Effective mental functioning requires that cognition be protected from emotional conflict due to interference by task-irrelevant emotionally salient stimuli. The neural mechanisms by which the brain detects and resolves emotional conflict are still largely unknown, however. Drawing on the classic Stroop conflict task, we developed a protocol that allowed us to dissociate the generation and monitoring of emotional conflict from its resolution. Using functional magnetic resonance imaging (fMRI), we find that activity in the amygdala and dorsomedial and dorsolateral prefrontal cortices reflects the amount of emotional conflict. By contrast, the resolution of emotional conflict is associated with activation of the rostral anterior cingulate cortex. Activation of the rostral cingulate is predicted by the amount of previous-trial conflict-related neural activity and is accompanied by a simultaneous and correlated reduction of amygdalar activity. These data suggest that emotional conflict is resolved through top-down inhibition of amygdalar activity by the rostral cingulate cortex.

A prominent model of how the brain regulates attention proposes that the anterior cingulate cortex monitors the occurrence of conflict between incompatible response tendencies and signals this information to a cognitive control system in dorsolateral prefrontal cortex. Cognitive control is thought to resolve conflict through the attentional biasing of perceptual processing, emphasizing task-relevant stimulus information. It is not known, however, whether conflict resolution is mediated by amplifying neural representations of task-relevant information, inhibiting representations of task-irrelevant information, or both. Here we manipulated trial-by-trial levels of conflict and control during a Stroop task using face stimuli, while recording hemodynamic responses from human visual cortex specialized for face processing. We show that, in response to high conflict, cognitive control mechanisms enhance performance by transiently amplifying cortical responses to task-relevant information rather than by inhibiting responses to task-irrelevant information. These results implicate attentional target-feature amplification as the primary mechanism for conflict resolution through cognitive control.

The human brain protects the processing of task-relevant stimuli from interference ("conflict") by task-irrelevant stimuli via attentional biasing mechanisms. The lateral prefrontal cortex has been implicated in resolving conflict between competing stimuli by selectively enhancing task-relevant stimulus representations in sensory cortices. Conversely, recent data suggest that conflict from emotional distracters may be resolved by an alternative route, wherein the rostral anterior cingulate cortex inhibits amygdalar responsiveness to task-irrelevant emotional stimuli. Here we tested the proposal of 2 dissociable, distracter-specific conflict resolution mechanisms, by acquiring functional magnetic resonance imaging data during resolution of conflict from either nonemotional or emotional distracters. The results revealed 2 distinct circuits: a lateral prefrontal "cognitive control" system that resolved nonemotional conflict and was associated with enhanced processing of task-relevant stimuli in sensory cortices, and a rostral anterior cingulate "emotional control" system that resolved emotional conflict and was associated with decreased amygdalar responses to emotional distracters. By contrast, activations related to both emotional and nonemotional conflict monitoring were observed in a common region of the dorsal anterior cingulate. These data suggest that the neuroanatomical networks recruited to overcome conflict vary systematically with the nature of the conflict, but that they may share a common conflict-detection mechanism.

Responses to threat-related stimuli are influenced by conscious and unconscious processes, but the neural systems underlying these processes and their relationship to anxiety have not been clearly delineated. Using fMRI, we investigated the neural responses associated with the conscious and unconscious (backwardly masked) perception of fearful faces in healthy volunteers who varied in threat sensitivity (Spielberger trait anxiety scale). Unconscious processing modulated activity only in the basolateral subregion of the amygdala, while conscious processing modulated activity only in the dorsal amygdala (containing the central nucleus). Whereas activation of the dorsal amygdala by conscious stimuli was consistent across subjects and independent of trait anxiety, activity in the basolateral amygdala to unconscious stimuli, and subjects' reaction times, were predicted by individual differences in trait anxiety. These findings provide a biological basis for the unconscious emotional vigilance characteristic of anxiety and a means for investigating the mechanisms and efficacy of treatments for anxiety.

