Publications by authors named "Georgia Panagiotaropoulou"

5 Publications

  • Page 1 of 1

Functional brain imaging of speeded decision processing in Parkinson's disease and comparison with Schizophrenia.

Psychiatry Res Neuroimaging 2021 08 1;314:111312. Epub 2021 Jun 1.

Laboratory of Cognitive Neuroscience, University Mental Health, Neurosciences and Precision Medicine Research Institute "COSTAS STEFANIS", Athens, Greece; 2nd Department of Psychiatry, National and Kapodistrian University of Athens, School of Medicine, University General Hospital "Attikon", Athens, Greece.. Electronic address:

This study examined whether Parkinson's disease (PD) and schizophrenia (SCZ) share a hypo dopaminergic dysfunction of the prefrontal cortex leading to cognitive impairments in decision processing. 24 medicated PD patients and 28 matched controls performed the Eriksen flanker two-choice reaction time (RT) task while brain activity was measured throughout, using functional Magnetic Resonance Imaging (fMRI). Results were directly compared to those of 30 SCZ patients and 30 matched controls. Significant differences between SCZ and PD were found, through directly comparing the z-score deviations from healthy controls across all behavioral measures, where only SCZ patients showed deviances from controls. Similarly a direct comparison of z-score activation deviations from controls indicated significant differences in prefrontal and cingulate cortical activation between SCZ and PD, where only SCZ patients showed hypo-activation of these areas compared to controls. The hypo-activation of the dorsolateral prefrontal cortex was related to larger RT variability (ex-Gaussian tau) in SCZ but not PD patients. Overall, the concluding evidence does not support a shared neural substrate of cognitive dysfunction, since the deficit in speeded decision processing and the related cortical hypo-activation observed in SCZ were absent in PD.
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http://dx.doi.org/10.1016/j.pscychresns.2021.111312DOI Listing
August 2021

Genome-wide association study of more than 40,000 bipolar disorder cases provides new insights into the underlying biology.

Nat Genet 2021 06 17;53(6):817-829. Epub 2021 May 17.

Department of Neuroscience, Istituto Di Ricerche Farmacologiche Mario Negri IRCCS, Milan, Italy.

Bipolar disorder is a heritable mental illness with complex etiology. We performed a genome-wide association study of 41,917 bipolar disorder cases and 371,549 controls of European ancestry, which identified 64 associated genomic loci. Bipolar disorder risk alleles were enriched in genes in synaptic signaling pathways and brain-expressed genes, particularly those with high specificity of expression in neurons of the prefrontal cortex and hippocampus. Significant signal enrichment was found in genes encoding targets of antipsychotics, calcium channel blockers, antiepileptics and anesthetics. Integrating expression quantitative trait locus data implicated 15 genes robustly linked to bipolar disorder via gene expression, encoding druggable targets such as HTR6, MCHR1, DCLK3 and FURIN. Analyses of bipolar disorder subtypes indicated high but imperfect genetic correlation between bipolar disorder type I and II and identified additional associated loci. Together, these results advance our understanding of the biological etiology of bipolar disorder, identify novel therapeutic leads and prioritize genes for functional follow-up studies.
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http://dx.doi.org/10.1038/s41588-021-00857-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8192451PMC
June 2021

RICOPILI: Rapid Imputation for COnsortias PIpeLIne.

Bioinformatics 2020 02;36(3):930-933

Stanley Center for Psychiatric Research, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA.

Summary: Genome-wide association study (GWAS) analyses, at sufficient sample sizes and power, have successfully revealed biological insights for several complex traits. RICOPILI, an open-sourced Perl-based pipeline was developed to address the challenges of rapidly processing large-scale multi-cohort GWAS studies including quality control (QC), imputation and downstream analyses. The pipeline is computationally efficient with portability to a wide range of high-performance computing environments. RICOPILI was created as the Psychiatric Genomics Consortium pipeline for GWAS and adopted by other users. The pipeline features (i) technical and genomic QC in case-control and trio cohorts, (ii) genome-wide phasing and imputation, (iv) association analysis, (v) meta-analysis, (vi) polygenic risk scoring and (vii) replication analysis. Notably, a major differentiator from other GWAS pipelines, RICOPILI leverages on automated parallelization and cluster job management approaches for rapid production of imputed genome-wide data. A comprehensive meta-analysis of simulated GWAS data has been incorporated demonstrating each step of the pipeline. This includes all the associated visualization plots, to allow ease of data interpretation and manuscript preparation. Simulated GWAS datasets are also packaged with the pipeline for user training tutorials and developer work.

