Low noise HRTFs and delay line corrections are detrimental to the prediction of ITD discrimination thresholds from environmental statistics
Interaural Time Difference (ITD) is the main cue for azimuthal auditory perception in humans. ITD... more Interaural Time Difference (ITD) is the main cue for azimuthal auditory perception in humans. ITDs at each frequency contribute differently to azimuth discrimination, which can be quantified by their azimuthal Fisher Information. Consistently, human ITD discrimination thresholds are predicted by the azimuthal information. However, this prediction is poor for frequencies below 500 Hz. Such poor prediction could be ascribed to the strategy of quantifying azimuthal information using HRTFs obtained in unnaturalistic anechoic chambers or by using a direct method which does not incorporate the delay lines proposed by the Jeffress-Colburn model. In the present study, we obtained ITD discrimination thresholds from extensive sampling across frequency and ITD, and applied multiple strategies for quantifying azimuthal information. These strategies employed HRTFs obtained in realistic and anechoic chambers, with and without considering delay lines. We found that ITD discriminability thresholds ...
The search for biological causes of mental disorders has up to now met with limited success, lead... more The search for biological causes of mental disorders has up to now met with limited success, leading to growing dissatisfac-tion with diagnostic classifications. However, it is question-able whether most clinical syndromes should be expected to correspond to specific microscale brain alterations, as multiple low-level causes could lead to similar symptoms in different individuals. In order to evaluate the potential multifactorial-ity of alterations related to psychiatric illness, we performed a parametric exploration of published computational models of schizophrenia. By varying multiple parameters simultane-ously, such as receptor conductances, connectivity patterns, and background excitation, we generated 5625 different ver-sions of an attractor-based network model of schizophrenia symptoms. Among networks presenting activity within valid ranges, 154 parameter combinations out of 3002 (5.1%)
Je tiens à remercier l'ensemble des personnes qui ont contribué à la réalisation de ce mémoire. T... more Je tiens à remercier l'ensemble des personnes qui ont contribué à la réalisation de ce mémoire. Tout d'abord, je remercie mon directeur de mémoire, M. Grégory Munoz, enseignantchercheur à l'Université de Nantes, pour sa disponibilité, ses précieux conseils et son extrême bienveillance. Je remercie vivement les conseillers pédagogiques de circonscription qui se sont très longuement entretenus avec moi, qui ont répondu à mes innombrables sollicitations et avec qui j'ai eu beaucoup de plaisir à échanger sur notre passion commune : la formation. Je remercie sincèrement les enseignants qui m'ont fait confiance, m'ont accueillie dans leur classe et ont accepté d'être enregistrés lors des entretiens. Je remercie, par ailleurs, l'Inspectrice de l'Éducation Nationale qui m'a donnée son accord pour suivre l'expérimentation menée sur sa circonscription. Je remercie les étudiants de la promotion pour leurs petits « trucs et astuces » en tous genres qui m'ont aidée à conduire cette recherche. Je remercie mes proches, David Isvelin, Corinne Ménard et Martine Meunier pour leur soutien, leur avis critique, la lecture et la relecture de ce mémoire. Enfin, je remercie mes enfants Jade, Léon et Lino pour la petite aide apportée à la maison pendant l'année d'étude de leur maman.
A neural code adapted to the statistical structure of sensory cues may optimize perception. We in... more A neural code adapted to the statistical structure of sensory cues may optimize perception. We investigated whether interaural time difference (ITD) statistics inherent in natural acoustic scenes are parameters determining spatial discriminability. The natural ITD rate of change across azimuth (ITDrc) and ITD variability over time (ITDv) were combined in a Fisher information statistic to assess the amount of azimuthal information conveyed by this sensory cue. We hypothesized that natural ITD statistics underlie the neural code for ITD and thus influence spatial perception. To test this hypothesis, sounds with invariant statistics were presented to measure human spatial discriminability and spatial novelty detection. Human auditory spatial perception showed correlation with natural ITD statistics, supporting our hypothesis. Further analysis showed that these results are consistent with classic models of ITD coding and can explain the ITD tuning distribution observed in the mammalian ...
