N Smyrnis

Summary

Affiliation: University of Athens
Country: Greece

Publications

  1. ncbi request reprint Parallel processing of spatial and serial order information before moving to a remembered target
    Nikolaos Smyrnis
    Cognition and Action Group, National University of Athens, Eginition Hospital, 74 Vas Sofias Ave, 11528, Athens, Greece
    J Neurophysiol 93:3703-8. 2005
  2. ncbi request reprint The mirror antisaccade task: direction-amplitude interaction and spatial accuracy characteristics
    Ioannis Evdokimidis
    Cognition and Action Group, Neurology Clinic, Aeginition Hospital, Vas Sofias 72 74, Athens, 11528, Greece
    Exp Brain Res 174:304-11. 2006
  3. ncbi request reprint COMT Val158Met moderation of stress-induced psychosis
    Nicholas C Stefanis
    Division of Psychological Medicine, Institute of Psychiatry, London, UK
    Psychol Med 37:1651-6. 2007
  4. doi request reprint Monitoring antisaccades: inter-individual differences in cognitive control and the influence of COMT and DRD4 genotype variations
    Emmanouil Kattoulas
    Cognition and Action Group, Neurology Department, School of Medicine, Eginitio Hospital, National and Kapodistrian University of Athens, Athens, Greece
    Exp Brain Res 203:453-63. 2010
  5. doi request reprint Single-trial magnetoencephalography signals encoded as an unfolding decision process
    Nikolaos Smyrnis
    Cognition and Action Group, Neurology Department, National and Kapodistrian University of Athens, Medical School, Aeginition Hospital, 72 V Sofias Ave, Athens 11528, Greece
    Neuroimage 59:3604-10. 2012
  6. doi request reprint Amplitude spectrum EEG signal evidence for the dissociation of motor and perceptual spatial working memory in the human brain
    Nikolaos Smyrnis
    Cognition and Action Group, Neurology Department, Aeginition Hospital, National and Kapodistrian University of Athens, Athens, Greece
    Exp Brain Res 232:659-73. 2014
  7. pmc Association of RGS4 variants with schizotypy and cognitive endophenotypes at the population level
    Nicholas C Stefanis
    University Mental Health Research Institute, Athens, Greece
    Behav Brain Funct 4:46. 2008
  8. ncbi request reprint "Motor oblique effect": perceptual direction discrimination and pointing to memorized visual targets share the same preference for cardinal orientations
    Nikolaos Smyrnis
    Cognition and Action Group, Neurology Department, National and Kapodistrian University of Athens, Eginition Hospital, 72 Vas Sofias Avenue, Athens GR 11528, Greece
    J Neurophysiol 97:1068-77. 2007
  9. ncbi request reprint Active eye fixation performance in 940 young men: effects of IQ, schizotypy, anxiety and depression
    N Smyrnis
    Psychiatry Department, National University of Athens, Aeginition Hospital, 72 Vas Sofias Ave, 11528, Athens, Greece
    Exp Brain Res 156:1-10. 2004
  10. doi request reprint Larger variability of saccadic reaction times in schizophrenia patients
    Nikolaos Smyrnis
    Psychiatry Department, National and Kapodistrian University of Athens, Eginition Hospital, 72 Vassilisis Sofias Ave, 11528, Athens, Greece
    Psychiatry Res 168:129-36. 2009

Collaborators

Detail Information

Publications41

  1. ncbi request reprint Parallel processing of spatial and serial order information before moving to a remembered target
    Nikolaos Smyrnis
    Cognition and Action Group, National University of Athens, Eginition Hospital, 74 Vas Sofias Ave, 11528, Athens, Greece
    J Neurophysiol 93:3703-8. 2005
    ..These results strongly favor independent, parallel working memory systems for processing space and order information in the motor system...
  2. ncbi request reprint The mirror antisaccade task: direction-amplitude interaction and spatial accuracy characteristics
    Ioannis Evdokimidis
    Cognition and Action Group, Neurology Clinic, Aeginition Hospital, Vas Sofias 72 74, Athens, 11528, Greece
    Exp Brain Res 174:304-11. 2006
    ..This distorted amplitude modulation of mirror antisaccade amplitude was completely lost in corrected antisaccades that followed a directional error...
