Neural correlates underlying humans’ differential sensitivity to emotionally negative stimuli of varying valences: an ERP study

The present study aims to investigate the neural correlates underlying humans’ sensitivity to valence differences in negative stimuli. Event-related potentials (ERPs) for highly negative (HN), moderately negative (MN), and Neutral pictures were recorded while subjects perform a standard/deviant categorization task, irrespective of the emotional valence of the deviants. The results show more negative ERP deflections during HN condition than during MN condition at each 50 ms interval from 350 to 650 ms after stimulus onset (at P3 and slow negative wave (SNW) components). Moreover, emotional effect was also observed for MN stimuli at P3 component (350—450 ms interval). Dipole analyses on the HN-MN difference wave during 350—450 ms interval (P3 component) and that during 450—650 ms interval (SNW component) were both localized to the right medial temporal lobe. Thus, the present study confirmed the human sensitivity to valence variations in emotionally negative stimuli, and further showed that the right medial temporal lobe, in particular, the right hippocampus/amygdala complex, may be the critical neural substrates underlying humans’ differential sensitivity to emotionally negative stimuli of varying valences.     

＂Aha!＂ effects in a guessing Chinese logogriph task： An event-related potential study

In the present study, high-density event-related potentials （ERPs） were recorded to examine the electrophysiologic correlates of ＂Aha!＂ effects in a guessing Chinese Iogogriph task by using a two-stage model for learning-testing. Results showed that： Firstly Successful Guessing elicited a more negative ERP deflection （N350） than Recognition did in the time window from 300--350 ms after onset of the stimuli. A voltage map of the difference wave （Successful Guessing minus Recognition） showed strong activity at the front-central region. Dipole analysis localized the generator of the N350 in the vicinity of the posterior cingulate cortex （PCC） and the inferior frontal gyrus. Secondly, a greater late positive component （LPC） in Successful Guessing than Recognition was found between 600 and 700 ms post-stimulus. Dipole analysis localized the generator of LPC in the right parahippocampal gyrus.     

Modulation of human global／local perception by low spatial frequency filtering

We investigated the effect of low spatial frequency (SF) filtering on neural substrates underlying global and local processing in the peripheral vision by measuring hemodynamic responses with functional magnetic resonance imaging (fMRI). Subjects identified global or local shapes of compound letters that were either broadband in spatialfrequency spectrum or contrast balanced (CB) to removed low SFs and displayed randomly in the left or right visual fields. Attention to both broadband and CB global shapes generated stronger activation over the medial occipital cortex relative to local attention. Lateralized activations in association with global processing were observed over the right temporal-parietal junction for broadband stimuli whereas over the right fusiform gyrns for CB stimuli. Attention to CB local shapes resulted in activations in the medial frontal cortex, bilateral inferior frontal and superior temporal cortices.The results were discussed in terms of the competition between global and local information in determining brain activations in association with global/local processing of compound stimuli.     

Neural correlates of moral judgment of lying： An event-related-potential study

The present study investigated neural mechanisms of moral judgment of lying in adults using high-density event-related potentials (ERPs). Participants were recruited to do moral judgment of 200 stories including two types of lying and their corresponding truth-telling. The results showed that both types of lying were judged more negative than their corresponding truth-telling, and moral judgment of black lying was more negative than that of modest lying. There were two main components of the ERPs evoked by the test stimuli. One was an early component, peaking at about 200 ms, and the other was a late component, peaking at about 400 ms. Over the frontal scalp sites, the early component was positive and the late component was negative, while they both reversed over the posterior sites. The ERPs of both types of lying was more positive than that of their corresponding truth-telling in the time window of 600—900 ms at the posterior sites.     

Neural correlates of moral judgment of lying： An event-related-potential study

The present study investigated neural mechanisms of moral judgment of lying in adults using high-density event-related potentials (ERPs). Participants were recruited to do moral judgment of 200 stories including two types of lying and their corresponding truth-telling. The results showed that both types of lying were judged more negative than their corresponding truth-telling, and moral judgment of black lying was more negative than that of modest lying. There were two main components of the ERPs evoked by the test stimuli. One was an early component, peaking at about 200 ms, and the other was a late component, peaking at about 400 ms. Over the frontal scalp sites, the early component was positive and the late component was negative, while they both reversed over the posterior sites. The ERPs of both types of lying was more positive than that of their corresponding truth-telling in the time window of 600—900 ms at the posterior sites.     

