Emotion recognition following human pulvinar damage

Macaque claustrum, pulvinar and putative dorsolateral amygdala support the cross-modal association of social audio-visual stimuli based on meaning

Social communication draws on several cognitive functions such as perception, emotion recognition and attention. The association of audio-visual information is essential to the processing of species-specific communication signals. In this study, we use functional magnetic resonance imaging in order to identify the subcortical areas involved in the cross-modal association of visual and auditory information based on their common social meaning. We identified three subcortical regions involved in audio-visual processing of species-specific communicative signals: the dorsolateral amygdala, the claustrum and the pulvinar. These regions responded to visual, auditory congruent and audio-visual stimulations. However, none of them was significantly activated when the auditory stimuli were semantically incongruent with the visual context, thus showing an influence of visual context on auditory processing. For example, positive vocalization (coos) activated the three subcortical regions when presented in the context of positive facial expression (lipsmacks) but not when presented in the context of negative facial expression (aggressive faces). In addition, the medial pulvinar and the amygdala presented multisensory integration such that audiovisual stimuli resulted in activations that were significantly higher than those observed for the highest unimodal response. Last, the pulvinar responded in a task-dependent manner, along a specific spatial sensory gradient. We propose that the dorsolateral amygdala, the claustrum and the pulvinar belong to a multisensory network that modulates the perception of visual socioemotional information and vocalizations as a function of the relevance of the stimuli in the social context. SIGNIFICANCE STATEMENT: Understanding and correctly associating socioemotional information across sensory modalities, such that happy faces predict laughter and escape scenes predict screams, is essential when living in complex social groups. With the use of functional magnetic imaging in the awake macaque, we identify three subcortical structures-dorsolateral amygdala, claustrum and pulvinar-that only respond to auditory information that matches the ongoing visual socioemotional context, such as hearing positively valenced coo calls and seeing positively valenced mutual grooming monkeys. We additionally describe task-dependent activations in the pulvinar, organizing along a specific spatial sensory gradient, supporting its role as a network regulator.

The binding of negative emotional stimuli with spatial information in working memory: A possible role for the episodic buffer

Introduction

Remembering where negative events occur has undeniable adaptive value, however, how these memories are formed remains elusive. We investigated the role of working memory subcomponents in binding emotional and visuo-spatial information using an emotional version of the object relocation task (EORT).

Methods

After displaying black rectangles simultaneously, emotional pictures (from the International Affective Pictures System) appeared sequentially over each rectangle. Participants repositioned the rectangles as accurately as possible after all stimuli had disappeared. During the EORT encoding phase, a verbal trail task was administered concurrently to selectively interfere with the central executive (CE). The immediate post-encoding administration of an object feature-report task was used to interfere with the episodic buffer (EB).

Results

Only the EB-interfering task prevented the emotion-enhancing effect of negative pictures. The latter effect was not observed with a concurrent executive task.

Discussion

Overall, our findings suggest that pre-attentive automatic processes are primarily involved in binding emotional and visuo-spatial information in the EB.

Pulvinar Response Profiles and Connectivity Patterns to Object Domains

Distributed cortical regions show differential responses to visual objects belonging to different domains varying by animacy (e.g., animals vs tools), yet it remains unclear whether this is an organization principle also applying to the subcortical structures. Combining multiple fMRI activation experiments (two main experiments and six validation datasets; 12 females and 9 males in the main Experiment 1; 10 females and 10 males in the main Experiment 2), resting-state functional connectivity, and task-based dynamic causal modeling analysis in human subjects, we found that visual processing of images of animals and tools elicited different patterns of response in the pulvinar, with robust left lateralization for tools, and distinct, bilateral (with rightward tendency) clusters for animals. Such domain-preferring activity distribution in the pulvinar was associated with the magnitude with which the voxels were intrinsically connected with the corresponding domain-preferring regions in the cortex. The pulvinar-to-right-amygdala path showed a one-way shortcut supporting the perception of animals, and the modulation connection from pulvinar to parietal showed an advantage to the perception of tools. These results incorporate the subcortical regions into the object processing network and highlight that domain organization appears to be an overarching principle across various processing stages in the brain.SIGNIFICANCE STATEMENT Viewing objects belonging to different domains elicited different cortical regions, but whether the domain organization applied to the subcortical structures (e.g., pulvinar) was unknown. Multiple fMRI activation experiments revealed that object pictures belonging to different domains elicited differential patterns of response in the pulvinar, with robust left lateralization for tool pictures, and distinct, bilateral (with rightward tendency) clusters for animals. Combining the resting-state functional connectivity and dynamic causal modeling analysis on task-based fMRI data, we found domain-preferring activity distribution in the pulvinar aligned with that in cortical regions. These results highlight the need for coherent visual theories that explain the mechanisms underlying the domain organization across various processing stages.

Relay and higher-order thalamic nuclei show an intertwined functional association with cortical-networks

Almost all functional processing in the cortex strongly depends on thalamic interactions. However, in terms of functional interactions with the cerebral cortex, the human thalamus nuclei still partly constitute a terra incognita. Hence, for a deeper understanding of thalamic-cortical cooperation, it is essential to know how the different thalamic nuclei are associated with cortical networks. The present work examines network-specific connectivity and task-related topical mapping of cortical areas with the thalamus. The study finds that the relay and higher-order thalamic nuclei show an intertwined functional association with different cortical networks. In addition, the study indicates that relay-specific thalamic nuclei are not only involved with relay-specific behavior but also in higher-order functions. The study enriches our understanding of interactions between large-scale cortical networks and the thalamus, which may interest a broader audience in neuroscience and clinical research.

Multisensory integration in neurons of the medial pulvinar of macaque monkey

The pulvinar is a heterogeneous thalamic nucleus, which is well developed in primates. One of its subdivisions, the medial pulvinar, is connected to many cortical areas, including the visual, auditory, and somatosensory cortices, as well as with multisensory areas and premotor areas. However, except for the visual modality, little is known about its sensory functions. A hypothesis is that, as a region of convergence of information from different sensory modalities, the medial pulvinar plays a role in multisensory integration. To test this hypothesis, 2 macaque monkeys were trained to a fixation task and the responses of single-units to visual, auditory, and auditory-visual stimuli were examined. Analysis revealed auditory, visual, and multisensory neurons in the medial pulvinar. It also revealed multisensory integration in this structure, mainly suppressive (the audiovisual response is less than the strongest unisensory response) and subadditive (the audiovisual response is less than the sum of the auditory and the visual responses). These findings suggest that the medial pulvinar is involved in multisensory integration.

