Differential modulation of performance in insight and divergent thinking tasks with tDCS

While both insight and divergent thinking tasks are used to study creativity, there are reasons to believe that the two may call upon very different mechanisms. To explore this hypothesis, we administered a verbal insight task (riddles) and a divergent thinking task (verbal fluency) to 16 native English speakers and 16 non-native English speakers after they underwent Transcranial Direct Current Stimulation (tDCS) of the left middle temporal gyrus and right temporo- parietal junction. We found that, in the case of the insight task the depolarization of right temporo-parietal junction and hyperpolarization of left middle temporal gyrus resulted in increased performance, relative to both the control condition and the reverse stimulation condition in both groups (non-native > native speakers). However, in the case of the divergent thinking task, the same pattern of stimulation resulted in a decrease in performance, compared to the reverse stimulation condition, in the non-native speakers. We explain this dissociation in terms of differing task demands of divergent thinking and insight tasks and speculate that the greater sensitivity of non-native speakers to tDCS stimulation may be a function of less entrenched neural networks for non-native languages

Reason and Less

A new, biologically driven model of human behavior in which reason is tethered to the evolutionarily older autonomic, instinctive, and associative systems. In Reason and Less, Vinod Goel explains the workings of the tethered mind. Reason does not float on top of our biology but is tethered to evolutionarily older autonomic, instinctive, and associative systems. After describing the conceptual and neuroanatomical basis of each system, Goel shows how they interact to generate a blended response. Goel's commonsense account drives human behavior back into the biology, where it belongs, and provides a richer set of tools for understanding how we pursue food, sex, and politics. Goel takes the reader on a journey through psychology (cognitive, behavioral, developmental, and evolutionary), neuroscience, philosophy, ethology, economics, and political science to explain the workings of the tethered mind. One key insight that holds everything together is that feelings—generated in old, widely conserved brain stem structures—are evolution's solution to initiating and selecting all behaviors, and provide the common currency for the different systems to interact. Reason is as much about feelings as are lust and the taste of chocolate cake. All systems contribute to behavior and the overall control structure is one that maximizes pleasure and minimizes displeasure. Tethered rationality has some sobering and challenging implications for such real-world human behaviors as climate change denial, Trumpism, racism, or sexism. They cannot be changed simply by targeting beliefs but will require more drastic measures, the nature of which depends on the specific behavior in question. Having an accurate model of human behavior is the crucial first step

Comparison of Well-Structured & Ill-Structured Task Environments and Problem Spaces

Many of our results in the problem-solving literature are fh)m puzzle-game domains. Intuitively, most of us feel that there are differences between puzzle problems and open-ended, real-world problems. There has been some attempt to capture these differences in the vocabulary of "ill-structured" and "well-structured" prooblems. However, there seem to be no empirical studies directed at this distinction. This paper examines and compares the task environments and problem spaces of a prototypical well-structured problem (cryptarithmetic) with the task environments and problem spaces of a class of prototypical illstructured problems (design problems). Results indicate substantive differences, both in the task environments and the problem spaces

The effect of partner-directed emotion in social exchange decision-making

Despite the prevalence of studies examining economic decision-making as a purely rational phenomenon, common sense suggests that emotions affect our decision-making particularly in a social context. To explore the influence of emotions on economic decision-making, we manipulated opponent-directed emotions prior to engaging participants in two social exchange decision-making games (the Trust Game and the Prisoner's Dilemma). Participants played both games with three different (fictional) partners and their tendency to defect was measured. Prior to playing each game, participants exchanged handwritten “essays” with their partners, and subsequently exchanged evaluations of each essay. The essays and evaluations, read by the participant, were designed to induce either anger, sympathy, or a neutral emotional response toward the confederate with whom they would then play the social exchange games. Galvanic skin conductance level (SCL) showed enhanced physiological arousal during anger induction compared to both the neutral and sympathy conditions. In both social exchange games, participants were most likely to defect against their partner after anger induction and least likely to defect after sympathy induction, with the neutral condition eliciting intermediate defection rates. This pattern was found to be strongest in participants exhibiting low cognitive control (as measured by a Go/no-Go task). The findings indicate that emotions felt toward another individual alter how one chooses to interact with them, and that this influence depends both on the specific emotion induced and the cognitive control of the individual

Dissociable Neural Systems Underwrite Logical Reasoning in the Context of Induced Emotions with Positive and Negative Valence

How emotions influence syllogistic reasoning is not well understood. fMRI was employed to investigate the effects of induced positive or negative emotion on syllogistic reasoning. Specifically, on a trial-by-trial basis participants were exposed to a positive, negative, or neutral picture, immediately prior to engagement in a reasoning task. After viewing and rating the valence and intensity of each picture, participants indicated by keypress whether or not the conclusion of the syllogism followed logically from the premises. The content of all syllogisms was neutral, and the influence of belief-bias was controlled for in the study design. Emotion did not affect reasoning performance, although there was a trend in the expected direction based on accuracy rates for the positive (63%) and negative (64%) versus neutral (70%) condition. Nevertheless, exposure to positive and negative pictures led to dissociable patterns of neural activation during reasoning. Therefore, the neural basis of deductive reasoning differs as a function of the valence of the context