Differences of relevance in implicit and explicit memory tests: An ERP study

An ERP study was conducted to explore the differences between other-relevant words and possessor-relevant words in implicit and explicit memory tests. The results show that other-relevant words are associated with a more negative ERP than possessor-relevant words during 300--900 ms whether in the implicit or the explicit memory tests. The N400 effect is also found in semantic processing of social materials. There is an ERP dissociation of retrieval formats between the implicit and the explicit memory tests during 700--900 ms, namely, there is no difference between other-relevant words and possessor-relevant words in the implicit memory while there is a significant difference between them in the explicit memory. Observed through Curry 6.0, the analysis of neural sources for other-relevant words and possessor-relevant words indicates that they have different locations. At 400 ms, activity is found in the left precuneus during possessor-relevant words processing. Both the right and the left precuneus are activated during other-relevant words processing. However, at 600 ms their location is both in the left precuneus. In a word, our results show that there exists a cognitive difference between other-relevant words and possessor-relevant words, and other-relevant words closely related to the percipient himself/herself are strongly responded to, which reflects that there is a bigger attention bias to the stimuli concerning the percipient himself/herself than to processor-relevant words.     

Interactions between working memory and selective attention

Event-related potential (ERP) was used to examine the interactions between working memory and se- lective attention. We combined two unrelated tasks, one requiring working memory and the other se- lective attention, which were performed by some undergraduates. The ERP results revealed that both congruent and incongruent stimuli in the selective attention task evoked an N400 component, reaching the peak point at around 500 ms. The N400 evoked by incongruent stimuli was more negative than that of congruent, which indicated the difference of semantic N400. Furthermore, working memory load had a significant influence on the N400 evoked by selective attention task in parietal region. And working memory load showed difference in the ERPs of working memory retrieval in central and parietal regions. The ERPs of probe under high working memory load were more positive from 350 to 550 ms post-stimulus; however, stimulus type of selective attention had no influence on working memory re- trieval. The present study shows that working memory does not play a major role in the selective at- tention, especially in ignoring distracter, but it influences the performance of the selective attention as the background. The congruency of target and distracter in the selective attention task does not influ- ence the working memory retrieval.     

Effects of forward masking on the responses of the inferior collicular neurons in the big brown bats, Eptesicus fuscus

The present study explores the forward masking of the two-tone stimuli in sequence that evoked responses in the inferior colliculns (IC) of the echolocating bats. The results indicate that forward masking is obvious in the acoustic responses of the IC neurons to the two-tone stimuli.Meanwhile the intensity sensitivity of the neurons responding to the probe increases with the inter-tone interval decreasing. The effects of forward masking are correlated with the relative intensity and the interval between the masker and probe. That is, the effects of forward masking are reduced with the masker intensity decreasing and enhanced with the probe intensity decreasing and the inter-tone interval shortened. The present study suggests that there is a correlation between the characteristics of the response to the probe and the dynamic conditions of the postsynaptic currents in the IC neurons.     

Relationship between the partitioning properties of motoneuron recruitment and the needle feeling propagation

Histological and physiological studies indicated that most skeletal muscles can be divided into a series of relatively independent sub-volumes: "neuromuscular compartments" and the partitioning property of the muscle result in the localization of muscle reflex. In the present experiment we studied the recruitment properties of medial gastracnemius (MG) muscle motoneuron pool of decerebrate cat with two kinds of local mechanical stimulation: local stretch and acupuncture-like stimuli. The results indicate that: (ⅰ) there is an obvious property of localization of recruitment activity, only the MNs which innervate the stimulated compartment were recruited by weaker and shorter stimuli; (ⅱ) recruitment activity spread to those MNs which supply the adjacent and distal compartments during the strength of stimulation or duration of the stimulation was increased; and (ⅲ) the recruitment property of muscle activity elicited by the local mechanical stimulation is thought similar to that of "needle feeling" along the meridian pathway during stimulation of acupuncture point.     

