Investigating the Neural Mechanisms of Aware and Unaware Fear Memory with fMRI

Pavlovian fear conditioning is often used in combination with functional magnetic resonance imaging (fMRI) in humans to investigate the neural substrates of associative learning ^1-5. In these studies, it is important to provide behavioral evidence of conditioning to verify that differences in brain activity are learning-related and correlated with human behavior. Fear conditioning studies often monitor autonomic responses (e.g. skin conductance response; SCR) as an index of learning and memory ^6-8. In addition, other behavioral measures can provide valuable information about the learning process and/or other cognitive functions that influence conditioning. For example, the impact unconditioned stimulus (UCS) expectancies have on the expression of the conditioned response (CR) and unconditioned response (UCR) has been a topic of interest in several recent studies ^9-14. SCR and UCS expectancy measures have recently been used in conjunction with fMRI to investigate the neural substrates of aware and unaware fear learning and memory processes ¹⁵. Although these cognitive processes can be evaluated to some degree following the conditioning session, post-conditioning assessments cannot measure expectations on a trial-to-trial basis and are susceptible to interference and forgetting, as well as other factors that may distort results ^16,17 .Monitoring autonomic and behavioral responses simultaneously with fMRI provides a mechanism by which the neural substrates that mediate complex relationships between cognitive processes and behavioral/autonomic responses can be assessed. However, monitoring autonomic and behavioral responses in the MRI environment poses a number of practical problems. Specifically, 1) standard behavioral and physiological monitoring equipment is constructed of ferrous material that cannot be safely used near the MRI scanner, 2) when this equipment is placed outside of the MRI scanning chamber, the cables projecting to the subject can carry RF noise that produces artifacts in brain images, 3) artifacts can be produced within the skin conductance signal by switching gradients during scanning, 4) the fMRI signal produced by the motor demands of behavioral responses may need to be distinguished from activity related to the cognitive processes of interest. Each of these issues can be resolved with modifications to the setup of physiological monitoring equipment and additional data analysis procedures. Here we present a methodology to simultaneously monitor autonomic and behavioral responses during fMRI, and demonstrate the use of these methods to investigate aware and unaware memory processes during fear conditioning. Download video file.^{(83M, mov)}     

To Be or Want to Be: Disentangling the Role of Actual versus Ideal Self in Implicit Self-Esteem

A growing body of work suggests that both depressed and non-depressed individuals display implicit positivity towards the self. In the current study, we examined whether this positivity can be underpinned by two qualitatively distinct propositions related to actual (‘I am good’) or ideal (‘I want to be good’) self-esteem. Dysphoric and non-dysphoric participants completed a self-esteem Implicit Association Test (IAT) as well an Implicit Relational Assessment Procedure (IRAP) targeting their actual self-esteem and an IRAP targeting ideal self-esteem. Both groups demonstrated similar and positive IAT effects. A more complex picture emerged with regard to the IRAP effects. Whereas non-dysphorics did not differ in their actual and ideal self-esteem, their dysphoric counterparts demonstrated lower actual than ideal self-esteem. Our results suggest that closer attention to the role of propositional processes in implicit measures may unlock novel insight into the relationship between implicit self-esteem and depression.     

What Do I Want and When Do I Want It: Brain Correlates of Decisions Made for Self and Other

A number of recent functional Magnetic Resonance Imaging (fMRI) studies on intertemporal choice behavior have demonstrated that so-called emotion- and reward-related brain areas are preferentially activated by decisions involving immediately available (but smaller) rewards as compared to (larger) delayed rewards. This pattern of activation was not seen, however, when intertemporal choices were made for another (unknown) individual, which speaks to that activation having been triggered by self-relatedness. In the present fMRI study, we investigated the brain correlates of individuals who passively observed intertemporal choices being made either for themselves or for an unknown person. We found higher activation within the ventral striatum, medial prefrontal and orbitofrontal cortex, pregenual anterior cingulate cortex, and posterior cingulate cortex when an immediate reward was possible for the observer herself, which is in line with findings from studies in which individuals actively chose immediately available rewards. Additionally, activation in the dorsal anterior cingulate cortex, posterior cingulate cortex, and precuneus was higher for choices that included immediate options than for choices that offered only delayed options, irrespective of who was to be the beneficiary. These results indicate that (1) the activations found in active intertemporal decision making are also present when the same decisions are merely observed, thus supporting the assumption that a robust brain network is engaged in immediate gratification; and (2) with immediate rewards, certain brain areas are activated irrespective of whether the observer or another person is the beneficiary of a decision, suggesting that immediacy plays a more general role for neural activation. An explorative analysis of participants’ brain activation corresponding to chosen rewards, further indicates that activation in the aforementioned brain areas depends on the mere presence, availability, or actual reception of immediate rewards.     

