Segregation of cognitive and emotional function in the prefrontal cortex: a stereotactic meta-analysis

Value judgments and self-control of action: the role of the medial frontal cortex

Humans generate actions in relation to perceived events in the environment. Events are valuated in terms of subjective (personal) relevance or meaning, i.e. "what does this mean to me?". Similarly, making sense or gaining meaning from sensations (i.e., "perception") from one's own body and of mental images, such as memories or intentions, involves valuation from a subjective perspective. Here, we review recent findings in neurophysiology and neuroimaging suggesting that the medial frontal cortex comprises cortical relay nodes that afford the attribution of self-relevant, immediate and intuitive (implicit) meaning. In addition, we describe recent data that suggest that the medial frontal cortex participates also in the explicit appraisal of certain stimuli, namely, emotional face expressions, occurring as early as 150 ms following the stimulus. We propose that the medial frontal cortex subserves egocentric "value" judgments (both implicit and explicit), which are critical for self-control of action.

Preceding attention and the dorsomedial prefrontal cortex: process specificity versus domain dependence

The dorsomedial prefrontal cortex (DMPFC) has been shown to be involved in attending different states, all including a strong emotional component. It remains unclear, though, whether neural activity in the DMPFC is predominantly determined by either a particular domain, as emotional stimuli, or by a specific process, as attention. Here, we used functional magnetic resonance imaging to test the alternative hypotheses of domain- versus process-specificity in DMPFC. Subjects had to perceive pictures from three different domains, sexual, emotional, and neutral stimuli, in both a nonattended, i.e., unexpected, and attended, i.e., expected mode. Our results show DMPFC activation during attended, i.e., expected stimulus perception when compared with nonattended, i.e., unexpected stimuli perception. DMPFC activation and corresponding behavioral changes (reaction time, subjective ratings) were observed in all three domains, sexual, emotional, and neutral stimuli. As opposed to those process-specific effects that were found predominantly in posterior DMPFC, a process by domain interaction was found to be characteristic for more anterior parts of the DMPFC. Taken together, our findings favour the hypothesis that neural activity in the posterior DMPFC is determined by a specific process, i.e., attending stimuli, and thus characterized by process-specificity rather than by a particular domain, i.e., sexual, emotional, or neutral stimuli, reflecting domain-specificity. This suggests that the anterior and posterior DMPFC is involved in the process of attending mental states while remaining more (posterior DMPFC) or less (anterior DMPFC) independent of the type or domain of the respective stimulus.

Functional brain correlates of social and nonsocial processes in autism spectrum disorders: an activation likelihood estimation meta-analysis

BACKGROUND

Functional neuroimaging studies of autism spectrum disorders (ASD) have examined social and nonsocial paradigms, although rarely in the same study. Here, we provide an objective, unbiased survey of functional brain abnormalities in ASD, related to both social and nonsocial processing.

METHODS

We conducted two separate voxel-wise activation likelihood estimation meta-analyses of 39 functional neuroimaging studies consisting of 24 studies examining social processes (e.g., theory of mind, face perception) and 15 studies examining nonsocial processes (e.g., attention control, working memory). Voxel-wise significance threshold was p<.05, corrected by false discovery rate.

RESULTS

Compared with neurotypical control (NC) subjects, ASD showed greater likelihood of hypoactivation in two medial wall regions: perigenual anterior cingulate cortex (ACC) in social tasks only and dorsal ACC in nonsocial studies. Further, right anterior insula, recently linked to social cognition, was more likely to be hypoactivated in ASD in the analyses of social studies. In nonsocial studies, group comparisons showed greater likelihood of activation for the ASD group in the rostral ACC region that is typically suppressed during attentionally demanding tasks.

CONCLUSIONS

Despite substantial heterogeneity of tasks, the rapidly increasing functional imaging literature showed ASD-related patterns of hypofunction and aberrant activation that depended on the specific cognitive domain, i.e., social versus nonsocial. These results provide a basis for targeted extensions of these findings with younger subjects and a range of paradigms, including analyses of default mode network regulation in ASD.