Gray Matter Volume of Thalamic Nuclei in Traumatized North Korean Refugees

The current study investigated differences in the regional gray matter (GM) volume of specific thalamic nuclei between North Korean (NK) refugees and South Korean (SK) residents. It also investigated associations between thalamic GM volume changes and psychological symptoms. Psychological evaluations and magnetic resonance imaging were conducted on 50 traumatized NK refugees and 55 non-traumatized SK residents. The regional GM volume ratios in the bilateral thalami were calculated for all participants using voxel-based morphometry. NK refugees showed greater GM volume ratios in the right medial-posterior nuclei and left medial nuclei compared with SK residents. NK refugees also exhibited more depressive symptoms than SK residents. However, increased GM volume ratios in both right medial-posterior nuclei and left medial nuclei were correlated with fewer depressive symptoms in NK refugees, but not in SK residents. The findings indicate that traumatized NK refugees had increased GM volumes in the right medial-posterior nuclei and left medial nuclei, which were associated with fewer depressive symptoms. The enlarged specific thalamic nuclei presented among refugees in the current study might be associated with a neurobiological compensatory mechanism that prevents the development or progression of depression in refugees after repetitive traumatic experiences.

Extrastriatal dopamine D2/3 receptor binding, functional connectivity, and autism socio-communicational deficits: a PET and fMRI study

The social motivation hypothesis of autism proposes that social communication symptoms in autism-spectrum disorder (ASD) stem from atypical social attention and reward networks, where dopamine acts as a crucial mediator. However, despite evidence indicating that individuals with ASD show atypical activation in extrastriatal regions while processing reward and social stimuli, no previous studies have measured extrastriatal dopamine D2/3 receptor (D2/3R) availability in ASD. Here, we investigated extrastriatal D2/3R availability in individuals with ASD and its association with ASD social communication symptoms using positron emission tomography (PET). Moreover, we employed a whole-brain multivariate pattern analysis of resting-state functional magnetic resonance imaging (fMRI) to identify regions where functional connectivity atypically correlates with D2/3R availability depending on ASD diagnosis. Twenty-two psychotropic-free males with ASD and 24 age- and intelligence quotient-matched typically developing males underwent [¹¹C]FLB457 PET, fMRI, and clinical symptom assessment. Participants with ASD showed lower D2/3R availability throughout the D2/3R-rich extrastriatal regions of the dopaminergic pathways. Among these, the posterior region of the thalamus, which primarily comprises the pulvinar, displayed the largest effect size for the lower D2/3R availability, which correlated with a higher score on the Social Affect domain of the Autism Diagnostic Observation Schedule-2 in participants with ASD. Moreover, lower D2/3R availability was correlated with lower functional connectivity of the thalamus-superior temporal sulcus and cerebellum-medial occipital cortex, specifically in individuals with ASD. The current findings provide novel molecular evidence for the social motivation theory of autism and offer a novel therapeutic target.

Effects of Parent Emotion Socialization on the Neurobiology Underlying Adolescent Emotion Processing: A Multimethod fMRI Study

Parents' emotion socialization (ES) practices impact socioemotional development throughout adolescence. Little is known, however, regarding the neurobiology underlying these effects. This study used functional magnetic resonance imaging (fMRI) to examine how parent ES practices relate to adolescent brain function during emotion processing. Thirty-three adolescents (ages 14-16) reported on ES practices of a focal parent (primarily mothers) using the Emotions as a Child (EAC) Scale. Adolescents also completed a conflict discussion task with this parent, and parents' statements were coded for emotional valence. Adolescents performed two fMRI tasks: a standard emotion processing (EP) task (n = 32) and the Testing Emotional Attunement and Mutuality (TEAM) task (n = 27). The EP task consisted of viewing emotional pictures and either reacting naturally or using cognitive reappraisal to regulate emotional responses. The TEAM task was performed with the parent and included trials during which adolescents were shown that their parent made an error, costing the dyad $5. Parent negative verbalizations during the conflict discussion were associated with greater activity in the thalamus during the emotion reactivity condition of the EP task and in the thalamus, superior medial and superior frontal gyri, anterior insula, and dorsolateral prefrontal cortex during the costly error condition of the TEAM task. Unsupportive ES was associated with greater activity in the supplementary motor area and less activity in the paracentral gyrus and amygdala during the costly error condition of the TEAM task. This study supports the premise that ES influences adolescents' emotion-related neural processing, particularly when using ecologically valid tasks in social contexts.

Right Hemisphere Dominance for Unconscious Emotionally Salient Stimuli

The present review will focus on evidence demonstrating the prioritization in visual processing of fear-related signals in the absence of awareness. Evidence in hemianopic patients without any form of blindsight or affective blindsight in classical terms will be presented, demonstrating that fearful faces, via a subcortical colliculo-pulvinar-amygdala pathway, have a privileged unconscious visual processing and facilitate responses towards visual stimuli in the intact visual field. Interestingly, this fear-specific implicit visual processing in hemianopics has only been observed after lesions to the visual cortices in the left hemisphere, while no effect was found in patients with damage to the right hemisphere. This suggests that the subcortical route for emotional processing in the right hemisphere might provide a pivotal contribution to the implicit processing of fear, in line with evidence showing enhanced right amygdala activity and increased connectivity in the right colliculo-pulvinar-amygdala pathway for unconscious fear-conditioned stimuli and subliminal fearful faces. These findings will be discussed within a theoretical framework that considers the amygdala as an integral component of a constant and continuous vigilance system, which is preferentially invoked with stimuli signaling ambiguous environmental situations of biological relevance, such as fearful faces.

Structural brain correlates of irritability and aggression in early manifest Huntington's disease

In Huntington's disease (HD), irritability and aggressive behavior represent highly prevalent and disabling neuropsychiatric symptoms. However, their structural brain correlates have not been extensively explored. Here, we rated the severity of irritability and aggression (IAs) using the Problem Behaviors Assessment for HD (PBA-s) in 31 early HD participants. The IAs score was computed as the mean severity score for the irritability plus the mean severity aggression PBA-s items. Seventeen patients were classified as IAs (IAs score > 2) and 14 as non-IAs. All participants had available T1-MRI data. A grey matter volume voxel-based morphometry group comparison was performed, using age, motor status, severity of other PBA-s items and disease burden as covariates. Aside from irritability, aggression and obsessive-compulsive behavior, both groups were comparable in terms of other clinical and sociodemographic variables. In the IAs group, a significant reduction of grey-matter volume (GMV) was found in the bilateral caudate, putamen and globus pallidus, left pulvinar nucleus, right superior temporal pole (BA 38), left mid temporal gyrus (BA 21), right inferior temporal gyrus (BA 20) and left medial OPFC (BA 11). Lower GMV in the left pulvinar nucleus was significantly associated with higher anxiety and lower GMV in the left medial OPFC was significantly associated with higher suicidality. In sum, IAs in HD is associated with structural brain damage in a set of key nodes involved in the expression and down-regulation of negative emotions.

