1
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Chaves MF, Rodrigues C, Ribeiro S, Mota NB, Copelli M. Grammatical impairment in schizophrenia: An exploratory study of the pronominal and sentential domains. PLoS One 2023; 18:e0291446. [PMID: 37699027 PMCID: PMC10497169 DOI: 10.1371/journal.pone.0291446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 08/30/2023] [Indexed: 09/14/2023] Open
Abstract
Schizophrenia (SZ) is a severe mental disorder associated with a variety of linguistic deficits, and recently it has been suggested that these deficits are caused by an underlying impairment in the ability to build complex syntactic structures and complex semantic relations. Aiming at contributing to determining the specific linguistic profile of SZ, we investigated the usage of pronominal subjects and sentence types in two corpora of oral dream and waking reports produced by speakers with SZ and participants without SZ (NSZ), both native speakers of Brazilian Portuguese. Narratives of 40 adult participants (20 SZ, and 20 NSZ-sample 1), and narratives of 31 teenage participants (11 SZ undergoing first psychotic episode, and 20 NSZ-sample 2) were annotated and statistically analyzed. Overall, narratives of speakers with SZ presented significantly higher rates of matrix sentences, null pronouns-particularly null 3Person referential pronouns-and lower rates of non-anomalous truncated sentences. The high rate of matrix sentences correlated significantly with the total PANSS scores, suggesting an association between the overuse of simple sentences and SZ symptoms in general. In contrast, the high rate of null pronouns correlated significantly with positive PANSS scores, suggesting an association between the overuse of null pronominal forms and the positive symptoms of SZ. Finally, a cross-group analysis between samples 1 and 2 indicated a higher degree of grammatical impairment in speakers with multiple psychotic episodes. Altogether, the results strengthen the notion that deficits at the pronominal and sentential levels constitute a cross-cultural linguistic marker of SZ.
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Affiliation(s)
- Monica F. Chaves
- Department of Letters and Literature, Pontifical Catholic University of Rio de Janeiro, PUC-Rio, Rio de Janeiro, RJ, Brazil
| | - Cilene Rodrigues
- Department of Letters and Literature, Pontifical Catholic University of Rio de Janeiro, PUC-Rio, Rio de Janeiro, RJ, Brazil
| | - Sidarta Ribeiro
- Brain Institute, Federal University of Rio Grande do Norte, UFRN, Natal, RN, Brazil
| | - Natália B. Mota
- Department of Psychiatry, Federal University of Rio de Janeiro, UFRJ, Rio de Janeiro, RJ, Brazil
| | - Mauro Copelli
- Department of Physics, Federal University of Pernambuco, UFPE, Recife, PE, Brazil
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2
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Piuvezam HC, Marin B, Copelli M, Muñoz MA. Unconventional criticality, scaling breakdown, and diverse universality classes in the Wilson-Cowan model of neural dynamics. Phys Rev E 2023; 108:034110. [PMID: 37849106 DOI: 10.1103/physreve.108.034110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 08/04/2023] [Indexed: 10/19/2023]
Abstract
The Wilson-Cowan model constitutes a paradigmatic approach to understanding the collective dynamics of networks of excitatory and inhibitory units. It has been profusely used in the literature to analyze the possible phases of neural networks at a mean-field level, e.g., assuming large fully connected networks. Moreover, its stochastic counterpart allows one to study fluctuation-induced phenomena, such as avalanches. Here we revisit the stochastic Wilson-Cowan model paying special attention to the possible phase transitions between quiescent and active phases. We unveil eight possible types of such transitions, including continuous ones with scaling behavior belonging to known universality classes-such as directed percolation and tricritical directed percolation-as well as six distinct ones. In particular, we show that under some special circumstances, at a so-called "Hopf tricritical directed percolation" transition, rather unconventional behavior is observed, including the emergence of scaling breakdown. Other transitions are discontinuous and show different types of anomalies in scaling and/or exhibit mixed features of continuous and discontinuous transitions. These results broaden our knowledge of the possible types of critical behavior in networks of excitatory and inhibitory units and are, thus, of relevance to understanding avalanche dynamics in actual neuronal recordings. From a more general perspective, these results help extend the theory of nonequilibrium phase transitions into quiescent or absorbing states.
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Affiliation(s)
| | - Bóris Marin
- Centro de Matemática, Computação e Cognição, Universidade Federal do ABC, São Bernardo do Campo, Brazil
| | - Mauro Copelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife PE 50670-901, Brazil
| | - Miguel A Muñoz
- Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, Granada, Spain
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3
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Dalla Porta L, Castro DM, Copelli M, Carelli PV, Matias FS. Feedforward and feedback influences through distinct frequency bands between two spiking-neuron networks. Phys Rev E 2021; 104:054404. [PMID: 34942789 DOI: 10.1103/physreve.104.054404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 09/27/2021] [Indexed: 11/07/2022]
Abstract
Several studies on brain signals suggested that bottom-up and top-down influences are exerted through distinct frequency bands among visual cortical areas. It was recently shown that theta and gamma rhythms subserve feedforward, whereas the feedback influence is dominated by the alpha-beta rhythm in primates. A few theoretical models for reproducing these effects have been proposed so far. Here we show that a simple but biophysically plausible two-network motif composed of spiking-neuron models and chemical synapses can exhibit feedforward and feedback influences through distinct frequency bands. Different from previous studies, this kind of model allows us to study directed influences not only at the population level, by using a proxy for the local field potential, but also at the cellular level, by using the neuronal spiking series.
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Affiliation(s)
- Leonardo Dalla Porta
- Systems Neuroscience, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona 08036, Spain
| | - Daniel M Castro
- Departamento de Física, Universidade Federal de Pernambuco, Recife PE 50670-901, Brazil
| | - Mauro Copelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife PE 50670-901, Brazil
| | - Pedro V Carelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife PE 50670-901, Brazil
| | - Fernanda S Matias
- Instituto de Física, Universidade Federal de Alagoas, Maceió, Alagoas 57072-970, Brazil
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4
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Mota NB, Pinheiro S, Guerreiro A, Copelli M, Ribeiro S. Nonsemantic word graphs of texts spanning ∼ 4500 years, including pre-literate Amerindian oral narratives. Data Brief 2021; 38:107296. [PMID: 34458523 PMCID: PMC8379624 DOI: 10.1016/j.dib.2021.107296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 05/11/2021] [Accepted: 08/12/2021] [Indexed: 11/09/2022] Open
Abstract
Non-semantic word graphs obtained from oral reports are useful to describe cognitive decline in psychiatric conditions such as Schizophrenia, as well as education-related gains in discourse structure during typical development. Here we provide non-semantic word graph attributes of texts spanning approximately 4500 years of history, and pre-literate Amerindian oral narratives. The dataset assessed comprises 707 literary texts representative of 9 different Afro-Eurasian traditions (Syro-Mesopotamian, Egyptian, Hinduist, Persian, Judeo-Christian, Greek-Roman, Medieval, Modern and Contemporary), and Amerindian narratives (N = 39) obtained from a single ethnic group from South America (Kalapalo, N = 18), or from a mixed ethnic group from South, Central and North America (non-Kalapalo, N = 21). The present article provides detailed information about each text or narrative, including measurements of four graph attributes of interest: number of nodes (lexical diversity), repeated edges (short-range recurrence), largest strongly connected component (long-range recurrence), and average shortest path (graph length).
