Nikolai Axmacher

Summary

Affiliation: University of Bonn
Country: Germany

Publications

  1. ncbi request reprint Memory formation by neuronal synchronization
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, Sigmund Freud Str 25, 53105 Bonn, Germany
    Brain Res Rev 52:170-82. 2006
  2. doi request reprint Intracranial EEG correlates of expectancy and memory formation in the human hippocampus and nucleus accumbens
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, 53105 Bonn, Germany
    Neuron 65:541-9. 2010
  3. doi request reprint Memory consolidation by replay of stimulus-specific neural activity
    Lorena Deuker
    Department of Epileptology, University of Bonn, D 53127 Bonn, Germany, Donders Institute for Brain, Cognition and Behaviour, Radboud University, 6525 HR Nijmegen, The Netherlands, Helmholtz Institute for Radiation and Nuclear Physics, University of Bonn, D 53115 Bonn, Germany, Department of Psychology, University of Bonn, 53111 Bonn, Germany, Center for Economics and Neuroscience, University of Bonn, 53127 Bonn, Germany, German Center for Neurodegenerative Diseases DZNE, 53175 Bonn, Germany
    J Neurosci 33:19373-83. 2013
  4. doi request reprint Neuroelectric signatures of reward learning and decision-making in the human nucleus accumbens
    Michael X Cohen
    Department of Epileptology and Center for Life and Brain, University of Bonn, Bonn, Germany
    Neuropsychopharmacology 34:1649-58. 2009
  5. doi request reprint Good vibrations: cross-frequency coupling in the human nucleus accumbens during reward processing
    Michael X Cohen
    University of Bonn, Germany
    J Cogn Neurosci 21:875-89. 2009
  6. doi request reprint Sleep-dependent directional coupling between human neocortex and hippocampus
    Tobias Wagner
    Department of Epileptology, University of Bonn, Germany
    Cortex 46:256-63. 2010
  7. ncbi request reprint Sustained neural activity patterns during working memory in the human medial temporal lobe
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, 53105 Bonn, Germany
    J Neurosci 27:7807-16. 2007
  8. doi request reprint Medial temporal theta/alpha power enhancement precedes successful memory encoding: evidence based on intracranial EEG
    Juergen Fell
    Department of Epileptology, University of Bonn, D 53105 Bonn, Germany
    J Neurosci 31:5392-7. 2011
  9. doi request reprint Working memory-related hippocampal deactivation interferes with long-term memory formation
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, D 53105 Bonn, Germany
    J Neurosci 29:1052-960. 2009
  10. ncbi request reprint The role of sleep in declarative memory consolidation--direct evidence by intracranial EEG
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, 53105 Bonn, Germany
    Cereb Cortex 18:500-7. 2008

Collaborators

Detail Information

Publications50

  1. ncbi request reprint Memory formation by neuronal synchronization
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, Sigmund Freud Str 25, 53105 Bonn, Germany
    Brain Res Rev 52:170-82. 2006
    ..In summary, synchronization of neural assemblies in different frequency ranges induces specific forms of cellular plasticity during subsequent stages of memory formation...
  2. doi request reprint Intracranial EEG correlates of expectancy and memory formation in the human hippocampus and nucleus accumbens
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, 53105 Bonn, Germany
    Neuron 65:541-9. 2010
    ..These results are consistent with the hypothesis that activity in a loop involving the hippocampus and the nucleus accumbens promotes encoding of unexpected events...
  3. doi request reprint Memory consolidation by replay of stimulus-specific neural activity
    Lorena Deuker
    Department of Epileptology, University of Bonn, D 53127 Bonn, Germany, Donders Institute for Brain, Cognition and Behaviour, Radboud University, 6525 HR Nijmegen, The Netherlands, Helmholtz Institute for Radiation and Nuclear Physics, University of Bonn, D 53115 Bonn, Germany, Department of Psychology, University of Bonn, 53111 Bonn, Germany, Center for Economics and Neuroscience, University of Bonn, 53127 Bonn, Germany, German Center for Neurodegenerative Diseases DZNE, 53175 Bonn, Germany
    J Neurosci 33:19373-83. 2013
    ..They move beyond previous studies because replay was investigated on the level of individual stimuli and because reactivations were not evoked by sensory cues but occurred spontaneously. ..
