms that can suppress the processing of conflicting input and enhance that of the relevant input. However, the temporal cascade of brain processes invoked in response to conflicting stimuli remains poorly understood. By examining evoked electrical brain responses in a novel, hemifield-specific, visual-flanker task, we demonstrate that task-irrelevant conflicting stimulus input is quickly detected in higher level executive regions while simultaneously inducing rapid, recurrent modulation of sensory processing in the visual cortex. Importantly, however, both of these effects are larger for individuals with greater incongruency-related RT slowing. The combination of neural activation patterns and behavioral interference effects suggest that this initial sensory modulation induced by conflicting stimulus inputs reflects performance-degrading attentional distraction because of their incompatibility rather than any rapid task-enhancing cognitive control mechanisms. The present findings thus provide neural evidence for a model in which attentional distraction is the key initial trigger for the temporal cascade of processes by which the human brain responds to conflicting stimulus input in the environment

Cognitive Control: beyond priming, in aging and across domains

This research project aimed to address many issues related to cognitive control, such as its relationship with repetition priming, its modification in older adults and whether it can be considered a general supra-modality mechanism or rather a set of domain specific ones. The cognitive control mechanism is a top-down modulation involved in conflict resolution processes that is supposed to facilitate the discrimination between signal and noise, or targets and distractors. In the present project cognitive control was investigated through the analysis of congruency (Stroop) and sequential congruency effects with a modification of verbal and spatial Stroop paradigms that exclude the priming confound in two consecutive trials. Results revealed that both congruency and sequential congruency effects are strongly modulated by repetition priming in a verbal Stroop task, whereas a spatial Stroop is only marginally influenced. The comparison of conflict measures and conflict-related ERPs showed that the mechanisms involved in the verbal and spatial tasks are only partially comparable. Both tasks showed congruency effects consistent with previous findings, while sequential congruency effects are apparent in the spatial Stroop performance but are reduced in the verbal task with respect to what is reported in previous studies. In the verbal task we pointed out that cognitive control is likely to detect not the actual conflict level but rather the conflict level change in the present trial with respect to the preceding one and consequently adjust attentional resources, exerting a direct influence on performance. On the other hand, some previous studies suggested that whenever a task presents a high conflict level a proactive inhibition state is activated in order to prevent automatic responses. The results from the spatial Stroop task suggested that the attentional regulatory mechanism for spatial conflict is likely to modulate this proactive inhibition default state on the basis of the preceding trial congruency. In this domain the modulations due to preceding trial congruency and the one due to current trial congruency do not interact in determining ERP components, and this probably generates the strong conflict sequential effects seen in the behavioural performance. Many cognitive aging theories assume a progressive decline in frontal brain areas and many authors reported an age-related deficit in conflict resolution abilities in varied conflict-related tasks, which goes beyond the general slowing showed by older adults. We investigated the effects of normal aging on cognitive control in the verbal and spatial domains, highlighting the fact that the age-related general slowing can account for most of the difference found between younger and older adults, and that the verbal congruency effect is the only measure that suffers from a specific decline. Moreover intelligence and cognitive reserve (CR) seemed to partially account for the inter-individual variability in conflict resolution performance, especially in cognitive aging. Finally, the hypothesis of a general, supra-domain cognitive control mechanism is discussed, since evidence reported in the present project rather supports the existence of more domain specific sub-mechanisms of cognitive control

Behavioral and electrophysiological correlates of cognitive control in ex-obese adults

Impaired cognitive control functions have been documented in obesity. It remains unclear whether these functions normalize after weight reduction. We compared ex-obese individuals, who successfully underwent substantial weight loss after bariatric surgery, to normal weight participants on measures of resistance to interference, cognitive flexibility and response inhibition, obtained from the completion of two Stroop tasks, a Switching task and a Go/NoGo task, respectively. To elucidate the underlying brain mechanisms, event-related potentials (ERPs) in the latter two tasks were examined. As compared to controls, patients were more susceptible to the predominant but task-irrelevant stimulus dimension (i.e., they showed a larger verbal Stroop effect), and were slower in responding on trials requiring a task-set change rather than a task-set repetition (i.e., they showed a larger switch cost). The ERP correlates revealed altered anticipatory control mechanisms (switch positivity) and an exaggerated conflict monitoring response (N2). The results suggest that cognitive control is critical even in ex-obese individuals and should be monitored to promote weight loss maintenance

Dissociable and Dynamic Components of Cognitive Control: A Developmental Electrophysiological Investigation

One standard task used to investigate the development of cognitive control is the Dimensional Change Card Sort (DCCS). Performance and patterns of brain activity associated with the DCCS show continued age-related advances into early adolescence. According to many theoretical accounts, the DCCS places demands on a single underlying executive control process. Three experiments examined the possibility that the DCCS places demands on multiple control processes that follow distinct developmental trajectories. In Experiment 1, rule switching and conflict processing made orthogonal contributions to DCCS performance. Rule switching was associated with a cue-locked late frontal negativity (LFN) event-related potential (ERP) and conflict processing was associated with stimulus-locked frontocentral N2. Moreover, rule switching and conflict processing followed distinct developmental trajectories. In Experiment 2, distributed cortical source models of the cue-locked LFN were associated with age-related differences in distributed network of regions associated with cognitive control. Source models of the stimulus-locked N2 were associated with conflict-related modulations in the anterior cingulate cortex (ACC) that varied as a function of age. In Experiment 3, dynamic modulations in conflict processing were associated with pronounced age-related behavioural and electrophysiological adaptations to prior conflict. Taken together the findings of the current set of studies suggest that multiple control processes underpin age-related advances in DCCS performance