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
A neural code adapted to the statistical structure of sensory cues may optimize perception. We in... more A neural code adapted to the statistical structure of sensory cues may optimize perception. We investigated whether interaural time difference (ITD) statistics inherent in natural acoustic scenes are parameters determining spatial discriminability. The natural ITD rate of change across azimuth (ITDrc) and ITD variability over time (ITDv) were combined in a Fisher information statistic to assess the amount of azimuthal information conveyed by this sensory cue. We hypothesized that natural ITD statistics underlie the neural code for ITD and thus influence spatial perception. To test this hypothesis, sounds with invariant statistics were presented to measure human spatial discriminability and spatial novelty detection. Human auditory spatial perception showed correlation with natural ITD statistics, supporting our hypothesis. Further analysis showed that these results are consistent with classic models of ITD coding and can explain the ITD tuning distribution observed in the mammalian brainstem.
Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (coronavirus d... more Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (coronavirus disease 2019; COVID-19) is associated with adverse outcomes in patients with cardiovascular disease (CVD). The aim of the study was to characterize the interaction between SARS-CoV-2 and Angiotensin-Converting Enzyme 2 (ACE2) functional networks with a focus on CVD. Methods: Using the network medicine approach and publicly available datasets, we investigated ACE2 tissue expression and described ACE2 interaction networks that could be affected by SARS-CoV-2 infection in the heart, lungs and nervous system. We compared them with changes in ACE-2 networks following SARS-CoV-2 infection by analyzing public data of human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). This analysis was performed using the Network by Relative Importance (NERI) algorithm, which integrates protein-protein interaction with co-expression networks. We also performed miRNA-target predictions to identify which miRNAs regulate ACE2-related networks and could play a role in the COVID19 outcome. Finally, we performed enrichment analysis for identifying the main COVID-19 risk groups. Results: We found similar ACE2 expression confidence levels in respiratory and cardiovascular systems, supporting that heart tissue is a potential target of SARS-CoV-2. Analysis of ACE2 interaction networks in infected hiPSC-CMs identified multiple hub genes with corrupted signaling which can be responsible for cardiovascular symptoms. The most affected genes were EGFR (Epidermal Growth Factor Receptor), FN1 (Fibronectin 1), TP53, HSP90AA1, and APP (Amyloid Beta Precursor Protein), while the most affected interactions were associated with MAST2 and CALM1 (Calmodulin 1). Enrichment analysis revealed multiple diseases associated with the interaction networks of ACE2, especially cancerous diseases, obesity, hypertensive disease, Alzheimer's disease, non-insulin-dependent diabetes mellitus, and congestive heart failure. Among affected ACE2-network components connected with the SARS-Cov-2 interactome, we identified AGT (Angiotensinogen), CAT (Catalase), DPP4 (Dipeptidyl Peptidase 4), CCL2 (C-C Motif Chemokine Ligand 2), TFRC (Transferrin Receptor) and CAV1 (Caveolin-1), associated with cardiovascular risk factors. We described for the first time miRNAs which were common regulators of ACE2 networks and virus-related proteins in all analyzed datasets. The top miRNAs regulating ACE2 networks were miR-27a-3p, miR-26b-5p, miR-10b-5p, miR-302c-5p, hsa-miR-587, hsa-miR-1305, hsa-miR-200b-3p, hsa-miR-124-3p, and hsa-miR-16-5p. Conclusion:
Low noise HRTFs and delay line corrections are detrimental to the prediction of ITD discrimination thresholds from environmental statistics
Interaural Time Difference (ITD) is the main cue for azimuthal auditory perception in humans. ITD... more Interaural Time Difference (ITD) is the main cue for azimuthal auditory perception in humans. ITDs at each frequency contribute differently to azimuth discrimination, which can be quantified by their azimuthal Fisher Information. Consistently, human ITD discrimination thresholds are predicted by the azimuthal information. However, this prediction is poor for frequencies below 500 Hz. Such poor prediction could be ascribed to the strategy of quantifying azimuthal information using HRTFs obtained in unnaturalistic anechoic chambers or by using a direct method which does not incorporate the delay lines proposed by the Jeffress-Colburn model. In the present study, we obtained ITD discrimination thresholds from extensive sampling across frequency and ITD, and applied multiple strategies for quantifying azimuthal information. These strategies employed HRTFs obtained in realistic and anechoic chambers, with and without considering delay lines. We found that ITD discriminability thresholds ...
