Cooperation and competition between the default mode network and frontal parietal network in the elderly.

Recent research has shown that the Default Mode Network (DMN) typically exhibits increased activation during processing of social and personal information but shows deactivation during working memory (WM) tasks. Previously, we reported the Frontal Parietal Network (FPN) and DMN showed coactivation during task preparation whereas the DMN exhibited deactivation during task execution in working memory tasks. Aging research has shown that older adults exhibited decreased functional connectivity in the DMN relative to younger adults. Here, we investigated whether age-related cognitive decline is related to a reduced relationship between the FPN and DMN using a working memory task during the execution period. First, we replicated our previous finding that the FPN and DMN showed coactivation during the preparation period, whereas the DMN showed deactivation during the execution period. The older adults showed reduced DMN activity during task preparation and reduced deactivation during task execution; however, they exhibited a higher magnitude of activation in the FPN than the young individuals during task execution. Functional connectivity analyses showed that the elderly group, compared to the young group, showed weaker correlations within the FPN and the DMN, weaker positive correlations between the FPN and DMN during task preparation, and weaker negative correlations between the FPN and DMN during execution. The results suggest that cognitive decline in the older adults might be related to reduced connectivity within the DMN as well as between the FPN and DMN.

Emotional neuroaesthetics of color experience: Views from single, paired, and complex color combinations.

Colors are critical for understanding the emotional aspect of the human artistic mind, such as that found in painting a landscape, still life, or portrait. First, we report how single colors are memorized in the brain; second, how pairs of colors harmonize in the dissociated brain under the influence of the emotional brain; third, we see how colored paintings are appreciated as beautiful or ugly in the dissociated brain areas led by the intrinsic reward system in the human brain. The orbitofrontal brain is probably one of the vital brain areas that brings us a value-based reward system that makes a unique contribution to emotional neuroaesthetics.

Does Implicit Self-Reference Effect Occur by the Instantaneous Own-Name?

Self-reference effect (SRE) is defined as better recall or recognition performance when the materials that are memorized refer to the self. The SRE paradigm usually requires participants to explicitly refer items to themselves, but some researchers have found that the SRE also can occur for implicitly self-referenced items. Few studies though have investigated the effect of self-related stimuli without awareness. In this study, we presented self-related (participants' names) or other (other's names or nouns) stimuli for a very short time between masks and then explicitly presented subsequent trait adjectives to participants. Recognition performance showed no significant differences between the own-name and the other two conditions in Experiment 1 that had random-order conditions. On the other hand, the result of Experiment 2 that had block-order conditions and greater prime stimuli suggests that SRE can occur as a result of the instantaneous stimulus: Subjects who showed better memory performance also had relatively high recognition of the trait adjectives that they viewed after their instantaneously presented own-name. This effect would show that self-representation can be activated by self-related stimuli without awareness and that subsequent items are unconsciously referenced to that self-representation.

Capacity differences in working memory based on resting state brain networks.

Herein, we compared the connectivity of resting-state networks between participants with high and low working memory capacity groups. Brain network connectivity was assessed under both resting and working memory task conditions. Task scans comprised dual-task (reading sentences while memorizing target words) and single-task (reading sentences) conditions. The low capacity group showed relatively stronger connectivity during resting-state in most brain regions, and the high capacity group showed a stronger connectivity between the medial prefrontal and posterior parietal cortices. During task performance, the dorsal attention and salience networks were relatively strongly connected in the high capacity group. In the comparison between dual- and single-task conditions, increased coupling between the anterior cingulate cortex and other attentional control-related areas were noted in the high capacity group. These findings suggest that working memory differences are related with network connectivity variations in attentional control-associated regions during both resting and task performance conditions.

Novel haemodialysis (HD) treatment employing molecular hydrogen (H2)-enriched dialysis solution improves prognosis of chronic dialysis patients: A prospective observational study.