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Affiliation(s)
- Natália Bezerra Mota
- Instituto do Cérebro, Universidade Federal do Rio Grande do Norte, Natal, Brazil.,Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil
| | - Sylvia Pinheiro
- Instituto do Cérebro, Universidade Federal do Rio Grande do Norte, Natal, Brazil
| | - Antonio Guerreiro
- Departamento de Antropologia, Universidade Estadual de Campinas, Campinas, Brazil
| | - Mauro Copelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil
| | - Sidarta Ribeiro
- Instituto do Cérebro, Universidade Federal do Rio Grande do Norte, Natal, Brazil
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5
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Carlos FLP, Ubirakitan MM, Rodrigues MCA, Aguilar-Domingo M, Herrera-Gutiérrez E, Gómez-Amor J, Copelli M, Carelli PV, Matias FS. Anticipated synchronization in human EEG data: Unidirectional causality with negative phase lag. Phys Rev E 2021; 102:032216. [PMID: 33075996 DOI: 10.1103/physreve.102.032216] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 07/15/2020] [Indexed: 11/07/2022]
Abstract
Understanding the functional connectivity of the brain has become a major goal of neuroscience. In many situations the relative phase difference, together with coherence patterns, has been employed to infer the direction of the information flow. However, it has been recently shown in local field potential data from monkeys the existence of a synchronized regime in which unidirectionally coupled areas can present both positive and negative phase differences. During the counterintuitive regime, called anticipated synchronization (AS), the phase difference does not reflect the causality. Here we investigate coherence and causality at the alpha frequency band (f∼10 Hz) between pairs of electroencephalogram (EEG) electrodes in humans during a GO/NO-GO task. We show that human EEG signals can exhibit anticipated synchronization, which is characterized by a unidirectional influence from an electrode A to an electrode B, but the electrode B leads the electrode A in time. To the best of our knowledge, this is the first verification of AS in EEG signals and in the human brain. The usual delayed synchronization (DS) regime is also present between many pairs. DS is characterized by a unidirectional influence from an electrode A to an electrode B and a positive phase difference between A and B which indicates that the electrode A leads the electrode B in time. Moreover we show that EEG signals exhibit diversity in the phase relations: the pairs of electrodes can present in-phase, antiphase, or out-of-phase synchronization with a similar distribution of positive and negative phase differences.
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Affiliation(s)
| | - Maciel-Monteiro Ubirakitan
- Grupo de Neurodinâmica, Departamento de Fisiologia e Farmacologia, Universidade Federal de Pernambuco, Recife PE 50670-901, Brazil.,Spanish Foundation for Neurometrics Development, Department of Psychophysics & Psychophysiology, 30100, Murcia, Spain
| | - Marcelo Cairrão Araújo Rodrigues
- Grupo de Neurodinâmica, Departamento de Fisiologia e Farmacologia, Universidade Federal de Pernambuco, Recife PE 50670-901, Brazil
| | - Moisés Aguilar-Domingo
- Spanish Foundation for Neurometrics Development, Department of Psychophysics & Psychophysiology, 30100, Murcia, Spain.,Department of Human Anatomy and Psychobiology, Faculty of Psychology, University of Murcia, 30100 Espinardo Campus, Murcia, Spain
| | - Eva Herrera-Gutiérrez
- Department of Developmental and Educational Psychology, Faculty of Psychology, University of Murcia, 30100 Espinardo Campus, Murcia, Spain
| | - Jesús Gómez-Amor
- Department of Human Anatomy and Psychobiology, Faculty of Psychology, University of Murcia, 30100 Espinardo Campus, Murcia, Spain
| | - Mauro Copelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife PE 50670-901, Brazil
| | - Pedro V Carelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife PE 50670-901, Brazil
| | - Fernanda S Matias
- Instituto de Física, Universidade Federal de Alagoas, Maceió, Alagoas 57072-970 Brazil
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6
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Lotfi N, Fontenele AJ, Feliciano T, Aguiar LAA, de Vasconcelos NAP, Soares-Cunha C, Coimbra B, Rodrigues AJ, Sousa N, Copelli M, Carelli PV. Signatures of brain criticality unveiled by maximum entropy analysis across cortical states. Phys Rev E 2021; 102:012408. [PMID: 32795006 DOI: 10.1103/physreve.102.012408] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 07/01/2020] [Indexed: 11/07/2022]
Abstract
It has recently been reported that statistical signatures of brain criticality, obtained from distributions of neuronal avalanches, can depend on the cortical state. We revisit these claims with a completely different and independent approach, employing a maximum entropy model to test whether signatures of criticality appear in urethane-anesthetized rats. To account for the spontaneous variation of cortical states, we parse the time series and perform the maximum entropy analysis as a function of the variability of the population spiking activity. To compare data sets with different numbers of neurons, we define a normalized distance to criticality that takes into account the peak and width of the specific heat curve. We found a universal collapse of the normalized distance to criticality dependence on the cortical state, on an animal by animal basis. This indicates a universal dynamics and a critical point at an intermediate value of spiking variability.
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Affiliation(s)
- Nastaran Lotfi
- Departamento de Física, Universidade Federal de Pernambuco, Recife, PE 50670-901, Brazil
| | - Antonio J Fontenele
- Departamento de Física, Universidade Federal de Pernambuco, Recife, PE 50670-901, Brazil
| | - Thaís Feliciano
- Departamento de Física, Universidade Federal de Pernambuco, Recife, PE 50670-901, Brazil
| | - Leandro A A Aguiar
- Departamento de Física, Universidade Federal de Pernambuco, Recife, PE 50670-901, Brazil
| | - Nivaldo A P de Vasconcelos
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, 4710-057, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, 4806-909, Portugal
| | - Carina Soares-Cunha
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, 4710-057, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, 4806-909, Portugal
| | - Bárbara Coimbra
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, 4710-057, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, 4806-909, Portugal
| | - Ana João Rodrigues
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, 4710-057, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, 4806-909, Portugal
| | - Nuno Sousa
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, 4710-057, Portugal.,ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães, 4806-909, Portugal
| | - Mauro Copelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife, PE 50670-901, Brazil
| | - Pedro V Carelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife, PE 50670-901, Brazil
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7
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Torres AR, Mota NB, Adamy N, Naschold A, Lima TZ, Copelli M, Weissheimer J, Pegado F, Ribeiro S. Selective Inhibition of Mirror Invariance for Letters Consolidated by Sleep Doubles Reading Fluency. Curr Biol 2021; 31:909. [PMID: 33621496 DOI: 10.1016/j.cub.2021.01.082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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8
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Lotfi N, Feliciano T, Aguiar LAA, Silva TPL, Carvalho TTA, Rosso OA, Copelli M, Matias FS, Carelli PV. Statistical complexity is maximized close to criticality in cortical dynamics. Phys Rev E 2021; 103:012415. [PMID: 33601583 DOI: 10.1103/physreve.103.012415] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 01/04/2021] [Indexed: 11/07/2022]
Abstract
Complex systems are typically characterized as an intermediate situation between a complete regular structure and a random system. Brain signals can be studied as a striking example of such systems: cortical states can range from highly synchronous and ordered neuronal activity (with higher spiking variability) to desynchronized and disordered regimes (with lower spiking variability). It has been recently shown, by testing independent signatures of criticality, that a phase transition occurs in a cortical state of intermediate spiking variability. Here we use a symbolic information approach to show that, despite the monotonical increase of the Shannon entropy between ordered and disordered regimes, we can determine an intermediate state of maximum complexity based on the Jensen disequilibrium measure. More specifically, we show that statistical complexity is maximized close to criticality for cortical spiking data of urethane-anesthetized rats, as well as for a network model of excitable elements that presents a critical point of a nonequilibrium phase transition.
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Affiliation(s)
- Nastaran Lotfi
- Departamento de Física, Universidade Federal de Pernambuco, Recife PE 50670-901, Brazil
| | - Thaís Feliciano
- Departamento de Física, Universidade Federal de Pernambuco, Recife PE 50670-901, Brazil
| | - Leandro A A Aguiar
- Departamento de Ciências Fundamentais e Sociais, Universidade Federal da Paraíba, Areia PB 58397-000, Brazil
| | | | - Tawan T A Carvalho
- Departamento de Física, Universidade Federal de Pernambuco, Recife PE 50670-901, Brazil
| | - Osvaldo A Rosso
- Instituto de Física, Universidade Federal de Alagoas, Maceió, Alagoas 57072-970, Brazil
| | - Mauro Copelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife PE 50670-901, Brazil
| | - Fernanda S Matias
- Instituto de Física, Universidade Federal de Alagoas, Maceió, Alagoas 57072-970, Brazil
| | - Pedro V Carelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife PE 50670-901, Brazil
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9
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Carvalho TTA, Fontenele AJ, Girardi-Schappo M, Feliciano T, Aguiar LAA, Silva TPL, de Vasconcelos NAP, Carelli PV, Copelli M. Subsampled Directed-Percolation Models Explain Scaling Relations Experimentally Observed in the Brain. Front Neural Circuits 2021; 14:576727. [PMID: 33519388 PMCID: PMC7843423 DOI: 10.3389/fncir.2020.576727] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 11/30/2002] [Indexed: 12/14/2022] Open
Abstract
Recent experimental results on spike avalanches measured in the urethane-anesthetized rat cortex have revealed scaling relations that indicate a phase transition at a specific level of cortical firing rate variability. The scaling relations point to critical exponents whose values differ from those of a branching process, which has been the canonical model employed to understand brain criticality. This suggested that a different model, with a different phase transition, might be required to explain the data. Here we show that this is not necessarily the case. By employing two different models belonging to the same universality class as the branching process (mean-field directed percolation) and treating the simulation data exactly like experimental data, we reproduce most of the experimental results. We find that subsampling the model and adjusting the time bin used to define avalanches (as done with experimental data) are sufficient ingredients to change the apparent exponents of the critical point. Moreover, experimental data is only reproduced within a very narrow range in parameter space around the phase transition.
