Shen Tu

Neural correlates of mental preparation for successful insight problem solving

A distinct type of mental preparation (activity in medial frontal and temporal areas) had been found to facilitate insight problem solving independent of specific problems [25]. In order to explore whether neural activity during a preparatory interval (mental preparation) is associated with which insight problems would be solved or not, we developed a task that uses Chinese logogriphs (riddles) as materials. Blood oxygenation level-dependent fMRI contrasts between Successful and Unsuccessful mental preparation were measured. Results showed that mental preparation leading to successful problem solving involves heightened activity in the left middle/medial frontal gyrus, the left middle/superior temporal gyrus, the right cerebellum, the bilateral claustrum and the left postcentral gyrus. We discussed the role of these areas in mental preparation for successful insight problem solving.

The impact of social comparison on the neural substrates of reward processing: An event-related potential study

Event-related potentials (ERPs) were recorded to explore the electrophysiological correlates of reward processing in the social comparison context when subjects performed a simple number estimation task that entailed monetary rewards for correct answers. Three social comparison stimulus categories (three relative reward levels/self reward related to the other subjects) were mainly prepared: Self:Other=1:2 (Disadvantageous inequity condition); Self:Other=1:1 (Equity condition); and Self:Other=2:1 (Advantageous inequity condition). Results showed that: both Disadvantageous and Advantageous inequity elicited a more negative ERP deflection (N350-550) than did Equity between 350 and 550 ms, and the generators of N350-550 were localized near the parahippocampal gyrus and the medial frontal/anterior cingulate cortex, which might be related to monitor and control reward prediction error during reward processing. Then, Disadvantageous and Advantageous inequity both elicited a more late negative complex (LNC1 and LNC2) than did Equity between 550 and 750 ms. The generators of LNC1 and LNC2 were both localized near the caudate nucleus, which might be related to reward processing under social comparison.

Differentiation of stages in joke comprehension: Evidence from an ERP study

This study aimed to investigate the mechanisms underlying joke comprehension using event-related potentials (ERPs). Fourteen healthy college students were presented with the context of a story without its joke or nonjoke ending, and then, when the story ending was presented, they were asked to make a funny/unfunny judgment about these endings. The behavioral results showed that there was no significant difference between funny and unfunny items, which meant that subjects could understand funny items as easily as unfunny ones. However, the ERP results showed that funny items initially elicited a more negative ERP deflection (N350-450) over frontocentral scalp regions. Dipole analysis localized the generators in the left temporal gyrus and the left medial frontal gyrus; it is suggested that these areas might be involved in detecting the incongruent element in joke comprehension. Between 600 and 800 ms, funny items subsequently elicited a more negative ERP deflection (N600-800) over frontocentral scalp regions and a more positive ERP deflection (P600-800) over posterior scalp regions. Dipole analysis localized the generator in the anterior cingulate cortex (ACC), an area involved in the breaking of mental set/expectation and the forming of novel associations. Finally, funny items elicited a more positive ERP deflection (P1250-1400) over anterior and posterior scalp regions. Dipole analysis localized the generators in the middle frontal gyrus and the fusiform gyrus, areas that might be related to the affective appreciation stage in joke process. Unlike that of Coulson and Kutas (2001), the present study might support the hypothesis of a three stage model of humor processing (humor detection, resolution of incongruity and humor appreciation).

Spatiotemporal cortical activation underlying self-referencial processing evoked by self-hand

Event-related potentials (ERPs) were recorded to explore the electrophysiological correlates of self-referencial processing when subjects were asked to judge whether the stimuli (their hands) were their own or not. ERP results showed that: first, own hand elicited a greater positive component (P350-500) than did other hand in the time window of 350-500 ms, and the generator of P350-500 was localized in the anterior cingulate cortex (ACC), which might be related to retrieval and identification of self-referencial information due to their sensitivity to self-hand. Second, own hand elicited a more positive component (LPC) than did other hand in the later time window. Dipole analysis revealed that the generators were localized in the parahippocampal gyrus and the medial frontal gyrus, which might be involved in making a self-referencial decision based on retrieval of self-hand information.

The time course of Chinese riddles solving: evidence from an ERP study.

The electrophysiological correlates of successful insight and routine problem solving were studied in 12 healthy subjects using high-density event-related potentials (ERPs). Results showed that insight problems elicited a more negative ERP deflection (N300-800) than did routine problems between 300 and 800 ms, and a more negative ERP deflection (N1200-1500) than did routine problems between 1200 and 1500 ms over the fronto-central scalp regions. However, insight problems elicited a more positive ERP deflection (P300-800) than did routine problems between 300 and 800 ms, and a more positive ERP deflection (P1200-1500) than did routine problems between 1200 and 1500 ms over the parieto-occipital scalp regions. Dipole source analysis showed that two dipoles were located in the anterior cingulate cortex (ACC) and the parahippocampal gyrus between 300 and 800 ms, and two dipoles were located in the parahippocampal gyrus and the superior frontal gyrus between 1200 and 1500 ms. We discussed the implications of these ERP components in insight problem solving.

