Social relations between humans critically depend on our affective experiences of others. Oxytocin enhances prosocial behavior, but its effect on humans’ affective experience of others is not known. We tested whether oxytocin influences affective ratings, and underlying
brain activity, of faces that have been aversively conditioned. Using a standard conditioning procedure, we induced differential negative affective ratings in faces exposed to an aversive conditioning compared with nonconditioning manipulation. This differential negative
evaluative effect was abolished by treatment with oxytocin, an effect associated with an attenuation of activity in anterior medial temporal and anterior cingulate cortices. In amygdala and fusiform gyrus, this modulation was stronger for faces with direct gaze, relative to
averted gaze, consistent with a relative specificity for socially relevant cues. The data suggest that oxytocin modulates the expression of evaluative conditioning for socially relevant faces via influences on amygdala and fusiform gyrus, an effect that may explain its prosocial
effects.
Understanding how organisms deal with probabilistic stimulus-reward associations has been ad-vanced by a convergence between reinforcement learning models and primate physiology, which demonstrated that the brain encodes a reward prediction error signal. However, organisms must also predict the level of risk associated with reward forecasts, monitor the errors in those risk predictions, and update these in light of new information. Risk prediction serves a dual purpose: (1) to guide choice in risk-sensitive organisms and (2) to modulate learning of uncertain rewards. To date, it is not known whether or how the brain accomplishes risk prediction. Using functional imaging during a simple gambling task in which we constantly changed risk, we show that an early-onset activation in the human insula correlates significantly with risk prediction error and that its time course is consistent with a role in rapid updating. Additionally, we show that activa-tion previously associated with general uncertainty emerges with a delay consistent with a role in risk prediction. The activations correlating with risk prediction and risk prediction errors are the analogy for risk of activations correlating with reward prediction and reward prediction errors for reward expectation. As such, our findings indicate that our understanding of the neural basis of reward anticipation under uncertainty needs to be expanded to include risk prediction.
To monitor the environment for social threat humans must build affective evaluations of others. These evaluations are malleable and to a high degree shaped by responses engendered by specific social encounters. The precise neuronal mechanism by which these evaluations are constructed is poorly understood. We tested a hypothesis that conjoint activity in amygdala and fusiform gyrus would correlate with acquisition of social stimulus value. We tested this using a reinforcement learning algorithm,
Q-learning, that assigned values to faces as a function of a history of pairing, or not pairing, with aversive shocks. Behaviourally, we observed a correlation between conditioning induced changes in skin conductance response (SCR) and subjective ratings for likeability of faces. Activity in both amygdala and fusiform gyrus (FG) correlated with the output of the reinforcement learning
algorithm parameterized by these ratings. In amygdala, this effect was greater for averted than direct gaze faces. Furthermore, learning-related activity change in these regions correlated with SCR and subjective ratings. We conclude that amygdala and fusiform encode affective value in a manner that closely approximates a standard computational solution to learning.
The analysis of the competitive environment – monopoly, oligopoly or many competitors –in which international organizations act, has been neglected in scholarly
research. Both this external and the internal type of competition in international organizations are rather weak and performance is far from ideal. To strengthen both
types of competition, several tentative proposals are advanced. They range from the introduction of an international competition agency, the use of prediction markets, matching contributions, to the employment of elements of direct democracy via randomly elected trustees. These proposals are put forward to stimulate discussion
and to advance new ideas about the design of international organizations.
The Hayling Sentence Completion Task (HSCT) is known to
activate left hemisphere frontal and temporal language regions. However, the effective connectivity between frontal and temporal language regions associated with the task has yet to be examined. The aims of the study were to examine activation and effective connectivity during the HSCT using a functional magnetic resonance imaging (fMRI) paradigm in which participants made overt verbal responses. We predicted that producing an incongruent response (response suppression), compared to a congruent one (response initiation), would be associated with greater activation in the left prefrontal cortex and an increase
in the effective connectivity between temporal and frontal
regions. Fifteen participants were scanned while completing
80 sentence stems. The congruency and constraint of sentences varied across trials. Dynamic Causal Modeling (DCM) and Bayesian Model Selection (BMS) were used to compare a set of alternative DCMs of fronto-temporal connectivity. The HSCT activated regions in the left temporal and prefrontal cortices, and the cuneus. Response suppression was associated with greater activation in the left middle and orbital frontal gyri and the bilateral precuneus than response initiation. Left middle temporal and frontal regions identified by the conventional fMRI
analyses were entered into the DCM analysis. Using a systematic BMS procedure, the optimal DCM showed that the connection from the left middle temporal gyrus, which was driven by verbal stimuli per se, was significantly increased in strength during response suppression compared to initiation. Greater effective connectivity between left temporal and prefrontal regions during response suppression may reflect the transfer of information from posterior temporal regions where semantic and lexical information
is stored to prefrontal regions where it is manipulated
in preparation for an appropriate response.
