Anticipation of conflict monitoring in the anterior cingulate cortex and the prefrontal cortex

Competition between learned reward and error outcome predictions in anterior cingulate cortex

The anterior cingulate cortex (ACC) is implicated in performance monitoring and cognitive control. Non-human primate studies of ACC show prominent reward signals, but these are elusive in human studies, which instead show mainly conflict and error effects. Here we demonstrate distinct appetitive and aversive activity in human ACC. The error likelihood hypothesis suggests that ACC activity increases in proportion to the likelihood of an error, and ACC is also sensitive to the consequence magnitude of the predicted error. Previous work further showed that error likelihood effects reach a ceiling as the potential consequences of an error increase, possibly due to reductions in the average reward. We explored this issue by independently manipulating reward magnitude of task responses and error likelihood while controlling for potential error consequences in an Incentive Change Signal Task. The fMRI results ruled out a modulatory effect of expected reward on error likelihood effects in favor of a competition effect between expected reward and error likelihood. Dynamic causal modeling showed that error likelihood and expected reward signals are intrinsic to the ACC rather than received from elsewhere. These findings agree with interpretations of ACC activity as signaling both perceptions of risk and predicted reward.

Working-memory fMRI reveals cingulate hyperactivation in euthymic major depression

While cognitive impairments are well documented for the acute episode of major depressive disorder (MDD), less is known about cognitive functioning in the euthymic state. For working memory, dysfunctional activation of lateral prefrontal and cingulate cortex has been reported in the acute episode. This study investigates working-memory function and its neurobiological correlate in euthymic MDD patients, particularly whether dysfunctional activation persists when depressive symptoms improve. We investigated 56 subjects with functional magnetic resonance imaging (fMRI) at 3 Tesla. To challenge working-memory function, a classical verbal n-back task (0-, 1-, and 2-back) was used in 28 well-characterized, euthymic, unipolar MDD patients and 28 healthy control subjects matched according to age, sex, and educational level. Data were analyzed using SPM5. In the absence of significant behavioral differences, we observed comparable overall patterns of brain activation in both groups. As expected, both groups showed stronger activation of the typical working-memory network with increasing memory load. However, significant hyperactivation of the cingulate cortex was observed in euthymic patients, while lateral prefrontal activation was comparable between patients and controls. Working-memory challenge in the euthymic state of MDD revealed a dissociation of lateral prefrontal and cingulate brain function. Cingulate function, which is important for both emotional and cognitive processing and their integration, is still abnormal when mood is restored. This could reflect a different speed of normalization in prefrontal and limbic cortices, persistent systematic changes in neuronal networks after an episode of MDD, or a compensatory mechanism to maintain working-memory performance.

Decision-making under risk: an fMRI study

Recent research has focused on decision-making under risk and its neural bases. Two kinds of bad decisions under risk may be defined: too risky decisions and too cautious decisions. Here we show that suboptimal decisions of both kinds lead to increased activity in the anterior cingulate cortex in a Blackjack gambling task. Moreover, this increased activity is related to the avoidance of the negatively evaluated decision under risk. These findings complement other results suggesting an important role of the dorsal anterior cingulate cortex in reward-based decision-making and conflict resolution.

Anticipating conflict facilitates controlled stimulus-response selection

Cognitive control can be triggered in reaction to previous conflict, as suggested by the finding of sequential effects in conflict tasks. Can control also be triggered proactively by presenting cues predicting conflict ("proactive control")? We exploited the high temporal resolution of ERPs and controlled for sequential effects to ask whether proactive control based on anticipating conflict modulates neural activity related to cognitive control, as may be predicted from the conflict-monitoring model. ERPs associated with conflict detection (N2) were measured during a cued flanker task. Symbolic cues were either informative or neutral with respect to whether the target involved conflicting or congruent responses. Sequential effects were controlled by analyzing the congruency of the previous trial. The results showed that cueing conflict facilitated conflict resolution and reduced the N2 latency. Other potentials (frontal N1 and P3) were also modulated by cueing conflict. Cueing effects were most evident after congruent than after incongruent trials. This interaction between cueing and sequential effects suggests neural overlap between the control networks triggered by proactive and reactive signals. This finding clarifies why previous neuroimaging studies, in which reactive sequential effects were not controlled, have rarely found anticipatory effects upon conflict-related activity. Finally, the high temporal resolution of ERPs was critical to reveal a temporal modulation of conflict detection by proactive control. This novel finding suggests that anticipating conflict speeds up conflict detection and resolution. Recent research suggests that this anticipatory mechanism may be mediated by preactivation of ACC during the preparatory interval.