  4. doi request reprint Neuroelectric signatures of reward learning and decision-making in the human nucleus accumbens
    Michael X Cohen
    Department of Epileptology and Center for Life and Brain, University of Bonn, Bonn, Germany
    Neuropsychopharmacology 34:1649-58. 2009
    ....
  5. doi request reprint Good vibrations: cross-frequency coupling in the human nucleus accumbens during reward processing
    Michael X Cohen
    University of Bonn, Germany
    J Cogn Neurosci 21:875-89. 2009
    ..Gamma-alpha synchronization may reflect an electrophysiological gating mechanism in the human nucleus accumbens, and the phase differences in gamma-alpha coupling may reflect a reward information coding scheme similar to phase coding...
  6. doi request reprint Sleep-dependent directional coupling between human neocortex and hippocampus
    Tobias Wagner
    Department of Epileptology, University of Bonn, Germany
    Cortex 46:256-63. 2010
    ..These results question the standard model of hippocampal-neocortical interactions and suggest that sleep-dependent consolidation is accomplished by an active retrieval of hippocampal information by the neocortex...
  7. ncbi request reprint Sustained neural activity patterns during working memory in the human medial temporal lobe
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, 53105 Bonn, Germany
    J Neurosci 27:7807-16. 2007
    ..Our results thus provide direct evidence for sustained neural activity patterns during working memory maintenance in the MTL, and show that these patterns depend on WM load...
  8. doi request reprint Medial temporal theta/alpha power enhancement precedes successful memory encoding: evidence based on intracranial EEG
    Juergen Fell
    Department of Epileptology, University of Bonn, D 53105 Bonn, Germany
    J Neurosci 31:5392-7. 2011
    ....
  9. doi request reprint Working memory-related hippocampal deactivation interferes with long-term memory formation
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, D 53105 Bonn, Germany
    J Neurosci 29:1052-960. 2009
    ..However, deactivations of the hippocampus as previously observed during WM maintenance of individual items predicts failure of LTM encoding...
  10. ncbi request reprint The role of sleep in declarative memory consolidation--direct evidence by intracranial EEG
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, 53105 Bonn, Germany
    Cereb Cortex 18:500-7. 2008
    ..These results suggest that sleep facilitates rapid processing through the hippocampus but is not necessary for information transfer into the neocortex per se...
  11. doi request reprint Activation of the caudal anterior cingulate cortex due to task-related interference in an auditory Stroop paradigm
    Sven Haupt
    Department of Epileptology, University of Bonn, Bonn, Germany
    Hum Brain Mapp 30:3043-56. 2009
    ..Taken together, we found (besides activation of regions well-known from visual Stroop tasks) activation of the very caudal and posterior part of the ACC due to task-related interference in an auditory Stroop task...
  12. doi request reprint Ripples in the medial temporal lobe are relevant for human memory consolidation
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, Sigmund Freud Str 25, D 53105 Bonn, Germany
    Brain 131:1806-17. 2008
    ....
  13. doi request reprint Interference of working memory load with long-term memory formation
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, Bonn, Germany
    Eur J Neurosci 29:1501-13. 2009
    ..Taken together, these findings suggest that high WM demands interfere with LTM encoding and thus support the idea that WM and LTM processes interact in the MTL...
  14. doi request reprint Electrophysiological signature of working and long-term memory interaction in the human hippocampus
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, Sigmund Freud Str 25, D 53105 Bonn, Germany
    Eur J Neurosci 31:177-88. 2010
    ..Together, these findings indicate that multi-item WM and LTM encoding interfere within the hippocampus...
  15. doi request reprint Memory modulation by weak synchronous deep brain stimulation: a pilot study
    Juergen Fell
    Department of Epileptology, University of Bonn, Sigmund Freud Str 25, D 53105 Bonn, Germany
    Brain Stimul 6:270-3. 2013
    ....
  16. doi request reprint Local category-specific gamma band responses in the visual cortex do not reflect conscious perception
    Jaan Aru
    Max Planck Institute for Brain Research, 60528 Frankfurt am Main, Germany
    J Neurosci 32:14909-14. 2012
    ..This result contradicts the proposal that local gamma band responses in the higher-order visual cortex reflect conscious perception...