  3. ncbi request reprint COMT Val158Met moderation of stress-induced psychosis
    Nicholas C Stefanis
    Division of Psychological Medicine, Institute of Psychiatry, London, UK
    Psychol Med 37:1651-6. 2007
    ..This study aimed to investigate whether a functional polymorphism in the catechol-O-methyltransferase (COMT Val(158)Met) gene moderates the psychosis-inducing effects of stress...
  4. doi request reprint Monitoring antisaccades: inter-individual differences in cognitive control and the influence of COMT and DRD4 genotype variations
    Emmanouil Kattoulas
    Cognition and Action Group, Neurology Department, School of Medicine, Eginitio Hospital, National and Kapodistrian University of Athens, Athens, Greece
    Exp Brain Res 203:453-63. 2010
    ..On the other hand, DRD4 genotype variations were related to differences in antisaccade error rate while not affecting error-monitoring sensitivity...
  5. doi request reprint Single-trial magnetoencephalography signals encoded as an unfolding decision process
    Nikolaos Smyrnis
    Cognition and Action Group, Neurology Department, National and Kapodistrian University of Athens, Medical School, Aeginition Hospital, 72 V Sofias Ave, Athens 11528, Greece
    Neuroimage 59:3604-10. 2012
    ..The present findings demonstrate that non-averaged, single-trial MEG recordings can be used to test models of cognitive processes, like decision-making, in humans...
  6. doi request reprint Amplitude spectrum EEG signal evidence for the dissociation of motor and perceptual spatial working memory in the human brain
    Nikolaos Smyrnis
    Cognition and Action Group, Neurology Department, Aeginition Hospital, National and Kapodistrian University of Athens, Athens, Greece
    Exp Brain Res 232:659-73. 2014
    ..This result provides clear evidence for the dissociation of motor and perceptual spatial working memory. ..
  7. pmc Association of RGS4 variants with schizotypy and cognitive endophenotypes at the population level
    Nicholas C Stefanis
    University Mental Health Research Institute, Athens, Greece
    Behav Brain Funct 4:46. 2008
    ..abstract:..
  8. ncbi request reprint "Motor oblique effect": perceptual direction discrimination and pointing to memorized visual targets share the same preference for cardinal orientations
    Nikolaos Smyrnis
    Cognition and Action Group, Neurology Department, National and Kapodistrian University of Athens, Eginition Hospital, 72 Vas Sofias Avenue, Athens GR 11528, Greece
    J Neurophysiol 97:1068-77. 2007
    ..We conclude that a similarly distorted representation of target direction is present for memorized pointing movements and perceptual direction discrimination...
  9. ncbi request reprint Active eye fixation performance in 940 young men: effects of IQ, schizotypy, anxiety and depression
    N Smyrnis
    Psychiatry Department, National University of Athens, Aeginition Hospital, 72 Vas Sofias Ave, 11528, Athens, Greece
    Exp Brain Res 156:1-10. 2004
    ..A connection of such a difficulty with the frontal lobes and their role in the control of voluntary inhibitory functions is discussed...
  10. doi request reprint Larger variability of saccadic reaction times in schizophrenia patients
    Nikolaos Smyrnis
    Psychiatry Department, National and Kapodistrian University of Athens, Eginition Hospital, 72 Vassilisis Sofias Ave, 11528, Athens, Greece
    Psychiatry Res 168:129-36. 2009
    ..This information-processing difference could be the result of a difference in the build-up of neuronal activity involved in the generation of visually guided saccades in the frontal cortex...
  11. ncbi request reprint Attentional facilitation of response is impaired for antisaccades but not for saccades in patients with schizophrenia: implications for cortical dysfunction
    Nikolaos Smyrnis
    Cognition and Action Group, Neurology and Psychiatry Department, Aeginition Hospital, National University of Athens, 72 Vas Sofias Ave, 11528, Athens, Greece
    Exp Brain Res 159:47-54. 2004
    ..Our results, in addition to many other recent findings, could lead to specific hypotheses on cortical dysfunction in schizophrenia...
  12. ncbi request reprint Smooth pursuit eye movements in 1,087 men: effects of schizotypy, anxiety, and depression
    Nikolaos Smyrnis
    University Mental Health Research Institute, Athens, Greece
    Exp Brain Res 179:397-408. 2007
    ....