Ablative neurosurgery for mental disorders: is there still a role in the 21st century? A personal perspective

Object

The author presents his personal perspective on ablative neurosurgical techniques used to perform bilateral anterior cingulotomy (BACI) and bilateral anterior capsulotomy (BACA) for ameliorating the symptoms of refractory obsessive-compulsive disorder (OCD) and treatment refractory depression (TRD). With depression predicted to be the second most common cause of disability in the world by the year 2020 and the birth of electric neurostimulation representing an attractive alternative treatment option for TRD and OCD, it is desirable to revisit the pros and cons of these treatment options.

Methods

The author reviewed the surgical methods and outcome (including neuroimaging findings) in all cases in which ablative neurosurgery was performed at Ninewells Hospital and Medical School over the last 2 decades.

Results

The advantages of ablative procedures (BACI and BACA) from patients’ and psychiatrists’ perspectives are that the ablative procedures are one-off procedures that do not require lifelong commitment to program the stimulation devices, fix hardware failures, or change exhausted batteries. From the perspective of healthcare funding bodies, the relatively low cost of these treatments is an advantage. The main disadvantages of BACI and BACA are the perceived higher complication rates, the irreversibility of the surgical lesions, and the stigma associated with brain destruction in psychiatric patients that are still unpalatable in the community at large. However, some patients still choose a one-off procedure in preference to any other options presented to them.

Conclusions

There is still place for BACI and BACA in modern neurosurgery for mental disorders, at least in the short term for those who do not want to commit to lifelong device programming and maintenance.

Variability of the paracingulate sulcus and morphometry of the medial frontal cortex: associations with cortical thickness, surface area, volume, and sulcal depth

The structural and functional consequences of interindividual variations in cortical morphology are poorly understood. In this study, we examined the relationship between one well-characterized variation of the medial frontal lobes, variability of the paracingulate sulcus (PCS), and grey matter volume, cortical thickness, surface area, and sulcal depth of the adjacent anterior cingulate cortex (ACC) and paracingulate cortex (PaC). Seventy-seven healthy individuals were assigned to one of four groups depending on PCS incidence in both hemispheres: left-present, right-absent; left-absent, right-present; both absent; or both present. Comparing these groups on each measure yielded four primary findings: (1) The presence of a PCS was associated with increased PaC and decreased ACC grey matter volume in the hemisphere in which it was apparent, with an almost identical pattern being observed for surface area; (2) there was a more complex relationship between PCS variability and regional thickness, such that a PCS in the left hemisphere was associated with increased left PaC and right ACC thickness, with no comparable effects being observed for the presence of a right PCS; (3) the depths of all major left hemisphere sulci in the region were strongly positively correlated, whereas no such associations were apparent in the right hemisphere; and (4) a leftward asymmetry in PaC thickness was specifically associated with better performance on a test of spatial working memory ability. These results provide evidence for a complex interhemispheric relationship between sulcal variability and cortical morphometry, and indicate that such relationships may be important for understanding individual differences in cognitive abilities.

Functional neuroimaging of belief, disbelief, and uncertainty

OBJECTIVE

The difference between believing and disbelieving a proposition is one of the most potent regulators of human behavior and emotion. When one accepts a statement as true, it becomes the basis for further thought and action; rejected as false, it remains a string of words. The purpose of this study was to differentiate belief, disbelief, and uncertainty at the level of the brain.

METHODS

We used functional magnetic resonance imaging (fMRI) to study the brains of 14 adults while they judged written statements to be "true" (belief), "false" (disbelief), or "undecidable" (uncertainty). To characterize belief, disbelief, and uncertainty in a content-independent manner, we included statements from a wide range of categories: autobiographical, mathematical, geographical, religious, ethical, semantic, and factual.

RESULTS

The states of belief, disbelief, and uncertainty differentially activated distinct regions of the prefrontal and parietal cortices, as well as the basal ganglia.

INTERPRETATION

Belief and disbelief differ from uncertainty in that both provide information that can subsequently inform behavior and emotion. The mechanism underlying this difference appears to involve the anterior cingulate cortex and the caudate. Although many areas of higher cognition are likely involved in assessing the truth-value of linguistic propositions, the final acceptance of a statement as "true" or its rejection as "false" appears to rely on more primitive, hedonic processing in the medial prefrontal cortex and the anterior insula. Truth may be beauty, and beauty truth, in more than a metaphorical sense, and false propositions may actually disgust us.