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Affiliation(s)
- Tawan T A Carvalho
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil
| | | | - Mauricio Girardi-Schappo
- Department of Physics, University of Ottawa, Ottawa, ON, Canada.,Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Thaís Feliciano
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil
| | - Leandro A A Aguiar
- Departamento de Ciências Fundamentais e Sociais, Universidade Federal da Paraíba, Areia, Brazil
| | - Thais P L Silva
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil
| | - Nivaldo A P de Vasconcelos
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,Life and Health Sciences Research Institute/Biomaterials, Biodegradables and Biomimetics, Braga, Portugal
| | - Pedro V Carelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil
| | - Mauro Copelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil
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10
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Sanz C, Pallavicini C, Carrillo F, Zamberlan F, Sigman M, Mota N, Copelli M, Ribeiro S, Nutt D, Carhart-Harris R, Tagliazucchi E. The entropic tongue: Disorganization of natural language under LSD. Conscious Cogn 2021; 87:103070. [PMID: 33307427 DOI: 10.1016/j.concog.2020.103070] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 09/10/2020] [Accepted: 11/28/2020] [Indexed: 02/09/2023]
Abstract
Serotonergic psychedelics have been suggested to mirror certain aspects of psychosis, and, more generally, elicit a state of consciousness underpinned by increased entropy of on-going neural activity. We investigated the hypothesis that language produced under the effects of lysergic acid diethylamide (LSD) should exhibit increased entropy and reduced semantic coherence. Computational analysis of interviews conducted at two different time points after 75 μg of intravenous LSD verified this prediction. Non-semantic analysis of speech organization revealed increased verbosity and a reduced lexicon, changes that are more similar to those observed during manic psychoses than in schizophrenia, which was confirmed by direct comparison with reference samples. Importantly, features related to language organization allowed machine learning classifiers to identify speech under LSD with accuracy comparable to that obtained by examining semantic content. These results constitute a quantitative and objective characterization of disorganized natural speech as a landmark feature of the psychedelic state.
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Affiliation(s)
- Camila Sanz
- Departamento de Física, Universidad de Buenos Aires and Instituto de Física de Buenos Aires (IFIBA - CONICET), Pabellón I, Ciudad Universitaria (1428), CABA, Buenos Aires, Argentina
| | - Carla Pallavicini
- Departamento de Física, Universidad de Buenos Aires and Instituto de Física de Buenos Aires (IFIBA - CONICET), Pabellón I, Ciudad Universitaria (1428), CABA, Buenos Aires, Argentina; Fundación para la lucha contra las enfermedades neurológicas de la infancia (FLENI), Montañeses 2325, C1428 CABA, Buenos Aires, Argentina
| | - Facundo Carrillo
- Applied Artificial Intelligence Lab (ICC-CONICET), Pabellón I, Ciudad Universitaria (1428), CABA, Buenos Aires, Argentina
| | - Federico Zamberlan
- Departamento de Física, Universidad de Buenos Aires and Instituto de Física de Buenos Aires (IFIBA - CONICET), Pabellón I, Ciudad Universitaria (1428), CABA, Buenos Aires, Argentina
| | - Mariano Sigman
- Universidad Torcuato Di Tella, Juan Pablo Sáenz Valiente 1010, C1428BIJ CABA, Buenos Aires, Argentina
| | - Natalia Mota
- Brain Institute, Federal University of Rio Grande do Norte, Av. Sen. Salgado Filho, 3000 Candelária, Natal, Brazil
| | - Mauro Copelli
- Physics Department, Federal University of Pernambuco, Av. Prof. Moraes Rego 1235, Cidade Universitária, Recife, PE 50670-901, Brazil
| | - Sidarta Ribeiro
- Brain Institute, Federal University of Rio Grande do Norte, Av. Sen. Salgado Filho, 3000 Candelária, Natal, Brazil
| | - David Nutt
- Centre for Psychedelic Research, Department of Medicine, Imperial College London, Kensington, London SW7 2DD, United Kingdom
| | - Robin Carhart-Harris
- Centre for Psychedelic Research, Department of Medicine, Imperial College London, Kensington, London SW7 2DD, United Kingdom
| | - Enzo Tagliazucchi
- Departamento de Física, Universidad de Buenos Aires and Instituto de Física de Buenos Aires (IFIBA - CONICET), Pabellón I, Ciudad Universitaria (1428), CABA, Buenos Aires, Argentina.
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11
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Pinheiro S, Mota NB, Sigman M, Fernández-Slezak D, Guerreiro A, Tófoli LF, Cecchi G, Copelli M, Ribeiro S. The History of Writing Reflects the Effects of Education on Discourse Structure: Implications for Literacy, Orality, Psychosis and the Axial Age. Trends Neurosci Educ 2020; 21:100142. [PMID: 33303107 DOI: 10.1016/j.tine.2020.100142] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Revised: 09/22/2020] [Accepted: 09/24/2020] [Indexed: 11/28/2022]
Abstract
BACKGROUND Graph analysis detects psychosis and literacy acquisition. Bronze Age literature has been proposed to contain childish or psychotic features, which would only have matured during the Axial Age (∼800-200 BC), a putative boundary for contemporary mentality. METHOD Graph analysis of literary texts spanning ∼4,500 years shows remarkable asymptotic changes over time. RESULTS While lexical diversity, long-range recurrence and graph length increase away from randomness, short-range recurrence declines towards random levels. Bronze Age texts are structurally similar to oral reports from literate typical children and literate psychotic adults, but distinct from poetry, and from narratives by preliterate preschoolers or Amerindians. Text structure reconstitutes the "arrow-of-time", converging to educated adult levels at the Axial Age onset. CONCLUSION The educational pathways of oral and literate traditions are structurally divergent, with a decreasing range of recurrence in the former, and an increasing range of recurrence in the latter. Education is seemingly the driving force underlying discourse maturation.
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Affiliation(s)
- Sylvia Pinheiro
- Instituto do Cérebro, Universidade Federal do Rio Grande do Norte, Natal, Brazil
| | - Natália Bezerra Mota
- Instituto do Cérebro, Universidade Federal do Rio Grande do Norte, Natal, Brazil.; Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil
| | - Mariano Sigman
- Laboratorio de Neurociencia, Universidad Torcuato Di Tella, Buenos Aires, Argentina.; CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas), Argentina.; Facultad de Lenguas y Educación, Universidad Nebrija, Madrid, Spain
| | - Diego Fernández-Slezak
- Departamento de Computación, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.; Instituto de Investigación en Ciencias de la Computación, CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Antonio Guerreiro
- Departamento de Antropologia, Universidade Estadual de Campinas, Campinas, Brazil
| | - Luís Fernando Tófoli
- Departamento de Psicologia Médica e Psiquiatria, Universidade Estadual de Campinas, Campinas, Brazil
| | - Guillermo Cecchi
- Computational Biology Center - Neuroscience, IBM T.J. Watson Research Center, Yorktown Heights, USA
| | - Mauro Copelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil..
| | - Sidarta Ribeiro
- Instituto do Cérebro, Universidade Federal do Rio Grande do Norte, Natal, Brazil..
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12
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Lima Dias Pinto I, Copelli M. Oscillations and collective excitability in a model of stochastic neurons under excitatory and inhibitory coupling. Phys Rev E 2019; 100:062416. [PMID: 31962449 DOI: 10.1103/physreve.100.062416] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Indexed: 06/10/2023]
Abstract
We study a model with excitable neurons modeled as stochastic units with three states, representing quiescence, firing, and refractoriness. The transition rates between quiescence and firing depend exponentially on the number of firing neighbors, whereas all other rates are kept constant. This model class was shown to exhibit collective oscillations (synchronization) if neurons are spiking autonomously, but not if neurons are in the excitable regime. In both cases, neurons were restricted to interact through excitatory coupling. Here we show that a plethora of collective phenomena appear if inhibitory coupling is added. Besides the usual transition between an absorbing and an active phase, the model with excitatory and inhibitory neurons can also undergo reentrant transitions to an oscillatory phase. In the mean-field description, oscillations can emerge through supercritical or subcritical Hopf bifurcations, as well as through infinite period bifurcations. The model has bistability between active and oscillating behavior, as well as collective excitability, a regime where the system can display a peak of global activity when subject to a sufficiently strong perturbation. We employ a variant of the Shinomoto-Kuramoto order parameter to characterize the phase transitions and their system-size dependence.
