TY - GEN A1 - Winkelbeiner, Nicola Lisa A1 - Wandt, Viktoria Klara Veronika A1 - Ebert, Franziska A1 - Lossow, Kristina A1 - Bankoglu, Ezgi E. A1 - Martin, Maximilian A1 - Mangerich, Aswin A1 - Stopper, Helga A1 - Bornhorst, Julia A1 - Kipp, Anna Patricia A1 - Schwerdtle, Tanja T1 - A Multi-Endpoint Approach to Base Excision Repair Incision Activity Augmented by PARylation and DNA Damage Levels in Mice BT - Impact of Sex and Age T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Investigation of processes that contribute to the maintenance of genomic stability is one crucial factor in the attempt to understand mechanisms that facilitate ageing. The DNA damage response (DDR) and DNA repair mechanisms are crucial to safeguard the integrity of DNA and to prevent accumulation of persistent DNA damage. Among them, base excision repair (BER) plays a decisive role. BER is the major repair pathway for small oxidative base modifications and apurinic/apyrimidinic (AP) sites. We established a highly sensitive non-radioactive assay to measure BER incision activity in murine liver samples. Incision activity can be assessed towards the three DNA lesions 8-oxo-2’-deoxyguanosine (8-oxodG), 5-hydroxy-2’-deoxyuracil (5-OHdU), and an AP site analogue. We applied the established assay to murine livers of adult and old mice of both sexes. Furthermore, poly(ADP-ribosyl)ation (PARylation) was assessed, which is an important determinant in DDR and BER. Additionally, DNA damage levels were measured to examine the overall damage levels. No impact of ageing on the investigated endpoints in liver tissue were found. However, animal sex seems to be a significant impact factor, as evident by sex-dependent alterations in all endpoints investigated. Moreover, our results revealed interrelationships between the investigated endpoints indicative for the synergetic mode of action of the cellular DNA integrity maintaining machinery. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1021 KW - maintenance of genomic integrity KW - ageing KW - sex KW - DNA damage KW - base excision repair (incision activity) KW - DNA damage response KW - poly(ADP-ribosyl)ation KW - liver Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-484831 SN - 1866-8372 IS - 1021 ER - TY - JOUR A1 - Winkelbeiner, Nicola Lisa A1 - Wandt, Viktoria Klara Veronika A1 - Ebert, Franziska A1 - Lossow, Kristina A1 - Bankoglu, Ezgi E. A1 - Martin, Maximilian A1 - Mangerich, Aswin A1 - Stopper, Helga A1 - Bornhorst, Julia A1 - Kipp, Anna Patricia A1 - Schwerdtle, Tanja T1 - A Multi-Endpoint Approach to Base Excision Repair Incision Activity Augmented by PARylation and DNA Damage Levels in Mice BT - Impact of Sex and Age JF - International Journal of Molecular Sciences N2 - Investigation of processes that contribute to the maintenance of genomic stability is one crucial factor in the attempt to understand mechanisms that facilitate ageing. The DNA damage response (DDR) and DNA repair mechanisms are crucial to safeguard the integrity of DNA and to prevent accumulation of persistent DNA damage. Among them, base excision repair (BER) plays a decisive role. BER is the major repair pathway for small oxidative base modifications and apurinic/apyrimidinic (AP) sites. We established a highly sensitive non-radioactive assay to measure BER incision activity in murine liver samples. Incision activity can be assessed towards the three DNA lesions 8-oxo-2’-deoxyguanosine (8-oxodG), 5-hydroxy-2’-deoxyuracil (5-OHdU), and an AP site analogue. We applied the established assay to murine livers of adult and old mice of both sexes. Furthermore, poly(ADP-ribosyl)ation (PARylation) was assessed, which is an important determinant in DDR and BER. Additionally, DNA damage levels were measured to examine the overall damage levels. No impact of ageing on the investigated endpoints in liver tissue were found. However, animal sex seems to be a significant impact factor, as evident by sex-dependent alterations in all endpoints investigated. Moreover, our results revealed interrelationships between the investigated endpoints indicative for the synergetic mode of action of the cellular DNA integrity maintaining machinery. KW - maintenance of genomic integrity KW - ageing KW - sex KW - DNA damage KW - base excision repair (incision activity) KW - DNA damage response KW - poly(ADP-ribosyl)ation KW - liver Y1 - 2020 U6 - https://doi.org/10.3390/ijms21186600 SN - 1422-0067 VL - 21 IS - 18 PB - Molecular Diversity Preservation International CY - Basel ER - TY - JOUR A1 - Sanders, Lloyd P. A1 - Lomholt, Michael A. A1 - Lizana, Ludvig A1 - Fogelmark, Karl A1 - Metzler, Ralf A1 - Ambjoernsson, Tobias T1 - Severe slowing-down and universality of the dynamics in disordered interacting many-body systems: ageing and ultraslow diffusion JF - New journal of physics : the open-access journal for physics N2 - Low-dimensional, many-body systems are often characterized by ultraslow dynamics. We study a labelled particle in a generic system of identical particles with hard-core interactions in a strongly disordered environment. The disorder is manifested through intermittent motion with scale-free sticking times at the single particle level. While for a non-interacting particle we find anomalous diffusion of the power-law form < x(2)(t)> similar or equal to t(alpha) of the mean squared displacement with 0 < alpha < 1, we demonstrate here that the combination of the disordered environment with the many-body interactions leads to an ultraslow, logarithmic dynamics < x(2)(t)> similar or equal to log(1/2)t with a universal 1/2 exponent. Even when a characteristic sticking time exists but the fluctuations of sticking times diverge we observe the mean squared displacement < x(2)(t)> similar or equal to t(gamma) with 0 < gamma < 1/2, that is slower than the famed Harris law < x(2)(t)> similar or equal to t(1/2) without disorder. We rationalize the results in terms of a subordination to a counting process, in which each transition is dominated by the forward waiting time of an ageing continuous time process. KW - single-file diffusion KW - continuous time random walks KW - ageing Y1 - 2014 U6 - https://doi.org/10.1088/1367-2630/16/11/113050 SN - 1367-2630 VL - 16 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Safdari, Hadiseh A1 - Cherstvy, Andrey G. A1 - Chechkin, Aleksei V. A1 - Thiel, Felix A1 - Sokolov, Igor M. A1 - Metzler, Ralf T1 - Quantifying the non-ergodicity of scaled Brownian motion JF - Journal of physics : A, Mathematical and theoretical N2 - We examine the non-ergodic properties of scaled Brownian motion (SBM), a non-stationary stochastic process with a time dependent diffusivity of the form D(t) similar or equal to t(alpha-1). We compute the ergodicity breaking parameter EB in the entire range of scaling exponents a, both analytically and via extensive computer simulations of the stochastic Langevin equation. We demonstrate that in the limit of long trajectory lengths T and short lag times Delta the EB parameter as function of the scaling exponent a has no divergence at alpha - 1/2 and present the asymptotes for EB in different limits. We generalize the analytical and simulations results for the time averaged and ergodic properties of SBM in the presence of ageing, that is, when the observation of the system starts only a finite time span after its initiation. The approach developed here for the calculation of the higher time averaged moments of the particle displacement can be applied to derive the ergodic properties of other stochastic processes such as fractional Brownian motion. KW - scaled Brownian motion KW - anomalous diffusion KW - ageing Y1 - 2015 U6 - https://doi.org/10.1088/1751-8113/48/37/375002 SN - 1751-8113 SN - 1751-8121 VL - 48 IS - 37 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Reifegerste, Jana A1 - Meyer, Antje A1 - Zwitserlood, Pienie T1 - Inflectional complexity and experience affect plural processing in younger and older readers of Dutch and German JF - Language, cognition and neuroscience N2 - According to dual-route models of morphological processing, regular inflections can be retrieved as whole-word forms or decomposed into morphemes. Baayen, Dijkstra, and Schreuder [(1997). Singulars and plurals in Dutch: Evidence for a parallel dual-route model. Journal of Memory and Language, 37, 94–117. doi:10.1006/jmla.1997.2509] proposed a dual-route model in which singular-dominant plurals (“brides”) are decomposed, while plural-dominant plurals (“peas”) are accessed as whole-word units. We report two lexical-decision experiments investigating how plural processing is influenced by participants’ age and morphological complexity of the language (German/Dutch). For all Dutch participants and older German participants, we replicated the interaction between number and dominance reported by Baayen and colleagues. Younger German participants showed a main effect of number, indicating decomposition of all plurals. Access to stored forms seems to depend on morphological richness and experience with word forms. The data pattern fits neither full-decomposition nor full-storage models, but is compatible with dual-route models. KW - Morphological processing KW - morphological complexity KW - ageing KW - lexical decision KW - plural processing Y1 - 2016 U6 - https://doi.org/10.1080/23273798.2016.1247213 SN - 2327-3798 SN - 2327-3801 VL - 32 IS - 4 SP - 471 EP - 487 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - JOUR A1 - Metzler, Ralf A1 - Cherstvy, Andrey G. A1 - Chechkin, Aleksei V. A1 - Bodrova, Anna S. T1 - Ultraslow scaled Brownian motion JF - New journal of physics : the open-access journal for physics N2 - We define and study in detail utraslow scaled Brownian motion (USBM) characterized by a time dependent diffusion coefficient of the form . For unconfined motion the mean squared displacement (MSD) of USBM exhibits an ultraslow, logarithmic growth as function of time, in contrast to the conventional scaled Brownian motion. In a harmonic potential the MSD of USBM does not saturate but asymptotically decays inverse-proportionally to time, reflecting the highly non-stationary character of the process. We show that the process is weakly non-ergodic in the sense that the time averaged MSD does not converge to the regular MSD even at long times, and for unconfined motion combines a linear lag time dependence with a logarithmic term. The weakly non-ergodic behaviour is quantified in terms of the ergodicity breaking parameter. The USBM process is also shown to be ageing: observables of the system depend on the time gap between initiation of the test particle and start of the measurement of its motion. Our analytical results are shown to agree excellently with extensive computer simulations. KW - anomalous diffusion KW - stochastic processes KW - ageing Y1 - 2015 U6 - https://doi.org/10.1088/1367-2630/17/6/063038 SN - 1367-2630 VL - 17 IS - 063038 PB - Dt. Physikalische Ges., IOP CY - Bad Honnef, London ER - TY - GEN A1 - Metzler, Ralf A1 - Cherstvy, Andrey G. A1 - Chechkin, Aleksei V. A1 - Bodrova, Anna S. T1 - Ultraslow scaled Brownian motion T2 - New journal of physics : the open-access journal for physics N2 - We define and study in detail utraslow scaled Brownian motion (USBM) characterized by a time dependent diffusion coefficient of the form . For unconfined motion the mean squared displacement (MSD) of USBM exhibits an ultraslow, logarithmic growth as function of time, in contrast to the conventional scaled Brownian motion. In a harmonic potential the MSD of USBM does not saturate but asymptotically decays inverse-proportionally to time, reflecting the highly non-stationary character of the process. We show that the process is weakly non-ergodic in the sense that the time averaged MSD does not converge to the regular MSD even at long times, and for unconfined motion combines a linear lag time dependence with a logarithmic term. The weakly non-ergodic behaviour is quantified in terms of the ergodicity breaking parameter. The USBM process is also shown to be ageing: observables of the system depend on the time gap between initiation of the test particle and start of the measurement of its motion. Our analytical results are shown to agree excellently with extensive computer simulations. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 188 KW - anomalous diffusion KW - stochastic processes KW - ageing Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-78618 ER - TY - THES A1 - Elin, Kirill T1 - Morphological processing in older adults T1 - Morphologische Verarbeitung bei älteren Erwachsenen BT - evidence from Russian and German BT - Evidenz aus dem Russischen und dem Deutschen N2 - Over the last decades mechanisms of recognition of morphologically complex words have been extensively examined in order to determine whether all word forms are stored and retrieved from the mental lexicon as wholes or whether they are decomposed into their morphological constituents such as stems and affixes. Most of the research in this domain focusses on English. Several factors have been argued to affect morphological processing including, for instance, morphological structure of a word (e.g., existence of allomorphic stem alternations) and its linguistic nature (e.g., whether it is a derived word or an inflected word form). It is not clear, however, whether processing accounts based on experimental evidence from English would hold for other languages. Furthermore, there is evidence that processing mechanisms may differ across various populations including children, adult native speakers and language learners. Recent studies claim that processing mechanisms could also differ between older and younger adults (Clahsen & Reifegerste, 2017; Reifegerste, Meyer, & Zwitserlood, 2017). The present thesis examined how properties of the morphological structure, types of