Anterior cingulotomy for major depression: clinical outcome and relationship to lesion characteristics

BACKGROUND

Anterior cingulotomy (ACING) is a neurosurgical treatment for chronic refractory depression, pain, and obsessive-compulsive disorder. Anterior cingulotomy involves the placement of bilateral lesions in the anterior cingulate under stereotactic guidance. Although a long-established therapeutic intervention, the optimal location and volume of lesions are not known, but it is generally believed that efficacious lesions interrupt the fibers of the cingulum bundle.

METHODS

Using T2-weighted magnetic resonance imaging, we tested the hypothesis that lesions placed more anteriorly would be associated with a better clinical response. We also tested a secondary hypothesis that a superior clinical response would be associated with larger lesion volumes.

RESULTS

When assessed 12 months following surgery, a superior clinical response was associated with more anterior lesions but, unexpectedly, with smaller lesion volumes. Specifically, the best clinical response was associated with total (right plus left hemisphere) lesion volumes of 1000 to 2000 mm(3) centered at Montreal Neurological Institute (MNI) coordinates (+/- 9,19,30).

CONCLUSIONS

There is considerable evidence from neuroimaging studies that more rostral areas within the anterior cingulate cortex are functionally and structurally abnormal in patients with major depressive disorder. Anteriorly placed ACING lesions would target and modify function within such regions. It should not be assumed that larger lesions are associated with a better response. These findings of relationships between lesion characteristics and clinical response argue against the suggestion that ACING represents a placebo treatment.

Anatomical abnormalities of the anterior cingulate and paracingulate cortex in patients with bipolar I disorder

Abnormalities of the anterior cingulate cortex (ACC) are thought to be involved in the pathophysiology of bipolar disorder, but structural Magnetic Resonance Imaging (MRI) studies have reported variable findings. Reasons for this include a failure to consider variability in regional cortical folding patterns and a reliance on relatively coarse measures (e.g., volume) to index anatomical change. We sought to overcome these limitations by combining a novel protocol for parcellating the ACC and adjacent paracingulate cortex (PaC) that accounts for inter-individual variations in sulcal and gyral morphology with a cortical surface-based approach that allowed calculation of regional grey matter volume, surface area and cortical thickness in 24 patients with bipolar I disorder and 24 matched controls. No changes in grey matter volume or surface area were identified in any region, but patients did show significant reductions in cortical thickness in the left rostral PaC and right dorsal PaC that were not attributable to group differences in cortical folding patterns. These findings suggest that bipolar disorder is associated with more pronounced changes in the PaC, and that reliance on volumetric measures alone may obscure more subtle differences.

Neural correlates of levels of emotional awareness during trauma script-imagery in posttraumatic stress disorder

OBJECTIVE

To examine individual differences in levels of emotional awareness as a predictor of the blood oxygenation level dependent (BOLD) response to trauma script-driven imagery in trauma-exposed individuals with (n = 25) and without (n = 16) posttraumatic stress disorder (PTSD).

METHODS

Participants completed the Levels of Emotional Awareness Scale (LEAS) and a functional magnetic resonance imaging trauma script-driven imagery paradigm.

RESULTS

Patients with PTSD exhibited lower LEAS scores in comparison with the control group. LEAS scores correlated positively with BOLD activity during trauma script-imagery in the ventral anterior cingulate cortex (vACC) in healthy controls, whereas LEAS scores correlated negatively with activation of vACC in individuals with PTSD.

CONCLUSION

Patients with PTSD exhibit lower than average levels of emotional awareness. Levels of emotional awareness are differentially associated with vACC response during trauma script-driven imagery in healthy controls versus individuals with PTSD.

Neural correlates of reexperiencing, avoidance, and dissociation in PTSD: symptom dimensions and emotion dysregulation in responses to script-driven trauma imagery

Research suggests that responses to script-driven trauma imagery in posttraumatic stress disorder (PTSD) include reexperiencing and dissociative symptom subtypes. This functional magnetic resonance imaging (fMRI) study employed a dimensional approach to characterizing script-driven imagery responses, using the Responses to Script-Driven Imagery Scale and correlational analyses of relationships between severity of state posttraumatic symptoms and neural activation. As predicted, state reexperiencing severity was associated positively with right anterior insula activity and negatively with right rostral anterior cingulate cortex (rACC). Avoidance correlated negatively with rACC and subcallosal anterior cingulate activity. In addition, as predicted, dissociation correlated positively with activity in the left medial prefrontal and right superior temporal cortices, and negatively with the left superior temporal cortex. Theoretical and clinical implications are discussed, particularly with respect to an emotion-dysregulation account of PTSD.