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Affiliation(s)
| | - Mauro Copelli
- Physics Department, Federal University of Pernambuco (UFPE), Recife, PE 50670-901, Brazil
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13
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Santos FAN, Raposo EP, Coutinho-Filho MD, Copelli M, Stam CJ, Douw L. Topological phase transitions in functional brain networks. Phys Rev E 2019; 100:032414. [PMID: 31640025 DOI: 10.1103/physreve.100.032414] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Indexed: 06/10/2023]
Abstract
Functional brain networks are often constructed by quantifying correlations between time series of activity of brain regions. Their topological structure includes nodes, edges, triangles, and even higher-dimensional objects. Topological data analysis (TDA) is the emerging framework to process data sets under this perspective. In parallel, topology has proven essential for understanding fundamental questions in physics. Here we report the discovery of topological phase transitions in functional brain networks by merging concepts from TDA, topology, geometry, physics, and network theory. We show that topological phase transitions occur when the Euler entropy has a singularity, which remarkably coincides with the emergence of multidimensional topological holes in the brain network. The geometric nature of the transitions can be interpreted, under certain hypotheses, as an extension of percolation to high-dimensional objects. Due to the universal character of phase transitions and noise robustness of TDA, our findings open perspectives toward establishing reliable topological and geometrical markers for group and possibly individual differences in functional brain network organization.
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Affiliation(s)
- Fernando A N Santos
- Departamento de Matemática, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brazil and Laboratório de Física Teórica e Computacional, Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brazil
| | - Ernesto P Raposo
- Laboratório de Física Teórica e Computacional, Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brazil
| | - Maurício D Coutinho-Filho
- Laboratório de Física Teórica e Computacional, Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brazil
| | - Mauro Copelli
- Laboratório de Física Teórica e Computacional, Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brazil
| | - Cornelis J Stam
- Department of Clinical Neurophysiology and MEG Center, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, 1081 HV, Amsterdam, The Netherlands
| | - Linda Douw
- Department of Anatomy & Neurosciences, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam Neuroscience, 1081 HZ, Amsterdam, The Netherlands
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14
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Dalla Porta L, Matias FS, Dos Santos AJ, Alonso A, Carelli PV, Copelli M, Mirasso CR. Exploring the Phase-Locking Mechanisms Yielding Delayed and Anticipated Synchronization in Neuronal Circuits. Front Syst Neurosci 2019; 13:41. [PMID: 31496943 PMCID: PMC6712169 DOI: 10.3389/fnsys.2019.00041] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 08/05/2019] [Indexed: 11/24/2022] Open
Abstract
Synchronization is one of the brain mechanisms allowing the coordination of neuronal activity required in many cognitive tasks. Anticipated Synchronization (AS) is a specific type of out-of-phase synchronization that occurs when two systems are unidirectionally coupled and, consequently, the information is transmitted from the sender to the receiver, but the receiver leads the sender in time. It has been shown that the primate cortex could operate in a regime of AS as part of normal neurocognitive function. However it is still unclear what is the mechanism that gives rise to anticipated synchronization in neuronal motifs. Here, we investigate the synchronization properties of cortical motifs on multiple scales and show that the internal dynamics of the receiver, which is related to its free running frequency in the uncoupled situation, is the main ingredient for AS to occur. For biologically plausible parameters, including excitation/inhibition balance, we found that the phase difference between the sender and the receiver decreases when the free running frequency of the receiver increases. As a consequence, the system switches from the usual delayed synchronization (DS) regime to an AS regime. We show that at three different scales, neuronal microcircuits, spiking neuronal populations and neural mass models, both the inhibitory loop and the external current acting on the receiver mediate the DS-AS transition for the sender-receiver configuration by changing the free running frequency of the receiver. Therefore, we propose that a faster internal dynamics of the receiver system is the main mechanism underlying anticipated synchronization in brain circuits.
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Affiliation(s)
- Leonardo Dalla Porta
- System Neuroscience Group, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | - Fernanda S Matias
- Instituto de Física, Universidade Federal de Alagoas, Maceió, Brazil
| | | | - Ana Alonso
- Instituto de Física Interdisciplinar y Sistemas Complejos (IFISC, UIB-CSIC), Palma, Spain
| | - Pedro V Carelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil
| | - Mauro Copelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil
| | - Claudio R Mirasso
- Instituto de Física Interdisciplinar y Sistemas Complejos (IFISC, UIB-CSIC), Palma, Spain
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15
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Fontenele AJ, de Vasconcelos NAP, Feliciano T, Aguiar LAA, Soares-Cunha C, Coimbra B, Dalla Porta L, Ribeiro S, Rodrigues AJ, Sousa N, Carelli PV, Copelli M. Criticality between Cortical States. Phys Rev Lett 2019; 122:208101. [PMID: 31172737 DOI: 10.1103/physrevlett.122.208101] [Citation(s) in RCA: 95] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 02/18/2019] [Indexed: 05/21/2023]
Abstract
Since the first measurements of neuronal avalanches, the critical brain hypothesis has gained traction. However, if the brain is critical, what is the phase transition? For several decades, it has been known that the cerebral cortex operates in a diversity of regimes, ranging from highly synchronous states (with higher spiking variability) to desynchronized states (with lower spiking variability). Here, using both new and publicly available data, we test independent signatures of criticality and show that a phase transition occurs in an intermediate value of spiking variability, in both anesthetized and freely moving animals. The critical exponents point to a universality class different from mean-field directed percolation. Importantly, as the cortex hovers around this critical point, the avalanche exponents follow a linear relation that encompasses previous experimental results from different setups and is reproduced by a model.
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Affiliation(s)
- Antonio J Fontenele
- Physics Department, Federal University of Pernambuco (UFPE), Recife, PE 50670-901, Brazil
| | - Nivaldo A P de Vasconcelos
- Physics Department, Federal University of Pernambuco (UFPE), Recife, PE 50670-901, Brazil
- Department of Biomedical Engineering, Federal University of Pernambuco, Recife, PE 50670-901, Brazil
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga 4710-057, Portugal
- ICVS/3Bs-PT Government Associate Laboratory, 4806-909, Braga/Guimarães, Portugal
| | - Thaís Feliciano
- Physics Department, Federal University of Pernambuco (UFPE), Recife, PE 50670-901, Brazil
| | - Leandro A A Aguiar
- Physics Department, Federal University of Pernambuco (UFPE), Recife, PE 50670-901, Brazil
- Departamento de Morfologia e Fisiologia Animal, Universidade Federal Rural de Pernambuco (UFRPE), Recife, PE 52171-900, Brazil
| | - Carina Soares-Cunha
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga 4710-057, Portugal
- ICVS/3Bs-PT Government Associate Laboratory, 4806-909, Braga/Guimarães, Portugal
| | - Bárbara Coimbra
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga 4710-057, Portugal
- ICVS/3Bs-PT Government Associate Laboratory, 4806-909, Braga/Guimarães, Portugal
| | - Leonardo Dalla Porta
- Physics Department, Federal University of Pernambuco (UFPE), Recife, PE 50670-901, Brazil
- Systems Neuroscience, Institut dInvestigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036, Barcelona, Spain
| | - Sidarta Ribeiro
- Brain Institute, Federal University of Rio Grande do Norte (UFRN), Natal, RN 59056-450, Brazil
| | - Ana João Rodrigues
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga 4710-057, Portugal
- ICVS/3Bs-PT Government Associate Laboratory, 4806-909, Braga/Guimarães, Portugal
| | - Nuno Sousa
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga 4710-057, Portugal
- ICVS/3Bs-PT Government Associate Laboratory, 4806-909, Braga/Guimarães, Portugal
| | - Pedro V Carelli
- Physics Department, Federal University of Pernambuco (UFPE), Recife, PE 50670-901, Brazil
| | - Mauro Copelli
- Physics Department, Federal University of Pernambuco (UFPE), Recife, PE 50670-901, Brazil
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16
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Dalla Porta L, Copelli M. Modeling neuronal avalanches and long-range temporal correlations at the emergence of collective oscillations: Continuously varying exponents mimic M/EEG results. PLoS Comput Biol 2019; 15:e1006924. [PMID: 30951525 PMCID: PMC6469813 DOI: 10.1371/journal.pcbi.1006924] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 04/17/2019] [Accepted: 03/06/2019] [Indexed: 01/17/2023] Open
Abstract
We revisit the CROS ("CRitical OScillations") model which was recently proposed as an attempt to reproduce both scale-invariant neuronal avalanches and long-range temporal correlations. With excitatory and inhibitory stochastic neurons locally connected in a two-dimensional disordered network, the model exhibits a transition where alpha-band oscillations emerge. Precisely at the transition, the fluctuations of the network activity have nontrivial detrended fluctuation analysis (DFA) exponents, and avalanches (defined as supra-threshold activity) have power law distributions of size and duration. We show that, differently from previous results, the exponents governing the distributions of avalanche size and duration are not necessarily those of the mean-field directed percolation universality class (3/2 and 2, respectively). Instead, in a narrow region of parameter space, avalanche exponents obtained via a maximum-likelihood estimator vary continuously and follow a linear relation, in good agreement with results obtained from M/EEG data. In that region, moreover, the values of avalanche and DFA exponents display a spread with positive correlations, reproducing human MEG results.