Recent studies have revealed unique biological characteristics of molecular hydrogen (H2) as an anti-inflammatory agent. We developed a novel haemodialysis (E-HD) system delivering an H2 (30-80 ppb)-enriched dialysis solution by water electrolysis, and conducted a non-randomized, non-blinded, prospective observational study exploring its clinical impact. Prevalent chronic HD patients were allocated to either the E-HD (n = 161) group or the conventional HD (C-HD: n = 148) group, and received the respective HD treatments during the study. The primary endpoint was a composite of all-cause mortality and development of non-lethal cardio-cerebrovascular events (cardiac disease, apoplexy, and leg amputation due to peripheral artery disease). During the 3.28-year mean observation period, there were no differences in dialysis parameters between the two groups; however, post-dialysis hypertension was ameliorated with significant reductions in antihypertensive agents in the E-HD patients. There were 91 events (50 in the C-HD group and 41 in the E-HD group). Multivariate analysis of the Cox proportional hazards model revealed E-HD as an independent significant factor for the primary endpoint (hazard ratio 0.59; [95% confidence interval: 0.38-0.92]) after adjusting for confounding factors (age, cardiovascular disease history, serum albumin, and C-reactive protein). HD applying an H2-dissolved HD solution could improve the prognosis of chronic HD patients.

Possible clinical effects of molecular hydrogen (H2) delivery during hemodialysis in chronic dialysis patients: Interim analysis in a 12 month observation.

BACKGROUND AND AIM: It is supposed that enhanced oxidative stress and inflammation are involved with the poor clinical outcomes in patients on chronic dialysis treatment. Recent studies have shown that molecular hydrogen (H2) is biologically active as an anti-inflammatory agent. Thus, we developed a novel hemodialysis (E-HD) system which delivers H2 (30 to 80 ppb)-enriched dialysis solution, to conduct a prospective observational study (UMIN000004857) in order to compare the long-term outcomes between E-HD and conventional-HD (C-HD) in Japan. The present interim analysis aimed to look at potential clinical effects of E-HD during the first 12 months observation. SUBJECTS AND METHOD: 262 patients (140, E-HD; 122, C-HD) were subjected for analysis for comprehensive clinical profiles. They were all participating in the above mentioned study, and they had been under the respective HD treatment for 12 consecutive months without hospitalization. Collected data, such as, physical and laboratory examinations, medications, and self-assessment questionnaires on subjective symptoms (i.e., fatigue and pruritus) were compared between the two groups. RESULTS: In a 12-month period, no clinical relevant differences were found in dialysis-related parameters between the two groups. However, there were differences in the defined daily dose of anti-hypertensive agents, and subjective symptoms, such as severe fatigue, and pruritus, which were all less in the E-HD group. Multivariate analysis revealed E-HD was an independent significant factor for the reduced use of anti-hypertensive agents as well as the absence of severe fatigue and pruritus at 12 months after adjusting for confounding factors. CONCLUSION: The data indicates E-HD could have substantial clinical benefits beyond conventional HD therapy, and support the rationale to conduct clinical trials of H2 application to HD treatment.

How Two Brains Make One Synchronized Mind in the Inferior Frontal Cortex: fNIRS-Based Hyperscanning During Cooperative Singing.

One form of communication that is common in all cultures is people singing together. Singing together reflects an index of cognitive synchronization and cooperation of human brains. Little is known about the neural synchronization mechanism, however. Here, we examined how two brains make one synchronized behavior using cooperated singing/humming between two people and hyperscanning, a new brain scanning technique. Hyperscanning allowed us to observe dynamic cooperation between interacting participants. We used functional near-infrared spectroscopy (fNIRS) to simultaneously record the brain activity of two people while they cooperatively sang or hummed a song in face-to-face (FtF) or face-to-wall (FtW) conditions. By calculating the inter-brain wavelet transform coherence between two interacting brains, we found a significant increase in the neural synchronization of the left inferior frontal cortex (IFC) for cooperative singing or humming regardless of FtF or FtW compared with singing or humming alone. On the other hand, the right IFC showed an increase in neural synchronization for humming only, possibly due to more dependence on musical processing.

The rostral prefrontal cortex underlies individual differences in working memory capacity: An approach from the hierarchical model of the cognitive control.