The social brain?

The notion that there is a ‘social brain’ in humans specialized for social interactions has received considerable support from brain imaging and, to a lesser extent, from lesion studies. Specific roles for the various components of the social brain are beginning to emerge. For example, the amygdala attaches emotional value to faces, enabling us to recognize expressions such as fear and trustworthiness, while the posterior superior temporal sulcus predicts the end point of the complex trajectories created when agents act upon the world. It has proved more difficult to assign a role to medial prefrontal cortex, which is consistently activated when people think about mental states. I suggest that this region may have a special role in the second-order representations needed for communicative acts when we have to represent someone else's representation of our own mental state. These cognitive processes are not specifically social, since they can be applied in other domains. However, these cognitive processes have been driven to ever higher levels of sophistication by the complexities of social interaction.

Time-varying amygdala response to emotional faces in generalized social phobia

BACKGROUND

Individuals with social phobia (SP) have altered behavioral and neural responses to emotional faces and are hypothesized to have deficits in inhibiting emotion-related amygdala responses. We tested for such amygdala deficits to emotional faces in a sample of individuals with SP.

METHOD

We used functional magnetic resonance imaging (fMRI) to examine the neural substrates of emotional face processing in 14 generalized SP (gSP) and 14 healthy comparison (HC) participants. Analyses focused on the temporal dynamics of the amygdala, prefrontal cortex (PFC), and fusiform face area (FFA) across blocks of neutral, fear, contempt, anger, and happy faces in gSP versus HC participants.

RESULTS

Amygdala responses in participants with gSP occurred later than the HC participants to fear, angry, and happy faces. Parallel PFC responses were found for happy and fear faces. There were no group differences in temporal response patterns in the FFA.

CONCLUSIONS

This finding might reflect a neural correlate of atypical orienting responses among individuals with gSP. Commonly reported SP deficits in habituation might reflect neural regions associated with emotional self-evaluations rather than the amygdala. This study highlights the importance of considering time-varying modulation when examining emotion-related processing in individuals with gSP.

Regional cortical thinning in subjects with violent antisocial personality disorder or schizophrenia

Violent behavior is associated with antisocial personality disorder and to a lesser extent with schizophrenia. Neuroimaging studies have suggested that several biological systems are disturbed in schizophrenia, and structural changes in frontal and temporal lobe regions are reported in both antisocial personality disorder and schizophrenia. The neural substrates that underlie violent behavior specifically and their structural analogs, however, remain poorly understood. Nor is it known whether a common biological basis exists for aggressive, impulsive, and violent behavior across these clinical populations. To explore the correlates of violence with brain structure in antisocial personality disorder and schizophrenia, the authors used magnetic resonance imaging data to investigate for the first time, to the authors' knowledge, regional differences in cortical thickness in violent and nonviolent individuals with schizophrenia and/or antisocial personality disorder and in healthy comparison subjects. Subject groups included right-handed men closely matched for demographic variables (total number of subjects=56). Violence was associated with cortical thinning in the medial inferior frontal and lateral sensory motor cortex, particularly in the right hemisphere, and surrounding association areas (Brodmann's areas 10, 11, 12, and 32). Only violent subjects with antisocial personality disorder exhibited cortical thinning in inferior mesial frontal cortices. The biological underpinnings of violent behavior may therefore vary between these two violent subject groups in which the medial frontal cortex is compromised in antisocial personality disorder exclusively, but laminar abnormalities in sensorimotor cortices may relate to violent behavior in both antisocial personality disorder and schizophrenia.