linguistic operations involved (i.e., the linguistic contrast between inflection and derivation) and characteristics of the particular population such as older adults (e.g., potential effects of ageing as a result of the cognitive decline or greater experience and exposure of older adults) affect initial, supposedly automatic stages of morphological processing in Russian and German. To this end, a series of masked priming experiments was conducted. In experiments on Russian, the processing of derived -ost’ nouns (e.g., glupost’ ‘stupidity’) and of inflected forms with and without allomorphic stem alternations in 1P.Sg.Pr. (e.g., igraju – igrat’ ‘to play’ vs. košu – kosit’ ‘to mow’) was examined. The first experiment on German examined and directly compared processing of derived -ung nouns (e.g., Gründung ‘foundation’) and inflected -t past participles (e.g., gegründet ‘founded’), whereas the second one investigated the processing of regular and irregular plural forms (-s forms such as Autos ‘cars’ and -er forms such as Kinder ‘children’, respectively). The experiments on both languages have shown robust and comparable facilitation effects for derived words and regularly inflected forms without stem changes (-t participles in German, forms of -aj verbs in Russian). Observed morphological priming effects could be clearly distinguished from purely semantic or orthographic relatedness between words. At the same time, we found a contrast between forms with and without allomorphic stem alternations in Russian and regular and irregular forms in German, with significantly more priming for unmarked stems (relative to alternated ones) and significantly more priming for regular (compared) word forms. These findings indicate the relevance of morphological properties of a word for initial stages of processing, contrary to claims made in the literature holding that priming effects are determined by surface form and meaning overlap only. Instead, our findings are more consistent with approaches positing a contrast between combinatorial, rule-based and lexically-stored forms (Clahsen, Sonnenstuhl, & Blevins, 2003). The doctoral dissertation also addressed the role of ageing and age-related cognitive changes on morphological processing. The results obtained on this research issue are twofold. On the one hand, the data demonstrate effects of ageing on general measures of language performance, i.e., overall longer reaction times and/or higher accuracy rates in older than younger individuals. These findings replicate results from previous studies, which have been linked to the general slowing of processing speed at older age and to the larger vocabularies of older adults. One the other hand, we found that more specific aspects of language processing appear to be largely intact in older adults as revealed by largely similar morphological priming effects for older and younger adults. These latter results indicate that initial stages of morphological processing investigated here by means of the masked priming paradigm persist in older age. One caveat should, however, be noted. Achieving the same performance as a younger individual in a behavioral task may not necessarily mean that the same neural processes are involved. Older people may have to recruit a wider brain network than younger individuals, for example. To address this and related possibilities, future studies should examine older people’s neural representations and mechanisms involved in morphological processing. N2 - In den letzten Jahrzehnten wurden die Mechanismen zur Erkennung morphologisch komplexer Wörter umfassend untersucht, um zu erforschen, ob alle Wortformen als Ganzes aus dem mentalen Lexikon abgerufen werden oder ob sie in ihre morphologischen Bestandteile (z. B. Wortstamm und Affixe) zerlegt werden. Der meisten Studien in diesem Bereich konzentrieren sich aufs Englische. Es wurde oft behauptet, dass mehrere Faktoren die morphologische Verarbeitung beeinflussen, darunter zum Beispiel die morphologische Struktur eines Wortes (z. B. das Vorhandensein allomorphischen Stammwechsels) und seine linguistische Natur (z. B. ob es sich um ein abgeleitetes Wort oder eine flektierte Wortform handelt). Es ist jedoch nicht klar, ob die postulierten Verarbeitungsmechanismen, die fast ausschließlich auf experimentellen Beweisen aus dem Englischen basieren, für andere Sprachen genauso gelten. Darüber hinaus gibt es Hinweise darauf, dass sich Verarbeitungsmechanismen in verschiedenen Bevölkerungsgruppen – einschließlich Kindern, erwachsenen Muttersprachlern und Sprachlernern – unterscheiden können. Neuere Studien behaupten, dass