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Affiliation(s)
- Leonardo Dalla Porta
- Departamento de Física, Universidade Federal de Pernambuco (UFPE), Recife, PE, Brazil
| | - Mauro Copelli
- Departamento de Física, Universidade Federal de Pernambuco (UFPE), Recife, PE, Brazil
- * E-mail:
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17
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Kinouchi O, Brochini L, Costa AA, Campos JGF, Copelli M. Stochastic oscillations and dragon king avalanches in self-organized quasi-critical systems. Sci Rep 2019; 9:3874. [PMID: 30846773 PMCID: PMC6405991 DOI: 10.1038/s41598-019-40473-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 01/28/2019] [Indexed: 12/04/2022] Open
Abstract
In the last decade, several models with network adaptive mechanisms (link deletion-creation, dynamic synapses, dynamic gains) have been proposed as examples of self-organized criticality (SOC) to explain neuronal avalanches. However, all these systems present stochastic oscillations hovering around the critical region that are incompatible with standard SOC. Here we make a linear stability analysis of the mean field fixed points of two self-organized quasi-critical systems: a fully connected network of discrete time stochastic spiking neurons with firing rate adaptation produced by dynamic neuronal gains and an excitable cellular automata with depressing synapses. We find that the fixed point corresponds to a stable focus that loses stability at criticality. We argue that when this focus is close to become indifferent, demographic noise can elicit stochastic oscillations that frequently fall into the absorbing state. This mechanism interrupts the oscillations, producing both power law avalanches and dragon king events, which appear as bands of synchronized firings in raster plots. Our approach differs from standard SOC models in that it predicts the coexistence of these different types of neuronal activity.
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Affiliation(s)
- Osame Kinouchi
- Universidade de São Paulo, Departamento de Física-FFCLRP, Ribeirão Preto, SP, Brazil.
| | - Ludmila Brochini
- Universidade de São Paulo, Instituto de Matemática e Estatística, São Paulo, SP, Brazil
| | - Ariadne A Costa
- Universidade Federal de Goiás, Unidade Acadêmica Especial de Ciências Exatas, Jataí, GO, Brazil
| | | | - Mauro Copelli
- Universidade de São Paulo, Departamento de Física-FFCLRP, Ribeirão Preto, SP, Brazil.,Universidade Federal de Pernambuco, Departamento de Física, Recife, PE, Brazil
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18
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Mota NB, Sigman M, Cecchi G, Copelli M, Ribeiro S. The maturation of speech structure in psychosis is resistant to formal education. NPJ Schizophr 2018; 4:25. [PMID: 30531913 PMCID: PMC6286358 DOI: 10.1038/s41537-018-0067-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 11/08/2018] [Indexed: 01/07/2023]
Abstract
Discourse varies widely with age, level of education, and psychiatric state. Word graphs have been recently shown to provide behavioral markers of formal thought disorders in psychosis (e.g., disorganized flow of ideas) and to track literacy acquisition in children with typical development. Here we report that a graph-theoretical computational analysis of verbal reports from subjects spanning 6 decades of age and 2 decades of education reveals asymptotic changes over time that depend more on education than age. In typical subjects, short-range recurrence and lexical diversity stabilize after elementary school, whereas graph size and long-range recurrence only steady after high school. Short-range recurrence decreases towards random levels, while lexical diversity, long-range recurrence, and graph size increase away from near-randomness towards a plateau in educated adults. Subjects with psychosis do not show similar dynamics, presenting at adulthood a children-like discourse structure. Typical subjects increase the range of word recurrence over school years, but the same feature in subjects with psychosis resists education.
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Affiliation(s)
- Natália Bezerra Mota
- Instituto do Cérebro, Universidade Federal do Rio Grande do Norte, Natal, Brazil.,Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil
| | - Mariano Sigman
- Laboratorio de Neurociencia, Universidad Torcuato Di Tella, Buenos Aires, Argentina.,CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas), Buenos Aires, Argentina.,Facultad de Lenguas y Educación, Universidad Nebrija, Madrid, Spain
| | - Guillermo Cecchi
- Computational Biology Center - Neuroscience, IBM T.J. Watson Research Center, Yorktown Heights, USA
| | - Mauro Copelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil.
| | - Sidarta Ribeiro
- Instituto do Cérebro, Universidade Federal do Rio Grande do Norte, Natal, Brazil.
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19
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Cabral T, Mota NB, Fraga L, Copelli M, McDaniel MA, Ribeiro S. Post-class naps boost declarative learning in a naturalistic school setting. NPJ Sci Learn 2018; 3:14. [PMID: 30631475 PMCID: PMC6220199 DOI: 10.1038/s41539-018-0031-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 07/18/2018] [Accepted: 07/19/2018] [Indexed: 05/05/2023]
Abstract
Laboratory evidence of a positive effect of sleep on declarative memory consolidation suggests that naps can be used to boost school learning in a scalable, low-cost manner. The few direct investigations of this hypothesis have so far upheld it, but departed from the naturalistic setting by testing non-curricular contents presented by experimenters instead of teachers. Furthermore, nap and non-nap groups were composed of different children. Here we assessed the effect of post-class naps on the retention of Science and History curricular contents presented by the regular class teacher to 24 students from 5th grade. Retention was repeatedly measured 3-4 days after content learning, with weekly group randomization over 6 consecutive weeks. Contents followed by long naps (>30 min), but not short naps (<30 min), were significantly more retained than contents followed by waking (Cohen's d = 0.7962). The results support the use of post-class morning naps to enhance formal education.
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Affiliation(s)
- Thiago Cabral
- Laboratory of Memory, Sleep and Dreams, Brain Institute, Federal University of Rio Grande do Norte (UFRN), Natal, Brazil
| | - Natália B. Mota
- Laboratory of Memory, Sleep and Dreams, Brain Institute, Federal University of Rio Grande do Norte (UFRN), Natal, Brazil
- Department of Physics, Federal University of Pernambuco (UFPE), Recife, Brazil
| | - Lucia Fraga
- State School Berilo Wanderley, Natal, Brazil
| | - Mauro Copelli
- Department of Physics, Federal University of Pernambuco (UFPE), Recife, Brazil
| | - Mark A. McDaniel
- Department of Psychological and Brain Sciences, Washington University, St. Louis, USA
| | - Sidarta Ribeiro
- Laboratory of Memory, Sleep and Dreams, Brain Institute, Federal University of Rio Grande do Norte (UFRN), Natal, Brazil
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20
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Mirasso CR, Carelli PV, Pereira T, Matias FS, Copelli M. Anticipated and zero-lag synchronization in motifs of delay-coupled systems. Chaos 2017; 27:114305. [PMID: 29195321 DOI: 10.1063/1.5006932] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Anticipated and zero-lag synchronization have been observed in different scientific fields. In the brain, they might play a fundamental role in information processing, temporal coding and spatial attention. Recent numerical work on anticipated and zero-lag synchronization studied the role of delays. However, an analytical understanding of the conditions for these phenomena remains elusive. In this paper, we study both phenomena in systems with small delays. By performing a phase reduction and studying phase locked solutions, we uncover the functional relation between the delay, excitation and inhibition for the onset of anticipated synchronization in a sender-receiver-interneuron motif. In the case of zero-lag synchronization in a chain motif, we determine the stability conditions. These analytical solutions provide an excellent prediction of the phase-locked regimes of Hodgkin-Huxley models and Roessler oscillators.
