The functional dissociation of posterior parietal regions during multimodal memory formation

The incidental acquisition of multimodal associations is a key memory function for everyday life. While the posterior parietal cortex has been frequently shown to be involved for these memory functions, ventral and dorsal regions revealed differences in their functional recruitment and the precise difference in multimodal memory processing with respect to the associative process has not been differentiated. Using an incidental multimodal learning task, we isolated the associative process during multimodal learning and recollection. The result of the present functional magnetic resonance imaging (fMRI) study demonstrated that during both learning and recollection a clear functional differentiation between ventral and dorsal posterior parietal regions was found and can be related directly to the associative process. The recruitment of a ventral region, the angular gyrus, was specific for learning and recollection of multimodal associations. In contrast, a dorsal region, the superior parietal lobule, could be attributed to memory guided attentional processing. Independent of the memory stage, we assumed a general role for the angular gyrus in the generation of associative representations and updating of fixed association, episodic memory.     

Headache-related circuits and high frequencies evaluated by EEG,MRI, PET as potential biomarkers to differentiate chronic and episodic migraine: Evidence from a systematic review

BackgroundThe diagnosis of migraine is mainly clinical and self-reported, which makes additional examinations unnecessary in most cases. Migraine can be subtyped into chronic (CM) and episodic (EM). Despite the very high prevalence of migraine, there are no evidence-based guidelines for differentiating between these subtypes other than the number of days of migraine headache per month. Thus, we consider it timely to perform a systematic review to search for physiological evidence from functional activity (as opposed to anatomical structure) for the differentiation between CM and EM, as well as potential functional biomarkers. For this purpose, Web of Science (WoS), Scopus, and PubMed databases were screened.FindingsAmong the 24 studies included in this review, most of them (22) reported statistically significant differences between the groups of CM and EM. This finding is consistent regardless of brain activity acquisition modality, ictal stage, and recording condition for a wide variety of analyses. That speaks for a supramodal and domain-general differences between CM and EM that goes beyond a differentiation based on the days of migraine per month. Together, the reviewed studies demonstrates that electro- and magneto-physiological brain activity (M/EEG), as well as neurovascular and metabolic recordings from functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), show characteristic patterns that allow to differentiate between CM and EM groups.ConclusionsAlthough a clear brain activity-based biomarker has not yet been identified to distinguish these subtypes of migraine, research is approaching headache specialists to a migraine diagnosis based not only on symptoms and signs reported by patients. Future studies based on M/EEG should pay special attention to the brain activity in medium and fast frequency bands, mainly the beta band. On the other hand, fMRI and PET studies should focus on neural circuits and regions related to pain and emotional processing.     

刺激养老穴激活脑功能区的不同阈值分析

目的为针刺的fMRI研究的统计分析选择合宜的的阈值。方法选取健康青年志愿者12例,进行刺激养老穴的fMRI研究,采用组块模式,使用SPM2对扫描后图像进行后处理,采用校正和非校正来统计分析脑功能激活情况。结果在校正象情况下（组分析,FWE,0．05,K≥10）,养老穴主要激活了左顶叶的顶下小叶BA40,右侧额叶的额下回BA45、BA46,其次为左侧颞中回、颞下回BA37,左额上回BA10。而非校正情况下,激活点非常广泛。结论在穴位的脑功能激活实验应选择校正像分析。     

Causal effect of disconnection lesions on interhemispheric functional connectivity in rhesus monkeys

In the absence of external stimuli or task demands, correlations in spontaneous brain activity (functional connectivity) reflect patterns of anatomical connectivity. Hence, resting-state functional connectivity has been used as a proxy measure for structural connectivity and as a biomarker for brain changes in disease. To relate changes in functional connectivity to physiological changes in the brain, it is important to understand how correlations in functional connectivity depend on the physical integrity of brain tissue. The causal nature of this relationship has been called into question by patient data suggesting that decreased structural connectivity does not necessarily lead to decreased functional connectivity. Here we provide evidence for a causal but complex relationship between structural connectivity and functional connectivity: we tested interhemispheric functional connectivity before and after corpus callosum section in rhesus monkeys. We found that forebrain commissurotomy severely reduced interhemispheric functional connectivity, but surprisingly, this effect was greatly mitigated if the anterior commissure was left intact. Furthermore, intact structural connections increased their functional connectivity in line with the hypothesis that the inputs to each node are normalized. We conclude that functional connectivity is likely driven by corticocortical white matter connections but with complex network interactions such that a near-normal pattern of functional connectivity can be maintained by just a few indirect structural connections. These surprising results highlight the importance of network-level interactions in functional connectivity and may cast light on various paradoxical findings concerning changes in functional connectivity in disease states.     