  13. ncbi request reprint Effect of schizotypy on cognitive performance and its tuning by COMT val158 met genotype variations in a large population of young men
    Nikolaos Smyrnis
    University Mental Health Research Institute, Psychiatry Department, National and Kapodistrian University of Athens, Eginition Hospital, Athens, Greece
    Biol Psychiatry 61:845-53. 2007
    ..The relation of schizotypy and state psychopathology to cognitive performance and its link to catechol-O-methyltransferase (COMT) val(158) met genotype variations was studied in a large sample of young men...
  14. ncbi request reprint Antisaccade performance of 1,273 men: effects of schizotypy, anxiety, and depression
    Nikolaos Smyrnis
    University Mental Health Research Institute, Neurology Department, National University of Athens, Greece
    J Abnorm Psychol 112:403-14. 2003
    ..This effect was independent of anxiety and depression, suggesting that a specific group of psychosis-prone individuals has a characteristic deviance in antisaccade performance that is not present in the general population...
  15. ncbi request reprint Single-pulse transcranial magnetic stimulation of parietal and prefrontal areas in a memory delay arm pointing task
    Nikolaos Smyrnis
    Cognition and Action Group, Neurology and Psychiatry Department, National University of Athens, Aeginition Hospital, Athens GR 11528, Greece
    J Neurophysiol 89:3344-50. 2003
    ....
  16. pmc Schizophrenia-related neuregulin-1 single-nucleotide polymorphisms lead to deficient smooth eye pursuit in a large sample of young men
    Nikolaos Smyrnis
    Psychiatry Department, National and Kapodistrian University of Athens Medical School, Eginition Hospital, 72 Vas Sofias Avenue, Athens, Greece
    Schizophr Bull 37:822-31. 2011
    ..NRG1 genotype variations were related to smooth eye pursuit variations both at the SNP level and at the haplotype level adding to the validation of this gene as a candidate gene for the disorder...
  17. doi request reprint Metric issues in the study of eye movements in psychiatry
    Nikolaos Smyrnis
    Psychiatry Department, National and Kapodistrian University of Athens, Medical School, Eginition Hospital, 72 Vas Sofias Avenue, Athens 11528, Greece
    Brain Cogn 68:341-58. 2008
    ..A future research program could derive a set of tentative recommendations for test standardization...
  18. ncbi request reprint The antisaccade task in a sample of 2,006 young males. II. Effects of task parameters
    N Smyrnis
    University Mental Health Research Institute, National University of Athens, Athens, Greece
    Exp Brain Res 147:53-63. 2002
    ..In particular, the smaller this latency was, the higher the probability of an error. These findings are discussed in light of current hypotheses on antisaccade production mechanisms involving mainly the superior colliculus...
  19. doi request reprint Schizophrenia-related RGS4 gene variations specifically disrupt prefrontal control of saccadic eye movements
    E Kattoulas
    Kapodistrian University of Athens, Athens, Greece
    Psychol Med 42:757-67. 2012
    ....
  20. ncbi request reprint Frontal-parietal activation differences observed before the execution of remembered saccades: an event-related potentials study
    I Evdokimidis
    Cognition Action Group, Neurology Department, National University of Athens Medical School, Aeginitio Hospital, Vas Sofias 72 74, Athens GR 11528, Greece
    Brain Res Cogn Brain Res 12:89-99. 2001
    ..This specific activation pattern of frontal and parietal areas, observed for the MEM task only, requires further investigation focusing on the temporal pattern of activation of large brain areas involved in working memory processing...
  21. ncbi request reprint Systematic errors of planar arm movements provide evidence for space categorization effects and interaction of multiple frames of reference
    P Gourtzelidis
    Neurology Department, National University of Athens, Aeginition Hospital, Greece
    Exp Brain Res 139:59-69. 2001
    ..The presence of the stable visual cue may impose an additional cue-centered (allocentric) reference frame...
  22. ncbi request reprint The antisaccade task in a sample of 2,006 young men. I. Normal population characteristics
    I Evdokimidis
    Cognition and Action Group, National University of Athens, Neurology Clinic, Aeginition Hospital, 72 Vas Sofias Ave, Athens 11528, Greece
    Exp Brain Res 147:45-52. 2002
    ..This report offers an analysis of the interindividual variation in the performance of the antisaccade task and discusses some of the sources of this variation...
