Stimulus-induced reversal of information flow through a cortical network for animacy perception

Decades of research have demonstrated that a region of the right fusiform gyrus (FG) and right posterior superior temporal sulcus (pSTS) responds preferentially to static faces and biological motion, respectively. Despite this view, both regions activate in response to both stimulus categories and to a range of other stimuli, such as goal-directed actions, suggesting that these regions respond to characteristics of animate agents more generally. Here we propose a neural model for animacy detection composed of processing streams that are initially differentially sensitive to cues signaling animacy, but that ultimately act in concert to support reasoning about animate agents. We use dynamic causal modeling, a measure of effective connectivity, to demonstrate that the directional flow of information between the FG and pSTS is initially dependent on the characteristics of the animate agent presented, a key prediction of our proposed network for animacy detection.

Schizophrenia miR-137 locus risk genotype is associated with dorsolateral prefrontal cortex hyperactivation

BACKGROUND

miR-137 dysregulation has been implicated in the etiology of schizophrenia, but its functional role remains to be determined.

METHODS

Functional magnetic resonance imaging scans were acquired on 48 schizophrenia patients and 63 healthy volunteers (total sample size N = 111 subjects), with similar mean age and sex distribution, while subjects performed a Sternberg Item Response Paradigm with memory loads of one, three, and five numbers. Dorsolateral prefrontal cortex (DLPFC) retrieval activation for the working memory load of three numbers, for which hyperactivation had been shown in schizophrenia patients compared with control subjects, was extracted. The genome-wide association study confirmed schizophrenia risk single nucleotide polymorphism rs1625579 (miR-137 locus) was genotyped (schizophrenia: GG n = 0, GT n = 9, TT n = 39; healthy volunteers: GG = 2, GT n = 15, and TT n = 46). Fisher's exact test examined the effect of diagnosis on rs1625579 allele frequency distribution (p = nonsignificant). Mixed model regression analyses examined the effects of diagnosis and genotype on working memory performance measures and DLPFC activation.

RESULTS

Patients showed significantly higher left DLPFC retrieval activation on working memory load 3, lower working memory performance, and longer response times compared with controls. There was no effect of genotype on working memory performance or response times in either group. However, individuals with the rs1625579 TT genotype had significantly higher left DLPFC activation than those with the GG/GT genotypes.

CONCLUSIONS

Our study suggests that the rs1625579 TT (miR-137 locus) schizophrenia risk genotype is associated with the schizophrenia risk phenotype DLPFC hyperactivation commonly considered a measure of brain inefficiency.

Repetition suppression of face-selective evoked and induced EEG recorded from human cortex

In functional MRI studies, repetition suppression refers to the reduction of hemodynamic activation to repeated stimulus presentation. For example, the repeated presentation of a face reduces the hemodynamic response evoked by faces in the fusiform gyrus. The neural events that underlie repetition suppression are not well understood. Indeed, in contrast to the hemodynamic response, the face-specific N200 recorded from subdural electrodes on the ventral occipitotemporal cortex, primarily along the fusiform gyrus, has been reported to be insensitive to face-identity repetition. We have previously described a face-specific broadband gamma (30-100 Hz) response at ventral face-specific N200 sites that is functionally dissociable from the N200. In this study, we investigate whether gamma and other components of the electroencephalogram spectrum are affected by face-identity repetition independently of the N200. Participants viewed sequentially presented identical faces. At sites on and around the fusiform gyrus, we found that face repetition modulated alpha (8-12 Hz), low-gamma (30-60 Hz), and high-gamma (60-100 Hz) synchrony, but not the N200. These findings provide evidence of a spatially co-localized progression of face processing. Whereas the N200 reflects an initial obligatory response that is less sensitive to face-identity repetition, the subsequent spectral fluctuations reflect more elaborative face processing and are thus sensitive to face novelty. It is notable that the observed modulations were different for different frequency bands. We observed repetition suppression of broadband gamma, but repetition enhancement of alpha synchrony. This difference is discussed with regard to an existing model of repetition suppression and behavioral repetition priming.