Crises tipo epilepsia de ausência são expressas no eletrocorticograma de ratos como surtos paroxí... more Crises tipo epilepsia de ausência são expressas no eletrocorticograma de ratos como surtos paroxísticos de descargas espícula-onda. O objetivo do presente trabalho foi desenvolver e testar um sistema automatizado de identificação de crises. O princípio do sistema é distinguir sinais de crise dos demais sinais pela análise da potência na faixa de frequência entre 7 e 11 Hz, que é alta apenas durante as crises. A rotina, elaborada no Matlab®, é informada com um intervalo de registro em que não ocorreram crises (crivo), a fim de estabelecer o critério de identificação. O sistema compara, por meio da transformada rápida de Fourier, o crivo com o registro inteiro. A saída do programa é uma tabela informando a presença de crises nesses intervalos. Quatro ratos Wistar geneticamente portadores de crises tipo ausência e implantados com eletrodos corticais tiveram eletrocorticograma por 80 minutos. As crises foram quantificadas manualmente minuto a minuto. O registro e a quantificação das cri...
The temporal order of an experience is a fundamental property of episodic memories, yet the mecha... more The temporal order of an experience is a fundamental property of episodic memories, yet the mechanism for the consolidation of temporal sequences in long-term memory is still unknown. A potential mechanism for memory consolidation depends on the reactivation of neuronal sequences in the hippocampus. Despite abundant evidence of sequence reactivation in the formation of spatial memory, the reactivation of hippocampal neuronal sequences carrying non-spatial information has been much less explored. In this work, we recorded the activity of time cell sequences while rats performed multiple 15-s treadmill runnings during the intertrial intervals of a spatial alternation memory task. We observed forward and reverse reactivations of time cell sequences often occurring during sharp-wave ripple events following reward consumption. Surprisingly, the reactivation events specifically engaged cells coding temporal information. The reactivation of time cell sequences may thus reflect the organiza...
The search for biological causes of mental disorders has up to now met with limited success, lead... more The search for biological causes of mental disorders has up to now met with limited success, leading to growing dissatisfac-tion with diagnostic classifications. However, it is question-able whether most clinical syndromes should be expected to correspond to specific microscale brain alterations, as multiple low-level causes could lead to similar symptoms in different individuals. In order to evaluate the potential multifactorial-ity of alterations related to psychiatric illness, we performed a parametric exploration of published computational models of schizophrenia. By varying multiple parameters simultane-ously, such as receptor conductances, connectivity patterns, and background excitation, we generated 5625 different ver-sions of an attractor-based network model of schizophrenia symptoms. Among networks presenting activity within valid ranges, 154 parameter combinations out of 3002 (5.1%)
Je tiens à remercier l'ensemble des personnes qui ont contribué à la réalisation de ce mémoire. T... more Je tiens à remercier l'ensemble des personnes qui ont contribué à la réalisation de ce mémoire. Tout d'abord, je remercie mon directeur de mémoire, M. Grégory Munoz, enseignantchercheur à l'Université de Nantes, pour sa disponibilité, ses précieux conseils et son extrême bienveillance. Je remercie vivement les conseillers pédagogiques de circonscription qui se sont très longuement entretenus avec moi, qui ont répondu à mes innombrables sollicitations et avec qui j'ai eu beaucoup de plaisir à échanger sur notre passion commune : la formation. Je remercie sincèrement les enseignants qui m'ont fait confiance, m'ont accueillie dans leur classe et ont accepté d'être enregistrés lors des entretiens. Je remercie, par ailleurs, l'Inspectrice de l'Éducation Nationale qui m'a donnée son accord pour suivre l'expérimentation menée sur sa circonscription. Je remercie les étudiants de la promotion pour leurs petits « trucs et astuces » en tous genres qui m'ont aidée à conduire cette recherche. Je remercie mes proches, David Isvelin, Corinne Ménard et Martine Meunier pour leur soutien, leur avis critique, la lecture et la relecture de ce mémoire. Enfin, je remercie mes enfants Jade, Léon et Lino pour la petite aide apportée à la maison pendant l'année d'étude de leur maman.
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