Changes of brain activity in the neural substrates for theory of mind during childhood and adolescence

Theory of mind (ToM) refers to the ability to attribute independent mental states, such as beliefs, preferences and desires, to the self and others. Neuroimaging studies of normal adults have consistently demonstrated the importance of particular brain regions for ToM, the superior temporal sulcus (STS), temporal pole (TP) and the medial prefrontal cortex (MPFC). However, there are little data showing how ToM develops during childhood and adolescence. Such data are important for understanding the development of social functioning and its disorders. The authors used functional magnetic resonance imaging to study age-related changes in brain activity associated with ToM during childhood and early adolescence (9-16 years). Normally developed children and adolescents demonstrated significant activation in the bilateral STS, the TP adjacent to the amygdala (TP/Amy) and the MPFC. Furthermore, the authors found a positive correlation between age and the degree of activation in the dorsal part of the MPFC; in contrast, a negative correlation was found for the ventral part of the MPFC. The authors also found a positive correlation between the Z coordinate of the peak activation in the MPFC and age. The data indicated that activity in the MPFC associated with ToM shifted from the ventral to the dorsal part of the MPFC during late childhood and adolescence. No age-related changes were found in the STS and the TP/Amy regions. The authors consider that the age-related brain activity observed in the present study may be associated with the maturation of the prefrontal cortex and the associated development of cognitive functions.

Prefrontal cortical functional abnormality in major depressive disorder: a stereotactic meta-analysis

OBJECTIVE

First, the objective was to test the hypothesis that prefrontal cortical regions most often reported to be maximally abnormal in studies of major depressive disorder, correspond to those regions reported maximally active when healthy subjects engage in diverse emotional tasks. Second, the objective was to determine whether such regions are reported typically to be either over or under-active.

METHOD

Medline and Embase were used to search for neuroimaging studies of major depressive disorder from 1990 to 2005. Forty-two original studies using voxel based techniques were included, and compared with data from our previous meta-analysis on healthy subjects which included one hundred and eighty-one original studies [Steele, J.D., Lawrie, S.M., 2004b. Segregation of cognitive and emotional function in the prefrontal cortex: a stereotactic meta-analysis. Neuroimage 21, 868-875].

RESULTS

The medial prefrontal cortex is the region reported maximally abnormal most often when healthy subjects experience emotion. The region is centred on Broadmans Area (BA) 32 but extends into BA 25. Two further clusters of reported loci were identified in the lateral prefrontal cortex: one in the lateral orbitofrontal region reported active when healthy subjects experience emotion (BA 47); the other centred on a dorsolateral region (BA 46 and 9) associated with cognitive tasks. No reporting bias for overactivity or underactivity was identified.

LIMITATIONS

This study pooled data from diverse studies deliberately. There were insufficient numbers of original studies to support sub-group analyses.

CONCLUSIONS

Despite the variability of reports in the literature, activity reported to be abnormal in depressive disorder is particularly localised to those brain regions that represent the substrate for normal emotional experience in healthy subjects.

Comorbidity implications in brain disease: Neuronal substrates of symptom profiles

The neuronal substrates underlying aspects of comorbidity in brain disease states may be described over psychiatric and neurologic conditions that include affective disorders, cognitive disorders, schizophrenia, obsessive-compulsive disorder, substance abuse disorders as well as the neurodegenerative disorders. Regional and circuitry analyses of biogenic amine systems that are implicated in neural and behavioural pathologies are elucidated using neuroimaging, electrophysiological, neurochemical, neuropharmacological and neurobehavioural methods that present demonstrations of the neuropathological phenomena, such as behavioural sensitisation, cognitive impairments, maladaptive reactions to environmental stress and serious motor deficits. Considerations of neuronal alterations that may or may not be associated with behavioural abnormalities examine differentially the implications of discrete areas within brains that have been assigned functional significance; in the case of the frontal lobes, differential deficits of ventromedial and dorsolateral prefrontal cortex may be associated with different aspects of cognition, affect, remission or response to medication thereby imparting a varying aspect to any investigation of comorbidity.

Cognitive impairment and fMRI in major depression

Cognitive impairment in depression may be one of the more practically important aspects of the illness, responsible for much of its morbidity. It also is at the heart of its psychopathology, may contribute to strategies of treatment, and may give us a more easily quantifiable measure of impaired function to correlate with brain activity. Functional magnetic resonance imaging (fMRI) is ideally suited to examine brain function in depression. It has the correct time window to repeatedly sample cognitive task performance; it does not require exposure to radioactive tracers and can therefore be repeated many times; it also can be linked with high resolution structural images acquired in the same imaging session that help identify the regions of activation and support the spatial transformation necessary to compare the scans of different subjects. fMRI has already produced a series of consistent results in depression, identifying increased activity of rostral anterior cingulate and other medial prefrontal structures during effortful tasks and on occasion also increased dorsolateral prefrontal activity, suggesting increased possibly compensatory activity to maintain task performance. Investigating the interplay between limbic (orbitomedial) and 'cognitive' dorsolateral structures clearly has the potential to clarify important illness mechanisms of depressive illness.