Time perception of emotional events

This study investigates whether the accuracy of time perception is influenced by the nature of emotional events and whether time perception has gender differences. Subjects were asked to control the presenting time of pictures of affective facial expressions and to match it with a pre-specified time range. Results showed that (1) compared with the neutral condition, subjects tended to underestimate the time for angry expressions and to overestimate the time for happy expressions; (2) women overestimated the time range much more than men for all the three types of expressions; (3) the size of overestimation steadily decreased over time ranges (0.5—6 sec), and the influence by the affective expressions was observed only at the short time ranges (0.5—2 sec.). These results suggest that time perception of emotional events is varied with emotional valence, and women tend to overestimate all the emotional events.     

Time perception of emotional events

This study investigates whether the accuracy of time perception is influenced by the nature of emotional events and whether time perception has gender differences. Subjects were asked to control the presenting time of pictures of affective facial expressions and to match it with a pre-specified time range. Results showed that (1) compared with the neutral condition, subjects tended to underestimate the time for angry expressions and to overestimate the time for happy expressions; (2) women overestimated the time range much more than men for all the three types of expressions; (3) the size of overestimation steadily decreased over time ranges (0.5—6 sec), and the influence by the affective expressions was observed only at the short time ranges (0.5—2 sec.). These results suggest that time perception of emotional events is varied with emotional valence, and women tend to overestimate all the emotional events.     

A potential ethnic difference in the association between 5-HTTLPR polymorphisms and the brain default mode network

The serotonin-transporter-linked polymorphic region （5-HTTLPR） is associated with mood disorders. This association is thought to be due to amygdala hyper- responsiveness to negative emotional stimuli as a result of reduced frontal cortical control. In Caucasians, the short form is associated with this effect, but in Han Chinese we recently found that the long form is involved. Serotonin receptors have rich expression in default mode network （DMN） regions and the recent studies have found an association between the short form of the 5-HTTLPR and DMN functional connectivity （FC） in Caucasians. The present study has investigated whether there may also be an ethnic difference in this influence of 5-HTTLPR on the DMN. We recruited 233 young Han Chinese subjects and calculated the resting-state default-network FC. Our study found that the L carriers had decreased FC in the bilateral medial prefrontal cortex, right parahippocampal gyrus, left middle temporal gyrus, and increased FC in left precuneus （Pcu） compared to SS. The PCC-Pcu FC in L carriers was significantly negatively correlated with the depression scores. Our findings, therefore, suggest that there is also a difference between Caucasian and Han Chinese subjects in the association between the different forms of the 5-HTTLPR and DMN functional connectivity.     

Relationship between perceptual and semantic levels of representation: An event-related potential study

An event-related potential study was conducted to make clear the relationships between perceptual and semantic levels of representation. Subjects judged the semantic relationship between a picture sample and a word match using the delayed match-to-sample paradigm. The experiment includes three types of matching trials, i.e., identical match trials, where the words had the same meanings as the pictures, categorical match trials where the words matched the pictures in category, and non-match trials where the words matched neither in identification nor in category with the pictures. The three conditions evoke significantly different N400-1ike and P300 ERP components. Specifically, for the N400-1ike negative responses, the averaged amplitude of the non-match condition is the largest and the most negative-going, that of the categorical match condition is less negative-going, and that of the identical match condition is the smallest among all three conditions. In addition, only the identical match condition evokes an early P300 component. As for the late P300 component, the averaged amplitude of the categorical match condition is more robust in the frontal brain areas. In contrast, ERPs of the non-match condition are stronger in the posterior brain areas. From 250 to 450 ms, the difference waves between the identical match and non-match conditions are located in the central areas, and the difference waves between categorical match and non-match conditions occur in the right frontal areas. Our results suggest that cross-form picture-word identical matching and categorical matching involve different underlying mechanisms. The existence of the early P300 component evokes by the identical match condition provides support for theories of template matching and facilitation model.     