A multisensory perspective onto primate pulvinar functions

Perception in ambiguous environments relies on the combination of sensory information from various sources. Most associative and primary sensory cortical areas are involved in this multisensory active integration process. As a result, the entire cortex appears as heavily multisensory. In this review, we focus on the contribution of the pulvinar to multisensory integration. This subcortical thalamic nucleus plays a central role in visual detection and selection at a fast time scale, as well as in the regulation of visual processes, at a much slower time scale. However, the pulvinar is also densely connected to cortical areas involved in multisensory integration. In spite of this, little is known about its multisensory properties and its contribution to multisensory perception. Here, we review the anatomical and functional organization of multisensory input to the pulvinar. We describe how visual, auditory, somatosensory, pain, proprioceptive and olfactory projections are differentially organized across the main subdivisions of the pulvinar and we show that topography is central to the organization of this complex nucleus. We propose that the pulvinar combines multiple sources of sensory information to enhance fast responses to the environment, while also playing the role of a general regulation hub for adaptive and flexible cognition.

The impact of child abuse on the neurobiology of self-processing in depressed adolescents

Child abuse is linked to lifetime psychopathology including abnormal self-processing. Given self-processing maturation in adolescence, we tested duration, presence, and abuse accumulation's impact upon self-processing neurobiology among depressed youth with (N = 54) and without an abuse history (N = 40). Youth evaluated positive and negative self-descriptors across four points of view in the scanner. Regression analyses showed that longer abuse duration (in days) was associated with lower activity in inferior temporal (e.g. insula, fusiform & parahippocampus), striatal, cerebellar and midbrain structures when processing negative self-descriptors with the least activity in youth exposed to 6+ abuse years. Abuse presence vs. absence was linked to higher neural activity. However, youth exposed to a single abuse instance to 3 years of abuse might drive that relative neural hyperactivity. Results support: 1) the toxic stress model of blunted overall neuro-reactivity underpinning emotion, sensorimotor gating, and social cognition during negative stimuli as an adaptation to pervasively toxic environments and 2) the differential impact of acute versus chronic stress upon neurophysiological indices. Finally, child abuse duration might impact these ancillary and higher socioemotional processes differently among depressed youth primarily for negative but not positive self-processing.

Development of lateral pulvinar resting state functional connectivity and its role in attention

OBJECTIVE

The lateral pulvinar nucleus (LPN) has a well-established role in visual attention. Oscillatory activity of the LPN is critical for cortico-cortical communication within and among occipital and temporal visual processing regions. However, the functional development of the LPN and its role in attention deficits is not understood. This study examined the development of thalamic functional connectivity and its relation to attention abilities.

METHOD

Resting state functional Magnetic Resonance Imaging images from 950 participants (ages 8-21) in the Philadelphia Neurodevelopmental Cohort (PNC) were used to examine age effects. Follow-up General Linear Models were performed to examine brain-behavior effects with Attention Deficit Hyperactivity Disorder (ADHD) symptom ratings and D-prime scores from the Penn Continuous Performance Task, a behavioral measure of selective attention.

RESULTS

LPN functional connectivity with ventral visual stream regions of the occipital and temporal cortices decreased with age, while LPN functional connectivity with the supplementary motor area increased with age. Weaker LPN connectivity in the inferior parietal lobule, supramarginal gyrus, posterior insula, and inferior frontal gyrus was associated with more ADHD symptoms; stronger pulvinar-cerebellar connectivity was also associated with more ADHD symptoms. Better D-prime scores were associated with greater connectivity between the pulvinar and superior parietal gyrus; better D-prime scores were associated with weaker pulvinar connectivity with striatal, middle temporal gyrus, and medial prefrontal cortex regions.

CONCLUSION

These findings implicate the LPN in the development of the ventral visual processing stream between late childhood and early adulthood and suggest that LPN connectivity with higher order attention networks is important for attention abilities.

Fear-related signals are prioritised in visual, somatosensory and spatial systems

The human brain has evolved a multifaceted fear system, allowing threat detection to enable rapid adaptive responses crucial for survival. Although many cortical and subcortical brain areas are believed to be involved in the survival circuits detecting and responding to threat, the amygdala has reportedly a crucial role in the fear system. Here, we review evidence demonstrating that fearful faces, a specific category of salient stimuli indicating the presence of threat in the surrounding, are preferentially processed in the fear system and in the connected sensory cortices, even when they are presented outside of awareness or are irrelevant to the task. In the visual domain, we discuss evidence showing in hemianopic patients that fearful faces, via a subcortical colliculo-pulvinar-amygdala pathway, have a privileged visual processing even in the absence of awareness and facilitate responses towards visual stimuli in the intact visual field. Moreover, evidence showing that somatosensory cortices prioritise fearful-related signals, to the extent that tactile processing is enhanced in the presence of fearful faces, will be also reported. Finally, we will review evidence revealing that fearful faces have a pivotal role in modulating responses in peripersonal space, in line with the defensive functional definition of PPS.

Laminar distribution of cortical projection neurons to the pulvinar: A comparative study in cats and mice

The cortical processing of visual information is thought to follow a hierarchical framework. This framework of connections between visual areas is based on the laminar patterns of direct feedforward and feedback cortico-cortical projections. However, this view ignores the cortico-thalamo-cortical projections to the pulvinar nucleus in the thalamus, which provides an alternative transthalamic information transfer between cortical areas. It was proposed that corticothalamic (CT) pathways follow a similar hierarchical pattern as cortico-cortical connections. Two main types of CT projections have been recognized: drivers and modulators. Drivers originate mainly in Layer 5 whereas modulators are from Layer 6. Little is known about the laminar distribution of these projections to the pulvinar across visual cortical areas. Here, we analyzed the distribution of CT neurons projecting to the lateral posterior (LP) thalamus in two species: cats and mice. Injections of the retrograde tracer fragment B of cholera toxin (CTb) were performed in the LP. The morphology and cortical laminar distribution of CTb-labeled neurons was assessed. In cats, neurons were mostly found in Layer 6 except in Area 17, where they were mostly in Layer 5. In contrast, CT neurons in mice were mostly located in Layer 6 across all areas. Thus, our results demonstrate that CT projections in mice do not follow the same organization as cats suggesting that the transthalamic pathways play distinct roles in these species.

Neural Circuits Underlying Innate Fear

Fear is defined as a fundamental emotion promptly arising in the context of threat and when danger is perceived. Fear can be innate or learned. Examples of innate fear include fears that are triggered by predators, pain, heights, rapidly approaching objects, and ancestral threats such as snakes and spiders. Animals and humans detect and respond more rapidly to threatening stimuli than to nonthreatening stimuli in the natural world. The threatening stimuli for most animals are predators, and most predators are themselves prey to other animals. Predatory avoidance is of crucial importance for survival of animals. Although humans are rarely affected by predators, we are constantly challenged by social threats such as a fearful or angry facial expression. This chapter will summarize the current knowledge on brain circuits processing innate fear responses to visual stimuli derived from studies conducted in mice and humans.