Predictability effects in auditory scene analysis: a review

Many sound sources emit signals in a predictable manner. The idea that predictability can be exploited to support the segregation of one source's signal emissions from the overlapping signals of other sources has been expressed for a long time. Yet experimental evidence for a strong role of predictability within auditory scene analysis (ASA) has been scarce. Recently, there has been an upsurge in experimental and theoretical work on this topic resulting from fundamental changes in our perspective on how the brain extracts predictability from series of sensory events. Based on effortless predictive processing in the auditory system, it becomes more plausible that predictability would be available as a cue for sound source decomposition. In the present contribution, empirical evidence for such a role of predictability in ASA will be reviewed. It will be shown that predictability affects ASA both when it is present in the sound source of interest (perceptual foreground) and when it is present in other sound sources that the listener wishes to ignore (perceptual background). First evidence pointing toward age-related impairments in the latter capacity will be addressed. Moreover, it will be illustrated how effects of predictability can be shown by means of objective listening tests as well as by subjective report procedures, with the latter approach typically exploiting the multi-stable nature of auditory perception. Critical aspects of study design will be delineated to ensure that predictability effects can be unambiguously interpreted. Possible mechanisms for a functional role of predictability within ASA will be discussed, and an analogy with the old-plus-new heuristic for grouping simultaneous acoustic signals will be suggested

The development of stimulus and response interference control in mid-childhood

Interference control, the ability to overcome distraction from irrelevant information, undergoes considerable improvement during childhood yet the mechanisms driving these changes remain unclear. The present study investigated the relative influence of interference at the level of the stimulus or the response. 7-, 10- and 20-year-olds completed a flanker paradigm in which stimulus and response interference were experimentally manipulated. The influence of stimulus interference decreased from 7- to 10-years whereas there was no difference in response interference across age groups. The findings demonstrate that a range of processes contribute to the development of interference control, and may influence performance to a greater or lesser extent depending on task requirements and the age of the child

Neuronal adaptation, novelty detection and regularity encoding in audition

The ability to detect unexpected stimuli in the acoustic environment and determine their behavioral relevance to plan an appropriate reaction is critical for survival. This perspective article brings together several viewpoints and discusses current advances in understanding the mechanisms the auditory system implements to extract relevant information from incoming inputs and to identify unexpected events. This extraordinary sensitivity relies on the capacity to codify acoustic regularities, and is based on encoding properties that are present as early as the auditory midbrain. We review state-of-the-art studies on the processing of stimulus changes using non-invasive methods to record the summed electrical potentials in humans, and those that examine single-neuron responses in animal models. Human data will be based on mismatch negativity (MMN) and enhanced middle latency responses (MLR). Animal data will be based on the activity of single neurons at the cortical and subcortical levels, relating selective responses to novel stimuli to the MMN and to stimulus-specific neural adaptation (SSA). Theoretical models of the neural mechanisms that could create SSA and novelty responses will also be discussed

Different methods to define utility functions yield different results and engage different neural processes

Although the concept of utility is fundamental to many economic theories, up to now a generally accepted method determining a subject’s utility function is not available. We investigated two methods that are used in economic sciences for describing utility functions by using response-locked event-related potentials in order to assess their neural underpinnings. For defining the certainty equivalent (CE), we used a lottery game with probabilities of 0.5, for identifying the subjects’ utility functions directly a standard bisection task was applied. Although the lottery tasks’ payoffs were only hypothetical, a pronounced negativity was observed resembling the error related negativity (ERN) previously described in action monitoring research, but this occurred only for choices far away from the indifference point between money and lottery. By contrast, the bisection task failed to evoke an ERN irrespective of the responses’ correctness. Based on these findings we are reasoning that only decisions made in the lottery task achieved a level of subjective relevance that activates cognitive-emotional monitoring. In terms of economic sciences, our findings support the view that the bisection method is unaffected by any kind of probability valuation or other parameters related to risk and in combination with the lottery task can, therefore, be used to differentiate between payoff and probability valuation.Utility function; neuroeconomics; error-related negativity; executive functions; cognitive electrophysiology; lottery,bisection

What absent switch costs and mixing costs during bilingual language comprehension can tell us about language control.

Epub 2019 Mar 28.In the current study, we set out to investigate language control, which is the process that minimizes cross-language interference, during bilingual language comprehension. According to current theories of bilingual language comprehension, language-switch costs, which are a marker for reactive language control, should be observed. However, a closer look at the literature shows that this is not always the case. Furthermore, little to no evidence for language-mixing costs, which are a marker for proactive language control, has been observed in the bilingual language comprehension literature. This is in line with current theories of bilingual language comprehension, as they do not explicitly account for proactive language control. In the current study, we further investigated these two markers of language control and found no evidence for comprehension-based language-switch costs in six experiments, even though other types of switch costs were observed with the exact same setup (i.e., task-switch costs, stimulus modality-switch costs, and production-based language-switch costs). Furthermore, only one out of three experiments showed comprehension-based language-mixing costs, providing the first tentative evidence for proactive language control during bilingual language comprehension. The implications of the absence and occurrence of these costs are discussed in terms of processing speed and parallel language activation. (PsycINFO Database Record (c) 2019 APA, all rights reserved)This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 706128. This research was also supported by grants ANR-11-LABX-0036 (BLRI), ANR-16-CONV-0002 (ILCB), and ANR-11-IDEX-0001-02 from the French National Research Council (ANR)