New animal model of emotional stress： Behavioral, neuroendocrine and immunological consequences

This report describes a new model of emotional stress, which was induced by randomly giving an empty water bottle to rats during watering periods per day for 14 consecutive days. The behavioral, endocrinological and immunological consequences were investigated. The data showed that the emotional stress activated both the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system, leading to the increased blood levels of corticosterone and catecholamine. It also elicited attacking and exploring behavior, suppressed the immune function of the rats, including leukocyte counts, weight of the spleen, and the level of specific anti-ovalbumin IgG antibody production. Presenting no water and no empty bottle to rats only evoked the exploring behavior, increased the corticosterone level and decreased the leukocyte counts. These findings demonstrate a role of psychological factors on behavioral, endocrinological and immunological functioning. The animal model described in the present study may serve as an analogue mimicking emotional stress experienced in humans (e.g. anger and/or anxiety), and may be useful for further studying the complex relationships among emotional stress, behavior, and immune function.     

The neural mechanisms of pain-related affect and memory

The pain experience includes a sensory-discriminative and an emotional-affective components. The affective dimension refers to the unpleasantness or aversion of sensation. The great progress at the genetic, molecular, cellular, and systemic levels on the study of the sensory dimension of pain has been made over past four decades. However, “to consider only the sensory features of pain, and ignore its motivational and affective properties, is to look at only part of the problem and not even the most important part of that”. A line of clinic observations indicate that the patients with chronic pain suffer from much more affective disturbance than pain itself. Obviously, physiological arousal and hypervigilance to pain cause negative affect, such as anxiety, anger, worry, aversion, even tendency of suicide, these negative affective states in turn enhance pain sensation. Today, more and more attention has been paid to the study on mechanisms underlying affective dimension of pain. In order to deepen and expand our understanding of the nature of pain, this review summarizes the main progress and recent findings from our laboratory regarding affective component of pain in neuroanatomy, neurophysiology, and cell biochemistry.     

Differentiating electrophysiological response to decrease and increase negative emotion regulation

We investigated the reappraisal and the time course of negative emotion regulation by performing event-related potential (ERP) recordings. We found that negative pictures elicited more positive P2 and late positivity potential (LPP) deflections than neutral pictures. This effect occurred between 150-2000 ms post-stimulus. Compared to the emotion maintaining condition, the emotion enhancing condition was associated with higher arousal ratings and displayed increased P2 and LPP amplitudes. The decrease condition was also associated with reduced picture-induced arousal; however, it led to increased P2 and LPP amplitudes. Furthermore, when compared with the maintain condition, both the enhancing and decrease conditions significantly enhanced LPP in the early stage (350-750 ms). Compared to previous studies using western subjects, the negative emotion LPP effects of the present study were shorter in duration and the decrease-emotion condition elicited larger LPPs.     

Late Holocene paleoenvironmental changes in the southern Okinawa Trough inferred from a diatom record

We analyzed sediment diatoms from core MD05-2908 to infer climate and paleoenvironmental changes in the southern Okinawa Trough (SOT) over the past 1000 years.Because the study area is located in the East Asia monsoon area and beneath the main axis of Kuroshio Current,the climatic and hydrographical conditions are strongly influenced by both of these factors.The species used as environmental indicators,including the Kuroshio Current species (KC species) and freshwater species,were investigated in this paper.Changes in the abundance of the two groups of species revealed significant variations in water temperature and hydrography in the SOT during the Medieval Warm Period (MWP) and the Little Ice Age (LIA).From 950-1500 AD,the abundance of the KC species increased fluctuantly,while the freshwater species decreased,showing that the influence of the Kuroshio Current was intensified at that interval and the precipitation of the study area was relatively low.The KC species decreased remarkably and was maintained at a low abundance during the interval of 1500-1900 AD,which suggests that the impact of the Kuroshio Current on the SOT weakened during the period corresponding to the LIA.Moreover,the high abundance of the freshwater species at the same interval indicates a distinct increase in precipitation in northeastern Taiwan,which may be correlated to the south-detention of the rainfall belt in China caused by the southward migration of the western Pacific subtropical high.     

