Induced gamma band responses predict recognition delays during object identification

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Induced gamma-band activity is related to the time point of object identification

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Prüfung von Kartoffelsorten auf deren besondere Eignung für den ökologischen Landbau

Ungünstige Wachstumsbedingungen oder ein früher Befall mit Krautfäule (Phytophthora infestans) begrenzen sehr häufig die Vegetationszeit im ökologischen Kartoffelanbau und beeinträchtigen den Marktwareertrag. In solchen Jahren könnten Sorten mit frühem Knollenansatz diese kurze Vegetationszeit für die Ertragsbildung besser nutzen als Sorten mit spätem Ansatz und langsamer Jugendentwicklung. Für den ökologischen Landbau ist über den zeitlichen Verlauf der Ertragsbildung vergleichsweise wenig bekannt. Daher war das Ziel der Untersuchungen zu klären, ob es Sortenunterschiede in der Ertragsbildung gibt, wann diese am besten feststellbar sind und ob Sorten über die Zeiternten ähnlich reagieren. Darüber hinaus sollen zusätzliche Informationen über Sortenmerkmale unter den Bedingungen des ökologischen Landbaus erarbeitet werden, um Landwirten und der Beratung Entscheidungshilfen für ihre Sortenwahl zur Verfügung zu stellen. Das Projekt „Prüfung von Kartoffelsorten auf deren besondere Eignung für den ökologischen Landbau“ (FKZ 09OE001) wird durch das Bundesprogramm Ökologischer Landbau gefördert

Coding of visual object features and feature conjunctions in the human brain

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Unique Minimal Liftings for Simplicial Polytopes

For a minimal inequality derived from a maximal lattice-free simplicial polytope in $\R^n$, we investigate the region where minimal liftings are uniquely defined, and we characterize when this region covers $\R^n$. We then use this characterization to show that a minimal inequality derived from a maximal lattice-free simplex in $\R^n$ with exactly one lattice point in the relative interior of each facet has a unique minimal lifting if and only if all the vertices of the simplex are lattice points.Comment: 15 page

PRIMING OF OBJECT CATEGORIZATION WITHIN AND ACROSS LEVELS OF SPECIFICITY

Identification of objects can occur at different levels of specificity. Dependingon task and context, an object can be classified at the superordinate level (as ananimal), at the basic level (a bird) or at the subordinate level (a sparrow). Whatare the interactions between these representational levels and do they rely onthe same sequential processes that lead to successful object identification? Inthis electroencephalogram study, a task-switching paradigm (covert naming orliving/non-living judgment) was used. Images of objects were repeated eitherwithin the same task, or with a switch from a covert naming task to a livingor non-living judgment and vice versa. While covert naming accesses entrylevel(basic or subordinate), living/non-living judgments rely on superordinateclassification. Our beha-vioural results demonstrated clear priming effectswithin both tasks. However, asymmetries were found when task-switching hadoccurred, with facilitation for covert naming but not for categorization. Wealso found lower accuracy and early-starting and persistent enhancements ofevent-related potentials (ERPs) for covert naming, indicating that this task wasmore difficult and involved more intense perceptual and semantic processing.Perceptual priming was marked by consistent reductions of the ERP componentL1 for repeated presentations, both with and without task switching. Additionalrepetition effects were found in early event-related activity between 150-190 ms(N1) when a repeated image had been named at initial presentation. We conclude that differences in N1 indicate task-related changes in the identification processitself. Such enhancements for covert naming again emerge in a later timewindow associated with depth of semantic processing. Meanwhile, L1 reflectsmodulations due to implicit memory of objects. In conclusion, evidence wasfound for representational overlap; changes in ERP markers started early andrevealed cross-task priming at the level of object structure analysis and moreintense perceptual and semantic processing for covert naming

Induced Gamma-band Activity Elicited by Visual Representation of Unattended Objects

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Post-learning hippocampal dynamics promote preferential retention of rewarding events

Reward motivation is known to modulate memory encoding, and this effect depends on interactions between the substantia nigra/ventral tegmental area complex (SN/VTA) and the hippocampus. It is unknown, however, whether these interactions influence offline neural activity in the human brain that is thought to promote memory consolidation. Here we used fMRI to test the effect of reward motivation on post-learning neural dynamics and subsequent memory for objects that were learned in high- and low-reward motivation contexts. We found that post-learning increases in resting-state functional connectivity between the SN/VTA and hippocampus predicted preferential retention of objects that were learned in high-reward contexts. In addition, multivariate pattern classification revealed that hippocampal representations of high-reward contexts were preferentially reactivated during post-learning rest, and the number of hippocampal reactivations was predictive of preferential retention of items learned in high-reward contexts. These findings indicate that reward motivation alters offline post-learning dynamics between the SN/VTA and hippocampus, providing novel evidence for a potential mechanism by which reward could influence memory consolidatio