Derek Evan Nee

Interference resolution: insights from a meta-analysis of neuroimaging tasks.

A quantitative meta-analysis was performed on 47 neuroimaging studies involving tasks purported to require the resolution of interference. The tasks included the Stroop, flanker, go/no-go, stimulus-response compatibility, Simon, and stop signal tasks. Peak density-based analyses of these combined tasks reveal that the anterior cingulate cortex, dorsolateral prefrontal cortex, inferior frontal gyrus, posterior parietal cortex, and anterior insula may be important sites for the detection and/or resolution of interference. Individual task analyses reveal differential patterns of activation among the tasks. We propose that the drawing of distinctions among the processing stages at which interference may be resolved may explain regional activation differences. Our analyses suggest that resolution processes acting upon stimulus encoding, response selection, and response execution may recruit different neural regions.

Common and unique components of response inhibition revealed by fMRI.

The ability to inhibit inappropriate responses is central to cognitive control, but whether the same brain mechanisms mediate inhibition across different tasks is not known. We present evidence for a common set of frontal and parietal regions engaged in response inhibition across three tasks: a go/no-go task, a flanker task, and a stimulus-response compatibility task. Regions included bilateral anterior insula/frontal operculum and anterior prefrontal, right dorsolateral and premotor, and parietal cortices. Insula activity was positively correlated with interference costs in behavioral performance in each task. Principal components analysis showed a coherent pattern of individual differences in these regions that was also positively correlated with performance in all three tasks. However, correlations among tasks were low, for both brain activity and performance. We suggest that common interference detection and/or resolution mechanisms are engaged across tasks, and that inter-task correlations in behavioral performance are low because they conflate measurements of common mechanisms with measurements of individual biases unique to each task.

Brain mechanisms of proactive interference in working memory

It has long been known that storage of information in working memory suffers as a function of proactive interference. Here we review the results of experiments using approaches from cognitive neuroscience to reveal a pattern of brain activity that is a signature of proactive interference. Many of these results derive from a single paradigm that requires one to resolve interference from a previous experimental trial. The importance of activation in left inferior frontal cortex is shown repeatedly using this task and other tasks. We review a number of models that might account for the behavioral and imaging findings about proactive interference, raising questions about the adequacy of these models.

Depression, rumination and the default network

Major depressive disorder (MDD) has been characterized by excessive default-network activation and connectivity with the subgenual cingulate. These hyper-connectivities are often interpreted as reflecting rumination, where MDDs perseverate on negative, self-referential thoughts. However, the relationship between connectivity and rumination has not been established. Furthermore, previous research has not examined how connectivity with the subgenual cingulate differs when individuals are engaged in a task or not. The purpose of the present study was to examine connectivity of the default network specifically in the subgenual cingulate both on- and off-task, and to examine the relationship between connectivity and rumination. Analyses using a seed-based connectivity approach revealed that MDDs show more neural functional connectivity between the posterior-cingulate cortex and the subgenual-cingulate cortex than healthy individuals during rest periods, but not during task engagement. Importantly, these rest-period connectivities correlated with behavioral measures of rumination and brooding, but not reflection.

Processes of Working Memory in Mind and Brain

Working memory is often conceptualized as storage buffers that retain information briefly, rehearsal processes that refresh the buffers, and executive processes that manipulate the contents of the buffers. We review evidence about the brain mechanisms that may underlie storage and rehearsal in working memory. We hypothesize that storage is mediated by the same brain structures that process perceptual information and that rehearsal engages a network of brain areas that also controls attention to external stimuli.

Neural mechanisms of proactive interference-resolution

The ability to mitigate interference from information that was previously relevant, but is no longer relevant, is central to successful cognition. Several studies have implicated left ventrolateral prefrontal cortex (VLPFC) as a region tied to this ability, but it is unclear whether this result generalizes across different tasks. In addition, it has been suggested that left anterior prefrontal cortex (APFC) also plays a role in proactive interference-resolution although support for this claim has been limited. The present study used event-related functional magnetic resonance imaging (fMRI) to investigate the role of these regions in resolving proactive-interference across two different tasks performed on the same subjects. Results indicate that both left VLPFC and left APFC are involved in the resolution of proactive interference across tasks. However, different functional networks related to each region suggest dissociable roles for the two regions. Additionally, regions of the posterior cingulate gyrus demonstrated unique involvement in facilitation when short- and long-term memory converged. This pattern of results serves to further specify models of proactive interference-resolution.