  23. ncbi request reprint Higher scores of self reported schizotypy in healthy young males carrying the COMT high activity allele
    D Avramopoulos
    University Mental Health Research Institute, Argyrocastrou and Ionias St, Papagou, Athens 15669, Greece
    Mol Psychiatry 7:706-11. 2002
    ..This finding is in the same direction as reported findings on schizophrenia and it adds to the list of evidence that COMT or a nearby gene in linkage disequilibrium is involved in the pathogenesis of the disease...
  24. ncbi request reprint An early transient 40 Hz activity discriminates a following pro-saccade from a no-move and anti-saccade choice
    N Smyrnis
    University Mental Health Research Institute, National University of Athens, Greece
    Exp Brain Res 139:287-96. 2001
    ..We conclude that this task specific transient oscillatory activity could be used as a probe in the study of the temporal dynamics of visuomotor transformations...
  25. ncbi request reprint Effects of direction on saccadic performance in relation to lateral preferences
    T S Constantinidis
    University Mental Health Research Institute, National University of Athens, Athens, Greece
    Exp Brain Res 150:443-8. 2003
    ..Other oculomotor tasks might be more sensitive to hemifield differences, or cerebral hemispheric asymmetry is not present at the level of cortical organization of saccades and antisaccades...
  26. ncbi request reprint Speed-accuracy trade-off in the performance of pointing movements in different directions in two-dimensional space
    N Smyrnis
    Neurology Department, National University of Athens, Medical School, Aeginition Hospital, Greece
    Exp Brain Res 134:21-31. 2000
    ..Thus a clear segmentation of movement execution in two phases is supported by these results. The implications of these results for theoretical models of speed-accuracy trade-off are discussed...
  27. ncbi request reprint A systematic directional error in 2-D arm movements increases with increasing delay between visual target presentation and movement execution
    N Smyrnis
    Neurology Department, National University of Athens, Eginition Hospital, Greece
    Exp Brain Res 131:111-20. 2000
    ..It is further proposed that the directional bias observed at the vicinity of the target might reflect a loss of cortical directional information with increasing delay between target presentation and movement onset...
  28. doi request reprint Serotonin transporter gene variants and prediction of stress-induced risk for psychological distress
    N C Stefanis
    University Mental Health Research Institute, Athens, Greece
    Genes Brain Behav 10:536-41. 2011
    ..In particular, variation within this gene may confer risk for paranoid/defensive reactions under conditions of environmental stress associated with military induction...
  29. doi request reprint Perception action interaction: the oblique effect in the evolving trajectory of arm pointing movements
    Asimakis Mantas
    Cognition and Action Group, Neurology Department, National and Kapodistrian University of Athens, Eginition Hospital, Athens, Greece
    Exp Brain Res 184:605-16. 2008
    ..It is finally argued that the motor oblique effect can be a useful probe for the study of perception-action interaction...
  30. ncbi request reprint Frontal lobe dysfunction in amyotrophic lateral sclerosis
    I Evdokimidis
    ENG Lab of Neurology Clinic of Athens Medical School, Aeginitio Hospital, Vas Sofias 72 74, 11528, Athens, Greece
    J Neurol Sci 195:25-33. 2002
    ..Finally, performance indices of the ocular motor tasks, in particular the DF, was correlated only with the degree of dysarthria...
  31. doi request reprint Memory pointing in children and adults: dissociations in the maturation of spatial and temporal movement parameters
    George Pantes
    Cognition and Action Group, Neurology Department, Medical School, Aeginition Hospital, National and Kapodistrian University of Athens, Athens, Greece
    Exp Brain Res 196:319-28. 2009
    ..The dissociation of memory and age effects suggests that motor working memory is already mature in young children...
  32. doi request reprint The effect of change in clinical state on eye movement dysfunction in schizophrenia
    Dimitra Kallimani
    Psychiatry Department, National and Kapodistrian University of Athens, Eginition Hospital, Athens, Greece
    Eur Psychiatry 24:17-26. 2009
    ..On the other hand, active fixation might be state-dependent adding to the evidence against its use as a candidate endophenotype in schizophrenia...