Acute effects of trauma-focused research procedures on participant safety and distress

The ethical conduct of research on posttraumatic stress disorder (PTSD) requires assessing the risks to study participants. Some previous findings suggest that patients with PTSD report higher distress compared to non-PTSD participants after trauma-focused research. However, the impact of study participation on participant risk, such as suicidal/homicidal ideation and increased desire to use drugs or alcohol, has not been adequately investigated. Furthermore, systematic evaluation of distress using pre- and post-study assessments, and the effects of study procedures involving exposure to aversive stimuli, are lacking. Individuals with a history of PTSD (n=68) and trauma-exposed non-PTSD controls (n=68) responded to five questions about risk and distress before and after participating in research procedures including a PTSD diagnostic interview and a behavioral task with aversive stimuli consisting of mild electrical shock. The desire to use alcohol or drugs increased modestly with study participation among the subgroup (n=48) of participants with current PTSD. Participation in these research procedures was not associated with increased distress or participant risk, nor did study participation interact with lifetime PTSD diagnosis. These results suggest some increase in distress with active PTSD but a participant risk profile that supports a favorable risk-benefit ratio for conducting research in individuals with PTSD.

Altered resting-state functional connectivity of basolateral and centromedial amygdala complexes in posttraumatic stress disorder

The amygdala is a major structure that orchestrates defensive reactions to environmental threats and is implicated in hypervigilance and symptoms of heightened arousal in posttraumatic stress disorder (PTSD). The basolateral and centromedial amygdala (CMA) complexes are functionally heterogeneous, with distinct roles in learning and expressing fear behaviors. PTSD differences in amygdala-complex function and functional connectivity with cortical and subcortical structures remain unclear. Recent military veterans with PTSD (n=20) and matched trauma-exposed controls (n=22) underwent a resting-state fMRI scan to measure task-free synchronous blood-oxygen level dependent activity. Whole-brain voxel-wise functional connectivity of basolateral and CMA seeds was compared between groups. The PTSD group had stronger functional connectivity of the basolateral amygdala (BLA) complex with the pregenual anterior cingulate cortex (ACC), dorsomedial prefrontal cortex, and dorsal ACC than the trauma-exposed control group (p<0.05; corrected). The trauma-exposed control group had stronger functional connectivity of the BLA complex with the left inferior frontal gyrus than the PTSD group (p<0.05; corrected). The CMA complex lacked connectivity differences between groups. We found PTSD modulates BLA complex connectivity with prefrontal cortical targets implicated in cognitive control of emotional information, which are central to explanations of core PTSD symptoms. PTSD differences in resting-state connectivity of BLA complex could be biasing processes in target regions that support behaviors central to prevailing laboratory models of PTSD such as associative fear learning. Further research is needed to investigate how differences in functional connectivity of amygdala complexes affect target regions that govern behavior, cognition, and affect in PTSD.

The impact of NMDA receptor blockade on human working memory-related prefrontal function and connectivity

Preclinical research suggests that N-methyl-D-aspartate glutamate receptors (NMDA-Rs) have a crucial role in working memory (WM). In this study, we investigated the role of NMDA-Rs in the brain activation and connectivity that subserve WM. Because of its importance in WM, the lateral prefrontal cortex, particularly the dorsolateral prefrontal cortex and its connections, were the focus of analyses. Healthy participants (n=22) participated in a single functional magnetic resonance imaging session. They received saline and then the NMDA-R antagonist ketamine while performing a spatial WM task. Time-course analysis was used to compare lateral prefrontal activation during saline and ketamine administration. Seed-based functional connectivity analysis was used to compare dorsolateral prefrontal connectivity during the two conditions and global-based connectivity was used to test for laterality in these effects. Ketamine reduced accuracy on the spatial WM task and brain activation during the encoding and early maintenance (EEM) period of task trials. Decrements in task-related activation during EEM were related to performance deficits. Ketamine reduced connectivity in the DPFC network bilaterally, and region-specific reductions in connectivity were related to performance. These results support the hypothesis that NMDA-Rs are critical for WM. The knowledge gained may be helpful in understanding disorders that might involve glutamatergic deficits such as schizophrenia and developing better treatments.

