Dongil Chung

Cognitive Motivations of Free Riding and Cooperation and Impaired Strategic Decision Making in Schizophrenia During a Public Goods Game

Schizophrenia is generally characterized by various positive and negative symptoms that are accompanied by significant social dysfunction. Various researchers investigated the functional impairments in schizophrenia including impaired theory of mind (TOM), poor integration of affective and cognitive information, and malfunctioning of adaptive and strategic learning process. However, most of the studies were limited to simplified cognitive tests or computerized choice games that exclude real social interaction. The aim of the current study was to investigate human strategies based on the incentives and particularly the cognitive and emotional motivations of free riding. We examined the decision patterns of 41 healthy subjects (HSs) and 37 schizophrenia patients (SZ) during the public goods game (PGG), one of the games simulating human cooperation and free riding in group interactions. Strategic decision processes during the iterative binary PGG were assessed in terms of cognitive understanding, loss sensitivity, and TOM. We found that greed and loss sensitivity both motivated free-riding behavior in the HS, but that they were more vulnerable to greedy incentives than to possible loss. More significantly, the SZ clearly displayed a lower prevalence of free riding and distinct decision patterns from HS. Nonstrategic and unexpectedly low free ridings in the SZ likely arise from poor integration of cognitive and affective information. We suggest that loss sensitivity and TOM as well as cognitive understanding are involved in regulation of the free riding and cooperative behavior.

Mathematically Gifted Adolescents Have Deficiencies in Social Valuation and Mentalization

Many mathematically gifted adolescents are characterized as being indolent, underachieving and unsuccessful despite their high cognitive ability. This is often due to difficulties with social and emotional development. However, research on social and emotional interactions in gifted adolescents has been limited. The purpose of this study was to observe differences in complex social strategic behaviors between gifted and average adolescents of the same age using the repeated Ultimatum Game. Twenty-two gifted adolescents and 24 average adolescents participated in the Ultimatum Game. Two adolescents participate in the game, one as a proposer and the other as a responder. Because of its simplicity, the Ultimatum Game is an apt tool for investigating complex human emotional and cognitive decision-making in an empirical setting. We observed strategic but socially impaired offers from gifted proposers and lower acceptance rates from gifted responders, resulting in lower total earnings in the Ultimatum Game. Thus, our results indicate that mathematically gifted adolescents have deficiencies in social valuation and mentalization.

Different Gain/Loss Sensitivity and Social Adaptation Ability in Gifted Adolescents during a Public Goods Game

Gifted adolescents are considered to have high IQs with advanced mathematical and logical performances, but are often thought to suffer from social isolation or emotional mal-adaptation to the social group. The underlying mechanisms that cause stereotypic portrayals of gifted adolescents are not well known. We aimed to investigate behavioral performance of gifted adolescents during social decision-making tasks to assess their affective and social/non-social cognitive abilities. We examined cooperation behaviors of 22 gifted and 26 average adolescents during an iterative binary public goods (PG) game, a multi-player social interaction game, and analyzed strategic decision processes that include cooperation and free-riding. We found that the gifted adolescents were more cooperative than average adolescents. Particularly, comparing the strategies for the PG game between the two groups, gifted adolescents were less sensitive to loss, yet were more sensitive to gain. Additionally, the behavioral characteristics of average adolescents, such as low trust of the group and herding behavior, were not found in gifted adolescents. These results imply that gifted adolescents have a high cognitive ability but a low ability to process affective information or to adapt in social groups compared with average adolescents. We conclude that gain/loss sensitivity and the ability to adapt in social groups develop to different degrees in average and gifted adolescents.

Gender differences revealed in the right posterior temporal areas during Navon letter identification tasks.

Gender differences in temporo-spectral EEG patterns during verbal cognitive performance are poorly understood. The aim of the present study was to examine whether the event-related dynamics of EEG differ between genders during the performance of Navon letter identification tasks (NLITs). To this end, the EEG patterns of 40 subjects were recorded during the NLIT performance. We compared behavioral outcomes, event-related temporo-spectral dynamics, and source distribution of neural oscillations within cortical regions of male and female subjects. We found that male subjects exhibited greater induced neural activities than female subjects in right temporo-parietal areas at theta and alpha frequency bands. Source imaging for the time ranges at which maximal gender differences were observed revealed gender-dependent estimated current densities in the right posterior temporal regions. These gender differences can be explained by the existence of distinct, gender-specific hemispheric specialization. Thus, gender differences should be considered during behavioral tasks and electrophysiological measurements.

