1,141 research outputs found

    Early error detection predicted by reduced pre-response control process: an ERP topographic mapping study

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    Advanced ERP topographic mapping techniques were used to study error monitoring functions in human adult participants, and test whether proactive attentional effects during the pre-response time period could later influence early error detection mechanisms (as measured by the ERN component) or not. Participants performed a speeded go/nogo task, and made a substantial number of false alarms that did not differ from correct hits as a function of behavioral speed or actual motor response. While errors clearly elicited an ERN component generated within the dACC following the onset of these incorrect responses, I also found that correct hits were associated with a different sequence of topographic events during the pre-response baseline time-period, relative to errors. A main topographic transition from occipital to posterior parietal regions (including primarily the precuneus) was evidenced for correct hits similar to 170-150 ms before the response, whereas this topographic change was markedly reduced for errors. The same topographic transition was found for correct hits that were eventually performed slower than either errors or fast (correct) hits, confirming the involvement of this distinctive posterior parietal activity in top-down attentional control rather than motor preparation. Control analyses further ensured that this pre-response topographic effect was not related to differences in stimulus processing. Furthermore, I found a reliable association between the magnitude of the ERN following errors and the duration of this differential precuneus activity during the pre-response baseline, suggesting a functional link between an anticipatory attentional control component subserved by the precuneus and early error detection mechanisms within the dACC. These results suggest reciprocal links between proactive attention control and decision making processes during error monitoring

    Overlapping neural systems represent cognitive effort and reward anticipation

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    Anticipating a potential benefit and how difficult it will be to obtain it are valuable skills in a constantly changing environment. In the human brain, the anticipation of reward is encoded by the Anterior Cingulate Cortex (ACC) and Striatum. Naturally, potential rewards have an incentive quality, resulting in a motivational effect improving performance. Recently it has been proposed that an upcoming task requiring effort induces a similar anticipation mechanism as reward, relying on the same cortico-limbic network. However, this overlapping anticipatory activity for reward and effort has only been investigated in a perceptual task. Whether this generalizes to high-level cognitive tasks remains to be investigated. To this end, an fMRI experiment was designed to investigate anticipation of reward and effort in cognitive tasks. A mental arithmetic task was implemented, manipulating effort (difficulty), reward, and delay in reward delivery to control for temporal confounds. The goal was to test for the motivational effect induced by the expectation of bigger reward and higher effort. The results showed that the activation elicited by an upcoming difficult task overlapped with higher reward prospect in the ACC and in the striatum, thus highlighting a pivotal role of this circuit in sustaining motivated behavior

    Within-trial effects of stimulus-reward associations

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    While a globally energizing influence of motivation has long been appreciated in psychological research, a series of more recent studies has described motivational influences on specific cognitive operations ranging from visual attention, to cognitive control, to memory formation. In the majority of these studies, a cue predicts the potential to win money in a subsequent task, thus allowing for modulations of proactive task preparation. Here we describe some recent studies using tasks that communicate reward availability without such cues by directly associating specific task features with reward. Despite abolishing the cue-based preparation phase, these studies show similar performance benefits. Given the clear difference in temporal structure, a central question is how these behavioral effects are brought about, and in particular whether control processes can rapidly be enhanced reactively. We present some evidence in favor of this notion. Although additional influences, for example sensory prioritization of reward-related features, could contribute to the reward-related performance benefits, those benefits seem to strongly rely on enhancements of control processes during task execution. Still, for a better mechanistic understanding of reward benefits in these two principal paradigms (cues vs. no cues), more work is needed that directly compares the underlying processes. We anticipate that reward benefits can be brought about in a very flexible fashion depending on the exact nature of the reward manipulation and task, and that a better understanding of these processes will not only be relevant for basic motivation research, but that it can also be valuable for educational and psychopathological contexts

    ERPs and their brain sources in perceptual and conceptual prospective memory tasks: commonalities and differences between the two tasks

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    The present study examined whether Event-Related Potential (ERP) components and their neural generators are common to perceptual and conceptual prospective memory (PM) tasks or specific to the form of PM cue involved. We used Independent Component Analysis (ICA) to study the contributions of brain source activities to scalp ERPs across the different phases of two event-based PM-tasks: (1) holding intentions during a delay (monitoring) (2) detecting the correct context to perform the delayed intention (cue detection) and (3) carrying out the action (realisation of delayed intentions). Results showed that monitoring for both perceptual and conceptual PM-tasks was characterised by an enhanced early occipital negativity (N200). In addition the conceptual PM-task showed a long-lasting effect of monitoring significant around 700 ms. Perceptual PM-task cues elicited an N300 enhancement associated with cue detection, whereas a midline N400-like response was evoked by conceptual PM-task cues. The Prospective Positivity associated with realisation of delayed intentions was observed in both conceptual and perceptual tasks. A common frontal-midline brain source contributed to the Prospective Positivity in both tasks and a strong contribution from parieto-frontal brain sources was observed only for the perceptually cued PM-task. These findings support the idea that: (1) The enhanced N200 can be understood as a neural correlate of a ‘retrieval mode’ for perceptual and conceptual PM-tasks, and additional strategic monitoring is implemented according the nature of the PM task; (2) ERPs associated with cue detection are specific to the nature of the PM cues; (3) Prospective Positivity reflects a general PM process, but the specific brain sources contributing to it depend upon the nature of the PM task