Relationship of resting brain hyperconnectivity and schizophrenia-like symptoms produced by the NMDA receptor antagonist ketamine in humans

N-methyl-D-aspartate glutamate receptor (NMDA-R) antagonists produce schizophrenia-like positive and negative symptoms in healthy human subjects. Preclinical research suggests that NMDA-R antagonists interfere with the function of gamma-aminobutyric acid (GABA) neurons and alter the brain oscillations. These changes have been hypothesized to contribute to psychosis. In this investigation, we evaluated the hypothesis that the NMDA-R antagonist ketamine produces alterations in cortical functional connectivity during rest that are related to symptoms. We administered ketamine to a primary sample of 22 subjects and to an additional, partially overlapping, sample of 12 subjects. Symptoms before and after the experimental session were rated with the Positive and Negative Syndrome Scale (PANSS). In the primary sample, functional connectivity was measured via functional magnetic resonance imaging almost immediately after infusion began. In the additional sample, this assessment was repeated after 45 min of continuous ketamine infusion. Global, enhanced functional connectivity was observed at both timepoints, and this hyperconnectivity was related to symptoms in a region-specific manner. This study supports the hypothesis that pathological increases in resting brain functional connectivity contribute to the emergence of positive and negative symptoms associated with schizophrenia.

Assessing the biosafety risks of pig manure for use as a feedstock for composting

The objective was to assess the biosafety risks of pig manure for use as a feedstock for composting. Salmonella was detected in the manure from half of the 30 pig farms sampled, with 52% of isolates recovered identified as multi-drug resistant S. Typhimurium. The highest prevalence (60%) was found on Salmonella category 2 and 3 farms i.e. those with medium and high Salmonella seroprevalence, respectively, although this was not statistically significant. Escherichia coli counts were, however, significantly higher in manure from Salmonella category 3 farms. Manure separation may be useful as a means of reducing/eliminating pathogens from manure prior to composting, as manure solids generated using a decanter centrifuge had lower E. coli and Enterococcus counts than manure. These findings should be taken into consideration when selecting pig manure for use as a feedstock for compost or other marketable manure by-products.

Probabilistic atlases for face and biological motion perception: an analysis of their reliability and overlap

Neuroimaging research has identified several category-selective regions in visual cortex that respond most strongly when viewing an exemplar image from a preferred category, such as faces. Recent studies, however, have suggested a more complex pattern of activation that has been heretofore unrecognized, e.g., the presence of additional patches of activation to faces beyond the well-studied fusiform face area, and the activation of ostensible face selective regions by animate motion of non-biological forms. Here, we characterize the spatial pattern of brain activity evoked by viewing faces or biological motion in large fMRI samples (N>120). We create probabilistic atlases for both face and biological motion activation, and directly compare their spatial patterns of activation. Our findings support the suggestion that the fusiform face area is composed of at least two separable foci of activation. The face-evoked response in the fusiform and nearby ventral temporal cortex has good reliability across runs; however, we found surprisingly high variability in lateral brain regions by faces, and for all brain regions by biological motion, which had an overall much lower effect size. We found that faces and biological motion evoke substantially overlapping activation distributions in both ventral and lateral occipitotemporal cortices. The peaks of activation for these different categories within these overlapping regions were close but distinct.

Neural correlates of opposing effects of emotional distraction on working memory and episodic memory: an event-related FMRI investigation