Brain Processes While Struggling With Evidence Accumulation During Facial Emotion Recognition: An ERP Study

The human brain is tuned to recognize emotional facial expressions in faces having a natural upright orientation. The relative contributions of featural, configural, and holistic processing to decision-making are as yet poorly understood. This study used a diffusion decision model (DDM) of decision-making to investigate the contribution of early face-sensitive processes to emotion recognition from physiognomic features (the eyes, nose, and mouth) by determining how experimental conditions tapping those processes affect early face-sensitive neuroelectric reflections (P100, N170, and P250) of processes determining evidence accumulation at the behavioral level. We first examined the effects of both stimulus orientation (upright vs. inverted) and stimulus type (photographs vs. sketches) on behavior and neuroelectric components (amplitude and latency). Then, we explored the sources of variance common to the experimental effects on event-related potentials (ERPs) and the DDM parameters. Several results suggest that the N170 indicates core visual processing for emotion recognition decision-making: (a) the additive effect of stimulus inversion and impoverishment on N170 latency; and (b) multivariate analysis suggesting that N170 neuroelectric activity must be increased to counteract the detrimental effects of face inversion on drift rate and of stimulus impoverishment on the stimulus encoding component of non-decision times. Overall, our results show that emotion recognition is still possible even with degraded stimulation, but at a neurocognitive cost, reflecting the extent to which our brain struggles to accumulate sensory evidence of a given emotion. Accordingly, we theorize that: (a) the P100 neural generator would provide a holistic frame of reference to the face percept through categorical encoding; (b) the N170 neural generator would maintain the structural cohesiveness of the subtle configural variations in facial expressions across our experimental manipulations through coordinate encoding of the facial features; and (c) building on the previous configural processing, the neurons generating the P250 would be responsible for a normalization process adapting to the facial features to match the stimulus to internal representations of emotional expressions.

Functional connectivity fingerprints of the human pulvinar: Decoding its role in cognition

The pulvinar is the largest thalamic nucleus in the brain and considered as a key structure in sensory processing and attention. Although its anatomy is well known, in particular thanks to studies in non-human primates, its role in perception and cognition remains poorly understood. Here, we used resting-state functional connectivity from a large sample of high-resolution data provided by the Human Connectome Project, combined with a large-scale meta-analysis approach to segregate and characterize the functional organization of the pulvinar nucleus. We identified five clusters per pulvinar with distinct connectivity profiles and determined their respective co-activation patterns. Using the Neurosynth database, we then investigated the functional significance of these co-activation networks. Our results confirm the functional heterogeneity of the pulvinar, revealing clearcut differences across clusters in terms of their connectivity patterns and associated cognitive domains. While the anterior and lateral clusters appear to be involved in action and attention domains, the ventromedial and dorsomedial clusters may preferentially subserve emotional processes and saliency detection. In contrast, the inferior cluster shows less specificity but correlates with perception and memory processes. Collectively, our results suggest that the pulvinar underwrites different components of cognition, supporting a central role in the coordination of cortico-subcortical processes mediated by distributed brain networks.

Age-related changes in repetition suppression of neural activity during emotional future simulation

Despite advances in understanding the consequences of age-related episodic memory decline for future simulation, much remains unknown regarding changes in the neural underpinnings of future thinking with age. We used a repetition suppression paradigm to explore age-related changes in the neural correlates of emotional future simulation. Younger and older adults simulated positive, negative, and neutral future events either 2 or 5 times. Reductions in neural activity for events simulated 5 versus 2 times (i.e., repetition suppression) identify brain regions responsive to the specific emotion of simulated events. Critically, older adults showed greater repetition suppression than younger adults in the temporal pole for negative simulations, and the cuneus for positive simulations. These findings suggest that older adults distance themselves from negative future possibilities by thinking about them in a more semantic way, consistent with the view that older adults down-regulate negative affect and up-regulate positive affect. More broadly this study increases our understanding of the impact of aging on the neural underpinnings of episodic future simulation.

Impaired visual search with paradoxically increased facilitation by emotional features after unilateral pulvinar damage

Posterior thalamic pulvinar nuclei have been implicated in different aspects of spatial attention, but their exact role in humans remain unclear. Most neuropsychological studies of attention deficits after pulvinar lesion have concerned single patients or small samples. Here we examined a group of 13 patients with focal damage to posterior thalamus on a visual search task with faces, allowing us to test several hypotheses concerning pulvinar function in controlling attention to visually salient or emotionally significant stimuli. Our results identified two subgroups of thalamic patients with distinct patterns of attentional responsiveness to emotional and colour features in face targets. One group with lesions located in anterior and ventral portions of thalamus showed intact performance, with a normal facilitation of visual search for faces with emotional (fearful or happy) expressions on both side of space, similar to healthy controls. By contrast, a second group showed a slower and poorer detection of face targets, most severe for neutral faces, but with a paradoxically enhanced facilitation by both colour and emotional features. This second group had lesions centred on the pulvinar, involving mainly the dorso-medial sectors in patients showing enhanced effects of colour features, but extending to more dorso-lateral sectors in those with enhanced effects of emotional features. These findings reveal that pulvinar nuclei are not critical for orienting attention to emotionally or visually salient features, but instead provide new evidence in support of previous hypotheses suggesting an important role in controlling attention in visual scenes with distracting information.

Pulvinar Lesions Disrupt Fear-Related Implicit Visual Processing in Hemianopic Patients

The processing of emotional stimuli in the absence of awareness has been widely investigated in patients with lesions to the primary visual pathway since the classical studies on affective blindsight. In addition, recent evidence has shown that in hemianopic patients without blindsight only unseen fearful faces can be implicitly processed, inducing enhanced visual encoding (Cecere et al., 2014) and response facilitation (Bertini et al., 2013, 2017) to stimuli presented in their intact field. This fear-specific facilitation has been suggested to be mediated by activity in the spared visual subcortical pathway, comprising the superior colliculus (SC), the pulvinar and the amygdala. This suggests that the pulvinar might represent a critical relay structure, conveying threat-related visual information through the subcortical visual circuit. To test this hypothesis, hemianopic patients, with or without pulvinar lesions, performed a go/no-go task in which they had to discriminate simple visual stimuli, consisting in Gabor patches, displayed in their intact visual field, during the simultaneous presentation of faces with fearful, happy, and neutral expressions in their blind visual field. In line with previous evidence, hemianopic patients without pulvinar lesions showed response facilitation to stimuli displayed in the intact field, only while concurrent fearful faces were shown in their blind field. In contrast, no facilitatory effect was found in hemianopic patients with lesions of the pulvinar. These findings reveal that pulvinar lesions disrupt the implicit visual processing of fearful stimuli in hemianopic patients, therefore suggesting a pivotal role of this structure in relaying fear-related visual information from the SC to the amygdala.