  17. pmc Ventromedial prefrontal cortex activation is associated with memory formation for predictable rewards
    Katharina A Bialleck
    Department of Epileptology, University of Bonn, Bonn, Germany
    PLoS ONE 6:e16695. 2011
    ..Taken together, these findings show that consumption of reliably predictable rewards facilitates LTM formation and is associated with activation of the vmPFC...
  18. ncbi request reprint Presurgical language fMRI in patients with drug-resistant epilepsy: effects of task performance
    Bernd Weber
    Department of Epileptology, University of Bonn, Bonn, Germany
    Epilepsia 47:880-6. 2006
    ..To determine whether language functional magnetic resonance imaging (fMRI) before epilepsy surgery can be similarly interpreted in patients with greatly different performance levels...
  19. doi request reprint Working memory representation in atypical language dominance
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, Bonn, Germany
    Hum Brain Mapp 30:2032-43. 2009
    ..The increased variability in right dominant subjects strongly suggests that a standard network of material-dependent WM processes exists in left dominant subjects, and that right dominant subjects use variable alternative networks...
  20. doi request reprint Phase-locking within human mediotemporal lobe predicts memory formation
    Juergen Fell
    Department of Epileptology, University of Bonn, Bonn, Germany
    Neuroimage 43:410-9. 2008
    ..Our data suggest that early mediotemporal phase adjustments constitute a relevant mechanism underlying declarative memory encoding...
  21. ncbi request reprint Rhinal-hippocampal coupling during declarative memory formation: dependence on item characteristics
    Juergen Fell
    Department of Epileptology, University of Bonn, Sigmund Freud Str 25, D 53105 Bonn, Germany
    Neurosci Lett 407:37-41. 2006
    ..Our data suggest, that broadband Rhinal-hippocampal coupling including the gamma range only occurs, when significant semantic associations are processed within rhinal cortex, as is the case for high-frequency words...
  22. doi request reprint Interaction of working memory and long-term memory in the medial temporal lobe
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, 53105 Bonn, Germany
    Cereb Cortex 18:2868-78. 2008
    ....
  23. pmc Monitoring the mind: the neurocognitive correlates of metamemory
    Anne T A Do Lam
    Department of Epileptology, University of Bonn, Bonn, Germany
    PLoS ONE 7:e30009. 2012
    ..Masking brain activation during predicted memory success with activation during retrieval success revealed BOLD increases of the mPFC. Our findings indicate that JOLs actually incorporate retrieval processes...
  24. doi request reprint Memory formation by refinement of neural representations: the inhibition hypothesis
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, Sigmund Freud Street 25, 53105 Bonn, Germany
    Behav Brain Res 189:1-8. 2008
    ..We suggest that during memory formation, the hippocampus renders neural representations more sparse by providing an inhibitory signal to the neocortex...
  25. pmc Cross-frequency coupling supports multi-item working memory in the human hippocampus
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, Bonn 53105, Germany
    Proc Natl Acad Sci U S A 107:3228-33. 2010
    ..Third, we describe how the precision of cross-frequency coupling predicts individual WM performance. These data support the idea that working memory in humans depends on a neural code using phase information...
  26. doi request reprint Memory processes during sleep: beyond the standard consolidation theory
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, Sigmund Freud Strasse 25, Bonn, Germany
    Cell Mol Life Sci 66:2285-97. 2009
    ..Here, we review the experimental evidence favoring and challenging these two views and suggest an integrative model of memory consolidation...
  27. pmc Nuclei accumbens phase synchrony predicts decision-making reversals following negative feedback
    Michael X Cohen
    Department of Epileptology and Center for Life and Brain and Department of Psychiatry and Psychotherapy, University of Bonn, 53105 Bonn, Germany
    J Neurosci 29:7591-8. 2009
    ..These findings suggest that a neural network including the nucleus accumbens bilaterally becomes functionally connected via theta phase synchrony to signal the need to adjust behavior...
  28. pmc Enhancement of neocortical-medial temporal EEG correlations during non-REM sleep
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, 53105 Bonn, Germany
    Neural Plast 2008:563028. 2008
    ....