A fundamental question in the emotional memory literature is why emotion enhances memory in some conditions but disrupts memory in other conditions. For example, separate studies have shown that emotional stimuli tend to be better remembered in long-term episodic memory (EM), whereas emotional distracters tend to impair working memory (WM) maintenance. The first goal of this study was to directly compare the neural correlates of EM enhancement (EME) and WM impairing (WMI) effects, and the second goal was to explore individual differences in these mechanisms. During event-related functional magnetic resonance imaging (fMRI), participants maintained faces in WM while being distracted by emotional or neutral pictures presented during the delay period. EM for the distracting pictures was tested after scanning and was used to identify successful encoding activity for the picture distracters. The first goal yielded two findings: (1) emotional pictures that disrupted face WM but enhanced subsequent EM were associated with increased amygdala (AMY) and hippocampal activity (ventral system) coupled with reduced dorsolateral PFC (dlPFC) activity (dorsal system); (2) trials in which emotion enhanced EM without disrupting WM were associated with increased ventrolateral PFC activity. The ventral-dorsal switch can explain EME and WMI, while the ventrolateral PFC effect suggests a coping mechanism. The second goal yielded two additional findings: (3) participants who were more susceptible to WMI showed greater amygdala increases and PFC reductions; (4) AMY activity increased and dlPFC activity decreased with measures of attentional impulsivity. Taken together, these results clarify the mechanisms linking the enhancing and impairing effects of emotion on memory, and provide insights into the role of individual differences in the impact of emotional distraction.

Nurses' preferred end-of-life treatment choices in five countries

BACKGROUND

Previous research has focused on physician's perspectives of end-of-life (EOL) decision making as well as patient and family EOL decision making. There is a lack of research pertaining to the EOL treatment preferences of nurses and especially nurses working in a variety of care settings.

AIM

The aim of this study was to compare nurses' EOL treatment preferences in Hong Kong, Ireland, Israel, Italy and the USA.

METHODS

A comparative descriptive design was used with a convenience sample of nurses (n = 1089). A survey questionnaire using EOL hypothetical clinical case scenarios was used to collect data between June 2011 and July 2012.

RESULTS

Nurses in every country consistently chose a more aggressive option for patients than for themselves or for a parent. The treatment preferences of nurses varied from country to country. Lack of knowledge of patients' wishes and duty of care were the main influencing factors on treatment preferences.

STUDY LIMITATIONS

The study was limited to the hypothetical nature of the scenarios; however, the study highlights numerous future research questions.

CONCLUSIONS

This study is the first to examine and compare nurses' preferred EOL treatment choices in five countries from three different continents. The findings of this study raise several important questions for healthcare researchers, for policy development, and highlight the need for further international collaboration.

Amygdala volume changes in posttraumatic stress disorder in a large case-controlled veterans group

CONTEXT

Smaller hippocampal volumes are well established in posttraumatic stress disorder (PTSD), but the relatively few studies of amygdala volume in PTSD have produced equivocal results.

OBJECTIVE

To assess a large cohort of recent military veterans with PTSD and trauma-exposed control subjects, with sufficient power to perform a definitive assessment of the effect of PTSD on volumetric changes in the amygdala and hippocampus and of the contribution of illness duration, trauma load, and depressive symptoms.

DESIGN

Case-controlled design with structural magnetic resonance imaging and clinical diagnostic assessments. We controlled statistically for the important potential confounds of alcohol use, depression, and medication use.

SETTING

Durham Veterans Affairs Medical Center, which is located in proximity to major military bases.

PATIENTS

Ambulatory patients (n = 200) recruited from a registry of military service members and veterans serving after September 11, 2001, including a group with current PTSD (n = 99) and a trauma-exposed comparison group without PTSD (n = 101).

MAIN OUTCOME MEASURE

Amygdala and hippocampal volumes computed from automated segmentation of high-resolution structural 3-T magnetic resonance imaging.

RESULTS

Smaller volume was demonstrated in the PTSD group compared with the non-PTSD group for the left amygdala (P = .002), right amygdala (P = .01), and left hippocampus (P = .02) but not for the right hippocampus (P = .25). Amygdala volumes were not associated with PTSD chronicity, trauma load, or severity of depressive symptoms.

CONCLUSIONS

These results provide clear evidence of an association between a smaller amygdala volume and PTSD. The lack of correlation between trauma load or illness chronicity and amygdala volume suggests that a smaller amygdala represents a vulnerability to developing PTSD or the lack of a dose-response relationship with amygdala volume. Our results may trigger a renewed impetus for investigating structural differences in the amygdala, its genetic determinants, its environmental modulators, and the possibility that it reflects an intrinsic vulnerability to PTSD.