In a recent fMRI study with identical word stimuli we demonstrated task-dependent lateralization of brain activity during visual processing, with left-hemispheric activations for letter decisions and right-hemispheric activations for visuospatial decisions (Stephan, K.E.,
Marshall, J.C., Friston, K.J., Rowe, J.B., Ritzl, A., Zilles, K., Fink, G.R., 2003. Lateralized Cognitive
Processes and Lateralized Task Control in the Human Brain. Science 301, 384–386). In order to explore the temporal dynamics of these lateralized processes we here recorded
multichannel event-related potentials (ERPs) using the same stimuli. ERP data were analysed with current source density reconstruction (CDR). Contrasting the ERP results
elicited by the two tasks, source deconvolution showed enhanced activity during letter decisions in Broca's area from 200–250 ms during letter decisions and during visuospatial decisions in the right posterior parietal cortex (PPC) from 175–200 msand 250–275 ms. Prior to
these activations ERP data revealed an initiation of activity within the anterior cingulate cortex (ACC) from 125–150 ms followed by a late activation of this region from 400–425 ms. Consistent with our previous fMRI study the current electrophysiological data support the
notion that lateralized cognitive processes may depend on task requirements rather than stimulus properties. The current results extend our previous findings as they allow insights into the temporal dynamics of these lateralized processes and their relations to task control processes. The temporal deconvolution of ERPs suggests an early differential involvement of Broca's area in letter-processing and of PPC during visuospatial processing. In addition, activation of ACC prior and after this differential activation is consistent with previous
findings suggesting that this area may be involved in cognitive control.
Mit dem Ausbruch des Ersten Weltkrieges am 1. August 1914 brach die liberale Wirtschaftsordnung nach einer langen Phase der Expansion buchstäblich über Nacht zusammen. Der Krieg entwickelte sich rasch zu einem hochtechnisierten Produktions- und Abnutzungskampf, der Millionen von Menschen das Leben kostete. Um die «Materialschlachten» durchstehen zu können, wurde nicht nur die Kontrolle und optimale Nutzung wirtschaftlicher Ressourcen, sondern auch die Schwächung der Schlagkraft des Gegners zu einer zentralen Aufgabe der Kriegsführung. Obwohl die Schweiz als neutrales Land nicht direkt in den Krieg verstrickt war, wirkten sich der immer härter geführte Wirtschaftskrieg und die Blockadepolitik der Entente auch auf die Schweizer Wirtschaft aus. Neuen Absatzmärkten und teilweise hohen Gewinnen standen eine zunehmende Regulierungsdichte und eine immer stärker eingeschränkte Handlungsfreiheit gegenüber. Anhand von 16 Fallstudien ermöglicht der vorliegende Band erstmals einen Einblick in die wechselvolle und spannende Geschichte von Schweizer Unternehmen im Ersten Weltkrieg. Entstanden ist eine Publikation, die alle wichtigen Branchen abdeckt und damit eine solide Grundlage für dieses noch kaum erforschte Thema legt.
The neurophysiology of eye movements has been studied extensively, and several computational models have been proposed for decision-making processes that underlie the generation of eye movements towards a visual stimulus in a situation of uncertainty. One class of models, known as linear rise-to-threshold models, provides an economical, yet broadly applicable, explanation for the observed
variability in the latency between the onset of a peripheral visual target and the saccade towards it. So
far, however, these models do not account for the dynamics of learning across a sequence of stimuli, and they do not apply to situations in which subjects are exposed to events with conditional probabilities. In this methodological paper, we extend the class of linear rise-to-threshold models to address these limitations. Specifically, we reformulate previous models in terms of a generative, hierarchical model, by combining two separate sub-models that account for the interplay between learning of target locations across trials and the decision-making process within trials. We derive a maximum-likelihood scheme for
parameter estimation as well as model comparison on the basis of log likelihood ratios. The utility of the
integrated model is demonstrated by applying it to empirical saccade data acquired from three healthy
subjects. Model comparison is used (i) to show that eye movements do not only reflect marginal but also
conditional probabilities of target locations, and (ii) to reveal subject-specific learning profiles over trials.
These individual learning profiles are sufficiently distinct that test samples can be successfully mapped
onto the correct subject by a naïve Bayes classifier. Altogether, our approach extends the class of linear
rise-to-threshold models of saccadic decision making, overcomes some of their previous limitations, and
enables statistical inference both about learning of target locations across trials and the decision-making process within trials.