  29. doi request reprint Nucleus accumbens deep brain stimulation decreases ratings of depression and anxiety in treatment-resistant depression
    Bettina H Bewernick
    Department of Psychiatry and Psychotherapy, University Hospital, 53105 Bonn, Germany
    Biol Psychiatry 67:110-6. 2010
    ..Since anhedonia is a feature of depression and there is evidence of dysfunction of the reward system, DBS to the nucleus accumbens (NAcc) might be promising...
  30. doi request reprint Interactions between medial temporal lobe, prefrontal cortex, and inferior temporal regions during visual working memory: a combined intracranial EEG and functional magnetic resonance imaging study
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, Life and Brain Center of Academic Research, D 53105 Bonn, Germany
    J Neurosci 28:7304-12. 2008
    ..These data indicate that WM for multiple items depends on an increased strength of top-down control of activity within the IT cortex by the MTL...
  31. doi request reprint The role of phase synchronization in memory processes
    Juergen Fell
    Department of Epileptology, University of Bonn, Sigmund Freud Strasse 25, D 53105 Bonn, Germany
    Nat Rev Neurosci 12:105-18. 2011
    ..A deeper understanding of how phase synchronization supports the flexibility of and interaction between memory systems may yield new insights into the functions of phase synchronization in general...
  32. ncbi request reprint Correlation between EEG rhythms during sleep: surface versus mediotemporal EEG
    Annkathrin Poepel
    Department of Epileptology, University of Bonn, Bonn, Germany
    Neuroreport 18:837-40. 2007
    ..In contrast, we found that within the hippocampus delta/theta power alternated in parallel with fast oscillations above 16 Hz during non-rapid-eye-movement sleep (positive correlations)...
  33. doi request reprint From alpha to gamma: electrophysiological correlates of meditation-related states of consciousness
    Juergen Fell
    Department of Epileptology, University of Bonn, Sigmund Freud Str 25, D 53105 Bonn, Germany
    Med Hypotheses 75:218-24. 2010
    ..While meditation formerly has been understood to comprise mainly passive relaxation states, recent EEG findings suggest that meditation is associated with active states which involve cognitive restructuring and learning...
  34. ncbi request reprint Phase/amplitude reset and theta-gamma interaction in the human medial temporal lobe during a continuous word recognition memory task
    Florian Mormann
    Department of Epileptology, University of Bonn, Germany
    Hippocampus 15:890-900. 2005
    ....
  35. pmc Graded effects of social conformity on recognition memory
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, Bonn, Germany
    PLoS ONE 5:e9270. 2010
    ..These findings indicate that differential effects of social conformity on recognition of items as old and new occur in situations with an intermediate level of group pressure...
  36. ncbi request reprint Association between scalp hair-whorl direction and hemispheric language dominance
    Bernd Weber
    Department of Epileptology, University of Bonn, Sigmund Freud Str 25, 53105 Bonn, Germany
    Neuroimage 30:539-43. 2006
    ..J.S., 2003. Human handedness and scalp hair-whorl direction develop from a common genetic mechanism. Genetics 1651, 269-276.] also affects cerebral language dominance...
  37. ncbi request reprint Human neocortical and hippocampal near-DC shifts are interconnected
    Juergen Fell
    Department of Epileptology, University of Bonn, D 53105 Bonn, Germany
    Hippocampus 17:413-9. 2007
    ..The finding that neocortical and hippocampal near-DC shifts are interconnected may open new perspectives for the prediction and control of mediotemporal lobe seizures...
  38. pmc Can the neural basis of repression be studied in the MRI scanner? New insights from two free association paradigms
    Jo Birger Schmeing
    Department of Epileptology, University of Bonn, Bonn, Germany
    PLoS ONE 8:e62358. 2013
    ..Unconscious repression of conflict-related material is arguably due to different processes, but has never been studied with neuroimaging methods...
  39. ncbi request reprint The specific contribution of neuroimaging versus neurophysiological data to understanding cognition
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, Bonn, Germany
    Behav Brain Res 200:1-6. 2009
    ..Taken together, we suggest that neuroscientific data contribute to the understanding of cognition by adding specific biological constraints and by extending the explanatory potential of psychological theories...
