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Both humans and animals are known to exhibit a violation of rationality known as “decoy effect”: introducing an irrelevant option (a decoy) can influence choices among other (relevant) options. Exactly how and why decoys trigger this effect is not known. It may be an example of fast heuristic decision-making, which is adaptive in natural environments, but may lead to biased choices in certain markets or experiments. We used fMRI and transcranial magnetic stimulation to investigate the neural underpinning of the decoy effect of both sexes. The left ventral striatum was more active when the chosen option dominated the decoy. This is consistent with the hypothesis that the presence of a decoy option influences the valuation of other options, making valuation context-dependent even when choices appear fully rational. Consistent with the idea that control is recruited to prevent heuristics from producing biased choices, the right inferior frontal gyrus, often implicated in inhibiting prepotent responses, connected more strongly with the striatum when subjects successfully overrode the decoy effect and made unbiased choices. This is further supported by our transcranial magnetic stimulation experiment: subjects whose right inferior frontal gyrus was temporarily disrupted made biased choices more often than a control group. Our results suggest that the neural basis of the decoy effect could be the context-dependent activation of the valuation area. But the differential connectivity from the frontal area may indicate how deliberate control monitors and corrects errors and biases in decision-making.SIGNIFICANCE STATEMENTStandard theories of rational decision-making assume context-independent valuations of available options. Motivated by the importance of this basic assumption, we used fMRI to study how the human brain assigns values to available options. We found activity in the valuation area to be consistent with the hypothesis that values depend on irrelevant aspects of the environment, even for subjects whose choices appear fully rational. Such context-dependent valuations may lead to biased decision-making. We further found differential connectivity from the frontal area to the valuation area depending on whether biases were successfully overcome. This suggests a mechanism for making rational choices despite the potential bias. Further support was obtained by a transcranial magnetic stimulation experiment, where subjects whose frontal control was temporarily disrupted made biased choices more often than a control group.

Few studies have investigated the effects of anxiety on contingent attentional capture. The present study examined contingent attentional capture in trait anxiety by applying a rapid serial visual presentation (RSVP) paradigm during electroencephalographic recording. Overall, the behavioral and electrophysiological results showed a larger capture effect when a distractor was the same color as the target compared to when the distractor was not of the target color. Moreover, high-anxiety individuals showed a larger N2pc in the target colored distractor condition and nontarget colored distractor condition compared to the distractor-absent condition. In addition, the reaction time was slower when distractors were presented in the left visual field compared to when they were in the right visual field. This pattern was not seen in low-anxiety individuals. The findings may indicate that high-anxiety individuals allocate attention to the target less efficiently and have reduced suppression of distractors compared to low-anxiety individuals who could suppress attention to the distractors more efficiently. Future work could valuably investigate the consequences of such differences in terms of benefits and disruption associated with attentional capture differences in a range of anxious populations in different risk monitoring situations.

Even during symptomatic remission, many patients with medication resistant depression (MRD) still demonstrate impaired cognitive function, especially executive function (EF). Theta-burst transcranial magnetic stimulation (TBS) modulates cortical excitability and may treat MRD. Evidences from previous studies show that intermittent TBS (iTBS) produces cortical excitatory effects, while continuous TBS (cTBS) produces a reduction of cortical excitability. EF is highly dependent on prefrontal activity, but the effects of different forms of prefrontal TBS on EF remain unknown.60 MRD patients were recruited and randomly assigned to one of four groups. Treatment was determined by the group to which an individual was assigned; A: cTBS 1800pulses/session; B: iTBS 1800pulses/session; C: a combination of cTBS+iTBS, 1800pulses/session for each; and D: sham TBS. Wisconsin Card Sorting Test (WCST) for the performance of EF was evaluated before and after 10 daily treatment sessionsRepeated measures ANOVA, with each WCST index at baseline and 2weeks after TBS as within-subject factors, demonstrated that a statistically significant interaction of TBS groups (G) and antidepressant responses [(R), responses were defined as50% reduction of depression scores after 2-weeks TBS treatment] on the before-versus-after changes of all WCST indexes (G×R, p0.05). Responders in Group B, but not in the other groups, showed a significant improvement in WCST performance. Only nonresponders in Group A showed a trend for EF worsening.Our findings showed that left prefrontal iTBS, not right prefrontal cTBS, improved EF, and this can be independent from its antidepressant effects.