Encoding the future: successful processing of intentions engages predictive brain networks

Evidence from cognitive, patient and neuroimaging research indicates that "remembering to remember" intentions, i.e., prospective memory (PM) retrieval, requires both general memory systems involving the medial temporal lobes and an executive system involving rostral PFC (BA 10). However, it is not known how prospective memories are initially formed. Using fMRI, we investigated whether brain activity during encoding of future intentions and present actions differentially predicted later memory for those same intentions (PM) and actions (retrospective memory). We identified two significant patterns of neural activity: a network linked to overall memory and another linked specifically to PM. While overall memory success was predicted by temporal lobe activations that included the hippocampus, PM success was also uniquely predicted by activations in additional regions, including left rostrolateral PFC and the right parahippocampal gyrus. This finding extends the role of these structures to the formation of individual intentions. It also provides the first evidence that PM encoding, like PM retrieval, is supported by both a common episodic memory network and an executive network specifically recruited by future-oriented processing.

Lateral inferior prefrontal cortex and anterior cingulate cortex are engaged at different stages in the solution of insight problems

Two studies used puzzles that required participants to find a word that satisfied a set of constraints. The first study used a remote-association task, where participants had to find a word that would form compound words with 3 other words. The second study required participants to complete a word fragment with an associate of another word. Both studies produced distinct patterns of activity in the lateral inferior prefrontal cortex (LIPFC) and the anterior cingulate cortex (ACC). Activation in the LIPFC rose only as long as the participants were trying to retrieve the solution and dropped off as soon as the solution was obtained. However, activation in the ACC increased upon the retrieval of a solution, reflecting the need to process that solution. The data of the second experiment are fit by an information-processing model that interprets the activity in the LIPFC as reflecting retrieval operations and the activity in the ACC as reflecting subgoal setting.

Motivation and cognitive control in the human prefrontal cortex

The prefrontal cortex (PFC) subserves cognitive control, that is, the ability to select thoughts or actions in relation to internal goals. Little is known, however, about how the PFC combines motivation and the selection processes underlying cognitive control. We used functional magnetic resonance imaging in humans and found that the medial and lateral PFC have a parallel hierarchical organization from posterior to anterior regions for motivating and selecting behaviors, respectively. Moreover, using functional connectivity analyses, we found that functional interactions in this parallel system from medial to lateral PFC regions convey motivational incentives on the basis of rewards/penalties regulating the differential engagement of lateral PFC regions in top-down selection. Our results indicate that motivation is a dissociable function, reveal how the PFC integrates motivation and cognitive control in the service of decision-making, and have major implications for current theories of prefrontal executive function.

Two mechanisms for task switching in the prefrontal cortex

Measuring the cognitive and neural sequelae of switching between tasks permits a window into the flexible functioning of the executive control system. Prolonged reaction times (RTs) after task switches are accompanied by increases in brain activity in the anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (dlPFC), but the contribution made by these regions to task level control remains controversial. Here, subjects performed a hybrid spatial Stroop/task-switching paradigm, requiring them to respond with a joystick movement to congruent or incongruent spatial/verbal cues. Relative to the previous trial, the active task either switched or remained the same. Calculating switch costs as a function of current and previous trial congruency, we observed both a general RT increase on every switch trial, and additional slowing and impairment to performance when the switch occurred on the second of two successive incongruent trials (iI trials). Imaging data revealed corresponding neural concomitants of these two switch costs: the ACC was activated by task switches regardless of trial type (including congruent trials in which task-relevant and task-irrelevant information did not clash), whereas the caudal dlPFC exhibited a switch cost that was unique to iI trials. We argue that the ACC configures the priorities associated with a new task, whereas the dlPFC tackles interference from recently active, rivalrous task sets. These data contribute to a literature arguing that human cognitive flexibility benefits from the setting of new priorities for future action as well as the overcoming of interference from previously active task sets.

The determiner congruency effect in language production investigated with functional MRI

In language production, naming a picture with a gender-marked determiner phrase is faster in the presence of a distractor noun with the same grammatical gender (congruent condition) as compared with a different grammatical gender (incongruent condition). We investigated the neural correlates of this determiner congruency effect in German with functional magnetic resonance imaging (fMRI). Participants named pictures of real objects with determiner phrases (e.g. "der Tisch"-the table) in the presence of a gender-congruent or gender-incongruent distractor noun. Different comparisons allow the following functional segregation within the prefrontal cortex. First, the comparison between picture naming versus rest revealed a steeper slope of the haemodynamic response function (HRF) in the gender-congruent than the gender-incongruent condition in the left BA 44, suggesting the involvement of BA 44 in determiner selection. HRF amplitude differences between the congruent and the incongruent condition were observed outside the language network in the right fronto-median wall (congruent > incongruent), and in the left premotor cortex, middle frontal gyrus, cerebellum, and inferior parietal lobe (incongruent > congruent). The latter regions are known to be involved in the processing of incongruence and conflict in general. The data thus reveal the involvement of the left BA 44 in the selection of determiners for language production.