Spontaneous and intentional trait inferences recruit a common mentalizing network to a different degree: Spontaneous inferences activate only its core areas

This fMRI study analyzes inferences on other persons' traits, whereby half of the participants were given spontaneous (“read”) instructions while the other half were given intentional (“infer the person's trait”) instructions. Several sentences described the behavior of a target person from which a strong trait could be inferred (trait diagnostic) or not (trait nondiagnostic). A direct contrast between spontaneous and intentional instructions revealed no significant differences, indicating that the same social mentalizing network was recruited. There was, however, a difference with respect to different brain areas that passed the significance threshold, suggesting that this common network was recruited to a different degree. Specifically, spontaneous inferences significantly recruited only core mentalizing areas, including the temporo-parietal junction and medial prefrontal cortex, whereas intentional inferences additionally recruited other brain areas, including the (pre)cuneus, superior temporal sulcus, temporal poles, and parts of the premotor and parietal cortex. These results suggest that intentional instructions invite observers to think more about the material they read, and consider it in many ways besides its social impact. Future research on the neurological underpinnings of trait inference might profit from the use of spontaneous instructions to get purer results that involve only the core brain areas in social judgment.     

Social,reward, and attention brain networks are involved when online bids for joint attention are met with congruent versus incongruent responses

Joint attention (JA) is a cornerstone of adaptive human social functioning. Little functional magnetic resonance imaging (fMRI) research has examined, in interactive paradigms, neural activation underlying bids for JA, met with a congruent or an incongruent social response. We developed a highly naturalistic fMRI paradigm utilizing eye-tracking to create real-time, contingent social responses to participant-initiated JA. During congruent responses to JA bids, we observed increased activation in the right amygdala, the right fusiform gyrus, anterior and dorsal anterior cingulate cortices, striatum, ventral tegmental area, and posterior parietal cortices. Incongruent responses to JA bids elicited increased activity localized to the right temporoparietal junction (TPJ) and bilateral cerebellum. No differences in eye-gaze patterns were observed during congruent or incongruent trials. Our results highlight the importance of utilizing interactive fMRI paradigms in social neuroscience and the impact of congruency in recruiting integrated social, reward, and attention circuits for processing JA.     

Early life Adversity,functional connectivity and cognitive performance in Schizophrenia: The mediating role of IL-6

ObjectiveExposure to childhood trauma (CT) is associated with cognitive impairment in schizophrenia, and deficits in social cognition in particular. Here, we sought to test whether IL-6 mediated the association between CT and social cognition both directly, and sequentially via altered default mode network (DMN) connectivity.MethodsThree-hundred-and-eleven participants (104 patients and 207 healthy participants) were included, with MRI data acquired in a subset of n = 147. CT was measured using the childhood trauma questionnaire (CTQ). IL-6 was measured in both plasma and in toll like receptor (TLR) stimulated whole blood. The CANTAB emotion recognition task (ERT) was administered to assess social cognition, and cortical connectivity was assessed based on resting DMN connectivity.ResultsHigher IL-6 levels, measured both in plasma and in toll-like receptor (TLR-2) stimulated blood, were significantly correlated with higher CTQ scores and lower cognitive and social cognitive function. Plasma IL-6 was further observed to partly mediate the association between higher CT scores and lower emotion recognition performance (CTQ total: β_indirect −0.0234, 95% CI: −0.0573 to −0.0074; CTQ physical neglect: β_indirect = −0.0316, 95% CI: −0.0741 to −0.0049). Finally, sequential mediation was observed between plasma IL-6 levels and DMN connectivity in mediating the effects of higher CTQ on lower social cognitive function (β_indirect = −0.0618, 95% CI: −0.1523 to −0.285).ConclusionThis work suggests that previous associations between CT and social cognition may be partly mediated via an increased inflammatory response. IL-6′s association with changes in DMN activity further suggest at least one cortical network via which CT related effects on cognition may be transmitted.     

POSITIVE AFFECT MODULATES ACTIVITY IN THE VISUAL CORTEX TO IMAGES OF HIGH CALORIE FOODS

Activity within the visual cortex can be influenced by the emotional salience of a stimulus, but it is not clear whether such cortical activity is modulated by the affective status of the individual. This study used functional magnetic resonance imaging (fMRI) to examine the relationship between affect ratings on the Positive and Negative Affect Schedule and activity within the occipital cortex of 13 normal-weight women while viewing images of high calorie and low calorie foods. Regression analyses revealed that when participants viewed high calorie foods, Positive Affect correlated significantly with activity within the lingual gyrus and calcarine cortex, whereas Negative Affect was unrelated to visual cortex activity. In contrast, during presentations of low calorie foods, affect ratings, regardless of valence, were unrelated to occipital cortex activity. These findings suggest a mechanism whereby positive affective state may affect the early stages of sensory processing, possibly influencing subsequent perceptual experience of a stimulus.     

THE EFFECT OF REPETITIVE ELECTRICAL STIMULATION ON THE MOTOR EVOKED HEMODYNAMIC RESPONSES

The aim of this study was to investigate the influence of short-term repetitive electrical stimulation (rES training session) on the motor-evoked hemodynamic responses. The fMRI echo-planar images (EPI) were recorded before and after the rES training. The right median nerve (MN) was stimulated during rES. The rES training resulted in a significant increase in activity in a number of supraspinal regions, including sensorimotor and associative cortical areas. On the subcortical level, the effect was also found in the cerebellum, the midbrain, and the thalamus. Possible mechanisms of the neuronal plastic changes observed after rES, and memory processes involved in learning are discussed.