Verarbeitungsmechanismen zwischen älteren und jüngeren Erwachsenen möglicherweise auch unterschiedlich sind (Clahsen & Reifegerste, 2017; Reifegerste, Meyer, & Zwitserlood, 2017). In der vorliegenden Dissertation wurde untersucht, wie die morphologische Struktur, die Art der zugrunde liegenden linguistischen Operationen (z. B., der linguistische Kontrast zwischen Flexion und Ableitung) sowie Merkmale der jeweiligen Population, wie ältere Erwachsene (z. B. mögliche Auswirkungen des Alterns infolge kognitiven Rückgangs oder größerer Erfahrung von älteren Menschen) die ersten, vermeintlich automatischen Stadien der morphologischen Verarbeitung im Russischen und Deutschen beeinflussen. Zu diesem Zweck wurde eine Reihe von maskierten Priming Experimenten (auf English: masked priming) durchgeführt. In den Experimenten übers Russische wurde die Verarbeitung von abgeleiteten -ost'-Substantiven (z. B. glupost' - 'Dummheit') und von flektierten Formen mit und ohne allomorphischen Stammwechsel in der ersten Person Singular Präsens (z. B. igraju - igrat' 'spielen' im Vergleich zu košu - kosit' 'mähen') untersucht. Darüber hinaus wurden im ersten Experiment übers Deutsche die Verarbeitung von abgeleiteten Substantiven (z. B. Gründung 'founding') und von -t-Partizipien (z. B. gegründet 'founded') untersucht und direkt verglichen, während das zweite Experiment die Verarbeitung von regulären und irregulären Plural-Formen (d. h., -s-Pluralen wie z. B. Autos 'cars' und -er-Formen wie z. B, Kinder 'children') erforschte. Die Experimente in beiden Sprachen zeigten robuste und vergleichbare Priming-Effekte für abgeleitete Wörter und regelmäßig flektierte Formen ohne Stammveränderung (einschließlich -t-Partizipien im Deutschen und Formen von -aj- Verben im Russischen). Die gefundenen morphologischen Priming-Effekte konnten von rein semantischen oder orthographischen Verbindungen zwischen Wörtern klar abgegrenzt werden. Gleichzeitig fanden wir einen Kontrast zwischen Formen mit und ohne allomorphischen Stammwechsel im Russischen sowie zwischen regulären und irregulären Formen im Deutschen, mit signifikant mehr Priming für unmarkierte Stämme (im Vergleich zu alternierenden) und signifikant mehr Priming für reguläre Wortformen (im Vergleich zu irregulären). Diese Ergebnisse weisen auf die Relevanz morphologischer Eigenschaften eines Wortes für die ersten automatischen Phasen der Worterkennung hin, im Gegensatz zu Behauptungen in der fachlichen Literatur, die besagen, dass Priming-Effekte nur durch das Überlappen von Wörtern auf orthographischer und/oder semantischer Ebene entstehen. Stattdessen sind unsere Ergebnisse mehr im Einklang mit Ansätzen, die einen Kontrast zwischen kombinatorischen und regelbasierten versus lexikalisch gespeicherten Formen postulieren (Clahsen, Sonnenstuhl, & Blevins, 2003). Die Doktorarbeit befasste sich auch mit der Rolle des Alterns und altersbedingten kognitiven Veränderungen bei der morphologischen Verarbeitung. Die Ergebnisse dieses Forschungsthemas sind zweierlei. Einerseits demonstrieren die Daten die Auswirkungen des Alterns auf allgemeine Aspekte der Sprachleistung wie zum Beispiel generell längere Reaktionszeiten und/oder weniger Fehler bei älteren als bei jüngeren Personen. Ähnliche Ergebnisse in früheren Studien wurden oft mit allgemeiner Verringerung der Verarbeitungsgeschwindigkeit im höheren Alter und mit dem größeren Wortschatz älterer Erwachsener in Verbindung gebracht. Anderseits stellten wir fest, dass spezifische Aspekte der Sprachverarbeitung bei älteren Erwachsenen weitgehend intakt sind, was sich durch größtenteils vergleichbare morphologische Priming-Effekte für ältere und jüngere Erwachsene zeigt. Diese letzteren Ergebnisse weisen darauf hin, dass die ersten Stadien der morphologischen Verarbeitung, die hier mittels maskierter Priming-Experimente untersucht wurden, im höheren Alter fortbestehen. Folgender Vorbehalt sollte jedoch beachtet werden: Das Erreichen der gleichen Leistung bei jüngeren und älteren Personen in solchen Aufgaben muss nicht unbedingt bedeuten, dass dieselben neuralen Prozesse beteiligt sind. Ältere Menschen müssen unter Umständen ein breiteres Gehirnnetzwerk rekrutieren als jüngere Menschen. Aus diesem Grund sollten zukünftige Studien auch die neuralen Repräsentationen und Mechanismen untersuchen, die an der morphologischen Verarbeitung bei jüngeren und älteren Menschen beteiligt sind. KW - morphology KW - processing KW - ageing KW - Russian KW - German KW - linguistics KW - Morphologie KW - Worterkennung KW - Altern KW - Russisch KW - Deutsch KW - Sprachwissenschaft Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-418605 