The ability to acquire and use several languages selectively is a unique and essential human capacity. Here we investigate the fundamental question of how multiple languages are represented in a human brain. We applied functional magnetic resonance imaging (fMRI) to determine the spatial relationship between native and second languages in the human cortex, and show that within the frontal-lobe language-sensitive regions (Broca's area), second languages acquired in adulthood ('late' bilingual subjects) are spatially separated from native languages. However, when acquired during the early language acquisition stage of development ('early' bilingual subjects), native and second languages tend to be represented in common frontal cortical areas. In both late and early bilingual subjects, the temporal-lobe language-sensitive regions (Wernicke's area) also show effectively little or no separation of activity based on the age of language acquisition. This discovery of language-specific regions in Broca's area advances our understanding of the cortical representation that underlies multiple language functions.

The past few decades have seen a rapid increase in the use of functional near-infrared spectroscopy (fNIRS) in cognitive neuroscience. This fast growth is due to the several advances that fNIRS offers over the other neuroimaging modalities such as functional magnetic resonance imaging and electroencephalography/magnetoencephalography. In particular, fNIRS is harmless, tolerant to bodily movements, and highly portable, being suitable for all possible participant populations, from newborns to the elderly and experimental settings, both inside and outside the laboratory. In this review we aim to provide a comprehensive and state-of-the-art review of fNIRS basics, technical developments, and applications. In particular, we discuss some of the open challenges and the potential of fNIRS for cognitive neuroscience research, with a particular focus on neuroimaging in naturalistic environments and social cognitive neuroscience.

Incoming sensory information is often ambiguous, and the brain has to make decisions during perception. "Predictive coding" proposes that the brain resolves perceptual ambiguity by anticipating the forthcoming sensory environment, generating a template against which to match observed sensory evidence. We observed a neural representation of predicted perception in the medial frontal cortex, while human subjects decided whether visual objects were faces or not. Moreover, perceptual decisions about faces were associated with an increase in top-down connectivity from the frontal cortex to face-sensitive visual areas, consistent with the matching of predicted and observed evidence for the presence of faces.

Background Persons with type 2 diabetes (T2D) are at risk for cognitive impairment and brain atrophy. The ACCORD Memory in Diabetes (MIND) Study investigated whether persons randomized to an intensive glycaemic therapeutic strategy targeting HbA1c to <6% had better cognitive function and a larger brain volume at 40 months than persons randomized to a standard strategy targeting HbA1c to 7%–7.9%. Methods ACCORD MIND was a double 2×2 factorial parallel group randomised trial conducted in 52 clinical sites in North America. Participants [age 55 – <80 years] with T2D, high HbA1c concentrations (>7.5%), and at high risk for cardiovascular events were randomised to treatment groups using a centralized web-based system. Clinic staff and participants were not blinded to treatment arm. The cognitive primary outcome, the Digit Symbol Substitution Test (DSST) score, was assessed at baseline, 20 and 40 months. Total brain volume (TBV), the primary brain structure outcome, was assessed with MRI at baseline and 40 months in a sub-set of 632 participants. All participants with follow-up data were included in the primary analyses. In February, 2008, increased mortality risk led to the termination of the intensive therapy and transition of those participants to standard glycaemic treatment. Results Randomised patients (n=2977; mean age 62.3 years) were consecutively enrolled; the final analysis included 1358 intensive and 1416 standard arm participants with a 20 or 40 month DSST score. Of the 614 with a baseline MRI, 230 intensive and 273 standard therapy participants were included in the analysis. There was no treatment difference in the DSST score. The intensive group had a greater TBV than the standard group (difference, 4.62; 95% CI 2.0 to7.3 cm3; p=0.0007). Interpretation Although significant differences in TBV favored the intensive therapy, cognitive outcomes were not different. Combined with the unfavorable effects on other ACCORD outcomes, MIND findings do not support using intensive therapy to reduce the adverse effects of diabetes on the brain in patients similar to MIND participants. (ClinicalTrials.gov number, NCT00182910).