Saccadic Compression of Rectangle and Kanizsa Figures: Now You See It,Now You Don't

Background

Observers misperceive the location of points within a scene as compressed towards the goal of a saccade. However, recent studies suggest that saccadic compression does not occur for discrete elements such as dots when they are perceived as unified objects like a rectangle.

Methodology/Principal Findings

We investigated the magnitude of horizontal vs. vertical compression for Kanizsa figure (a collection of discrete elements unified into single perceptual objects by illusory contours) and control rectangle figures. Participants were presented with Kanizsa and control figures and had to decide whether the horizontal or vertical length of stimulus was longer using the two-alternative force choice method. Our findings show that large but not small Kanizsa figures are perceived as compressed, that such compression is large in the horizontal dimension and small or nil in the vertical dimension. In contrast to recent findings, we found no saccadic compression for control rectangles.

Conclusions

Our data suggest that compression of Kanizsa figure has been overestimated in previous research due to methodological artifacts, and highlight the importance of studying perceptual phenomena by multiple methods.     

How It Came to Be: Carl O. Sauer, Franz Boas, and the Meaning of Anthropogeography

How It Came to Be: Carl O. Sauer, Franz Boas, and the Meaning of Anthropogeography. William W. Speth. Ellensburg, WA: Ephemera Press. 268 pp.     

What It Means to Be 98% Chimpanzee: Apes, People, and Their Genes.

What It Means to Be 98% Chimpanzee: Apes, People, and Their Genes. Jonathan Marks. Berkeley: University of California Press, 2002. 325 pp.     

The Effect of Implicitly Incentivized Faking on Explicit and Implicit Measures of Doping Attitude: When Athletes Want to Pretend an Even More Negative Attitude to Doping

The Implicit Association Test (IAT) aims to measure participants’ automatic evaluation of an attitude object and is useful especially for the measurement of attitudes related to socially sensitive subjects, e.g. doping in sports. Several studies indicate that IAT scores can be faked on instruction. But fully or semi-instructed research scenarios might not properly reflect what happens in more realistic situations, when participants secretly decide to try faking the test. The present study is the first to investigate IAT faking when there is only an implicit incentive to do so. Sixty-five athletes (22.83 years ± 2.45; 25 women) were randomly assigned to an incentive-to-fake condition or a control condition. Participants in the incentive-to-fake condition were manipulated to believe that athletes with lenient doping attitudes would be referred to a tedious 45-minute anti-doping program. Attitudes were measured with the pictorial doping brief IAT (BIAT) and with the Performance Enhancement Attitude Scale (PEAS). A one-way MANOVA revealed significant differences between conditions after the manipulation in PEAS scores, but not in the doping BIAT. In the light of our hypothesis this suggests that participants successfully faked an exceedingly negative attitude to doping when completing the PEAS, but were unsuccessful in doing so on the reaction time-based test. This study assessed BIAT faking in a setting that aimed to resemble a situation in which participants want to hide their attempts to cheat. The two measures of attitude were differentially affected by the implicit incentive. Our findings provide evidence that the pictorial doping BIAT is relatively robust against spontaneous and naïve faking attempts. (B)IATs might be less prone to faking than implied by previous studies.     

Painfully Aware: The Effects of Dissonance on Attitudes toward Factory Farming

ABSTRACT

We examine the moderating effects of cognitive dissonance on the persuasiveness of a message designed to influence attitudes and behaviors supportive of intensive-production animal agriculture, or “factory farming.” Existing research on human attitudes toward nonhuman animals indicates that generic disapproval of their suffering gratuitously at human hands is a social norm. However, studies also reveal an absence of related knowledge, attitudes, and behaviors seemingly implied by this stance. Such apparent inconsistencies may persist due to lack of awareness about and/or engagement with the issue of farm animal welfare. We used a two-group, between-subjects experimental design, and the subject pool consisted of 62 non-vegetarian university students. Following random assignment to either the commitment condition or a non-commitment control group, all participants received an informational booklet arguing for the prevalence of neglect and abuse in industrial animal agriculture. Commitment participants, however, first responded privately to a dichotomous, single-item questionnaire, either agreeing or disagreeing that “animals should not suffer needlessly in the production of meat.” Given that the need to resolve or avoid self-contradiction can motivate attitudinal realignment, we hypothesized that an educational intervention would be more sympathetically received by individuals who had already volunteered support for its central premise, than by those never invited to adopt a stance. Results supporting three of four hypotheses indicated significantly heightened receptivity to an anti-factory farming message following commitment to a pro-welfare position. Commitment participants tended to be more open to eating less meat, concerned with the issue, and accepting of the message's basic claims. A fourth hypothesis was not supported: participants across groups were ambivalent about source credibility. We infer that animal advocacy efforts may more effectively generate public support for the cause by framing appeals to capitalize on what polls show most people already believe (i.e., that animal cruelty ought to be prevented).     