Neuroimaging and behavioral evidence has suggested that the lateral prefrontal cortex is involved in individual differences in working memory capacity (WMC). However, few studies have localized the neural structures that differentiate high and low WMC individuals, considering the functional architecture of the prefrontal cortex. The present study aimed to identify a frontal region that underlies individual differences from the perspective of the hierarchical architecture of the frontal cortex. By manipulating an episodic factor of cognitive control (control in selecting an appropriate task set according to a temporal context) and using a parametric modulation analysis, we found that both high- and low- WMC individuals have similar activation patterns in the premotor cortex (BA6, 8), caudal prefrontal cortex (BA44, 45), and frontopolar cortex (BA10, 11), but differed in the rostral part of the prefrontal cortex (BA46/47); high WMC individuals showed greater activation in the higher episodic control condition, whereas low WMC individuals showed reduced activation when episodic control was required. Similar patterns of activation were found in the right inferior parietal and middle/inferior temporal cortices. These results indicate that the rostral prefrontal cortex, which supports episodic cognitive control, possibly by sending a weighting signal toward the inferior parietal and middle/inferior temporal cortices that modulate saliency and sensory processing, underlies individual differences in WMC. Episodic control account, which considers the organization of the prefrontal cortex, fits well with previous findings of individual differences in WMC.

Color harmony represented by activity in the medial orbitofrontal cortex and amygdala.

Observing paired colors with a different hue (in terms of chroma and lightness) engenders pleasantness from such harmonious combinations; however, negative reactions can emerge from disharmonious combinations. Currently, neural mechanisms underlying the esthetic and emotional aspects of color perception remain unknown. The current study reports evidence regarding the neural correlates of color harmony and disharmony. Functional magnetic resonance imaging was used to assess brain regions activated by harmonious or disharmonious color combinations in comparison to other stimuli. Results showed that the left medial orbitofrontal cortex (mOFC) and left amygdala were activated when participants observed harmonious and disharmonious stimuli, respectively. Taken together, these findings suggest that color disharmony may depend on stimulus properties and more automatic neural processes mediated by the amygdala, whereas color harmony is harder to discriminate based on color characteristics and is reflected by the esthetic value represented in the mOFC. This study has a limitation that we could not exclude the effect of preference for color combination, which has a strong positive correlation with color harmony.

Neural correlates of the self-reference effect: evidence from evaluation and recognition processes.

The self-reference effect (SRE) is defined as better recall or recognition performance when the memorized materials refer to the self. Recently, a number of neuroimaging studies using self-referential and other-referential tasks have reported that self- and other-referential judgments basically show greater activation in common brain regions, specifically in the medial prefrontal cortex (MPFC) when compared with nonmentalizing judgments, but that a ventral-to-dorsal gradient in MPFC emerges from a direct comparison between self- and other-judgments. However, most of these previous studies could not provide an adequate explanation for the neural basis of SRE because they did not directly compare brain activation for recognition/recall of the words referenced to the self with another person. Here, we used an event-related functional magnetic resonance imaging (fMRI) that measured brain activity during processing of references to the self and another, and for recognition of self and other referenced words. Results from the fMRI evaluation task indicated greater activation in ventromedial prefrontal cortex (VMPFC) in the self-referential condition. While in the recognition task, VMPFC, posterior cingulate cortex (PCC) and bilateral angular gyrus (AG) showed greater activation when participants correctly recognized self-referenced words versus other-referenced words. These data provide evidence that the self-referenced words evoked greater activation in the self-related region (VMPFC) and memory-related regions (PCC and AG) relative to another person in the retrieval phase, and that the words remained as a stronger memory trace that supports recognition.

Low cognitive load strengthens distractor interference while high load attenuates when cognitive load and distractor possess similar visual characteristics.

Studies on visual cognitive load have reported inconsistent effects of distractor interference when distractors have visual characteristic that are similar to the cognitive load. Some studies have shown that the cognitive load enhances distractor interference, while others reported an attenuating effect. We attribute these inconsistencies to the amount of cognitive load that a person is required to maintain. Lower amounts of cognitive load increase distractor interference by orienting attention toward visually similar distractors. Higher amounts of cognitive load attenuate distractor interference by depleting attentional resources needed to process distractors. In the present study, cognitive load consisted of faces (Experiments 1-3) or scenes (Experiment 2). Participants performed a selective attention task in which they ignored face distractors while judging a color of a target dot presented nearby, under differing amounts of load. Across these experiments distractor interference was greater in the low-load condition and smaller in the high-load condition when the content of the cognitive load had similar visual characteristic to the distractors. We also found that when a series of judgments needed to be made, the effect was apparent for the first trial but not for the second. We further tested an involvement of working memory capacity (WMC) in the load effect (Experiment 3). Interestingly, both high and low WMC groups received an equivalent effect of the cognitive load in the first distractor, suggesting these effects are fairly automatic.

High-performers use the phonological loop less to process mental arithmetic during working memory tasks.