Neural mechanisms of subliminal priming for traumatic episodic memory: an ERP study.

Event-related brain potentials (ERPs) were measured to study the electrophysiological mechanisms of subliminal priming of traumatic episodic memory. Twenty-four Chinese subjects who had experienced the great Sichuan earthquake in 2008 were classified either as normal control or as post-traumatic stress disorder (PTSD) subjects. Results showed that subliminally presented earthquake-related words elicited two significantly more positive ERP deflections (P2 and P300) than did earthquake-unrelated words between 250-300 ms and 340-400 ms post-stimulus periods for the PTSD group, but not for the control group. Dipole source analysis showed that the P2 was mainly generated in the posterior cingulate cortex (PCC), which appeared to be related to unconscious attentional resource allocation to the earthquake-related words. In addition, the P300 was found to be generated in the parahippocampal gyrus, which seemed to be related to the involuntary activation of traumatic episodic memory. These results indicated that catastrophic earthquake experiences made some subjects extremely sensitive and hyper-responsive to trauma-related information.

The electrophysiological effect of working memory load on involuntary attention in an auditory–visual distraction paradigm: an ERP study

Event-related brain potentials (ERPs) were used to examine the electrophysiological effect of working memory (WM) load on involuntary attention caused by a task-irrelevant sound in an auditory–visual distraction paradigm. The different WM loads were manipulated by requiring subjects to remember the order of either three digits (low-load condition) or seven digits (high-load condition), and the irrelevant auditory stimuli consisted of repetitive standard sounds (80%) and environmental novel sounds (20%). We found that the difference waves (novel-minus-standard) showed significant MMN and Novelty-P3 components in the two WM load conditions. The amplitude of MMN increased with increasing the WM load, which indicated a more engaged change detection process under high-load condition. Then, the amplitude of Novelty-P3 was attenuated under high-load condition, which indicated a much reduced involuntary orienting of attention to novel sounds when increasing the WM load. These results indicated the top–down control of involuntary attention might be mainly active at the early change detection stage and the control of the later involuntary orienting of attention might be passive.

An event-related potential study of deception to self preferences.

The spatiotemporal analysis of brain activation during the execution of deceptive decision-making was performed in 14 normal young adult subjects by using high-density event-related brain potentials (ERPs) with a delayed-response paradigm (subjects were required to hide their true attitudes for a moment). Our results showed that between 400 and 700 ms after stimulus onset, Deceptive items elicited a more negative ERP deflection (N400-700) than Truthful items, and between 1000 and 2000 ms, Deceptive items elicited a more positive ERP deflection (P1000-2000) than Truthful items. Analyses using dipole locations indicated that: (1) the generators of N400-700 were localized in the medial frontal gyrus (GFM) and middle temporal gyrus (GTM), which might be involved in conflict detection and control during deceptive decision-making; and (2) the generators of P1000-2000 were localized near the cuneus (CU) and the cingulate gyrus, which might be involved in conflict coordination in working memory due to deception.

Earthquake experience interference effects in a modified Stroop task: An ERP study

The effects of the modified Stroop task on ERP were investigated in 20 subjects who had experienced the Sichuan earthquake and a matched control group. ERP data showed that Incongruent stimuli elicited a more negative ERP deflection (N300-450) than did Congruent stimuli between 300 and 450 ms post-stimulus in the earthquake group but not found in the control group, and the N300-450 might reflect conflict monitor (the information of color and meaning do not match) in the early phase of perception identification due to their sensitivity to the external stimulus. Then, Incongruent stimuli elicited a more negative ERP deflection than did Congruent stimuli between 450 and 650 ms post-stimulus in both the groups. Dipole source analysis showed that the N450-650 was mainly generated in the ACC contributed to this effect in the control group, which might be related to monitor and conflict resolution. However, in the earthquake group, the N450-650 was generated in the thalamus, which might be involved in inhibiting and compensating of the ACC which may be related to conflict resolution process.

How personal earthquake experience impacts on the Stroop interference effect: An event‐related potential study

Event-related brain potentials (ERPs) were measured when 24 Chinese subjects performed the classical Stroop task. All of subjects had experienced the great Sichuan earthquake (5/12), with 12 people in each of the Far (Chengdu city) and the Close (Deyang city) earthquake experience groups. The behavioral data showed that the Stroop task yielded a robust Stroop interference effect as indexed by longer RT for incongruent than congruent color words in both the Chengdu and Deyang groups. Scalp ERP data showed that incongruent stimuli elicited a more negative ERP deflection (N400-600; Stroop interference effect) than did congruent stimuli between 400-600 ms in the Chengdu group, while the Stroop interference ERP effect was not found in the Deyang group. Dipole source analysis localized the generator of the N400-600 in the right prefrontal cortex (PFC) and was possibly related to conflict monitoring and cognitive control.