Cortical and subcortical mechanisms for precisely controlled force generation and force relaxation

Gripping objects during everyday manual tasks requires the coordination of muscle contractions and muscle relaxations. The vast majority of studies have focused on muscle contractions. Although previous work has examined the motor cortex during muscle relaxation, the role of brain areas beyond motor cortex remains to be elucidated. The present study used functional magnetic resonance imaging to directly compare slow and precisely controlled force generation and force relaxation in humans. Contralateral primary motor cortex and bilateral caudate nucleus had greater activity during force generation compared with force relaxation. Conversely, right dorsolateral prefrontal cortex (DLPFC) had greater activity while relaxing force compared with generating force. Also, anterior cingulate cortex had greater deactivation while relaxing force compared with generating force. These findings were further strengthened by the fact that force output parameters such as the amplitude, rate, duration, variability, and error did not affect the brain imaging findings. These results demonstrate that the neural mechanisms underlying slow and precisely controlled force relaxation differ across prefrontal-striatal and motor cortical-striatal circuits. Moreover, this study demonstrates that the DLPFC is not only involved in slow and precisely controlled force generation, but has greater involvement in regulating slow and precisely controlled muscle relaxation.

Anterior cingulate cortex makes 2 contributions to minimizing distraction

When we detect conflicting irrelevant stimuli (e.g., nearby conversations), we often minimize distraction by increasing attention to relevant stimuli. However, dissociating the neural substrates of processes that detect conflict and processes that increase attention has proven exceptionally difficult. Using a novel cross-modal attentional cueing task in humans, we observed regional specialization for these processes in the cognitive division of the anterior cingulate cortex (ACC(cd)). Activity in a dorsal subregion was associated with increasing attention to relevant stimuli, correlated with behavioral measures of orienting attention to those stimuli, and resembled activity in dorsolateral prefrontal regions that are also thought to bias attention toward relevant stimuli. In contrast, activity in a rostral subregion was associated only with detecting response conflict caused by irrelevant stimuli. These findings support a 2-component model for minimizing distraction and speak to a longstanding debate over how the ACC(cd) contributes to cognitive control.

Anticipatory activity in anterior cingulate cortex can be independent of conflict and error likelihood

Previous studies have found no agreement on whether anticipatory activity in the anterior cingulate cortex (ACC) reflects upcoming conflict, error likelihood, or actual control adjustments. Using event-related functional magnetic resonance imaging, we investigated the nature of preparatory activity in the ACC. Informative cues told the participants whether an upcoming target would or would not involve conflict in a Stroop-like task. Uninformative cues provided no such information. Behavioral responses were faster after informative than after uninformative cues, indicating cue-based adjustments in control. ACC activity was larger after informative than uninformative cues, as would be expected if the ACC is involved in anticipatory control. Importantly, this activation in the ACC was observed for informative cues even when the information conveyed by the cue was that the upcoming target evokes no response conflict and has low error likelihood. This finding demonstrates that the ACC is involved in anticipatory control processes independent of upcoming response conflict or error likelihood. Moreover, the response of the ACC to the target stimuli was critically dependent on whether the cue was informative or not. ACC activity differed among target conditions after uninformative cues only, indicating ACC involvement in actual control adjustments. Together, these findings argue strongly for a role of the ACC in anticipatory control independent of anticipated conflict and error likelihood, and also show that such control can eliminate conflict-related ACC activity during target processing. Models of frontal cortex conflict-detection and conflict-resolution mechanisms require modification to include consideration of these anticipatory control properties of the ACC.

Executive dysfunction and delay aversion in attention deficit hyperactivity disorder: nosologic and diagnostic implications

In this article the authors reflect on the role of executive function (EF) deficits and delay aversion (DAv) in the diagnosis of attention deficit hyperactivity disorder (ADHD). The authors, empirical review shows clearly that EF deficits and DAv are implicated in ADHD, although neither is necessary for ADHD nor specific to it. The constructs are somewhat dissociable from one another so that each may represent a distinctive feature associated with an ADHD subsample. The authors argue that neither EF deficits nor DAv add much value to the diagnosis of ADHD as it is currently conceptualized, but may be crucial in helping to partition heterogeneity in the condition, leading to the refinement of ADHD nosology.

A central circuit of the mind

The methodologies of cognitive architectures and functional magnetic resonance imaging can mutually inform each other. For example, four modules of the ACT-R (adaptive control of thought - rational) cognitive architecture have been associated with four brain regions that are active in complex tasks. Activity in a lateral inferior prefrontal region reflects retrieval of information in a declarative module; activity in a posterior parietal region reflects changes to problem representations in an imaginal module; activity in the anterior cingulate cortex reflects the updates of control information in a goal module; and activity in the caudate nucleus reflects execution of productions in a procedural module. Differential patterns of activation in such central regions can reveal the time course of different components of complex cognition.

Biological processes in prevention and intervention: the promotion of self-regulation as a means of preventing school failure

This paper examines interrelations between biological and social influences on the development of self-regulation in young children and considers implications of these interrelations for the promotion of self-regulation and positive adaptation to school. Emotional development and processes of emotion regulation are seen as influencing and being influenced by the development of executive cognitive functions, including working memory, inhibitory control, and mental flexibility important for the effortful regulation of attention and behavior. Developing self-regulation is further understood to reflect an emerging balance between processes of emotional arousal and cognitive regulation. Early childhood educational programs that effectively link emotional and motivational arousal with activities designed to exercise and promote executive functions can be effective in enhancing self-regulation, school readiness, and school success.