Evidence for a different role of the ventral and dorsal medial prefrontal cortex for social reactive aggression: An interactive fMRI study

Interactive paradigms inducing reactive aggression are absent in the brain mapping literature. We used a competitive reaction time task to investigate brain regions involved in social interaction and reactive aggression in sixteen healthy male subjects with fMRI. Subjects were provoked by increasingly aversive stimuli and were given the opportunity to respond aggressively against their opponent by administering a stimulus as retaliation. fMRI revealed an increase of medial prefrontal cortex (mPFC) activity during retaliation. The dorsal mPFC was active when subjects had to select the intensity of the retaliation stimulus, and its activity correlated with the selected stimulus strength. In contrast, ventral mPFC was active during observing the opponent suffering but also during retaliation independent of the stimulus strength. Ventral mPFC activation, stronger in low callous subjects, correlated positively with skin conductance response during observation of the suffering opponent. In conclusion, dorsal mPFC activation seems to represent cognitive operations related to more intense social interaction processes whereas the ventral mPFC might be involved in affective processes associated with compassion to the suffering opponent.

Social brain dysfunctions in schizophrenia: a review of neuroimaging studies

Several studies have indicated that schizophrenic patients show impaired performance in various aspects of social cognition, including theory of mind, emotion processing, and agency judgments. Neuroimaging studies that have compared patients and healthy subjects during such mental activity indicate an abnormal hemodynamic response in the medial prefrontal cortex, the prefrontal cortex, the amygdala, the inferior parietal lobe, i.e., a set of regions known to be critically involved in social cognition. This paper addresses a number of issues raised by schizophrenia research into theory of mind, emotion perception and self-agency with regards to the neural systems that mediate social cognition. In healthy subjects, typical brain patterns are associated with theory of mind, emotion perception and self-agency; some activated clusters overlap, while others are distinct. For instance, activations in the paracingulate gyrus are almost systematically associated with theory of mind tasks, while the amygdala is mainly involved in emotion perception tasks. Additional foci are frequently found activated during those tasks: superior temporal sulcus, inferior frontal area. Moreover, the inferior parietal lobe is thought to contribute to agency judgments. In the light of the data on brain abnormalities and neurochemical dysfunctions in schizophrenia, we discuss the interaction of social cognitive dysfunction with the supposed information processing abnormalities caused by dopamine dysregulation.

The influence of sulcal variability on morphometry of the human anterior cingulate and paracingulate cortex

Human anterior cingulate (ACC) and paracingulate (PaC) cortices play an important role in cognitive and affective regulation and have been implicated in numerous psychiatric and neurological conditions. The region they comprise displays marked inter-individual variability in sulcal and gyral architecture, and although recent evidence suggests that this variability has functional significance, it is often ignored in automated and region-of-interest (ROI) morphometric investigations. This has lead to confounded interpretation of results and inconsistent findings across a number of studies and in a variety of clinical populations. In this paper, we present a reliable method for parcellating the dorsal, ventral, and subcallosal ACC and PaC that accounts for individual variation in the local cortical folding pattern. We also investigated the effect of one well characterized morphological variation, the incidence of the paracingulate sulcus (PCS), on regional volumes in 24 (12 male, 12 female) healthy participants. The presence of a PCS was shown to affect both ACC and PaC volumes, such that it was associated with an 88% increase in paracingulate cortex and a concomitant 39% decrease in cingulate cortex. These findings illustrate the potential confounds inherent in morphometric approaches that ignore or attempt to minimize inter-individual variations in sulcal and gyral anatomy and underscore the need to consider this variability when attempting to understand disease processes or characterize brain structure-function relationships.