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Affiliation(s)
- Claudio R Mirasso
- Instituto de Física Interdisciplinar y Sistemas Complejos IFISC (CSIC-UIB), Universitat de les Illes Baleares, Campus UIB, E-07122 Palma de Mallorca, Spain
| | - Pedro V Carelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Tiago Pereira
- Instituto de Ciências Matemáticas e de Computação, Universidade de São Paulo, São Carlos, São Paulo, Brazil
| | - Fernanda S Matias
- Departamento de Física, Universidade Federal de Alagoas, Maceió, Alagoas, Brazil
| | - Mauro Copelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
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21
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Matias FS, Carelli PV, Mirasso CR, Copelli M. Anticipated synchronization in neuronal circuits unveiled by a phase-response-curve analysis. Phys Rev E 2017; 95:052410. [PMID: 28618595 DOI: 10.1103/physreve.95.052410] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Indexed: 11/07/2022]
Abstract
Anticipated synchronization (AS) is a counterintuitive behavior that has been observed in several systems. When AS occurs in a sender-receiver configuration, the latter can predict the future dynamics of the former for certain parameter values. In particular, in neuroscience AS was proposed to explain the apparent discrepancy between information flow and time lag in the cortical activity recorded in monkeys. Despite its success, a clear understanding of the mechanisms yielding AS in neuronal circuits is still missing. Here we use the well-known phase-response-curve (PRC) approach to study the prototypical sender-receiver-interneuron neuronal motif. Our aim is to better understand how the transitions between delayed to anticipated synchronization and anticipated synchronization to phase-drift regimes occur. We construct a map based on the PRC method to predict the phase-locking regimes and their stability. We find that a PRC function of two variables, accounting simultaneously for the inputs from sender and interneuron into the receiver, is essential to reproduce the numerical results obtained using a Hodgkin-Huxley model for the neurons. On the contrary, the typical approximation that considers a sum of two independent single-variable PRCs fails for intermediate to high values of the inhibitory coupling strength of the interneuron. In particular, it loses the delayed-synchronization to anticipated-synchronization transition.
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Affiliation(s)
- Fernanda S Matias
- Instituto de Física, Universidade Federal de Alagoas, Maceió, Alagoas 57072-970, Brazil
| | - Pedro V Carelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Pernambuco 50670-901, Brazil
| | - Claudio R Mirasso
- Instituto de Fisica Interdisciplinar y Sistemas Complejos, IFISC (CSIC-UIB), Campus Universitat de les Illes Balears, E-07122 Palma de Mallorca, Spain
| | - Mauro Copelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Pernambuco 50670-901, Brazil
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22
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Campos JGF, Costa ADA, Copelli M, Kinouchi O. Correlations induced by depressing synapses in critically self-organized networks with quenched dynamics. Phys Rev E 2017; 95:042303. [PMID: 28505838 DOI: 10.1103/physreve.95.042303] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Indexed: 11/07/2022]
Abstract
In a recent work, mean-field analysis and computer simulations were employed to analyze critical self-organization in networks of excitable cellular automata where randomly chosen synapses in the network were depressed after each spike (the so-called annealed dynamics). Calculations agree with simulations of the annealed version, showing that the nominal branching ratio σ converges to unity in the thermodynamic limit, as expected of a self-organized critical system. However, the question remains whether the same results apply to the biological case where only the synapses of firing neurons are depressed (the so-called quenched dynamics). We show that simulations of the quenched model yield significant deviations from σ=1 due to spatial correlations. However, the model is shown to be critical, as the largest eigenvalue of the synaptic matrix approaches unity in the thermodynamic limit, that is, λ_{c}=1. We also study the finite size effects near the critical state as a function of the parameters of the synaptic dynamics.
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Affiliation(s)
| | - Ariadne de Andrade Costa
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana 47405, USA.,Instituto de Computação, Universidade Estadual de Campinas, 13083-852 Campinas, São Paulo, Brazil
| | - Mauro Copelli
- Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco, Brazil
| | - Osame Kinouchi
- Departamento de Física, FFCLRP, Universidade de São Paulo, 14040-901 Ribeirão Preto, São Paulo, Brazil
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23
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Mota NB, Copelli M, Ribeiro S. Computational Tracking of Mental Health in Youth: Latin American Contributions to a Low-Cost and Effective Solution for Early Psychiatric Diagnosis. New Dir Child Adolesc Dev 2017; 2016:59-69. [PMID: 27254827 DOI: 10.1002/cad.20159] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The early onset of mental disorders can lead to serious cognitive damage, and timely interventions are needed in order to prevent them. In patients of low socioeconomic status, as is common in Latin America, it can be hard to identify children at risk. Here, we briefly introduce the problem by reviewing the scarce epidemiological data from Latin America regarding the onset of mental disorders, and discussing the difficulties associated with early diagnosis. Then we present computational psychiatry, a new field to which we and other Latin American researchers have contributed methods particularly relevant for the quantitative investigation of psychopathologies manifested during childhood. We focus on new technologies that help to identify mental disease and provide prodromal evaluation, so as to promote early differential diagnosis and intervention. To conclude, we discuss the application of these methods to clinical and educational practice. A comprehensive and quantitative characterization of verbal behavior in children, from hospitals and laboratories to homes and schools, may lead to more effective pedagogical and medical intervention.
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24
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Matias FS, Gollo LL, Carelli PV, Mirasso CR, Copelli M. Inhibitory loop robustly induces anticipated synchronization in neuronal microcircuits. Phys Rev E 2016; 94:042411. [PMID: 27841618 DOI: 10.1103/physreve.94.042411] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Indexed: 06/06/2023]
Abstract
We investigate the synchronization properties between two excitatory coupled neurons in the presence of an inhibitory loop mediated by an interneuron. Dynamic inhibition together with noise independently applied to each neuron provide phase diversity in the dynamics of the neuronal motif. We show that the interplay between the coupling strengths and the external noise controls the phase relations between the neurons in a counterintuitive way. For a master-slave configuration (unidirectional coupling) we find that the slave can anticipate the master, on average, if the slave is subject to the inhibitory feedback. In this nonusual regime, called anticipated synchronization (AS), the phase of the postsynaptic neuron is advanced with respect to that of the presynaptic neuron. We also show that the AS regime survives even in the presence of unbalanced bidirectional excitatory coupling. Moreover, for the symmetric mutually coupled situation, the neuron that is subject to the inhibitory loop leads in phase.
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Affiliation(s)
- Fernanda S Matias
- Instituto de Física, Universidade Federal de Alagoas, Maceió, Alagoas 57072-970, Brazil
| | - Leonardo L Gollo
- System Neuroscience Group, Queensland Institute of Medical Research, Brisbane QLD 4006, Australia
| | - Pedro V Carelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Pernambuco 50670-901, Brazil
| | - Claudio R Mirasso
- Instituto de Fisica Interdisciplinar y Sistemas Complejos, CSIC-UIB, Campus Universitat de les Illes Balears, E-07122 Palma de Mallorca, Spain
| | - Mauro Copelli
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Pernambuco 50670-901, Brazil
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Abstract
As few real systems comprise indistinguishable units, diversity is a hallmark of nature. Diversity among interacting units shapes properties of collective behavior such as synchronization and information transmission. However, the benefits of diversity on information processing at the edge of a phase transition, ordinarily assumed to emerge from identical elements, remain largely unexplored. Analyzing a general model of excitable systems with heterogeneous excitability, we find that diversity can greatly enhance optimal performance (by two orders of magnitude) when distinguishing incoming inputs. Heterogeneous systems possess a subset of specialized elements whose capability greatly exceeds that of the nonspecialized elements. We also find that diversity can yield multiple percolation, with performance optimized at tricriticality. Our results are robust in specific and more realistic neuronal systems comprising a combination of excitatory and inhibitory units, and indicate that diversity-induced amplification can be harnessed by neuronal systems for evaluating stimulus intensities.