Information processing can be biased toward behaviorally relevant and salient stimuli by top-down (goal-directed) and bottom-up (stimulus-driven) attentional control processes respectively. However, the neural basis underlying the integration of these processes is not well understood. We employed functional magnetic resonance imaging (fMRI) and transcranial direct-current stimulation (tDCS) in humans to examine the brain mechanisms underlying the interaction between these two processes. We manipulated the cognitive load involved in top-down processing and stimulus surprise involved in bottom-up processing in a factorial design by combining a majority function task and an oddball paradigm. We found that high cognitive load and high surprise level were associated with prolonged reaction time compared to low cognitive load and low surprise level, with a synergistic interaction effect, which was accompanied by a greater deactivation of bilateral temporoparietal junction (TPJ). In addition, the TPJ displayed negative functional connectivity with right middle occipital gyrus, which is involved in bottom-up processing (modulated by the interaction effect), and the right frontal eye field (FEF), which is involved in top-down control. The enhanced negative functional connectivity between the TPJ and right FEF was accompanied by a larger behavioral interaction effect across subjects. Application of cathodal tDCS over the right TPJ eliminated the interaction effect. These results suggest that the TPJ plays a critical role in processing bottom-up information for top-down control of attention.

How does the brain enable us to remember two or more object representations in visual working memory (VWM) without confusing them? This “gluing” process, or feature binding, refers to the ability to join certain features together while keeping them segregated from others. Recent neuroimaging research has reported higher BOLD response in the left temporal and parietal cortex during a binding-VWM task. However, less is known about how the two regions work in synchrony to support such process. In this study, we applied transcranial alternating current stimulation (tACS) over the left temporal and parietal cortex in gamma and theta frequency, with a phase difference of either 0° (in-phase) or 180° (anti-phase) to account for the different ways through which neural synchronization may occur. We found no facilitatory or inhibitory effect from sham, theta and in-phase gamma stimulation. Importantly, there was an enhancement effect from anti-phase gamma tACS that was binding-specific and such effect was only apparent in low-performing individuals who had room for improvement. Together, these results demonstrate that binding-VWM is supported by a temporally-precise oscillatory mechanism within the gamma frequency range and that the advantageous 180°-apart phase relationship also implies a possible temporal driver-to-receiver time-lag between the temporal and parietal cortex.

In the visual world, rapidly reorienting to relevant objects outside the focus of attention is vital for survival. This ability from the interaction between goal-directed and stimulus-driven attentional control is termed contingent reorienting. Neuroimaging studies have demonstrated activations of the ventral and dorsal attentional networks (DANs) which exhibit right hemisphere dominance, but the temporal dynamics of the attentional networks still remain unclear. The present study used event-related potential (ERP) to index the locus of spatial attention and Hilbert-Huang transform (HHT) to acquire the time-frequency information during contingent reorienting. The ERP results showed contingent reorienting induced significant N2pc on both hemispheres. In contrast, our time-frequency analysis found further that, unlike the N2pc, theta oscillation during contingent reorienting differed between hemispheres and experimental sessions. The inter-trial coherence (ITC) of the theta oscillation demonstrated that the two sides of the attentional networks became phase-locked to contingent reorienting at different stages. The left attentional networks were associated with contingent reorienting in the first experimental session whereas the bilateral attentional networks play a more important role in this process in the subsequent session. This phase-locked information suggests a dynamic temporal evolution of the involvement of different attentional networks in contingent reorienting and a potential role of the left ventral network in the first session.

