Reward prospect rapidly speeds up response inhibition via reactive control

Response inhibition is an important cognitive-control function that allows for already-initiated or habitual behavioral responses to be promptly withheld when needed. A typical paradigm to study this function is the stop-signal task. From this task, the stop-signal response time (SSRT) can be derived, which indexes how rapidly an already-initiated response can be canceled. Typically, SSRTs range around 200 ms, identifying response inhibition as a particularly rapid cognitive-control process. Even so, it has recently been shown that SSRTs can be further accelerated if successful response inhibition is rewarded. Since this earlier study effectively ruled out differential preparatory (proactive) control adjustments, the reward benefits likely relied on boosted reactive control. Yet, given how rapidly such control processes would need to be enhanced, alternative explanations circumventing reactive control are important to consider. We addressed this question with an fMRI study by gauging the overlap of the brain networks associated with reward-related and response-inhibition-related processes in a reward-modulated stop-signal task. In line with the view that reactive control can indeed be boosted swiftly by reward availability, we found that the activity in key brain areas related to response inhibition was enhanced for reward-related stop trials. Furthermore, we observed that this beneficial reward effect was triggered by enhanced connectivity between task-unspecific (reward-related) and task-specific (inhibition-related) areas in the medial prefrontal cortex (mPFC). The present data hence suggest that reward information can be translated very rapidly into behavioral benefits (here, within ~200 ms) through enhanced reactive control, underscoring the immediate responsiveness of such control processes to reward availability in general.     

An electrophysiological dissociation of craving and stimulus-dependent attentional capture in smokers

It has been suggested that over the course of an addiction, addiction-related stimuli become highly salient in the environment, thereby capturing an addict’s attention. To assess these effects neurally in smokers, and how they interact with craving, we recorded electroencephalography (EEG) in two sessions: one in which participants had just smoked (non-craving), and one in which they had abstained from smoking for 3 h (craving). In both sessions, participants performed a visual-search task in which two colored squares were presented to the left and right of fixation, with one color being the target to which they should shift attention and discriminate the locations of two missing corners. Task-irrelevant images, both smoking-related and non-smoking-related, were embedded in both squares, enabling the shift of spatial attention to the target to be examined as a function of the addiction-related image being present or absent in the target, the distractor, or both. Behaviorally, participants were slower to respond to targets containing a smoking-related image. Furthermore, when the target contained a smoking-related image, the neural responses indicated that attention had been shifted less strongly to the target; when the distractor contained a smoking-related image, the shift of attention to the contralateral target was stronger. These effects occurred independently of craving and suggest that participants were actively avoiding the smoking-related images. Together, these results provide an electrophysiological dissociation between addiction-related visual-stimulus processing and the neural activity associated with craving.     

The modulatory impact of reward and attention on global feature selection in human visual cortex

Reward powerfully influences human behaviour and perception, with reward effects being observed already on the level of basic sensory processing. Although reward-related modulations generally resemble those related to attentional selection, it is debated whether these effects indeed reflect the same selection operations. Here we focus on neuromagnetic indices of global colour-based attention in visual cortex, and ask whether reward elicits the same or separable underlying modulation effects. Observers performed a colour/orientation selection task where colour served to define the target as well as reward prospect. On each trial a target containing the target colour and one other colour was presented in the left visual field (VF) together with a bicoloured distractor in the right VF. Reward was delivered on correctly performed trials when the reward colour appeared in the target but not when it appeared in the distractor. The effect of global colour selection was assessed by comparing the brain response to the distractor depending on whether it contained the target colour, the reward colour, both, or neither. We observed that both the reward and target colour led to similar increases of the neuromagnetic response between ~200–260 ms originating from the same ventral extrastriate visual cortex areas, albeit slightly temporally lagged. Importantly, the response to the target and reward colour alone always added up to match the response size of their combined presentation. These results suggest that while reward and attention recruit the same global feature selection effects in extrastriate visual cortex, they are likely controlled by independent top-down influences.     