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Affiliation(s)
- Leonardo L Gollo
- Systems Neuroscience Group, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia; Centre for Integrative Brain Function, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Mauro Copelli
- Departamento de Física, Universidade Federal de Pernambuco , Recife PE , Brazil
| | - James A Roberts
- Systems Neuroscience Group, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia; Centre for Integrative Brain Function, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
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Ribeiro TL, Ribeiro S, Copelli M. Repertoires of Spike Avalanches Are Modulated by Behavior and Novelty. Front Neural Circuits 2016; 10:16. [PMID: 27047341 PMCID: PMC4802163 DOI: 10.3389/fncir.2016.00016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 03/07/2016] [Indexed: 11/13/2022] Open
Abstract
Neuronal avalanches measured as consecutive bouts of thresholded field potentials represent a statistical signature that the brain operates near a critical point. In theory, criticality optimizes stimulus sensitivity, information transmission, computational capability and mnemonic repertoires size. Field potential avalanches recorded via multielectrode arrays from cortical slice cultures are repeatable spatiotemporal activity patterns. It remains unclear whether avalanches of action potentials observed in forebrain regions of freely-behaving rats also form recursive repertoires, and whether these have any behavioral relevance. Here, we show that spike avalanches, recorded from hippocampus (HP) and sensory neocortex of freely-behaving rats, constitute distinct families of recursive spatiotemporal patterns. A significant number of those patterns were specific to a behavioral state. Although avalanches produced during sleep were mostly similar to others that occurred during waking, the repertoire of patterns recruited during sleep differed significantly from that of waking. More importantly, exposure to novel objects increased the rate at which new patterns arose, also leading to changes in post-exposure repertoires, which were significantly different from those before the exposure. A significant number of families occurred exclusively during periods of whisker contact with objects, but few were associated with specific objects. Altogether, the results provide original evidence linking behavior and criticality at the spike level: spike avalanches form repertoires that emerge in waking, recur during sleep, are diversified by novelty and contribute to object representation.
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Affiliation(s)
- Tiago L Ribeiro
- Section on Critical Brain Dynamics, National Institute of Mental Health (NIMH), National Institutes of Health (NIH)Bethesda, MD, USA; Physics Department, Federal University of Pernambuco (UFPE)Recife, PE, Brazil
| | - Sidarta Ribeiro
- Brain Institute, Federal University of Rio Grande do Norte (UFRN) Natal, RN, Brazil
| | - Mauro Copelli
- Physics Department, Federal University of Pernambuco (UFPE) Recife, PE, Brazil
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27
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Abstract
Dreaming and psychosis share important features, such as intrinsic sense perceptions independent of external stimulation, and a general lack of criticism that is associated with reduced frontal cerebral activity. Awareness of dreaming while a dream is happening defines lucid dreaming (LD), a state in which the prefrontal cortex is more active than during regular dreaming. For this reason, LD has been proposed to be potentially therapeutic for psychotic patients. According to this view, psychotic patients would be expected to report LD less frequently, and with lower control ability, than healthy subjects. Furthermore, psychotic patients able to experience LD should present milder psychiatric symptoms, in comparison with psychotic patients unable to experience LD. To test these hypotheses, we investigated LD features (occurrence, control abilities, frequency, and affective valence) and psychiatric symptoms (measure by PANSS, BPRS, and automated speech analysis) in 45 subjects with psychotic symptoms [25 with Schizophrenia (S) and 20 with Bipolar Disorder (B) diagnosis] versus 28 non-psychotic control (C) subjects. Psychotic lucid dreamers reported control of their dreams more frequently (67% of S and 73% of B) than non-psychotic lucid dreamers (only 23% of C; S > C with p = 0.0283, B > C with p = 0.0150). Importantly, there was no clinical advantage for lucid dreamers among psychotic patients, even for the diagnostic question specifically related to lack of judgment and insight. Despite some limitations (e.g., transversal design, large variation of medications), these preliminary results support the notion that LD is associated with psychosis, but falsify the hypotheses that we set out to test. A possible explanation is that psychosis enhances the experience of internal reality in detriment of external reality, and therefore lucid dreamers with psychotic symptoms would be more able to control their internal reality than non-psychotic lucid dreamers. Training dream lucidity is likely to produce safe psychological strengthening in a non-psychotic population, but in a psychotic population LD practice may further empower deliria and hallucinations, giving internal reality the appearance of external reality.
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Affiliation(s)
- Natália B. Mota
- Brain Institute, Federal University of Rio Grande do NorteNatal, Brazil
| | - Adara Resende
- Brain Institute, Federal University of Rio Grande do NorteNatal, Brazil
| | - Sérgio A. Mota-Rolim
- Brain Institute, Federal University of Rio Grande do NorteNatal, Brazil
- Onofre Lopes University Hospital, Federal University of Rio Grande do NorteNatal, Brazil
| | - Mauro Copelli
- Physics Department, Federal University of PernambucoRecife, Brazil
| | - Sidarta Ribeiro
- Brain Institute, Federal University of Rio Grande do NorteNatal, Brazil
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28
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Matias F, Millan AP, Martinez L, Canals S, Carelli P, Copelli M, Mirasso CR. On the basic mechanisms of anticipated synchronization in neuronal circuits. BMC Neurosci 2015. [PMCID: PMC4697622 DOI: 10.1186/1471-2202-16-s1-p167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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29
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Matias FS, Gollo LL, Carelli PV, Copelli M, Mirasso CR. Reconstructing the directionality of coupling between cortical populations with negative phase lag. BMC Neurosci 2015. [PMCID: PMC4697500 DOI: 10.1186/1471-2202-16-s1-p166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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30
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Gollo LL, Copelli M, Roberts JA. Optimal signal detection with neuronal diversity: balancing the gullible and the prudent neurons. BMC Neurosci 2015. [PMCID: PMC4699188 DOI: 10.1186/1471-2202-16-s1-p208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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31
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Bedi G, Carrillo F, Cecchi GA, Slezak DF, Sigman M, Mota NB, Ribeiro S, Javitt DC, Copelli M, Corcoran CM. Automated analysis of free speech predicts psychosis onset in high-risk youths. NPJ Schizophr 2015; 1:15030. [PMID: 27336038 PMCID: PMC4849456 DOI: 10.1038/npjschz.2015.30] [Citation(s) in RCA: 293] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 06/19/2015] [Accepted: 07/06/2015] [Indexed: 12/22/2022]
Abstract
BACKGROUND/OBJECTIVES Psychiatry lacks the objective clinical tests routinely used in other specializations. Novel computerized methods to characterize complex behaviors such as speech could be used to identify and predict psychiatric illness in individuals. AIMS In this proof-of-principle study, our aim was to test automated speech analyses combined with Machine Learning to predict later psychosis onset in youths at clinical high-risk (CHR) for psychosis. METHODS Thirty-four CHR youths (11 females) had baseline interviews and were assessed quarterly for up to 2.5 years; five transitioned to psychosis. Using automated analysis, transcripts of interviews were evaluated for semantic and syntactic features predicting later psychosis onset. Speech features were fed into a convex hull classification algorithm with leave-one-subject-out cross-validation to assess their predictive value for psychosis outcome. The canonical correlation between the speech features and prodromal symptom ratings was computed. RESULTS Derived speech features included a Latent Semantic Analysis measure of semantic coherence and two syntactic markers of speech complexity: maximum phrase length and use of determiners (e.g., which). These speech features predicted later psychosis development with 100% accuracy, outperforming classification from clinical interviews. Speech features were significantly correlated with prodromal symptoms. CONCLUSIONS Findings support the utility of automated speech analysis to measure subtle, clinically relevant mental state changes in emergent psychosis. Recent developments in computer science, including natural language processing, could provide the foundation for future development of objective clinical tests for psychiatry.