The limits of human visual short-term memory (VSTM) have been well documented, and recent neuroscientific studies suggest that VSTM performance is associated with activity in the posterior parietal cortex. Here we show that artificially elevating parietal activity via positively charged electric current through the skull can rapidly and effortlessly improve people's VSTM performance. This artificial improvement, however, comes with an interesting twist: it interacts with people's natural VSTM capability such that low performers who tend to remember less information benefitted from the stimulation, whereas high performers did not. This behavioral dichotomy is explained by event-related potentials around the parietal regions: low performers showed increased waveforms in N2pc and contralateral delay activity (CDA), which implies improvement in attention deployment and memory access in the current paradigm, respectively. Interestingly, these components are found during the presentation of the test array instead of the retention interval, from the parietal sites ipsilateral to the target location, thus suggesting that transcranial direct current stimulation (tDCS) was mainly improving one's ability to suppress no-change distractors located on the irrelevant side of the display during the comparison stage. The high performers, however, did not benefit from tDCS as they showed equally large waveforms in N2pc and CDA, or SPCN (sustained parietal contralateral negativity), before and after the stimulation such that electrical stimulation could not help any further, which also accurately accounts for our behavioral observations. Together, these results suggest that there is indeed a fixed upper limit in VSTM, but the low performers can benefit from neurostimulation to reach that maximum via enhanced comparison processes, and such behavioral improvement can be directly quantified and visualized by the magnitude of its associated electrophysiological waveforms.

Activation of left anterior inferior frontal gyrus (aLIFG) and left middle temporal gyrus (LMTG) has been observed in some functional neuroimaging studies of lexical decision but not others. It is thus unclear whether these two regions are necessary for word recognition. By applying continuous theta-burst transcranial magnetic stimulation (TMS) which temporally suppresses local brain function, we examined whether aLIFG and LMTG play causal roles in word recognition in a visual lexical decision task (LDT). Furthermore, we manipulated stimulus onset asynchrony (SOA) between prime and target to test whether these regions contribute to word recognition differently. In the LDT task, target words were preceded by semantically related primes (Related Condition; RC) or semantically unrelated words (Unrelated Condition; UC), under both short (150 ms) and long (600 ms) SOA conditions. TMS of aLIFG and LMTG significantly affected the word recognition speed compared to TMS of Vertex. Our results provide evidence that both aLIFG and LMTG contribute to word recognition speed. Furthermore, at short SOA, TMS of aLIFG or LMTG prolonged reaction time (RT). In contrast, at long SOA, there was a significant region by SOA by TMS interaction such that TMS of aLIFG prolonged RT, whereas TMS of LMTG speeded RT. These results suggest that aLIFG and LMTG may play different roles in word recognition.

TiO2 was supported on porous materials, including NaY and Na-mordenite zeolites, as well as mesoporous MCM-41 molecular sieve by using impregnation method with organic solvents. The products were characterized with powder XRD, BET surface area measurement, TEM, IR, Raman and UV–VIS spectroscopies. The supported TiO2 was crystallized in anatase structure and the intensity of its X-ray diffraction peaks increased with TiO2 loading. In contrast, the total surface area of the supported catalyst decreased with TiO2 loading. A blue shift of the absorption edge in the UV–VIS spectra was observed when TiO2 particle size decreased, a phenomenon corresponding to the particle size quantization effect. For photodegradation of aromatic pollutants in water, the activity was found strongly influenced by the chemical nature of the pollutant and the surface property of the support. For volatile pollutants such as benzene and chlorobenzenes, molecular sieve supports facilitated the photodegradation reaction by providing high surface area for adsorption. Moreover, there is an optimal loading of TiO2 to achieve the best photocatalytic activity on various supports. The supports in contrast did not show positive contribution in degradation of hydrophilic pollutants such as phenol.

Near- and far-space coding in the human brain is a dynamic process. Areas in dorsal, as well as ventral visual association cortex, including right posterior parietal cortex (rPPC), right frontal eye field (rFEF), and right ventral occipital cortex (rVO), have been shown to be important in visuospatial processing, but the involvement of these areas when the information is in near or far space remains unclear. There is a need for investigations of these representations to help explain the pathophysiology of hemispatial neglect, and the role of near and far space is crucial to this. We used a conjunction visual search task using an elliptical array to investigate the effects of transcranial magnetic stimulation delivered over rFEF, rPPC, and rVO on the processing of targets in near and far space and at a range of horizontal eccentricities. As in previous studies, we found that rVO was involved in far-space search, and rFEF was involved regardless of the distance to the array. It was found that rPPC was involved in search only in far space, with a neglect-like effect when the target was located in the most eccentric locations. No effects were seen for any site for a feature search task. As the search arrays had higher predictability with respect to target location than is often the case, these data may form a basis for clarifying both the role of PPC in visual search and its contribution to neglect, as well as the importance of near and far space in these.