  33. ncbi request reprint Is the excess risk of psychosis-like experiences in urban areas attributable to altered cognitive development?
    N C Stefanis
    University Mental Health Research Institute UMHRI, Athens, Greece
    Soc Psychiatry Psychiatr Epidemiol 39:364-8. 2004
    ..Rates of psychotic disorder and related attenuated psychotic experiences are higher in urban areas. We examined to what degree differences between urban and rural areas could be attributed to differences in cognitive development...
  34. ncbi request reprint Variation in catechol-o-methyltransferase val158 met genotype associated with schizotypy but not cognition: a population study in 543 young men
    Nicholas C Stefanis
    Department of Psychiatry, National and Kapodistrian University of Athens, Eginition Hospital, Athens, Greece
    Biol Psychiatry 56:510-5. 2004
    ....
  35. ncbi request reprint Effect of COMT Val158Met polymorphism on the Continuous Performance Test, Identical Pairs Version: tuning rather than improving performance
    Nicholas C Stefanis
    Department of Psychiatry, National and Kapodistrian University of Athens Medical School, Eginition Hospital, 74 Vas Sofias Ave, Athens 11528, Greece
    Am J Psychiatry 162:1752-4. 2005
    ..The authors' goal was to determine whether, in confirmation of this prediction, performance on a measure of cognitive stability would be associated with Met loading...
  36. ncbi request reprint The effects of increasing memory load on the directional accuracy of pointing movements to remembered targets
    Christos Theleritis
    Cognition and Action Group, Neurology and Psychiatry Department, Aeginition Hospital, National University of Athens, 72 Vas Sofias Ave, 11528 Athens, Greece
    Exp Brain Res 157:518-25. 2004
    ..The difference between serial order and directional spatial accuracy is supported by neurophysiological and functional anatomical evidence of working memory subsystems in the prefrontal cortex...
  37. doi request reprint Arm movement metrics influence saccade metrics when looking and pointing towards a memorized target location
    Emmanouil Kattoulas
    Cognition and Action Group, Neurology Department, Eginitio Hospital, National and Kapodistrian University of Athens, Athens, Greece
    Exp Brain Res 189:323-38. 2008
    ..These data suggest that signals specifying the metrics of limb movements influence those specifying the metrics of preceding saccades at a programming stage...
  38. ncbi request reprint Factorial composition of self-rated schizotypal traits among young males undergoing military training
    Nicholas C Stefanis
    Athens University Medical School, Eginition Hospital, 72 74 Vas Sophias Ave, Athens, Greece
    Schizophr Bull 30:335-50. 2004
    ..This result is in agreement with recent findings supporting the notion of a multidimensional construct of the schizotypy and related schizophrenia phenotype...
  39. doi request reprint Factorial composition of the Aggression Questionnaire: a multi-sample study in Greek adults
    Silia Vitoratou
    University Mental Health Research Institute, Soranou Efesiou 2, Papagou, 156 01, Athens, Greece Department of Statistics, University of Economics and Business, Patision 76, 104 34 Athens, Greece
    Psychiatry Res 168:32-9. 2009
    ..The reliability (internal consistency) of the scale was satisfactory in all cases. Content validity of the 12-item AQ was confirmed by comparison with the Symptom Check-List 90 Revised...
  40. ncbi request reprint A neural model of decision-making by the superior colicullus in an antisaccade task
    Vassilis Cutsuridis
    Computational Intelligence Laboratory, Institute of Informatics and Telecommunications, Demokritos National Centre for Scientific Research, Agia Paraskevi, Athens GR 15310, Greece
    Neural Netw 20:690-704. 2007
    ..The resultant model reproduced the unimodal distributions of SRTs for correct antisaccades and erroneous prosaccades as well as the variability of SRTs and the percentage of erroneous prosaccade responses...
  41. ncbi request reprint EEG cortical potentials preceding vergence and combined saccade-vergence eye movements
    Zoi Kapoula
    Laboratoire de Physiologie de la Perception et de l Action, CNRS College de France, Paris, France
    Neuroreport 13:1893-7. 2002
    ..These findings suggest a cortical substrate for vergence eye movements in humans that is engaged in the natural exploration of visual space...