Gray Matter Volume of a Region in the Thalamic Pulvinar Is Specifically Associated with Novelty Seeking

Personality reflects the set of psychological traits and mechanisms characteristic for an individual. Geno-neuro-biologically inspired personality accounts have proposed a set of temperaments and characters that jointly compose personality profiles. The present study addresses the link between neurobiology and personality and investigates the association between temperament traits and regional gray matter volume. Furthermore, the specificity of these associations as well as the underlying components that drive the association are addressed. One hundred and four participants completed the Temperament and Character Inventory (TCI) and underwent structural magnetic resonance brain imaging. The participants included premanifest carriers of Huntington's disease, as this population is associated with temperament-related neuropsychiatric symptoms. Whole brain voxel-based multiple regression analyses on gray matter volume revealed a significant specific positive correlation between a region in the left thalamic pulvinar and novelty seeking score, controlled for the other traits (P_height < 0.05, FWE-corrected). No significant associations were observed for the other temperament traits. Region of interest analyses showed that this association is driven by the subscale NS2: impulsiveness. The results increase the knowledge of the structural neurobiology of personality and indicate that individual differences in novelty seeking reflect the structural differences observed in the brain in an area that is widely and densely connected, which is in line with the typically domain-general behavioral influence of personality traits on a wide range of affective, perceptual, mnemotic, executive, and other cognitive functions.

Orienting toward threat: Contributions of a subcortical pathway transmitting retinal afferents to the amygdala via the superior colliculus and pulvinar

Probabilistic diffusion tractography was used to provide the first direct evidence for a subcortical pathway from the retina to the amygdala, via the superior colliculus and pulvinar, that transmits visual stimuli signaling threat. A bias to orient toward threat was measured in a temporal order judgement saccade decision task, under monocular viewing, in a group of 19 healthy participants who also underwent diffusion weighted MR imaging. On each trial of the behavioural task a picture depicting threat was presented in one visual field and a competing non-threatening stimulus in the other. The onset interval between the two pictures was randomly varied and participants made a saccade toward the stimulus that they judged to have appeared first. The bias to orient toward threat was stronger when the threatening stimulus was in the temporal visual hemifield, suggesting that afferents via the retinotectal tract contributed to the bias. Probabalistic tractography was used to virtually dissect connections between the superior colliculus and the amygdala traversing the pulvinar. Individual differences in microstructure (fractional anisotropy) of the streamline predicted the magnitude of the bias to orient toward threat, providing supporting evidence for a functional role of the subcortical SC-amygdala pathway in processing threat in healthy humans.

Affective blindsight relies on low spatial frequencies

The human brain can process facial expressions of emotions rapidly and without awareness. Several studies in patients with damage to their primary visual cortices have shown that they may be able to guess the emotional expression on a face despite their cortical blindness. This non-conscious processing, called affective blindsight, may arise through an intact subcortical visual route that leads from the superior colliculus to the pulvinar, and thence to the amygdala. This pathway is thought to process the crude visual information conveyed by the low spatial frequencies of the stimuli. In order to investigate whether this is the case, we studied a patient (TN) with bilateral cortical blindness and affective blindsight. An fMRI paradigm was performed in which fearful and neutral expressions were presented using faces that were either unfiltered, or filtered to remove high or low spatial frequencies. Unfiltered fearful faces produced right amygdala activation although the patient was unaware of the presence of the stimuli. More importantly, the low spatial frequency components of fearful faces continued to produce right amygdala activity while the high spatial frequency components did not. Our findings thus confirm that the visual information present in the low spatial frequencies is sufficient to produce affective blindsight, further suggesting that its existence could rely on the subcortical colliculo-pulvino-amygdalar pathway.

Testosterone during Puberty Shifts Emotional Control from Pulvinar to Anterior Prefrontal Cortex

Increased limbic and striatal activation in adolescence has been attributed to a relative delay in the maturation of prefrontal areas, resulting in the increase of impulsive reward-seeking behaviors that are often observed during puberty. However, it remains unclear whether and how this general developmental pattern applies to the control of social emotional actions, a fundamental adult skill refined during adolescence. This domain of control pertains to decisions involving emotional responses. When faced with a social emotional challenge (e.g., an angry face), we can follow automatic response tendencies and avoid the challenge or exert control over those tendencies by selecting an alternative action. Using an fMRI-adapted social approach-avoidance task, this study identifies how the neural regulation of emotional action control changes as a function of human pubertal development in 14-year-old adolescents (n = 47). Pubertal maturation, indexed by testosterone levels, shifted neural regulation of emotional actions from the pulvinar nucleus of the thalamus and the amygdala to the anterior prefrontal cortex (aPFC). Adolescents with more advanced pubertal maturation showed greater aPFC activity when controlling their emotional action tendencies, reproducing the same pattern consistently observed in adults. In contrast, adolescents of the same age, but with less advanced pubertal maturation, showed greater pulvinar and amygdala activity when exerting similarly effective emotional control. These findings qualify how, in the domain of social emotional actions, executive control shifts from subcortical to prefrontal structures during pubertal development. The pulvinar and the amygdala are suggested as the ontogenetic precursors of the mature control system centered on the anterior prefrontal cortex.

SIGNIFICANCE STATEMENT

Adolescents can show distinct behavioral problems when emotionally aroused. This could be related to later development of frontal regions compared with deeper brain structures. This study found that when the control of emotional actions needs to be exerted, more mature adolescents, similar to adults, recruit the anterior prefrontal cortex (aPFC). Less mature adolescents recruit specific subcortical regions, namely the pulvinar and amygdala. These findings identify the subcortical pulvino-amygdalar pathway as a relevant precursor of a mature aPFC emotional control system, opening the way for a neurobiological understanding of how emotion control-related disorders emerge during puberty.

Specific patterns of neuronal loss in the pulvinar nucleus in dementia with lewy bodies

BACKGROUND

Complex visual hallucinations occur in 70%-80% of dementia with Lewy bodies patients and significantly affect well-being. Despite the prevalence of visual hallucinations in dementia with Lewy bodies, the neuropathological basis of this phenomenon is poorly understood. The pulvinar nucleus of the thalamus has not previously been neuropathologically examined, but has been linked to visual hallucinations in dementia with Lewy bodies. The objective of this study was to investigate whether neuropathological or morphometric changes occur in the pulvinar nucleus in dementia with Lewy bodies cases that may contribute to visual hallucinations.

METHODS

Postmortem pulvinar tissue was acquired from 8 individuals with dementia with Lewy bodies, 8 with Alzheimer's disease, and 8 control cases and was analyzed using stereological and quantitative neuropathological techniques.