Lesions to Polar/Orbital Prefrontal Cortex Selectively Impair Reasoning about Emotional Material

While it is widely accepted that lesions to orbital prefrontal cortex lead to emotion related disruptions and poor decision-making, there is very little patient data on this issue involving actual logical reasoning tasks. We tested patients with circumscribed, focal lesions largely confined to polar/orbital prefrontal cortex (BA 10 and 11) (N=17) on logical reasoning tasks involving neutral and emotional content, and compared their performance to that of an age and education-matched normal control group (N=22) and a posterior lesion control group (N=24). Our results revealed a significant group by content interaction driven by a selective impairment in the polar/orbital prefrontal cortex group compared to healthy normal controls and to the parietal patient group, in the emotional content reasoning trials. Subsequent analyses of congruent and incongruent reasoning trials indicated that this impairment was driven by the poor performance of patients with polar/orbital lesions in the incongruent trials. We conclude that the polar/orbital prefrontal cortex plays a critical role in filtering emotionally charged content from the material before it is passed on to the reasoning system in lateral/dorsal regions of prefrontal cortex. Where unfiltered content is passed to the reasoning engine, either as a result of pathology (as in the case of our patients) or as a result of individual differences, reasoning performance suffers

Differential roles of polar orbital prefrontal cortex and parietal lobes in logical reasoning with neutral and negative emotional content

© 2018 The Authors To answer the question of how brain pathology affects reasoning about negative emotional content, we administered a disjunctive logical reasoning task involving arguments with neutral content (e.g. Either there are tigers or women in NYC, but not both; There are no tigers in NYC; There are women in NYC) and emotionally laden content (e.g. Either there are pedophiles or politicians in Texas, but not both; There are politicians in Texas; There are no pedophiles in Texas) to 92 neurological patients with focal lesions to various parts of the brain. A Voxel Lesion Symptom Mapping (VLSM) analysis identified 16 patients, all with lesions to the orbital polar prefrontal cortex (BA 10 & 11), as being selectively impaired in the emotional reasoning condition. Another 17 patients, all with lesions to the parietal cortex, were identified as being impaired in the neutral content condition. The reasoning scores of these two patient groups, along with 23 matched normal controls, underwent additional analysis to explore the effect of belief bias. This analysis revealed that the differences identified above were largely driven by trials where there was an incongruency between the believability of the conclusion and the validity of the argument (i.e. valid argument/false conclusion or invalid argument/true conclusion). Patients with lesions to polar orbital prefrontal cortex underperformed in incongruent emotional content trials and over performed in incongruent neutral content trials (compared to both normal controls and patients with parietal lobe lesions). Patients with lesions to parietal lobes underperformed normal controls (at a trend level) in neutral trials where there was a congruency between the believability of the conclusion and the validity of the argument (i.e. valid argument/true conclusion or invalid argument/false conclusion). We conclude that lesions to the polar orbital prefrontal cortex (i) prevent these patients from enjoying any emotionally induced cognitive boost, and (ii) block the belief bias processing route in the neutral condition. Lesions to parietal lobes result in a generalized impairment in logical reasoning with neutral content

Prepubertal Buffalo (Bubalus bubalis) Leydig Cells: Isolation, Culture and Characterization

Abstract: Water buffalo (Bubalus bubalis) is an economically important livestock species in India. Male buffaloes display delayed sexual maturity as compared to the bulls (Bos taurus). Serum testosterone level, the key regulator of sexual maturity of males, is reported to be low in male buffaloes in comparison to bulls. Testosterone secretion and progression of spermatogenesis is mediated essentially by Leydig cells in the males. Establishment of primary culture for buffalo Leydig cells can provide an excellent tool to investigate the factors which regulate testicular steroidogenesis. Therefore, the objectives of the present study were to isolate, culture and characterize buffalo Leydig cells. Immunohistological analysis revealed that cytochrome P450, family 11, subfamily A, polypeptide 1 (CYP11A1) specifically mark the Leydig cells in prepubertal buffalo testis. Using enzymatic digestion and Percoll density gradient centrifugation, a cell population that consisted of approximately 95% pure Leydig cells was obtained as indicated by CYP11A1 staining. Purified Leydig cells were cultured in DMEM/F12 supplemented with 10% foetal bovine serum (FBS) for 72 h. The cultured Leydig cells proliferated, expressed Leydig-cell specific transcripts (STAR, HSD3B1, HSD3B6, and CYP17A1) and proteins (CYP11A1, HSD3B and LHCGR), and secreted testosterone. It was concluded from the present study that buffalo Leydig cells can be maintained in culture for 72 h. The primary culture of buffalo Leydig cells can be used for studying acute responses, biochemical properties and other factors regulating testicular steroidogenesis, independent of other testicular cell types