    Executive control in the anterior cingulate cortex

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    Converging evidence supports the hypothesis that the prefrontal cortex is critical for executive control. One prefrontal subregion, the anterior cingulate cortex has previously been shown to be active in situations involving high conflict, presentation of salient, distracting stimuli, and error processing, i.e. situations that occur when learning new response contingencies, when previously learned response strategies fail, or when a shift in attention or responding is required. These situations all involve goal-oriented monitoring of performance in order to effectively adjust cognitive processes. Several neuropsychological disorders, for instance schizophrenia, attention deficit hyperactivity disorder, and obsessive compulsive disorder, are correlated with morphological changes in the anterior cingulate cortex. Individuals with these disorders show impairments on tasks that require goal-oriented monitoring. The current studies used multiple behavioral paradigms to assess the effects of anterior cingulate cortex excitotoxic lesions in rats on executive control. Animals with anterior cingulate cortex lesions showed greater decline in cognitive capacity as tasks progressed, longer response latencies to conflicting stimuli, impaired reversal learning, impaired error processing, and impaired performance in the presence of previously relevant distractors. These results are consistent with the hypothesis that the anterior cingulate cortex is involved in executive control, specifically monitoring impairments in performance that signal the need to adjust cognitive control

    Investigating Cognitive Control And Task Switching Using The Macaque Oculomotor System

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    Cognitive control is crucial to voluntary behaviour. It is required to select appropriate goals and guide behaviour to achieve the desired outcomes. Cognitive control is particularly important for the ability to adapt behaviour to changes in the external environment and internal goals, and to quickly switch between different tasks. Successful task switching involves a network of brain areas to select, maintain, implement, and execute the appropriate task. Uncovering the neural mechanisms of this goal-directed behaviour using lesions, functional neuroimaging, and neurophysiology studies is central to cognitive neuroscience. The oculomotor system provides a valuable framework for understanding the neural mechanisms of cognitive control, as it is anatomically and functionally well characterized. In this project, pro-saccade and anti-saccade tasks were used to investigate the contributions of oculomotor and cognitive brain areas to different stages of task processing. In Chapter 2, non-human primates performed cued and randomly interleaved pro-saccade and anti-saccade tasks while neural activity was recorded in the superior colliculus (SC). In Chapter 3, non-human primates performed cued and randomly interleaved pro-saccade and anti-saccade tasks while local field potential activity was recorded in the SC and reversible cryogenic deactivation was applied to the dorsolateral prefrontal cortex (DLPFC). In Chapter 4, non-human primates performed uncued and cued pro-saccade and anti-saccade switch tasks while reversible cryogenic deactivation was applied to the dorsal anterior cingulate cortex (dACC). The first study clarifies that macaque monkeys demonstrate similar error rate and reaction time switch costs to humans performing cued and randomly interleaved pro-saccade and anti-saccade tasks. These switch costs were associated with switch-related differences in stimulus-related activity in the SC that were resolved by the time of saccade onset. The second study shows that bilateral DLPFC deactivation decreases preparatory beta and gamma power in the superior colliculus. In addition, the correlation of gamma power with spike rate in the SC was attenuated by DLPFC deactivation. Lastly, bilateral dACC deactivation in the third study impairs anti-saccade performance and increases saccadic reaction times for pro-saccades and anti-saccades. Deactivation of the dACC also impairs the ability to integrate feedback from the previous trial. Overall, these findings suggest unique roles for the dACC, DLPFC, and SC in cognitive control and task switching. The dACC may monitor feedback to select the appropriate task and implement cognitive control, the DLPFC may maintain the current task-set and modulate the activity of other brain areas, and the SC may be modulated by task switching processes and contribute to the production of switch costs

    Predicting success: patterns of cortical activation and deactivation prior to response inhibition

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    The present study investigated the relationships between attention and other preparatory processes prior to a response inhibition task and the processes involved in the inhibition itself. To achieve this, a mixed fMRI design was employed to identify the functional areas activated during both inhibition decision events and the block of trials following a visual cue introduced 2 to 7 sec prior (cue period). Preparing for successful performance produced increases in activation for both the cue period and the inhibition itself in the frontoparietal cortical network. Furthermore, preparation produced activation decreases in midline areas (insula and medial prefrontal) argued to be responsible for monitoring internal emotional states, and these cue period deactivations alone predicted subsequent success or failure. The results suggest that when cues are provided to signify the imminent requirement for behavioral control, successful performance results from a coordinated pattern of preparatory activation in task-relevant areas and deactivation of task-irrelevant ones

    The time course of cognitive control : behavioral and EEG studies

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