RESULTS

Lewy body pathology was present throughout the pulvinar in dementia with Lewy bodies but was most severe in the medial pulvinar. Neuronal loss was found in the lateral pulvinar in dementia with Lewy bodies and Alzheimer's disease but was more severe in dementia with Lewy bodies.

CONCLUSIONS

The pulvinar has an important role in visual attention, visual target selection and affective visual perception. These functions are thought to be deficient in dementia with Lewy bodies and may contribute a vulnerability to visual hallucinations. Therefore, this study has demonstrated neuropathological changes that may promote the manifestation of visual hallucinations in dementia with Lewy bodies. © 2017 International Parkinson and Movement Disorder Society.

The functional activity and effective connectivity of pulvinar are modulated by individual differences in threat-related attentional bias

The pulvinar is important in selective attention, particularly to visual stimuli under the focus of attention. However, the pulvinar is assumed to process emotional stimuli even outside the focus of attention, because of its tight connection with the amygdala. We therefore investigated how unattended emotional stimuli affect the pulvinar and its effective connectivity (EC) while considering individual differences in selective attention. fMRI in 41 healthy human subjects revealed that the amygdala, but not the pulvinar, more strongly responded to unattended fearful faces than to unattended neutral faces (UF > UN), although we observed greater EC from the pulvinar to the amygdala. Interestingly, individuals with biased attention toward threat (i.e., attentional bias) showed significantly increased activity (UF > UN) and reduced grey matter volume in the pulvinar. These individuals also exhibited stronger EC from the pulvinar to the attention-related frontoparietal network (FPN), whereas individuals with greater attentional control showed more enhanced EC from the pulvinar to the amygdala, but not the FPN (UF > UN). The pulvinar may filter unattended emotional stimuli whose sensitivity depends on individual threat-related attentional bias. The connectivity patterns of the pulvinar may thus be determined based on individual differences in threat-related attentional bias and attentional control.

Adaptive Pulvinar Circuitry Supports Visual Cognition

The pulvinar is the largest thalamic nucleus in primates and one of the most mysterious. Endeavors to understand its role in vision have focused on its abundant connections with the visual cortex. While its connectivity mapping in the cortex displays a broad topographic organization, its projections are also marked by considerable convergence and divergence. As a result, the pulvinar is often regarded as a central forebrain hub. Moreover, new evidence suggests that its comparatively modest input from structures such as the retina and superior colliculus may critically shape the functional organization of the visual cortex, particularly during early development. Here we review recent studies that cast fresh light on how the many convergent pathways through the pulvinar contribute to visual cognition.

Human anterior thalamic nuclei are involved in emotion-attention interaction

Patients treated with deep brain stimulation (DBS) provide an opportunity to study affective processes in humans with "lesion on demand" at key nodes in the limbic circuitries, such as at the anterior thalamic nuclei (ANT). ANT has been suggested to play a role in emotional control with its connection to the orbitofrontal cortex and the anterior cingulate cortex. However, direct evidence for its role in emotional function in human subjects is lacking. Reported side effects of ANT-DBS in the treatment of refractory epilepsy include depression related symptoms. In line with these mood-related clinical side effects, we have previously reported that stimulating the anterior thalamus increased emotional interference in a visual attention task as indicated by prolonged reaction times due to threat-related emotional distractors. We used event-related potentials to investigate potential attentional mechanism behind this behavioural observation. We hypothesized that ANT-DBS leads to greater attention capture by threat-related distractors. We tested this hypothesis using centro-parietal N2-P3 peak-to-peak amplitude as a measure of allocated attentional resources. Six epileptic patients treated with deep brain stimulation at ANT participated in the study. Electroencephalography was recorded while the patients performed a computer based Executive-Reaction Time test with threat-related emotional distractors. During the task, either ANT or a thalamic control location was stimulated, or the stimulation was turned off. Stimulation of ANT was associated with increased centro-parietal N2-P3 amplitude and increased reaction time in the context of threat-related emotional distractors. We conclude that high frequency electric stimulation of ANT leads to greater attentional capture by emotional stimuli. This is the first study to provide direct evidence from human subjects with on-line electric manipulation of ANT for its role in emotion-attention interaction.

Repetition-Related Reductions in Neural Activity during Emotional Simulations of Future Events

Simulations of future experiences are often emotionally arousing, and the tendency to repeatedly simulate negative future outcomes has been identified as a predictor of the onset of symptoms of anxiety. Nonetheless, next to nothing is known about how the healthy human brain processes repeated simulations of emotional future events. In this study, we present a paradigm that can be used to study repeated simulations of the emotional future in a manner that overcomes phenomenological confounds between positive and negative events. The results show that pulvinar nucleus and orbitofrontal cortex respectively demonstrate selective reductions in neural activity in response to frequently as compared to infrequently repeated simulations of negative and positive future events. Implications for research on repeated simulations of the emotional future in both non-clinical and clinical populations are discussed.

Connectivity between the superior colliculus and the amygdala in humans and macaque monkeys: virtual dissection with probabilistic DTI tractography

It has been suggested that some cortically blind patients can process the emotional valence of visual stimuli via a fast, subcortical pathway from the superior colliculus (SC) that reaches the amygdala via the pulvinar. We provide in vivo evidence for connectivity between the SC and the amygdala via the pulvinar in both humans and rhesus macaques. Probabilistic diffusion tensor imaging tractography revealed a streamlined path that passes dorsolaterally through the pulvinar before arcing rostrally to traverse above the temporal horn of the lateral ventricle and connect to the lateral amygdala. To obviate artifactual connectivity with crossing fibers of the stria terminalis, the stria was also dissected. The putative streamline between the SC and amygdala traverses above the temporal horn dorsal to the stria terminalis and is positioned medial to it in humans and lateral to it in monkeys. The topography of the streamline was examined in relation to lesion anatomy in five patients who had previously participated in behavioral experiments studying the processing of emotionally valenced visual stimuli. The pulvinar lesion interrupted the streamline in two patients who had exhibited contralesional processing deficits and spared the streamline in three patients who had no deficit. Although not definitive, this evidence supports the existence of a subcortical pathway linking the SC with the amygdala in primates. It also provides a necessary bridge between behavioral data obtained in future studies of neurological patients, and any forthcoming evidence from more invasive techniques, such as anatomical tracing studies and electrophysiological investigations only possible in nonhuman species.

The Distinct Role of the Amygdala, Superior Colliculus and Pulvinar in Processing of Central and Peripheral Snakes

Introduction

Visual processing of ecologically relevant stimuli involves a central bias for stimuli demanding detailed processing (e.g., faces), whereas peripheral object processing is based on coarse identification. Fast detection of animal shapes holding a significant phylogenetic value, such as snakes, may benefit from peripheral vision. The amygdala together with the pulvinar and the superior colliculus are implicated in an ongoing debate regarding their role in automatic and deliberate spatial processing of threat signals.