Valuation in major depression is intact and stable in a non-learning environment

The clinical diagnosis and symptoms of major depressive disorder (MDD) have been closely associated with impairments in reward processing. In particular, various studies have shown blunted neural and behavioral responses to the experience of reward in depression. However, little is known about whether depression affects individuals’ valuation of potential rewards during decision-making, independent from reward experience. To address this question, we used a gambling task and a model-based analytic approach to measure two types of individual sensitivity to reward values in participants with MDD: ‘risk preference,’ indicating how objective values are subjectively perceived, and ‘inverse temperature,’ determining the degree to which subjective value differences between options influence participants’ choices. On both of these measures of value sensitivity, participants with MDD were comparable to non-psychiatric controls. In addition, both risk preference and inverse temperature were stable over four laboratory visits and comparable between the groups at each visit. Neither valuation measure varied with severity of clinical symptoms in MDD. These data suggest intact and stable value processing in MDD during risky decision-making.

Spatiotemporal dynamics and functional correlates of evoked neural oscillations with different spectral powers in human visual cortex

OBJECTIVE To investigate spatiotemporal characteristics and functional correlates of evoked oscillations (EOs) at different frequency bands in human visual cortex. METHODS Flash visual evoked potentials (FVEPs) were recorded from 11 epilepsy patients with intracranial electrodes placed over the occipital and adjacent cortices. Spatiotemporal characteristics of spectral powers and correlation with various visual responses elicited by electrical cortical stimulations were analyzed in the same electrodes. RESULTS High γ (60-150 Hz) EOs were first recorded in the cuneus and lingual gyri around the calcarine sulcus. Low γ (30-60 Hz) EOs appeared also in the mesial occipital cortex slightly later and lasted longer than high γ EGOs. In contrast, lower frequency (LF) <30 Hz EOs were recorded more diffusely from occipital surfaces with delayed onset and longer duration. High γ EOs were predominantly associated with simple form visual responses, whereas low γ and LF EOs were with intermediate form and LF EOs with complex form responses. CONCLUSIONS FVEP spectral power analysis directly recorded from human visual cortex showed distinct spatiotemporal distributions in high and low γ, or LF bands that have different functional correlates. SIGNIFICANCE Phase-locked EOs in these frequency bands may have special neuroanatomical and functional organization during early visual processing.

EEG Source localization analysis for local-global visual processing using sLORETA

The aim of this study was to assess whether Standardized Low Resolution Brain Electromagnetic Tomography (sLORETA) can detect differences in EEG source distribution during local and global stimuli cognition process or not. We recorded the cortical brain activity from 40 subjects (M:F=20:20) during local and global stimuli cognition process. The stimuli were generated based on the modified version of Navons hierarchical structured stimuli (Navon, 1977). We found the differences in 4~8 Hz theta oscillation during the task between male and female groups in sLORETA patterns, particularly in the right temporal cortex. We also found the similar theta oscillation patterns in power spectrum analysis: higher synchronized theta activity between posterior parietal lobe and frontal lobe was found in female group than that of male group. These findings suggest higher dependence on local-global stimulation cognition and memory recall in female. We suggest that sLORETA can be a good tool for detecting local-global stimulus cognition and be a good diagnostic for the neuropsychiatric disorders related to the local-global processing such as Obsessive-compulsive disorder and Posttraumatic stress disorder

Epidemiology of trichomoniasis in South Korea and increasing trend in incidence, health insurance review and assessment 2009-2014