  40. ncbi request reprint Hippocampal control of repetition effects for associative stimuli
    Nico A W Kremers
    Department of Epileptology, University of Bonn, Bonn, Germany
    Hippocampus 24:892-902. 2014
    ..These findings suggest that both repetition enhancement and repetition suppression effects are influenced by a modulating signal from the hippocampus. © 2014 Wiley Periodicals, Inc. ..
  41. pmc Are autobiographical memories inherently social? Evidence from an fMRI study
    Linda Wilbers
    Department of Epileptology, University of Bonn, Bonn, Germany
    PLoS ONE 7:e45089. 2012
    ....
  42. pmc Common genetic variation of the APOE gene and personality
    Christian Montag
    Department of Psychology, University of Bonn, Kaiser Karl Ring 9, Bonn D 53111, Germany
    BMC Neurosci 15:64. 2014
    ....
  43. pmc Playing nice: a multi-methodological study on the effects of social conformity on memory
    Lorena Deuker
    Department of Epileptology, University of Bonn Bonn, Germany
    Front Hum Neurosci 7:79. 2013
    ..Overall, this study demonstrates how the mechanisms leading to complex social behavior such as conformity can be studied by combining genetic analyses and fMRI in social neuroscience paradigms...
  44. doi request reprint The analogy between dreams and the ancient art of memory is tempting but superficial
    Nikolai Axmacher
    Department of Epileptology, University of Bonn, 53105 Bonn, Germany http epileptologie bonn de cms front_content php idcat 470
    Behav Brain Sci 36:607-8; discussion 634-59. 2013
    ....
  45. pmc Natural memory beyond the storage model: repression, trauma, and the construction of a personal past
    Nikolai Axmacher
    Department of Epileptology, University of Bonn Bonn, Germany
    Front Hum Neurosci 4:211. 2010
    ..We suggest several experimental paradigms that allow for the investigation of the neural correlates of repressed memories and trauma-induced memory distortions based on a constructivist memory concept...
  46. ncbi request reprint Inhibition of GABA release by presynaptic ionotropic GABA receptors in hippocampal CA3
    Nikolai Axmacher
    Johannes Müller Institut für Physiologie, Humboldt Universitat Berlin, Tucholskystr 2, 10117 Berlin, Germany
    Neuroreport 15:329-34. 2004
    ..We conclude that the release of GABA from hippocampal CA3 interneurons is regulated by a negative feedback via presynaptic ionotropic GABA autoreceptors...
  47. pmc Intrinsic cellular currents and the temporal precision of EPSP-action potential coupling in CA1 pyramidal cells
    Nikolai Axmacher
    INSERM EMI 0224, CHU Pitie Salpetriere, UPMC, 105 Boulevard de l Hôpital, 75013 Paris, France
    J Physiol 555:713-25. 2004
    ..The resulting inward-outward current sequences enhance the temporal precision of EPSP-spike coupling. Thus, CA1 pyramidal cells initiate action potentials with different temporal precision, depending on stimulus properties...
  48. ncbi request reprint Transmitter metabolism as a mechanism of synaptic plasticity: a modeling study
    Nikolai Axmacher
    Johannes Müller Institut für Physiologie, Humboldt Universitat Berlin, 10117 Berlin, Germany
    J Neurophysiol 91:25-39. 2004
    ..Therefore, the model allows one to decide, at a given synapse, how transmitter metabolism is linked to presynaptic function and efficacy...
  49. ncbi request reprint Presynaptic ionotropic GABA receptors
    Andreas Draguhn
    Institut fur Physiologie und Pathophysiologie, Universitat Heidelberg, Im Neuenheimer Feld 326, 69120 Heidelberg, Germany
    Results Probl Cell Differ 44:69-85. 2008
    ....
  50. ncbi request reprint Two-photon imaging of spontaneous vesicular release in acute brain slices and its modulation by presynaptic GABAA receptors
    Nikolai Axmacher
    Johannes Müller Institut für Physiologie, Humboldt Universitat Berlin, 10117 Berlin, Germany
    Neuroimage 22:1014-21. 2004
    ..Those novel methods should be well suited to study pathophysiological changes in inhibition in resections obtained from neurosurgical treatment of epilepsy patients...