Methods

Here we tested twenty healthy participants in an fMRI task, and investigated the role of spatial demands (the main effect of central vs. peripheral vision) in the processing of fear-relevant ecological features. We controlled for stimulus dependence using true or false snakes; snake shapes or snake faces and for task constraints (implicit or explicit). The main idea justifying this double task is that amygdala and superior colliculus are involved in both automatic and controlled processes. Moreover the explicit/implicit instruction in the task with respect to emotion is not necessarily equivalent to explicit vs. implicit in the sense of endogenous vs. exogenous attention, or controlled vs. automatic processes.

Results

We found that stimulus-driven processing led to increased amygdala responses specifically to true snake shapes presented in the centre or in the peripheral left hemifield (right hemisphere). Importantly, the superior colliculus showed significantly biased and explicit central responses to snake-related stimuli. Moreover, the pulvinar, which also contains foveal representations, also showed strong central responses, extending the results of a recent single cell pulvinar study in monkeys. Similar hemispheric specialization was found across structures: increased amygdala responses occurred to true snake shapes presented to the right hemisphere, with this pattern being closely followed by the superior colliculus and the pulvinar.

Conclusion

These results show that subcortical structures containing foveal representations such as the amygdala, pulvinar and superior colliculus play distinct roles in the central and peripheral processing of snake shapes. Our findings suggest multiple phylogenetic fingerprints in the responses of subcortical structures to fear-relevant stimuli.

Flexible adaptive paradigms for fMRI using a novel software package 'Brain Analysis in Real-Time' (BART)

In this work we present a new open source software package offering a unified framework for the real-time adaptation of fMRI stimulation procedures. The software provides a straightforward setup and highly flexible approach to adapt fMRI paradigms while the experiment is running. The general framework comprises the inclusion of parameters from subject’s compliance, such as directing gaze to visually presented stimuli and physiological fluctuations, like blood pressure or pulse. Additionally, this approach yields possibilities to investigate complex scientific questions, for example the influence of EEG rhythms or fMRI signals results themselves. To prove the concept of this approach, we used our software in a usability example for an fMRI experiment where the presentation of emotional pictures was dependent on the subject’s gaze position. This can have a significant impact on the results. So far, if this is taken into account during fMRI data analysis, it is commonly done by the post-hoc removal of erroneous trials. Here, we propose an a priori adaptation of the paradigm during the experiment’s runtime. Our fMRI findings clearly show the benefits of an adapted paradigm in terms of statistical power and higher effect sizes in emotion-related brain regions. This can be of special interest for all experiments with low statistical power due to a limited number of subjects, a limited amount of time, costs or available data to analyze, as is the case with real-time fMRI.

Human pulvinar functional organization and connectivity

The human pulvinar is the largest thalamic area in terms of size and cortical connectivity. Although much is known about regional pulvinar structural anatomy, relatively little is known about pulvinar functional anatomy in humans. Cooccurrence of experimentally induced brain activity is a traditional metric used to establish interregional brain connectivity and forms the foundation of functional neuroimaging connectivity analyses. Because functional neuroimaging studies report task-related coactivations within a standardized space, meta-analysis of many whole-brain studies can define the brain's interregional coactivation across many tasks. Such an analysis can also detect and define variations in functional coactivations within a particular region. Here we use coactivation profiles reported in ∼ 7,700 functional neuroimaging studies to parcellate and define the pulvinar's functional anatomy. Parcellation of the pulvinar's coactivation profile identified five clusters per pulvinar of distinct functional coactivation. These clusters showed a high degree of symmetry across hemispheres and correspondence with the human pulvinar's cytoarchitecture. We investigated the functional coactivation profiles of each resultant pulvinar cluster with meta-analytic methods. By referencing existent neuroimaging and lesion-deficit literature, these profiles make a case for regional pulvinar specialization within the larger human attention-controlling network. Reference to this literature also informs specific hypotheses that can be tested in subsequent studies in healthy and clinical populations.

The Hidden Snake in the Grass: Superior Detection of Snakes in Challenging Attentional Conditions

Snakes have provided a serious threat to primates throughout evolution. Furthermore, bites by venomous snakes still cause significant morbidity and mortality in tropical regions of the world. According to the Snake Detection Theory (SDT Isbell, 2006; 2009), the vital need to detect camouflaged snakes provided strong evolutionary pressure to develop astute perceptual capacity in animals that were potential targets for snake attacks. We performed a series of behavioral tests that assessed snake detection under conditions that may have been critical for survival. We used spiders as the control stimulus because they are also a common object of phobias and rated negatively by the general population, thus commonly lumped together with snakes as “evolutionary fear-relevant”. Across four experiments (N = 205) we demonstrate an advantage in snake detection, which was particularly obvious under visual conditions known to impede detection of a wide array of common stimuli, for example brief stimulus exposures, stimuli presentation in the visual periphery, and stimuli camouflaged in a cluttered environment. Our results demonstrate a striking independence of snake detection from ecological factors that impede the detection of other stimuli, which suggests that, consistent with the SDT, they reflect a specific biological adaptation. Nonetheless, the empirical tests we report are limited to only one aspect of this rich theory, which integrates findings across a wide array of scientific disciplines.

The two-process theory of face processing: modifications based on two decades of data from infants and adults

Johnson and Morton (1991. Biology and Cognitive Development: The Case of Face Recognition. Blackwell, Oxford) used Gabriel Horn's work on the filial imprinting model to inspire a two-process theory of the development of face processing in humans. In this paper we review evidence accrued over the past two decades from infants and adults, and from other primates, that informs this two-process model. While work with newborns and infants has been broadly consistent with predictions from the model, further refinements and questions have been raised. With regard to adults, we discuss more recent evidence on the extension of the model to eye contact detection, and to subcortical face processing, reviewing functional imaging and patient studies. We conclude with discussion of outstanding caveats and future directions of research in this field.

