Dataset Information

Effect of Modulating Activity of DLPFC and Gender on Search Behavior: A tDCS Experiment.

ABSTRACT: Studies of search behavior have shown that individuals stop searching earlier and accept a lower point than predicted by the optimal, risk-neutral stopping rule. This behavior may be related to individual risk preferences. Studies have also found correlativity between risk preferences and the dorsolateral prefrontal cortex (DLPFC). As risk attitude plays a crucial role in search behavior, we studied whether modulating the activity of DLPFC, by using a transcranial direct current stimulation (tDCS) device, can change individual search behavior. We performed a sequential search task in which subjects decided when to accept a point randomly drawn from a uniform distribution. A total of 49 subjects (23 females, mean age = 21.84 ± 2.09 years, all right-handed) were recruited at Zhejiang University from May 2017 to September 2017. They repeated the task in 80 trials and received the stimulation at the end of the 40th trial. The results showed that after receiving right anodal/left cathodal stimulation, subjects increased their searching duration, which led to an increase in their accepted point from 778.17 to 826.12. That is, the subjects may have changed their risk attitude to search for a higher acceptable point and received a higher benefit. In addition, the effect of stimulation on search behavior was mainly driven by the female subjects rather than by the male subjects: the female subjects significantly increased their accepted point from 764.15 to 809.17 after right anodal/left cathodal stimulation, while the male subjects increased their accepted point from 794.18 to 845.49, but the change was not significant.

SUBMITTER: Yang X

PROVIDER: S-EPMC6110849 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Effect of Modulating Activity of DLPFC and Gender on Search Behavior: A tDCS Experiment.

Yang Xiaolan X Lin Yiyang Y Gao Mei M Jin Xuejun X

Frontiers in human neuroscience 20180821

Studies of search behavior have shown that individuals stop searching earlier and accept a lower point than predicted by the optimal, risk-neutral stopping rule. This behavior may be related to individual risk preferences. Studies have also found correlativity between risk preferences and the dorsolateral prefrontal cortex (DLPFC). As risk attitude plays a crucial role in search behavior, we studied whether modulating the activity of DLPFC, by using a transcranial direct current stimulation (tDC ...[more]

PMID: 30186126

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Project description:The profound nature of moral judgment has been discussed and debated for centuries. When facing the trade-off between pursuing moral rights and seeking better consequences, most people make different moral choices between two kinds of dilemmas. Such differences were explained by the dual-process theory involving an automatic emotional response and a controlled application of utilitarian decision-rules. In neurocognitive studies, the bilateral dorsolateral prefrontal cortex (DLPFC) has been demonstrated to play an important role in cognitive "rational" control processes in moral dilemmas. However, the profile of results across studies is not entirely consistent. Although one transcranial magnetic stimulation (TMS) study revealed that disrupting the right DLPFC led to less utilitarian responses, other TMS studies indicated that inhibition of the right DLPFC led to more utilitarian choices. Moreover, the right temporoparietal junction (TPJ) is essential for its function of integrating belief and intention in moral judgment, which is related to the emotional process according to the dual-process theory. Relatively few studies have reported the causal relationship between TPJ and participants' moral responses, especially in moral dilemmas. In the present study, we aimed to demonstrate a direct link between the neural and behavioral results by application of transcranial direct current stimulation (tDCS) in the bilateral DLPFC or TPJ of our participants. We observed that activating the right DLPFC as well as inhibiting the left DLPFC led to less utilitarian judgments, especially in moral-personal conditions, indicating that the right DLPFC plays an essential role, not only through its function of moral reasoning but also through its information integrating process in moral judgments. It was also revealed that altering the excitability of the bilateral TPJ using tDCS negligibly altered the moral response in non-moral, moral-impersonal and moral-personal dilemmas, indicating that bilateral TPJ may have little influence over moral judgments in moral dilemmas.

Project description:It has long been established that individuals with anxiety disorders tend to overgeneralize attributes of fearful stimuli to nonfearful stimuli, but there is little mechanistic understanding of the neural system that supports overgeneralization. To address this gap in our knowledge, this study examined effect of experimentally induced anxiety in humans on generalization using the behavioral pattern separation (BPS) paradigm. Healthy subjects of both sexes encoded and retrieved novel objects during periods of safety and threat of unpredictable shocks while we recorded brain activity with fMRI. During retrieval, subjects were instructed to differentiate among new, old, and altered images. We hypothesized that the hippocampus and dorsolateral prefrontal cortex (dlPFC) would play a key role in the effect of anxiety on BPS. The dlPFC, but not the hippocampus, showed increased activity for altered images compared with old images when retrieval occurred during periods of threat compared with safety. In addition, accuracy for altered items retrieved during threat was correlated with dlPFC activity. Together, these results suggest that overgeneralization in anxiety patients may be mediated by an inability to recruit the dlPFC, which mediates the cognitive control needed to overcome anxiety and differentiate between old and altered items during periods of threat.SIGNIFICANCE STATEMENT Anxiety and posttraumatic stress disorder patients generalize fear to nonfearful fear stimuli, making it difficult to regulate anxiety. Understanding how anxiety affects generalization is key to understanding the overgeneralization experienced by these patients. We examined this relationship in healthy subjects by studying how threat of shock affects neural responses to previously encountered stimuli. Although previous studies point to hippocampal involvement, we found that threat affected activity in the dorsolateral prefrontal cortex (dlPFC), rather than the hippocampus, when subjects encountered slightly altered versions of the previously encountered items. Importantly, this dlPFC activity predicted performance for these items. Together, these results suggest that the dlPFC is important for discrimination during elevated anxiety and that overgeneralization may reflect a deficit in dlPFC-mediated cognitive control.

Dataset Information

Effect of Modulating Activity of DLPFC and Gender on Search Behavior: A tDCS Experiment.

Publications

Effect of Modulating Activity of DLPFC and Gender on Search Behavior: A tDCS Experiment.

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