Local synchronization of resting-state dynamics encodes Gray's trait Anxiety

The Behavioral Inhibition System (BIS) as defined within the Reinforcement Sensitivity Theory (RST) modulates reactions to stimuli indicating aversive events. Gray’s trait Anxiety determines the extent to which stimuli activate the BIS. While studies have identified the amygdala-septo-hippocampal circuit as the key-neural substrate of this system in recent years and measures of resting-state dynamics such as randomness and local synchronization of spontaneous BOLD fluctuations have recently been linked to personality traits, the relation between resting-state dynamics and the BIS remains unexplored. In the present study, we thus examined the local synchronization of spontaneous fMRI BOLD fluctuations as measured by Regional Homogeneity (ReHo) in the hippocampus and the amygdala in twenty-seven healthy subjects. Correlation analyses showed that Gray’s trait Anxiety was significantly associated with mean ReHo in both the amygdala and the hippocampus. Specifically, Gray’s trait Anxiety explained 23% and 17% of resting-state ReHo variance in the left amygdala and the left hippocampus, respectively. In summary, we found individual differences in Gray’s trait Anxiety to be associated with ReHo in areas previously associated with BIS functioning. Specifically, higher ReHo in resting-state neural dynamics corresponded to lower sensitivity to punishment scores both in the amygdala and the hippocampus. These findings corroborate and extend recent findings relating resting-state dynamics and personality while providing first evidence linking properties of resting-state fluctuations to Gray’s BIS

The magnitude representation of small and large symbolic numbers in the left and right hemisphere: An event-related fMRI study

Numbers are known to be processed along the left and right intraparietal sulcus. The present study investigated hemispheric differences between the magnitude representation of small and large symbolic numbers. To this purpose, an fMRI adaptation paradigm was used, where the continuous presentation of a habituation number was interrupted by an occasional deviant number. The results presented a distance-dependent increase of activation: larger ratios of habituation and deviant number caused a larger recovery of activation. Similar activation patterns were observed for small and large symbolic numbers, which is in line with the idea of a more coarse magnitude representation for large numbers. Interestingly, this pattern of activation was only observed in the left parietal cortex, supporting the recently proposed idea of Ansari [Ansari, D. Does the parietal cortex distinguish between "10", "Ten," and Ten Dots? Neuron, 53, 165-167, 2007] that the left parietal cortex is specialized in the processing of encultured symbolically presented numbers.status: publishe

The neural origin of the priming distance effect : distance-dependent recovery of parietal activation using symbolic magnitudes

Numerical magnitudes are known to be processed in areas around the intraparietal sulci of the brain. We used an fMRI-adaptation paradigm to investigate how they are actually coded at the neural level. In a number identification task, we manipulated the numerical distance between prime and target numbers (same, close, and far pairs) and their symbolic notation (Arabic and verbal numerals). We show that bilateral parietal activations present a distance-dependent recovery of activation positively correlated with the distance between primes and targets: the larger the prime-target distance, the higher the recovery of activation. Importantly, this effect is only present for trials where an Arabic numeral precedes a verbal numeral and not the reverse. Together, these findings reveal the neural origin of the behavioral priming distance effect and demonstrate that the relative importance of the semantic and nonsemantic pathways in a dual-route model of number processing is modulated by symbolic notation. © 2009 Wiley-Liss, Inc

Masked primes can be genuinely semantically processed: A picture prime study

Van den Bussche and Reynvoet (2007) argued that since significant priming was observed for novel primes from a large category, subliminal primes can be processed semantically. However, a possible confound in this study was the presence of nonsemantic effects such as orthographic overlap between primes and targets. Therefore, the first aim of this study was to validate our previous claim when nonsemantic influences are avoided. The second aim was to investigate the impact of nonsemantic stimulus processing on priming effects by manipulating target set size. The results showed that when nonsemantic effects are eliminated by presenting primes as pictures and targets as words, significant priming emerged for large stimulus categories and a large target set. This cannot be explained by nonsemantic accounts of subliminal processing and shows that subliminal primes can be truly semantically processed. However, when using a limited amount of targets, stimulating nonsemantic processing, priming disappeared. This indicates that the task context will determine whether stimuli will be processed semantically or nonsemantically, which in turn can influence priming effects.status: publishe

Cooperative preferences fluctuate across the menstrual cycle

Social Value Orientation (SVO) refers to an individual's preference for the division of resources between the self and another person. Since evidence suggests that hormones influence several facets of human social behavior, we asked whether SVO might fluctuate across the female menstrual cycle. Using self-report data obtained in two independent online studies, we show that cooperative preferences, as indexed by SVO, are indeed significantly more prosocial in the early follicular compared to the midluteal phase in naturally ovulating women. Furthermore, when estimating hormonal variations from norm data, we found estradiol, but not progesterone or testosterone, to be a significant predictor of SVO across the menstrual cycle in both studies, with a negative correlation. Our findings provide evidence that the willingness to cooperate varies across the natural female menstrual cycle and highlight the potential of investigating psychological effects of ovarian sex hormones

How to trust a perfect stranger : predicting initial trust behavior from resting-state brain-electrical connectivity

Reciprocal exchanges can be understood as the updating of an initial belief about a partner. This initial level of trust is essential when it comes to establishing cooperation with an unknown partner, as cooperation cannot arise without a minimum of trust not justified by previous successful exchanges with this partner. Here we demonstrate the existence of a representation of the initial trust level before an exchange with a partner has occurred. Specifically, we can predict the Investor’s initial investment—i.e. his initial level of trust toward the unknown trustee in Round 1 of a standard 10-round Trust Game—from resting-state functional connectivity data acquired several minutes before the start of the Trust Game. Resting-state functional connectivity is, however, not significantly associated with the level of trust in later rounds, potentially mirroring the updating of the initial belief about the partner. Our results shed light on how the initial level of trust is represented. In particular, we show that a person’s initial level of trust is, at least in part, determined by brain electrical activity acquired well before the beginning of an exchange

Facial width-to-height ratio differs by social rank across organizations, countries, and value systems.

Facial Width-to-Height Ratio (fWHR) has been linked with dominant and aggressive behavior in human males. We show here that on portrait photographs published online, chief executive officers (CEOs) of companies listed in the Dow Jones stock market index and the Deutscher Aktienindex have a higher-than-normal fWHR, which also correlates positively with their company's donations to charitable causes and environmental awareness. Furthermore, we show that leaders of the world's most influential non-governmental organizations and even the leaders of the Roman Catholic Church, the popes, have higher fWHR compared to controls on public portraits, suggesting that the relationship between displayed fWHR and leadership is not limited to profit-seeking organizations. The data speak against the simplistic view that wider-faced men achieve higher social status through antisocial tendencies and overt aggression, or the mere signaling of such dispositions. Instead they suggest that high fWHR is linked with high social rank in a more subtle fashion in both competitive as well as prosocially oriented settings

Association between Gray’s trait Anxiety (SP) scores and mean Regional Homogeneity (ReHo) over the amygdala (upper panel) and the hippocampus (lower panel).

<p>Association between Gray’s trait Anxiety (SP) scores and mean Regional Homogeneity (ReHo) over the amygdala (upper panel) and the hippocampus (lower panel).</p