Availability And Implementation: RICOPILI has a flexible architecture to allow for ongoing development and incorporation of newer available algorithms and is adaptable to various HPC environments (QSUB, BSUB, SLURM and others). Specific links for genomic resources are either directly provided in this paper or via tutorials and external links. The central location hosting scripts and tutorials is found at this URL: https://sites.google.com/a/broadinstitute.org/RICOPILI/home.

Supplementary Information: Supplementary data are available at Bioinformatics online.
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http://dx.doi.org/10.1093/bioinformatics/btz633DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7868045PMC
February 2020

Evaluating cognitive models of visual word recognition using fMRI: Effects of lexical and sublexical variables.

Neuroimage 2016 Mar 13;128:328-341. Epub 2016 Jan 13.

Radiology and Medical Imaging Research Unit, University of Athens, Greece.

In this study predictions of the dual-route cascaded (DRC) model of word reading were tested using fMRI. Specifically, patterns of co-localization were investigated: (a) between pseudoword length effects and a pseudowords vs. fixation contrast, to reveal the sublexical grapho-phonemic conversion (GPC) system; and (b) between word frequency effects and a words vs. pseudowords contrast, to reveal the orthographic and phonological lexicon. Forty four native speakers of Greek were scanned at 3T in an event-related lexical decision task with three event types: (a) 150 words in which frequency, length, bigram and syllable frequency, neighborhood, and orthographic consistency were decorrelated; (b) 150 matched pseudowords; and (c) fixation. Whole-brain analysis failed to reveal the predicted co-localizations. Further analysis with participant-specific regions of interest defined within masks from the group contrasts revealed length effects in left inferior parietal cortex and frequency effects in the left middle temporal gyrus. These findings could be interpreted as partially consistent with the existence of the GPC system and phonological lexicon of the model, respectively. However, there was no evidence in support of an orthographic lexicon, weakening overall support for the model. The results are discussed with respect to the prospect of using neuroimaging in cognitive model evaluation.
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http://dx.doi.org/10.1016/j.neuroimage.2016.01.013DOI Listing
March 2016

Judging the judges' performance in rhythmic gymnastics.

Med Sci Sports Exerc 2015 Mar;47(3):640-8

1Sports Medicine Department, Faculty of Physical Education and Sports Science, National and Kapodistrian University of Athens, Athens, GREECE; 2School of Applied Mathematics and Physical Sciences, National Technical University of Athens, Athens, GREECE; 3School of Electrical and Computer Engineering, National Technical University of Athens, Athens, GREECE; 4Gymnastics Department, Faculty of Physical Education and Sports Science, National and Kapodistrian University of Athens, Athens, GREECE; 5Department of Health Sciences, "Foro Italico" University of Rome, Rome, ITALY; 6Neurology Department, National and Kapodistrian University of Athens, Aeginition Hospital, Athens, GREECE; 7Laboratory of Sensorimotor Control, University Mental Health Research Institute, Athens, GREECE; and 8Psychiatry Department, National and Kapodistrian University of Athens, Aeginition Hospital, Athens, GREECE.

Introduction: Rhythmic gymnastics (RG) is an aesthetic event balancing between art and sport that also has a performance rating system (Code of Points) given by the International Gymnastics Federation. It is one of the sports in which competition results greatly depend on the judges' evaluation. In the current study, we explored the judges' performance in a five-gymnast ensemble routine.

Methods: An expert-novice paradigm (10 international-level, 10 national-level, and 10 novice-level judges) was implemented under a fully simulated procedure of judgment in a five-gymnast ensemble routine of RG using two videos of routines performed by the Greek national team of RG. Simultaneous recordings of two-dimensional eye movements were taken during the judgment procedure to assess the percentage of time spent by each judge viewing the videos and fixation performance of each judge when an error in gymnast performance had occurred.

Results: All judge level groups had very modest performance of error recognition on gymnasts' routines, and the best international judges reported approximately 40% of true errors. Novice judges spent significantly more time viewing the videos compared with national and international judges and spent significantly more time fixating detected errors than the other two groups. National judges were the only group that made efficient use of fixation to detect errors.

Conclusions: The fact that international-level judges outperformed both other groups, while not relying on visual fixation to detect errors, suggests that these experienced judges probably make use of other cognitive strategies, increasing their overall error detection efficiency, which was, however, still far below optimum.
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http://dx.doi.org/10.1249/MSS.0000000000000425DOI Listing
March 2015
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