Attributing intentions to random motion engages the posterior superior temporal sulcus

The right posterior superior temporal sulcus (pSTS) is a neural region involved in assessing the goals and intentions underlying the motion of social agents. Recent research has identified visual cues, such as chasing, that trigger animacy detection and intention attribution. When readily available in a visual display, these cues reliably activate the pSTS. Here, using functional magnetic resonance imaging, we examined if attributing intentions to random motion would likewise engage the pSTS. Participants viewed displays of four moving circles and were instructed to search for chasing or mirror-correlated motion. On chasing trials, one circle chased another circle, invoking the percept of an intentional agent; while on correlated motion trials, one circle's motion was mirror reflected by another. On the remaining trials, all circles moved randomly. As expected, pSTS activation was greater when participants searched for chasing vs correlated motion when these cues were present in the displays. Of critical importance, pSTS activation was also greater when participants searched for chasing compared to mirror-correlated motion when the displays in both search conditions were statistically identical random motion. We conclude that pSTS activity associated with intention attribution can be invoked by top-down processes in the absence of reliable visual cues for intentionality.

Effects of chronic mild traumatic brain injury on white matter integrity in Iraq and Afghanistan war veterans

Mild traumatic brain injury (TBI) is a common source of morbidity from the wars in Iraq and Afghanistan. With no overt lesions on structural MRI, diagnosis of chronic mild TBI in military veterans relies on obtaining an accurate history and assessment of behavioral symptoms that are also associated with frequent comorbid disorders, particularly posttraumatic stress disorder (PTSD) and depression. Military veterans from Iraq and Afghanistan with mild TBI (n = 30) with comorbid PTSD and depression and non-TBI participants from primary (n = 42) and confirmatory (n = 28) control groups were assessed with high angular resolution diffusion imaging (HARDI). White matter-specific registration followed by whole-brain voxelwise analysis of crossing fibers provided separate partial volume fractions reflecting the integrity of primary fibers and secondary (crossing) fibers. Loss of white matter integrity in primary fibers (P < 0.05; corrected) was associated with chronic mild TBI in a widely distributed pattern of major fiber bundles and smaller peripheral tracts including the corpus callosum (genu, body, and splenium), forceps minor, forceps major, superior and posterior corona radiata, internal capsule, superior longitudinal fasciculus, and others. Distributed loss of white matter integrity correlated with duration of loss of consciousness and most notably with "feeling dazed or confused," but not diagnosis of PTSD or depressive symptoms. This widespread spatial extent of white matter damage has typically been reported in moderate to severe TBI. The diffuse loss of white matter integrity appears consistent with systemic mechanisms of damage shared by blast- and impact-related mild TBI that involves a cascade of inflammatory and neurochemical events.

Goal-directed actions activate the face-sensitive posterior superior temporal sulcus and fusiform gyrus in the absence of human-like perceptual cues

The conditions under which we identify entities as animate agents and the neural mechanisms supporting this ability are central questions in social neuroscience. Prior studies have focused upon 2 perceptual cues for signaling animacy: 1) surface features representing body forms such as faces, torsos, and limbs and 2) motion cues associated with biological forms. Here, we consider a third cue--the goal-directedness of an action. Regions in the social brain network, such as the right posterior superior temporal sulcus (pSTS) and fusiform face area (FFA), are activated by human-like motion and body form perceptual cues signaling animacy. Here, we investigate whether these same brain regions are activated by goal-directed motion even when performed by entities that lack human-like perceptual cues. We observed an interaction effect whereby the presence of either human-like perceptual cues or goal-directed actions was sufficient to activate the right pSTS and FFA. Only stimuli that lacked human-like perceptual cues and goal-directed actions failed to activate the pSTS and FFA at the same level.