Spatial working memory (SWM) is the ability to temporarily store and manipulate spatial information. It has a limited capacity and is quite vulnerable to interference. Dorsolateral prefrontal cortex (DLPFC) has been shown to be a part of the SWM network but its specific functional role still remains unknown. Here we applied transcranial direct current stimulation (tDCS), a noninvasive brain stimulation technique that provides polarity-specific stimulation over the targeted region, to investigate the specific role of the right DLPFC in resolving interference in SWM. A forward- and backward-recall computerized Corsi Block Tapping task (CBT), both with and without a concurrent motor interference task (the modified Luria manual sequencing task) was used to measure SWM capacity and reaction time. The results showed that motor interference impeded accuracy and prolonged reaction time in forward and backward recall for SWM. Anodal tDCS over right DLPFC yielded the tendency to shorten participants’ reaction time in the conditions with interference (forward with interference, and backward with interference). Most importantly, anodal tDCS significantly improved participants’ SWM span when cognitive demand was the highest (the “backward-recall with motor interference” condition). These results suggest that (1) the right DLPFC plays a crucial role in dealing with the cross-domain motor interference for spatial working memory and (2) the anodal tDCS over right DLPFC improved SWM capacity particularly when task difficulty demands more complex mental manipulations that could be due to the facilitatory effect of anodal tDCS which enhanced the DLPFC function within central executive system at the top-down attentional level.

The dorsal attentional network is known for its role in directing top-down visual attention towards task-relevant stimuli. This goal-directed nature of the dorsal network makes it a suitable candidate for processing and extracting predictive information from the visual environment. In this mini review we briefly summarize some of the findings that delineate the neural substrates that contribute to predictive learning at both levels within the dorsal attentional system: including the frontal eye field and posterior parietal cortex. We also discuss the similarities and differences between these two regions when it comes to learning predictive information. The current findings from the literature suggest that the frontal eye fields may be more involved in top-down spatial attention, whereas the parietal cortex is involved in processing task-relevant attentional influences driven by stimulus salience, both contribute to the processing of predictive cues at different time points.

The interaction between goal‐directed and stimulus‐driven attentional control allows humans to rapidly reorient to relevant objects outside the focus of attention—a phenomenon termed contingent reorienting. Neuroimaging studies have observed activation of the ventral and dorsal attentional networks, but specific involvement of each network remains unclear. The present study aimed to determine whether both networks are critical to the processes of top‐down contingent reorienting. To this end, we combined the contingent attentional capture paradigm with the use of transcranial magnetic stimulation (TMS) to interfere with temporoparietal junction (TPJ; ventral network) and frontal eye field (dorsal network) activity. The results showed that only right TPJ (rTPJ) TMS modulated contingent orienting. Furthermore, this modulation was highly dependent on visual fields: rTPJ TMS increased contingent capture in the left visual field and decreased the effect in the right visual field. These results demonstrate a critical involvement of the ventral network in attentional reorienting and reveal the spatial selectivity within such network. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.

The design of a NoC simulator can significantly affect its ability to explore various design space and simulation accuracy. It's not easy to achieve both wide-range design space exploration and detailed characterization of hardware components simultaneously. This paper presents a kind of NoC modeling in an object oriented flavor: object oriented NoC modeling (“OONoC” in brief). OONoC divides the NoC design space into many design blocks and each block into many abstraction levels. OONoC can extend the exploration space of NoC, study hardware characteristics, and significantly reduce the coding effort of a new NoC design.

Network-on-Chip (NoC) is a key component in the design of many cores on a chip. This paper presents a new system level NoC simulation framework, called “Network-On-Chip-centric System Exploration Platform” (NOCSEP). It divides NoC design space into blocks and models them using abstracted layers. Together with task-graph software modeling and simplified middle-layer modeling, it can estimate the performance of an on-chip interconnect rapidly and is therefore very suitable for quickly exploring design alternatives.