ER - TY - JOUR A1 - Cherstvy, Andrey G. A1 - Chechkin, Aleksei V. A1 - Metzler, Ralf T1 - Ageing and confinement in non-ergodic heterogeneous diffusion processes JF - Journal of physics : A, Mathematical and theoretical N2 - We study the effects of ageing-the time delay between initiation of the physical process at t = 0 and start of observation at some time t(a) > 0-and spatial confinement on the properties of heterogeneous diffusion processes (HDPs) with deterministic power-law space-dependent diffusivities, D(x) = D-0 vertical bar x vertical bar(alpha). From analysis of the ensemble and time averaged mean squared displacements and the ergodicity breaking parameter quantifying the inherent degree of irreproducibility of individual realizations of the HDP we obtain striking similarities to ageing subdiffusive continuous time random walks with scale-free waiting time distributions. We also explore how both processes can be distinguished. For confined HDPs we study the long-time saturation of the ensemble and time averaged particle displacements as well as the magnitude of the inherent scatter of time averaged displacements and contrast the outcomes to the results known for other anomalous diffusion processes under confinement. KW - stochastic processes KW - anomalous diffusion KW - ageing KW - weak ergodicity breaking Y1 - 2014 U6 - https://doi.org/10.1088/1751-8113/47/48/485002 SN - 1751-8113 SN - 1751-8121 VL - 47 IS - 48 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Bodrova, Anna S. A1 - Chechkin, Aleksei V. A1 - Cherstvy, Andrey G. A1 - Metzler, Ralf T1 - Ultraslow scaled Brownian motion JF - New journal of physics : the open-access journal for physics N2 - We define and study in detail utraslow scaled Brownian motion (USBM) characterized by a time dependent diffusion coefficient of the form D(t) similar or equal to 1/t. For unconfined motion the mean squared displacement (MSD) of USBM exhibits an ultraslow, logarithmic growth as function of time, in contrast to the conventional scaled Brownian motion. In a harmonic potential the MSD of USBM does not saturate but asymptotically decays inverse-proportionally to time, reflecting the highly non-stationary character of the process. We show that the process is weakly non-ergodic in the sense that the time averaged MSD does not converge to the regular MSD even at long times, and for unconfined motion combines a linear lag time dependence with a logarithmic term. The weakly non-ergodic behaviour is quantified in terms of the ergodicity breaking parameter. The USBM process is also shown to be ageing: observables of the system depend on the time gap between initiation of the test particle and start of the measurement of its motion. Our analytical results are shown to agree excellently with extensive computer simulations. KW - anomalous diffusion KW - stochastic processes KW - ageing Y1 - 2015 U6 - https://doi.org/10.1088/1367-2630/17/6/063038 SN - 1367-2630 VL - 17 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Behrends, Andreas A1 - Scheiner, Ricarda T1 - Octopamine improves learning in newly emerged bees but not in old foragers JF - JOURNAL OF EXPERIMENTAL BIOLOGY N2 - Honey bees (Apis mellifera) are well known for their excellent learning abilities. Although most age groups learn quickly to associate an odor with a sucrose reward, newly emerged bees and old foragers often perform poorly. For a long time, the reason for the poor learning performance of these age groups was unclear. We show that reduced sensitivity for sucrose is the cause for poor associative learning in newly emerged bees but not in old foragers. By increasing the sensitivity for sucrose through octopamine, we selectively improved the learning performance of insensitive newly emerged bees. Interestingly, the learning performance of foragers experiencing the same treatment remained low, despite the observed increase in sensitivity for the reward. We thus demonstrate that increasing sensitivity for the reward can improve the associative learning performance of bees when they are young but not when they had foraged for a long time. Importantly, octopamine can have very different effects on bees, depending on their initial sensory sensitivity. These differential effects of octopamine have important consequences for interpreting the action of biogenic amines on insect behavior. KW - honey bee KW - PER KW - olfactory conditioning KW - ageing KW - sucrose responsiveness Y1 - 2012 U6 - https://doi.org/10.1242/jeb.063297 SN - 0022-0949 VL - 215 IS - 7 SP - 1076 EP - 1083 PB - COMPANY OF BIOLOGISTS LTD CY - CAMBRIDGE ER -