Separating subjective emotion from the perception of emotion-inducing stimuli: An fMRI study

fMRI was used to dissociate neural responses temporally associated with the subjective experience of emotion from those associated with the perception of emotion-inducing stimuli in order to better define the emotion-related functions of the amygdala, lateral orbital frontal cortex (OFC), and hippocampus. Subjects viewed aversive pictures followed by an extended post-stimulus period of sustained subjective emotion. Brain regions showing activation paralleling the period of sustained subjective emotion were distinguished from those showing activation limited to the period of aversive picture presentation. Behavioral results showed that subjective ratings of emotion remained elevated for 20 s after offset of the aversive pictures. fMRI results showed that viewing aversive pictures activated the amygdala, lateral OFC, and hippocampus. Subjective emotion (present both during and after aversive pictures) was temporally associated with activation in the right lateral OFC and left hippocampus but not the amygdala. Ratings of subjective emotion were correlated with activation in the right lateral OFC and left hippocampus. The results support direct amygdala involvement in emotion perception but suggest that amygdala activation is not temporally associated with subjective emotion that occurs after the offset of emotion-related stimuli. The results are consistent with a general role for the lateral OFC in monitoring or reflecting on internal experience and show that hippocampal activation is sustained during a period of subjective emotion, possibly related to enhanced memory encoding for the aversive pictures.

Functional specialization within rostral prefrontal cortex (area 10): a meta-analysis

One of the least well understood regions of the human brain is rostral prefrontal cortex, approximating Brodmann's area 10. Here, we investigate the possibility that there are functional subdivisions within this region by conducting a meta-analysis of 104 functional neuroimaging studies (using positron emission tomography/functional magnetic resonance imaging). Studies involving working memory and episodic memory retrieval were disproportionately associated with lateral activations, whereas studies involving mentalizing (i.e., attending to one's own emotions and mental states or those of other agents) were disproportionately associated with medial activations. Functional variation was also observed along a rostral-caudal axis, with studies involving mentalizing yielding relatively caudal activations and studies involving multiple-task coordination yielding relatively rostral activations. A classification algorithm was trained to predict the task, given the coordinates of each activation peak. Performance was well above chance levels (74% for the three most common tasks; 45% across all eight tasks investigated) and generalized to data not included in the training set. These results point to considerable functional segregation within rostral prefrontal cortex.

Meeting of minds: the medial frontal cortex and social cognition

Social interaction is a cornerstone of human life, yet the neural mechanisms underlying social cognition are poorly understood. Recently, research that integrates approaches from neuroscience and social psychology has begun to shed light on these processes, and converging evidence from neuroimaging studies suggests a unique role for the medial frontal cortex. We review the emerging literature that relates social cognition to the medial frontal cortex and, on the basis of anatomical and functional characteristics of this brain region, propose a theoretical model of medial frontal cortical function relevant to different aspects of social cognitive processing.

Segregated neural representation of distinct emotion dimensions in the prefrontal cortex—an fMRI study

Emotions are frequently characterized by distinct dimensions such as valence, intensity, and recognition. However, the exact neural representation of these dimensions in different prefrontal cortical regions remains unclear. One of the problems in revealing prefrontal cortical representation is that the very same regions are also involved in cognitive functions associated with emotion processing. We therefore conducted an fMRI study involving the viewing of emotional pictures (using the International Affective Picture System; IAPS) and controlled for associated cognitive processing like judgment and preceding attention. Functional activation was correlated with subjective post-scanning ratings of valence, intensity, and recognition. Valence significantly correlated with the functional response in ventromedial prefrontal cortex (VMPFC) and dorsolateral prefrontal cortex (DLPFC), intensity with activation in ventrolateral prefrontal cortex (VLPFC) and dorsomedial prefrontal cortex (DMPFC), and recognition with the functional response in perigenual anterior cingulate cortex (PACC). In conclusion, our results indicate segregated neural representation of the different emotion dimensions in different prefrontal cortical regions.

Self-referential processing in our brain--a meta-analysis of imaging studies on the self

The question of the self has intrigued philosophers and psychologists for a long time. More recently, distinct concepts of self have also been suggested in neuroscience. However, the exact relationship between these concepts and neural processing across different brain regions remains unclear. This article reviews neuroimaging studies comparing neural correlates during processing of stimuli related to the self with those of non-self-referential stimuli. All studies revealed activation in the medial regions of our brains' cortex during self-related stimuli. The activation in these so-called cortical midline structures (CMS) occurred across all functional domains (e.g., verbal, spatial, emotional, and facial). Cluster and factor analyses indicate functional specialization into ventral, dorsal, and posterior CMS remaining independent of domains. Taken together, our results suggest that self-referential processing is mediated by cortical midline structures. Since the CMS are densely and reciprocally connected to subcortical midline regions, we advocate an integrated cortical-subcortical midline system underlying human self. We conclude that self-referential processing in CMS constitutes the core of our self and is critical for elaborating experiential feelings of self, uniting several distinct concepts evident in current neuroscience.