Differential contribution of cortical and subcortical visual pathways to the implicit processing of emotional faces: a tDCS study

The visual processing of emotional faces is subserved by both a cortical and a subcortical route. To investigate the specific contribution of these two functional pathways, two groups of neurologically healthy humans were tested using transcranial direct current stimulation (tDCS). In Experiment 1, participants received sham and active cathodal-inhibitory tDCS over the left occipital cortex, while, in control Experiment 2, participants received sham and active cathodal-inhibitory tDCS over the vertex, to exclude any unspecific effect of tDCS. After tDCS, participants performed a go/no-go task responding to happy or fearful target faces presented in the left visual field, while backwardly masked faces (emotionally congruent, incongruent, or neutral) were concurrently displayed in the right visual field. After both suppressing activity in the vertex (Experiment 2) and sham stimulation (Experiment 1 and 2) a reduction of reaction times was found for pairs of emotionally congruent stimuli. However, after suppressing the activity in the left occipital cortex, the congruency-dependent response facilitation disappeared, while a specific facilitative affect was evident when masked fearful faces were coupled with happy target faces. These results parallel the performances of hemianopic patients and suggest that when the occipital cortex is damaged or inhibited, and the visual processing for emotional faces is mainly dependent on the activation of the "low road" subcortical route, fearful faces represent the only visually processed stimuli capable of facilitating a behavioral response. This effect might reflect an adaptive mechanism implemented by the brain to quickly react to potential threats before their conscious identification.

Unseen fearful faces promote amygdala guidance of attention

Little is known about the network of brain regions activated prior to explicit awareness of emotionally salient social stimuli. We investigated this in a functional magnetic resonance imaging study using a technique that combined elements of binocular rivalry and motion flash suppression in order to prevent awareness of fearful faces and houses. We found increased left amygdala and fusiform gyrus activation for fearful faces compared to houses, despite suppression from awareness. Psychophysiological interaction analyses showed that amygdala activation was associated with task-specific (fearful faces greater than houses) modulation of an attention network, including bilateral pulvinar, bilateral insula, left frontal eye fields, left intraparietal sulcus and early visual cortex. Furthermore, we report an unexpected main effect of increased left parietal cortex activation associated with suppressed fearful faces compared to suppressed houses. This parietal finding is the first report of increased dorsal stream activation for a social object despite suppression, which suggests that information can reach parietal cortex for a class of emotionally salient social objects, even in the absence of awareness.

Cortical sensitivity to contrast polarity and orientation of faces is modulated by temporal-nasal hemifield asymmetry

Behavioral studies demonstrate that the efficiency of detection of faces is dependent on configural and contrast polarity information characteristic to human faces. Stimulus inversion or contrast polarity reversal can disrupt this process. We investigated whether a face-sensitive event-related potential component, the N170, is modulated by the orientation and contrast polarity of highly degraded schematic face-like patterns (Experiment 1) in the same manner as it is for face photographs (Experiment 2). Inversion and/or contrast reversal delayed and enhanced the N170 for both kinds of stimuli, suggesting that a white oval with three black squares is sufficient to elicit face-sensitive cortical responses. In Experiment 3 we further tested whether the extrageniculate visual pathways modulate early cortical responses to faces. We found that the N170 responses to configural and contrast information are modulated by temporal-nasal visual field asymmetry under monocular viewing conditions, suggesting the involvement of subcortical, extrageniculate visual pathways in face detection. These results are consistent with the idea that an ontogenetically early and primitive bias to orient towards face-like patterns with relevant configural and contrast information influences the early stages of cortical face processing.

Brain mechanisms for emotional influences on perception and attention: what is magic and what is not

The rapid and efficient selection of emotionally salient or goal-relevant stimuli in the environment is crucial for flexible and adaptive behaviors. Converging data from neuroscience and psychology have accrued during the last decade to identify brain systems involved in emotion processing, selective attention, and their interaction, which together act to extract the emotional or motivational value of sensory events and respond appropriately. An important hub in these systems is the amygdala, which may not only monitor the emotional value of stimuli, but also readily project to several other areas and send feedback to sensory pathways (including striate and extrastriate visual cortex). This system generates saliency signals that modulate perceptual, motor, as well as memory processes, and thus in turn regulate behavior appropriately. Here, we review our current views on the function and properties of these brain systems, with an emphasis on their involvement in the rapid and/or preferential processing of threat-relevant stimuli. We suggest that emotion signals may enhance processing efficiency and competitive strength of emotionally significant events through gain control mechanisms similar to those of other (e.g. endogenous) attentional systems, but mediated by distinct neural mechanisms in amygdala and interconnected prefrontal areas. Alterations in these brain mechanisms might be associated with psychopathological conditions, such as anxiety or phobia. We conclude that attention selection and awareness are determined by multiple attention gain control systems that may operate in parallel and use different sensory cues but act on a common perceptual pathway.

Emergent processes in cognitive-emotional interactions

Emotion and cognition have been viewed as largely separate entities in the brain. Within this framework, significant progress has been made in understanding specific aspects of behavior. Research in the past two decades, however, has started to paint a different picture of brain organization, one in which network interactions are key to understanding complex behaviors. From both basic and clinical perspectives, the characterization of cognitive-emotional interactions constitutes a fundamental issue in the investigation of the mind and brain. This review will highlight the interactive and integrative potential that exists in the brain to bring together the cognitive and emotional domains. First, anatomical evidence will be provided, focusing on structures such as hypothalamus, basal forebrain, amygdala, cingulate cortex, orbitofrontal cortex, and insula. Data on functional interactions will then be discussed, followed by a discussion of a dual competition framework, which describes cognitive-emotional interactions in terms of perceptual and cognitive competition mechanisms.

Reprint of: Emotion and cognition and the amygdala: from "what is it?" to "what's to be done?"

The amygdala is a fascinating, complex structure that lies at the center of much of our current thinking about emotion. Here, I will review data that suggest that the amygdala is involved in several processes linked to determining what a stimulus is and what the organism should therefore do - the two questions that are part of the title. This piece will focus on three main aspects of amygdala function, namely attention, value representation, and decision making, by reviewing both non-human and human data. Two mechanisms of affective attention will be described. The first involves projections from the central nucleus of the amygdala to the basal forebrain, which has extensive and diffuse projections throughout the cortical mantle. The second involves projections from the basal amygdala to multiple levels across the visual cortex. I will also describe how the basolateral amygdala is important for the representation of value and in decision making. Overall, it will be argued that the amygdala plays a key role in solving the following problem: How can a limited-capacity information processing system that receives a constant stream of diverse inputs be designed to selectively process those inputs that are most significant to the objectives of the system? "What is it?" and "What's to be done?" processes can then be viewed as important building blocks in the construction of emotion, a process that is intertwined with cognition. Furthermore, answering the two questions directs how resources should be mobilized as the organism seeks out additional information from the environment.

Emotion processing and the amygdala: from a 'low road' to 'many roads' of evaluating biological significance

A subcortical pathway through the superior colliculus and pulvinar to the amygdala is commonly assumed to mediate the non-conscious processing of affective visual stimuli. We review anatomical and physiological data that argue against the notion that such a pathway plays a prominent part in processing affective visual stimuli in humans. Instead, we propose that the primary role of the amygdala in visual processing, like that of the pulvinar, is to coordinate the function of cortical networks during evaluation of the biological significance of affective visual stimuli. Under this revised framework, the cortex has a more important role in emotion processing than is traditionally assumed.