This study investigated the effects of three working memory components-the central executive, phonological loop, and visuospatial sketchpad-on performance differences in complex mental arithmetic between individuals. Using the dual-task method, we examined how performance during two-digit addition was affected by load on the central executive (random tapping condition), phonological loop (articulatory suppression condition), and visuospatial sketchpad (spatial tapping condition) compared to that under no load (control condition) in high- and low-performers of complex mental arithmetic in Experiment 1. Low-performers showed an increase in errors under the random tapping and articulatory suppression conditions, whereas high-performers showed an increase of errors only under the random tapping condition. In Experiment 2, we conducted similar experiments on only the high-performers but used a shorter presentation time of each number. We found the same pattern for performing complex mental arithmetic as seen in Experiment 1. These results indicate that high-performers might reduce their dependence on the phonological loop, because the central executive enables them to choose a strategy in which they use less working memory capacity.

The anodal tDCS over the left posterior parietal cortex enhances attention toward a focus word in a sentence.

The posterior parietal cortex (PPC) has two attentional functions: top-down attentional control and stimulus-driven attentional processing. Using the focused version of the reading span test (RST), in which the target word to be remembered is the critical word for comprehending a sentence (focused word) or a non-focused word, we examined the effect of tDCS on resolution of distractor interference by the focused word in the non-focus condition (top-down attentional control) and on augmented/shrunk attentional capture by the focused word in both the focus and non-focus conditions (stimulus-driven attentional processing). Participants were divided into two groups: anodal tDCS (atDCS) and cathodal tDCS (ctDCS). Online stimulation was given while participants performed the RST. A post-hoc recognition task was also administered in which three kinds of words were presented: target words in the RST, distractor words in the RST, and novel words. atDCS augmented the effect of the focused word by increasing differences in performance between the focus and non-focus conditions. Such an effect was not observed in the ctDCS group. As for the recognition task, atDCS again produced the augmented effect of the focused words in the distractor recognition. On the other hand, ctDCS brought less recognition of non-focused target words in comparison to sham. The results indicate that atDCS promotes stimulus-driven attentional processing, possibly by affecting neural firing in the inferior parietal regions. In contrast, ctDCS appears to prevent retrieval of less important information from episodic memory, which may require top-down attentional processing.

Coactivation of the Default Mode Network regions and Working Memory Network regions during task preparation.

The Default Mode Network (DMN) regions exhibit deactivation during a wide variety of resource demanding tasks. However, recent brain imaging studies reported that they also show activation during various cognitive activities. In addition, studies have found a negative correlation between the DMN and the working memory network (WMN). Here, we investigated activity in the DMN and WMN regions during preparation and execution phases of a verbal working memory task. Results showed that the core DMN regions, including the medial prefrontal cortex and posterior cingulate cortex, and WMN regions were activated during preparation. During execution, however, the WMN regions were activated but the DMN regions were deactivated. The results suggest that activation of these network regions is affected by allocation of attentional resources to the task relevant regions due to task demands. This study extends our previous results by showing that the core DMN regions exhibit activation during task preparation and deactivation during task execution.

Serial changes of humor comprehension for four-frame comic Manga: an fMRI study.

Serial changes of humor comprehension evoked by a well organized four-frame comic Manga were investigated by fMRI in each step of humor comprehension. The neural substrates underlying the amusing effects in response to funny and mixed order manga were compared. In accordance with the time course of the four frames, fMRI activations changed serially. Beginning with the second frame (development scene), activation of the temporo-parietal junction (TPJ) was observed, followed by activations in the temporal and frontal areas during viewing of the third frame (turn scene). For the fourth frame (punch line), strong increased activations were confirmed in the medial prefrontal cortex (MPFC) and cerebellum. Interestingly, distinguishable activation differences in the cerebellum between funny and non-funny conditions were also found for the fourth frame. These findings suggest that humor comprehension evokes activation that initiates in the TPJ and expands to the MPFC and cerebellum at the convergence level.

Age and individual differences in visual working memory deficit induced by overload.