Effect of Soil Moisture Content on the Splash Phenomenon Reproducibility

One of the methods for testing splash (the first phase of water erosion) may be an analysis of photos taken using so-called high-speed cameras. The aim of this study was to determine the reproducibility of measurements using a single drop splash of simulated precipitation. The height from which the drops fell resulted in a splash of 1.5 m. Tests were carried out using two types of soil: Eutric Cambisol (loamy silt) and Orthic Luvisol (sandy loam); three initial pressure heads were applied equal to 16 kPa, 3.1 kPa, and 0.1 kPa. Images for one, five, and 10 drops were recorded at a rate of 2000 frames per second. It was found that (i) the dispersion of soil caused by the striking of the 1st drop was significantly different from the splash impact caused by subsequent drops; (ii) with every drop, the splash phenomenon proceeded more reproducibly, that is, the number of particles of soil and/or water that splashed were increasingly close to each other; (iii) the number of particles that were detached during the splash were strongly correlated with its surface area; and (iv) the higher the water film was on the surface the smaller the width of the crown was.     

是否应重新重视RNA在启动基因中的作用

比较真核生物与原核生物的区别,分析RNA活化基因的证据,作认为基因组中广泛存在的无转录、无编码功能的DNA序列及内含子RNA可能有重要的生物学功能,是控制同样基因在不同细胞类型中表达不同的特异性因素。     

A Population of Kisspeptin/Neurokinin B Neurons in the Arcuate Nucleus May Be the Central Target of the Male Effect Phenomenon in Goats

Exposure of females to a male pheromone accelerates pulsatile gonadotropin-releasing hormone (GnRH) secretion in goats. Recent evidence has suggested that neurons in the arcuate nucleus (ARC) containing kisspeptin and neurokinin B (NKB) play a pivotal role in the control of GnRH secretion. Therefore, we hypothesized that these neurons may be the central target of the male pheromone. To test this hypothesis, we examined whether NKB signaling is involved in the pheromone action, and whether ARC kisspeptin/NKB neurons receive input from the medial nucleus of the amygdala (MeA)—the nucleus suggested to relay pheromone signals. Ovariectomized goats were implanted with a recording electrode aimed at a population of ARC kisspeptin/NKB neurons, and GnRH pulse generator activity, represented by characteristic increases in multiple-unit activity (MUA) volleys, was measured. Pheromone exposure induced an MUA volley and luteinizing hormone (LH) pulse in control animals, whereas the MUA and LH responses to the pheromone were completely suppressed by the treatment with an NKB receptor antagonist. These results indicate that NKB signaling is a prerequisite for pheromone action. In ovariectomized goats, an anterograde tracer was injected into the MeA, and possible connections between the MeA and ARC kisspeptin/NKB neurons were examined. Histochemical observations demonstrated that a subset of ARC kisspeptin/NKB neurons receive efferent projections from the MeA. These results suggest that the male pheromone signal is conveyed via the MeA to ARC kisspeptin neurons, wherein the signal stimulates GnRH pulse generator activity through an NKB signaling-mediated mechanism in goats.     

The Pertinence of the Periodic Selection Phenomenon to Prokaryote Evolution

A quarter of a century ago, it was pointed out that evolution can act in an important conservative way, in addition to its normal progressive mode. Evolution to a fitter form via changes at one locus means that the descendants of an individual with an improved locus or set of loci will supplant the previous population and carry with them the bulk of the total genotype of that original individual in asexual populations. Inasmuch as that individual is most likely to be wild type at most other loci, neutral and even other positively selected mutations will be reduced or eliminated from the population, if they are rare at the time of the evolutionary advance. In the present paper this problem has been set up for a computer simulation. The computations show the limits within which this effect functions and the conditions under which it does not. The conclusion is that it is likely that evolution at a locus proceeds in the course of many population replacements or revolutions, mostly via the rare occasions when the revolution carries a previously infrequent mutational type into abundance.     

The Phenomenon of Personalization of the Environment: A Theoretical

The changes taking place in the residential environment have raised a very acute question: How to give due consideration to the distinctive features of the particular human being and the laws and patterns of his activity and social intercourse; how to include the "human element" in the ever more complicated mechanism of environmental planning as the man-made world, from the apartment to urban agglomerations, is shaped and transformed? Quests for an answer to this question over the past fifteen to twenty years have produced a new area of psychological investigation, most commonly referred to as "environmental psychology."