Trichomoniasis, which is caused by Trichomonas vaginalis, is one of the most common non-viral sexually transmitted infections; however, limited population-based data are available that describe patterns and trends of the disease. We summarized insurance claims of trichomoniasis cases reported during 2009–2014 to South Korea Health Insurance Review and Assessment Service. The average annual incidence in South Korea was 276.8 persons per 100,000 population, and a substantial sex-associated variation was observed. The incidence rate among female subjects trended upward over 6 years, that is, it increased from 501 in 2009 to 625.8 in 2014 per 100,000 female population, which indicates a 25% overall increase. This trend was sharpest in the ≥60 years group of female population. However, a 66% decrease in incidence rates was observed among male subjects (23.7 in 2009 to 15.7 in 2014 per 100,000 male population). Further, substantial decrease was observed in the ≥40 years groups of male population. The incidence of trichomoniasis varied across regions and was the highest in Jeju province of South Korea. Overall, as the incidence of trichomoniasis appears to have increased in South Korea during 2009–2014, the disease burden is increasing; hence, there is a need to better understand the disease transmission.

Risky decision-making in major depression is stable and intact

The clinical diagnosis and symptoms of major depressive disorder (MDD) have been closely associated with impairments in reward processing. In particular, various studies have shown blunted neural and behavioral responses to the experience of reward in depression. However, little is known about whether depression affects individuals’ valuation of potential rewards during decision-making, independent from reward experience. To address this question, we used a gambling task and a model-based analytic approach to measure two types of individual sensitivity to reward values in participants with MDD: ‘risk preference,’ indicating how objective values are subjectively perceived, and ‘inverse temperature,’ determining the degree to which subjective value differences between options influence participants’ choices. On both of these measures of value sensitivity, participants with MDD were comparable to non-psychiatric controls. In addition, both risk preference and inverse temperature were stable over four laboratory visits and comparable between the groups at each visit. Neither valuation measure varied with severity of clinical symptoms in MDD. These data suggest intact and stable value processing in MDD during risky decision-making.The clinical diagnosis and symptoms of major depressive disorder (MDD) have been closely associated with impairments in reward processing. In particular, various studies have shown blunted neural and behavioral responses to the experience of reward in depression. However, little is known about whether depression affects individuals′ valuation of potential rewards during decision-making, independent from reward experience. To address this question, we used a gambling task and a model-based analytic approach to measure two types of individual sensitivity to reward values in participants with MDD: ′risk preference,′ indicating how objective values are subjectively perceived and ′inverse temperature,′ determining the degree to which subjective value differences between options influences participants′ choices. On both of these measures of value sensitivity, participants with MDD were comparable to non-psychiatric controls. Both risk preference and inverse temperature were also stable over four laboratory visits and comparable between the groups at each visit. Moreover, neither value sensitivity measure varied with severity of clinical symptoms in MDD. These data suggest intact and stable value processing in MDD during risky decision-making.

Computational modeling of the negative priming effect based on inhibition patterns and working memory

Negative priming (NP), slowing down of the response for target stimuli that have been previously exposed, but ignored, has been reported in multiple psychological paradigms including the Stroop task. Although NP likely results from the interplay of selective attention, episodic memory retrieval, working memory, and inhibition mechanisms, a comprehensive theoretical account of NP is currently unavailable. This lacuna may result from the complexity of stimuli combinations in NP. Thus, we aimed to investigate the presence of different degrees of the NP effect according to prime-probe combinations within a classic Stroop task. We recorded reaction times (RTs) from 66 healthy participants during Stroop task performance and examined three different NP subtypes, defined according to the type of the Stroop probe in prime-probe pairs. Our findings show significant RT differences among NP subtypes that are putatively due to the presence of differential disinhibition, i.e., release from inhibition. Among the several potential origins for differential subtypes of NP, we investigated the involvement of selective attention and/or working memory using a parallel distributed processing (PDP) model (employing selective attention only) and a modified PDP model with working memory (PDP-WM, employing both selective attention and working memory). Our findings demonstrate that, unlike the conventional PDP model, the PDP-WM successfully simulates different levels of NP effects that closely follow the behavioral data. This outcome suggests that working memory engages in the re-accumulation of the evidence for target response and induces differential NP effects. Our computational model complements earlier efforts and may pave the road to further insights into an integrated theoretical account of complex NP effects.