Many studies on working memory have assumed that one can determine an individual's fixed memory capacity. In the current study, we took an individual differences approach to investigate whether visual working memory (VWM) capacity was stable irrespective of the number of to-be-remembered objects and participant age. Younger and older adults performed a change detection task using several objects defined by color. Results showed wide variability in VWM capacity across memory set sizes, age, and individuals. A marked decrease in the number of objects held in VWM was observed in both younger and older adults with low memory capacity, but not among high-capacity individuals, when set size went well beyond the limits of VWM capacity. In addition, a decrease in the number of objects held in VWM was alleviated among low-capacity younger adults by increasing VWM encoding time; however, increasing encoding time did not benefit low-capacity older adults. These findings suggest that low-capacity individuals are likely to show decreases in VWM capacity induced by overload, and aging exacerbates this deficit such that it cannot be recovered by simply increasing encoding time. Overall, our findings challenge the prevailing assumption that VWM capacity is fixed and stable, encouraging a revision to the strict view that VWM capacity is constrained by a fixed number of distinct "slots" in which high-resolution object representations are stored.

Raise two effects with one scene: scene contexts have two separate effects in visual working memory of target faces.

Many people have experienced the inability to recognize a familiar face in a changed context, a phenomenon known as the "butcher-on-the-bus" effect. Whether this context effect is a facilitation of memory by old contexts or a disturbance of memory by novel contexts is of great debate. Here, we investigated how two types of contextual information associated with target faces influence the recognition performance of the faces using meaningful (scene) or meaningless (scrambled scene) backgrounds. The results showed two different effects of contexts: (1) disturbance on face recognition by changes of scene backgrounds and (2) weak facilitation of face recognition by the re-presentation of the same backgrounds, be it scene or scrambled. The results indicate that the facilitation and disturbance of context effects are actually caused by two different subcomponents of the background information: semantic information available from scene backgrounds and visual array information commonly included in a scene and its scrambled picture. This view suggests visual working memory system can control such context information, so that it switches the way to deal with the contexts information; inhibiting it as a distracter or activating it as a cue for recognizing the current target.

Extrapunitive and intropunitive individuals activate different parts of the prefrontal cortex under an ego-blocking frustration.

Different people make different responses when they face a frustrating situation: some punish others (extrapunitive), while others punish themselves (intropunitive). Few studies have investigated the neural structures that differentiate extrapunitive and intropunitive individuals. The present fMRI study explored these neural structures using two different frustrating situations: an ego-blocking situation which blocks a desire or goal, and a superego-blocking situation which blocks self-esteem. In the ego-blocking condition, the extrapunitive group (n = 9) showed greater activation in the bilateral ventrolateral prefrontal cortex, indicating that these individuals prefer emotional processing. On the other hand, the intropunitive group (n = 9) showed greater activation in the left dorsolateral prefrontal cortex, possibly reflecting an effortful control for anger reduction. Such patterns were not observed in the superego-blocking condition. These results indicate that the prefrontal cortex is the source of individual differences in aggression direction in the ego-blocking situation.

Medial prefrontal cortex dissociation between self and others in a referential task: an fMRI study based on word traits.

A number of recent neuroimaging studies using self referential tasks have investigated whether self referential processing depends on a unique neural basis that operates specifically in the medial prefrontal cortex. However, these studies have provided contradictory results despite the use of similar methodologies. We hypothesized that these discrepancies are partially related to the task-difficulty that presents dissociations reaction times in the self- and other-referential tasks. We therefore measured brain activity during self and other referential tasks to determine if such activity can be dissociated according to the reaction times (fast versus slow) for the trait words. Activation differed across self and other only in the slow word condition. The self referential condition with slow reaction time produced greater activation in the ventromedial prefrontal cortex, whereas the other referential condition with slow reaction time produced activation of the middle temporal gyrus. Results suggested that the task-difficulty might affect whether or not brain activities within MPFC would be dissociated between self- and other-referential processing.

When do negative and positive emotions modulate working memory performance?

The present study investigated when emotion modulates working memory from the perspective of neural activation. Using fMRI, we measured brain activity during the encoding and retrieval phases of a reading span test (RST) that used emotional contexts. The emotional RST required participants to read sentences that elicited negative, neural or positive emotional states while they were memorizing target words from the sentences. Compared with the neutral RST, the negative RST activated the right amygdala during the reading phase. Significant activation was also found in the parahippocampal gyrus, albeit only after activation of the amygdala became comparable to that in the neutral RST. In contrast, the positive RST activated the substantia nigra during the reading phase relative to the neutral RST. These findings suggest that negative and positive emotions modulate working memory through distinctive neural circuits. We also discuss possible relationships between emotional modulation and working memory capacity.