Executive inhibition in mental arithmetic

Event-related potentials (ERPs) were measured to investigate the executive inhibitory processes in mental arithmetic. Subjects had to compute arithmetic expressions visually presented in four chunks. ERP analyses were conducted for the second chunk comparing the “NoCalculate” to the “Calculate” conditions. In the Calculate condition subjects could compute intermediate results. In the NoCalculate condition subjects had to withhold the computation. The results showed a negative effect (N380) over frontocentral regions at about 380 ms, probably reflecting the calculation inhibition demand in the NoCalculate condition. In addition, the dN380 (NoCalculate-Calculate difference) was more pronounced in the right hemisphere, which is consistent with the findings of previous fMRI and PET studies that the right prefrontal cortex is closely associated with response inhibition. The results support the generalization of the frontocentral N2 as a neurobehavioral tool for investigating inhibitory executive control.     

Executive inhibition in mental arithmetic

Event-related potentials (ERPs) were measured to investigate the executive inhibitory processes in mental arithmetic. Subjects had to compute arithmetic expressions visually presented in four chunks. ERP analyses were conducted for the second chunk comparing the “NoCalculate” to the “Calculate” conditions. In the Calculate condition subjects could compute intermediate results. In the NoCalculate condition subjects had to withhold the computation. The results showed a negative effect (N380) over frontocentral regions at about 380 ms, probably reflecting the calculation inhibition demand in the NoCalculate condition. In addition, the dN380 (NoCalculate-Calculate difference) was more pronounced in the right hemisphere, which is consistent with the findings of previous fMRI and PET studies that the right prefrontal cortex is closely associated with response inhibition. The results support the generalization of the frontocentral N2 as a neurobehavioral tool for investigating inhibitory executive control.     

Jurassic-Cretaceous boundary in northeastern China: placement based on buchiid bivalves and dinoflagellate cysts

Global environments changed greatly during the Late Jurassic and Early Cretaceous, particularly during the Jurassic-Cretaceous boundary interval. Separation of the world into Tethyan, Boreal and other biogeographic realms complicates international correlation, and even the pelagic ammonites cannot play their characteristic role of principle correlation criteria. In the Boreal and North Pacific realms, the Late Jurassic and Cretaceous buchiid bivalve zones have very good calibration to Boreal ammonite zones, which, in turn, have approximate correlations to Tethyan ammonite zones. Therefore, buchiid bivalves provide a means to identify Upper Jurassic-Lower Cretaceous stages and the Jurassic-Cretaceous boundary interval. The base of the Buchia unschensis Zone is roughly coincident with the Boreal ammonite Craspedites exoticus subzone, Upper Volgian Craspedites okensis Zone, which in turn closely corresponds to the base of the Tethyan ammonite basal Berriasian Berriasella jacobi Zone. The top of the underlying Buchia russiensis Zone approximately coincides with that of the uppermost Middle Volgian, Boreal ammonite Epivirgatites variabilis Zone, which approximately corresponds to the Tethyan ammonite Durangites Zone of uppermost Tithonian. Buchia and dinoflagellate cyst assemblages from two regions in eastern Heilongjiang of northeastern China indicate the presence of the Jurassic-Cretaceous boundary interval. The Dong’anzhen Formation of Dong’an, Raohe County contains Middle Volgian-Lower Valanginian Buchia assemblages and the Jurassic-Cretaceous boundary is tentatively assigned to either the base of the Buchia fischeriana-Buchia unschensis assemblage or between the Buchia fischeriana-Buchia unschensis and Buchia russiensis-Buchia fischeriana assemblages. The Dongrong Formation from boreholes at Suibin, Suibin County, yields uppermost Oxfordian to basal Berriasian Buchia assemblages and Oxfordian-Barremian dinoflagellate cyst assemblages. Here, the Jurassic-Cretaceous boundary interval is probably between the Buchia cf. mosquensis-Buchia cf. rugosa assemblage (including Buchia ex gr. russiensis and Buchia ex gr. taimyrensis) and the overlying non-Buchia-bearing deposits.