Recent developments and current controversies in depression

In this review of the last 5 years' developments in research into depression we focus on recent advances and current controversies. We cover epidemiology and basic science as well as the treatment of depression in adults in all its forms. Depression in , as well as in has been covered in recent Seminars in The Lancet. Depression in adulthood remains a very common and under-treated condition, resulting in a high degree of disability. Increasingly detailed knowledge about impairment of information processing in depression is being supplemented by quantitative studies of the brain processes underlying these impairments. Most patients improve with present treatments. The mechanisms of action of antidepressants are not fully understood; the hypothesis that reversing hippocampal cell loss in depression may be their active principle is a fascinating new development. Moral panic about the claim that antidepressant serotonin reuptake inhibitors cause patients to commit suicide and become addicted to their medication may have disconcerted the public and members of the medical profession. We will try to describe the considerable effort that has gone into collecting evidence to enlighten this debate.

Individual differences in trait rumination and the neural systems supporting cognitive reappraisal

Cognitive reappraisal can alter emotional responses by changing one's interpretation of a situation's meaning. Functional neuroimaging has revealed that using cognitive reappraisal to increase or decrease affective responses involves left prefrontal activation and goal-appropriate increases or decreases in amygdala activation (Ochsner, Bunge, Gross, & Gabrieli, 2002; Ochsner, Ray, et al., 2004). The present study was designed to examine whether patterns of brain activation during reappraisal vary in relation to individual differences in trait rumination, which is the tendency to focus on negative aspects of one's self or negative interpretations of one's life. Individual differences in rumination correlated with increases in amygdala response when participants were increasing negative affect and with greater decreases in prefrontal regions implicated in self-focused thought when participants were decreasing negative affect. Thus, the propensity to ruminate may reflect altered recruitment of mechanisms that potentiate negative affect. These findings clarify relations between rumination and emotion regulation processes and may have important implications for mood and anxiety disorders.

Self-appraisal decisions evoke dissociated dorsal-ventral aMPFC networks

The anterior medial prefrontal cortex (aMPFC) is consistently active during personally salient decisions, yet the differential contributory processes of this region along the dorsal-ventral axis are less understood. Using a self-appraisal decision-making task and functional magnetic resonance imaging, we demonstrated task-dependent connectivity of ventral aMPFC with amygdala, insula, and nucleus accumbens, and dorsal aMPFC connectivity with dorsolateral PFC and bilateral hippocampus. These aMPFC networks appear to subserve distinct contributory processes inherent to self-appraisal decisions, specifically a dorsally mediated cognitive and a ventrally mediated affective/self-relevance network.

Neural predictive error signal correlates with depressive illness severity in a game paradigm

Considerable experimental evidence supports the existence of predictive error signals in various brain regions during associative learning in animals and humans. These regions include the prefrontal cortex, temporal lobe, cerebellum and monoamine systems. Various quantitative theories have been developed to describe behaviour during learning, including Rescorla-Wagner, Temporal Difference and Kalman filter models. These theories may also account for neural error signals. Reviews of imaging studies of depressive illness have consistently implicated the prefrontal and temporal lobes as having abnormal function, and sometimes structure, whilst the monoamine systems are directly influenced by antidepressant medication. It was hypothesised that such abnormalities may be associated with a dysfunction of associative learning that would be reflected by different predictive error signals in depressed patients when compared with healthy controls. This was tested with 30 subjects, 15 with a major depressive illness, using a gambling paradigm and fMRI. Consistent with the hypothesis, depressed patients differed from controls in having an increased error signal. Additionally, for some brain regions, the magnitude of the error signal correlated with Hamilton depression rating of illness severity. Structural equation modelling was used to investigate hypothesised change in effective connectivity between prespecified regions of interest in the limbic and paralimbic system. Again, differences were found that in some cases correlated with illness severity. These results are discussed in the context of quantitative theories of brain function, clinical features of depressive illness and treatments.