Neural correlates of access to short-term memory

Behavioral research has led to the view that items in short-term memory can be parsed into two categories: a single item in the focus of attention that is available for immediate cognitive processing and a small set of other items that are in a heightened state of activation but require retrieval for further use. We examined this distinction by using an item-recognition task. The results show that the item in the focus of attention is represented by increased activation in inferior temporal representational cortices relative to other information in short-term memory. Functional connectivity analyses suggest that activation of these inferior temporal regions is maintained via frontal- and posterior-parietal contributions. By contrast, other items in short-term memory demand retrieval mechanisms that are represented by increased activation in the medial temporal lobe and left mid-ventrolateral prefrontal cortex. These results show that there are two distinctly different sorts of access to information in short-term memory, and that access by retrieval operations makes use of neural machinery similar to that used in long-term memory retrieval.

Functional heterogeneity of conflict, error, task-switching, and unexpectedness effects within medial prefrontal cortex

The last decade has seen considerable discussion regarding a theoretical account of medial prefrontal cortex (mPFC) function with particular focus on the anterior cingulate cortex. The proposed theories have included conflict detection, error likelihood prediction, volatility monitoring, and several distinct theories of error detection. Arguments for and against particular theories often treat mPFC as functionally homogeneous, or at least nearly so, despite some evidence for distinct functional subregions. Here we used functional magnetic resonance imaging (fMRI) to simultaneously contrast multiple effects of error, conflict, and task-switching that have been individually construed in support of various theories. We found overlapping yet functionally distinct subregions of mPFC, with activations related to dominant error, conflict, and task-switching effects successively found along a rostral-ventral to caudal-dorsal gradient within medial prefrontal cortex. Activations in the rostral cingulate zone (RCZ) were strongly correlated with the unexpectedness of outcomes suggesting a role in outcome prediction and preparing control systems to deal with anticipated outcomes. The results as a whole support a resolution of some ongoing debates in that distinct theories may each pertain to corresponding distinct yet overlapping subregions of mPFC.

Common and distinct neural correlates of perceptual and memorial selection

A critical aspect of cognitive control is the ability to select goal-relevant information in the face of competing distraction. A popular account is that common top-down selection processes underlie the ability to select among competing percepts and memories. We test the degree to which selective attention and memorial selection recruit the same neural resources. We demonstrate that both functions elicit largely overlapping networks within the dorsolateral prefrontal cortex (DLPFC), frontal eye fields (FEF), premotor cortex, and superior parietal lobule (SPL). Despite the close commonalities of selective attention and memorial selection, our results demonstrate that the SPL and FEF show preferential involvement in selective attention, whereas left ventrolateral prefrontal cortex (VLPFC) is uniquely associated with memorial selection. Thus, the two sorts of selection are not identical. We show further that variations in shared selection circuits are associated with differences in behavioral performance, suggesting that economy of control is beneficial to performance.

CNTRICS Final Task Selection: Working Memory

The third meeting of the Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia (CNTRICS) was focused on selecting promising measures for each of the cognitive constructs selected in the first CNTRICS meeting. In the domain of working memory, the 2 constructs of interest were goal maintenance and interference control. CNTRICS received 3 task nominations for each of these constructs, and the breakout group for working memory evaluated the degree to which each of these tasks met prespecified criteria. For goal maintenance, the breakout group for working memory recommended the AX-Continuous Performance Task/Dot Pattern Expectancy task for translation for use in clinical trial contexts in schizophrenia research. For interference control, the breakout group recommended the recent probes and operation/symmetry span tasks for translation for use in clinical trials. This article describes the ways in which each of these tasks met the criteria used by the breakout group to recommend tasks for further development.