Ontogenese des Verhaltens von Totenkopf-Affen (Saimiri sciureus)

Zusammenfassung Zehn Totenkopf-Affenkinder, die in gemischten Gruppen aufwuchsen, wurden in einer Verlaufsuntersuchung über 1200 Std beobachtet. Die Ontogenese des Verhaltens von der Geburt bis ins vierte Lebensjahr hinein wird in sieben Phasen beschrieben. Neben der Mutter-Kind-Beziehung wird vor allem die Beziehung zwischen Kind und Gruppe berücksichtigt.Während des ersten Lebensmonats ist die Mutter-Kind-Beziehung überwiegend taktil gelenkt. Interaktionen des Säuglings mit Gruppenmitgliedern gibt es schon vom ersten Lebenstag an. Von der dritten Woche an entsteht die sog. Tante-Kind-Beziehung, eine enge, meist vielseitige Bindung zwischen dem Kind und einem Weibchen.Wenn das Kind im zweiten Lebensmonat motorisch selbständig wird, entwickelt sich eine stärker visuell orientierte Beziehung zur Mutter. Zugleich setzt die Entwöhnung ein, und das Kind erweitert die schon bestehenden sozialen Bindungen um die Spielpartner-Beziehung. Ein großer Teil der arttypischen Verhaltensweisen ist bis zu diesem Zeitpunkt aufgetreten.Mit 5 und mit 9 Monaten lockert sich die Mutter-Kind-Beziehung jeweils stufenweise. Gleichzeitig treten neue Verhaltensmuster auf, und andere Verhaltensweisen verändern sich in der Häufigkeit und im Kontext ihres Auftretens.Im letzten Entwöhnungsabschnitt vom 9. bis zum 14. Monat tritt das junge Männchen in Beziehung zum ranghöchsten Tier der Gruppe; diese Beziehung umfaßt Kampfspiele und allmählich zunehmende Unterdrückung während des zweiten und dritten Jahres, bis sie mit Erreichen der Geschlechtsreife im Alter von 2 Jahren und 9 Monaten in Rivalenkämpfe übergeht.Das Verhalten entwickelt sich aus angeborenen Elementen, die in phasenspezifischen Interaktionen mit den Gruppenmitgliedern durch Lernprozesse geformt werden. Protrahierte und progressive Entwöhnung, Partnerspiele, Abweisung und Unterdrückung sind die wesentlichen Vorgänge, die den sozialen Reifungsprozeß bestimmen.Die Gesetzmäßigkeiten der Entwicklung werden am Säuglings- und Mutterverhalten, an den Formen der Selbstbehauptung und der Unterordnung sowie an der Differenzierung der beiden Sexualrollen aufgezeigt und mit biologischen Reifungskriterien, wie Gewicht, Zahnen, motorische Entwicklung und Spermatogenese, korreliert.

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Summary The behavioral ontogeny of ten infant squirrel monkeys (Saimiri sciureus) raised in mixed groups was studied during more than 1200 hours of protracted observation, comprising a life span from birth to the third and parts of the fourth year. The complete development is divided into seven phases and emphasis is placed on infant-group rather than on mother-infant relationships.For the first month of life the most prominent type of interaction between mother and infant is tactile. Acoustic, tactile and visual interaction with group mates starts as early as the first day of life. From about two weeks on a strong social bond is established between the infant and a female group mate, the so-called aunt. Aunt-infant interactions show greater variation than mother-infant interactions.As the infant gains motor independence during its second month, motherinfant visual interaction increases and weaning starts. The infant begins to play with other juveniles. Most of the species-specific behavioral elements are already present.During the 5th and 9th months the mother-infant detachment progresses gradually. During these two periods new behavior patterns develop and others change in frequency and in context of occurrence.At the beginning of the second year, during final weaning, the juvenile male establishes a closer relationship to the alpha-animal. Play fighting and progressive suppression during the second and third year lead to severe fighting. The young male becomes sexually mature at 33 months.The behavior, based on innate elements, is developed further through learning during stage-specific interaction with group mates. Prolonged and progressive weaning, social play and various forms of rejective and suppressive behavior strongly influence the maturation of social behavior.The rules which govern behavioral development are exemplified by the mothernewborn behavior, dominant-submissive behavior, and the sexual role differentiation. The various periods are correlated with physical developmental criteria such as weight, toothing, motor development, and spermatogenesis.

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Herrn Professor Dr. Dr. h. c. Heinrich Klüver, Sewell L. Avery Distinguished Service Professor of Biological Psychology, University of Chicago, zum 70. Geburtstag gewidmet.

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Für die unermüdliche Hilfe beim Beobachten, Protokollieren und Auswerten der Resultate danken wir unseren technischen Assistentinnen Roswitha Koschnick, Helga Krohn, Ilse Kutschera und Sigrid Schürmann, für die aufopfernde Pflege der Tiere Herrn Erasmus Soiderer.