Function biomedical informatics research network recommendations for prospective multicenter functional MRI studies

This report provides practical recommendations for the design and execution of multicenter functional MRI (MC-fMRI) studies based on the collective experience of the Function Biomedical Informatics Research Network (FBIRN). The study was inspired by many requests from the fMRI community to FBIRN group members for advice on how to conduct MC-fMRI studies. The introduction briefly discusses the advantages and complexities of MC-fMRI studies. Prerequisites for MC-fMRI studies are addressed before delving into the practical aspects of carefully and efficiently setting up a MC-fMRI study. Practical multisite aspects include: (i) establishing and verifying scan parameters including scanner types and magnetic fields, (ii) establishing and monitoring of a scanner quality program, (iii) developing task paradigms and scan session documentation, (iv) establishing clinical and scanner training to ensure consistency over time, (v) developing means for uploading, storing, and monitoring of imaging and other data, (vi) the use of a traveling fMRI expert, and (vii) collectively analyzing imaging data and disseminating results. We conclude that when MC-fMRI studies are organized well with careful attention to unification of hardware, software and procedural aspects, the process can be a highly effective means for accessing a desired participant demographics while accelerating scientific discovery.

Brain imaging investigation of the impairing effect of emotion on cognition

Emotions can impact cognition by exerting both enhancing (e.g., better memory for emotional events) and impairing (e.g., increased emotional distractibility) effects (reviewed in (1)). Complementing our recent protocol (2) describing a method that allows investigation of the neural correlates of the memory-enhancing effect of emotion (see also (1, 3-5)), here we present a protocol that allows investigation of the neural correlates of the detrimental impact of emotion on cognition. The main feature of this method is that it allows identification of reciprocal modulations between activity in a ventral neural system, involved in 'hot' emotion processing (HotEmo system), and a dorsal system, involved in higher-level 'cold' cognitive/executive processing (ColdEx system), which are linked to cognitive performance and to individual variations in behavior (reviewed in (1)). Since its initial introduction (6), this design has proven particularly versatile and influential in the elucidation of various aspects concerning the neural correlates of the detrimental impact of emotional distraction on cognition, with a focus on working memory (WM), and of coping with such distraction (7,11), in both healthy (8-11) and clinical participants (12-14).

Neural systems for guilt from actions affecting self versus others

Guilt is a core emotion governing social behavior by promoting compliance with social norms or self-imposed standards. The goal of this study was to contrast guilty responses to actions that affect self versus others, since actions with social consequences are hypothesized to yield greater guilty feelings due to adopting the perspective and subjective emotional experience of others. Sixteen participants were presented with brief hypothetical scenarios in which the participant's actions resulted in harmful consequences to self (guilt-self) or to others (guilt-other) during functional MRI. Participants felt more intense guilt for guilt-other than guilt-self and guilt-neutral scenarios. Guilt scenarios revealed distinct regions of activity correlated with intensity of guilt, social consequences of actions, and the interaction of guilt by social consequence. Guilt intensity was associated with activation of the dorsomedial PFC, superior frontal gyrus, supramarginal gyrus, and anterior inferior frontal gyrus. Guilt accompanied by social consequences was associated with greater activation than without social consequences in the ventromedial and dorsomedial PFC, precuneus, posterior cingulate, and posterior superior temporal sulcus. Finally, the interaction analysis highlighted select regions that were more strongly correlated with guilt intensity as a function of social consequence, including the left anterior inferior frontal gyrus, left ventromedial PFC, and left anterior inferior parietal cortex. Our results suggest these regions intensify guilt where harm to others may incur a greater social cost.

The posterior superior temporal sulcus is sensitive to the outcome of human and non-human goal-directed actions

Prior studies have demonstrated that the posterior superior temporal sulcus (pSTS) is involved in analyzing the intentions underlying actions and is sensitive to the context within which actions occur. However, it is debated whether the pSTS is actually sensitive to goals underlying actions, or whether previous studies can be interpreted to suggest that the pSTS is instead involved in the allocation of visual attention towards unexpected events. In addition, little is known about whether the pSTS is specialized for reasoning about the actions of social agents or whether the pSTS is sensitive to the actions of both animate and inanimate entities. Here, using functional magnetic resonance imaging, we investigated activation in response to passive viewing of successful and unsuccessful animate and inanimate goal-directed actions. Activation in the right pSTS was stronger in response to failed actions compared to successful actions, suggesting that the pSTS plays a role in encoding the goals underlying actions. Activation in the pSTS did not differentiate between animate and inanimate actions, suggesting that the pSTS is sensitive to the goal-directed actions of both animate and inanimate entities.