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Affiliation(s)
- Gillinder Bedi
- Department of Psychiatry, College of Physicians and Surgeons of Columbia University, New York, NY, USA; Division on Substance Abuse, New York State Psychiatric Institute, New York, NY, USA
| | - Facundo Carrillo
- Department of computer Science, School of Sciences, Universidad de Buenos Aires , Buenos Aires, Argentina
| | - Guillermo A Cecchi
- Computational Biology Center-Neuroscience, IBM T.J. Watson Research Center , Yorktown Heights, NY, USA
| | - Diego Fernández Slezak
- Department of computer Science, School of Sciences, Universidad de Buenos Aires , Buenos Aires, Argentina
| | - Mariano Sigman
- Department of Physics, School of Sciences, Universidad de Buenos Aires , Buenos Aires, Argentina
| | - Natália B Mota
- Brain Institute, Federal University of Rio Grande do Norte , Natal, Brazil
| | - Sidarta Ribeiro
- Brain Institute, Federal University of Rio Grande do Norte , Natal, Brazil
| | - Daniel C Javitt
- Department of Psychiatry, College of Physicians and Surgeons of Columbia University, New York, NY, USA; Division of Experimental Therapeutics, New York State Psychiatric Institute, New York, NY, USA
| | - Mauro Copelli
- Department of Physics, Federal University of Pernambuco , Recife, Brazil
| | - Cheryl M Corcoran
- Department of Psychiatry, College of Physicians and Surgeons of Columbia University, New York, NY, USA; Division of Experimental Therapeutics, New York State Psychiatric Institute, New York, NY, USA
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32
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Bertola L, Mota NB, Copelli M, Satler/S. Diniz B, Ribeiro S, Malloy-Diniz LF. P4‐111: Semantic network and executive aspects impact semantic verbal fluency task in healthy elderly, mild cognitive impairment, and Alzheimer's disease patients. Alzheimers Dement 2015. [DOI: 10.1016/j.jalz.2015.06.1817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Laiss Bertola
- Federal University of Minas GeraisBelo HorizonteBrazil
| | | | | | | | - Sidarta Ribeiro
- Federal University of Rio Grande do NorteBelo HorizonteBrazil
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Bertola L, Mota NB, Copelli M, Rivero T, Diniz BS, Romano-Silva MA, Ribeiro S, Malloy-Diniz LF. Graph analysis of verbal fluency test discriminate between patients with Alzheimer's disease, mild cognitive impairment and normal elderly controls. Front Aging Neurosci 2014; 6:185. [PMID: 25120480 PMCID: PMC4114204 DOI: 10.3389/fnagi.2014.00185] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 07/09/2014] [Indexed: 12/26/2022] Open
Abstract
Verbal fluency is the ability to produce a satisfying sequence of spoken words during a given time interval. The core of verbal fluency lies in the capacity to manage the executive aspects of language. The standard scores of the semantic verbal fluency test are broadly used in the neuropsychological assessment of the elderly, and different analytical methods are likely to extract even more information from the data generated in this test. Graph theory, a mathematical approach to analyze relations between items, represents a promising tool to understand a variety of neuropsychological states. This study reports a graph analysis of data generated by the semantic verbal fluency test by cognitively healthy elderly (NC), patients with Mild Cognitive Impairment-subtypes amnestic (aMCI) and amnestic multiple domain (a+mdMCI)-and patients with Alzheimer's disease (AD). Sequences of words were represented as a speech graph in which every word corresponded to a node and temporal links between words were represented by directed edges. To characterize the structure of the data we calculated 13 speech graph attributes (SGA). The individuals were compared when divided in three (NC-MCI-AD) and four (NC-aMCI-a+mdMCI-AD) groups. When the three groups were compared, significant differences were found in the standard measure of correct words produced, and three SGA: diameter, average shortest path, and network density. SGA sorted the elderly groups with good specificity and sensitivity. When the four groups were compared, the groups differed significantly in network density, except between the two MCI subtypes and NC and aMCI. The diameter of the network and the average shortest path were significantly different between the NC and AD, and between aMCI and AD. SGA sorted the elderly in their groups with good specificity and sensitivity, performing better than the standard score of the task. These findings provide support for a new methodological frame to assess the strength of semantic memory through the verbal fluency task, with potential to amplify the predictive power of this test. Graph analysis is likely to become clinically relevant in neurology and psychiatry, and may be particularly useful for the differential diagnosis of the elderly.
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Affiliation(s)
- Laiss Bertola
- Laboratory of Clinical Neuroscience Investigations, Federal University of Minas Gerais Belo Horizonte, Brazil
| | - Natália B Mota
- Brain Institute, Federal University of Rio Grande do Norte Natal, Brazil
| | - Mauro Copelli
- Physics Department, Federal University of Pernambuco Recife, Brazil
| | - Thiago Rivero
- Laboratory of Clinical Neuroscience Investigations, Federal University of Minas Gerais Belo Horizonte, Brazil
| | - Breno Satler Diniz
- Laboratory of Clinical Neuroscience Investigations, Federal University of Minas Gerais Belo Horizonte, Brazil ; Mental Health Department, Faculty of Medicine, Federal University of Minas Gerais Belo Horizonte, Brazil
| | - Marco A Romano-Silva
- Mental Health Department, Faculty of Medicine, Federal University of Minas Gerais Belo Horizonte, Brazil ; Faculty of Medicine, National Institute of Science and Technology - Molecular Medicine, Federal University of Minas Gerais Belo Horizonte, Brazil
| | - Sidarta Ribeiro
- Brain Institute, Federal University of Rio Grande do Norte Natal, Brazil
| | - Leandro F Malloy-Diniz
- Laboratory of Clinical Neuroscience Investigations, Federal University of Minas Gerais Belo Horizonte, Brazil ; Mental Health Department, Faculty of Medicine, Federal University of Minas Gerais Belo Horizonte, Brazil
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Ribeiro TL, Ribeiro S, Belchior H, Caixeta F, Copelli M. Undersampled critical branching processes on small-world and random networks fail to reproduce the statistics of spike avalanches. PLoS One 2014; 9:e94992. [PMID: 24751599 PMCID: PMC3994033 DOI: 10.1371/journal.pone.0094992] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 03/19/2014] [Indexed: 11/18/2022] Open
Abstract
The power-law size distributions obtained experimentally for neuronal avalanches are an important evidence of criticality in the brain. This evidence is supported by the fact that a critical branching process exhibits the same exponent . Models at criticality have been employed to mimic avalanche propagation and explain the statistics observed experimentally. However, a crucial aspect of neuronal recordings has been almost completely neglected in the models: undersampling. While in a typical multielectrode array hundreds of neurons are recorded, in the same area of neuronal tissue tens of thousands of neurons can be found. Here we investigate the consequences of undersampling in models with three different topologies (two-dimensional, small-world and random network) and three different dynamical regimes (subcritical, critical and supercritical). We found that undersampling modifies avalanche size distributions, extinguishing the power laws observed in critical systems. Distributions from subcritical systems are also modified, but the shape of the undersampled distributions is more similar to that of a fully sampled system. Undersampled supercritical systems can recover the general characteristics of the fully sampled version, provided that enough neurons are measured. Undersampling in two-dimensional and small-world networks leads to similar effects, while the random network is insensitive to sampling density due to the lack of a well-defined neighborhood. We conjecture that neuronal avalanches recorded from local field potentials avoid undersampling effects due to the nature of this signal, but the same does not hold for spike avalanches. We conclude that undersampled branching-process-like models in these topologies fail to reproduce the statistics of spike avalanches.
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Affiliation(s)
- Tiago L. Ribeiro
- Physics Department, Federal University of Pernambuco (UFPE), Recife, Pernambuco, Brasil
- * E-mail:
| | - Sidarta Ribeiro
- Brain Institute, Federal University of Rio Grande do Norte (UFRN), Natal, Rio Grande do Norte, Brasil
| | - Hindiael Belchior
- Brain Institute, Federal University of Rio Grande do Norte (UFRN), Natal, Rio Grande do Norte, Brasil
| | - Fábio Caixeta
- Brain Institute, Federal University of Rio Grande do Norte (UFRN), Natal, Rio Grande do Norte, Brasil
| | - Mauro Copelli
- Physics Department, Federal University of Pernambuco (UFPE), Recife, Pernambuco, Brasil
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35
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Abstract
We study how the synaptic connections in a pair of excitable electronic neurons affect the coherence of their spike trains when the neurons are submitted to noise from independent sources. The coupling is provided by electronic circuits which mimic the dynamics of chemical AMPA synapses. In particular, we show that increasing the strength of an unidirectional synapse leads to a decrease of coherence in the post-synaptic neuron. More interestingly, we show that the decrease of coherence can be reverted if we add a synapse of sufficient strength in the reverse direction. Synaptic symmetry plays an important role in this process and, under the right choice of parameters, increases the network coherence beyond the value achieved at the resonance due to noise alone in uncoupled neurons. We also show that synapses with a longer time scale sharpen the dependency of the coherence on the synaptic symmetry. The results were reproduced by numerical simulations of a pair of synaptically coupled FitzHugh-Nagumo models.
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Affiliation(s)
- Bruno N. S. Medeiros
- Departamento de Fsica, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
- * E-mail:
| | - Mauro Copelli
- Departamento de Fsica, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
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Mota NB, Vasconcelos NAP, Lemos N, Pieretti AC, Kinouchi O, Cecchi GA, Copelli M, Ribeiro S. Speech graphs provide a quantitative measure of thought disorder in psychosis. PLoS One 2012; 7:e34928. [PMID: 22506057 PMCID: PMC3322168 DOI: 10.1371/journal.pone.0034928] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Accepted: 03/07/2012] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Psychosis has various causes, including mania and schizophrenia. Since the differential diagnosis of psychosis is exclusively based on subjective assessments of oral interviews with patients, an objective quantification of the speech disturbances that characterize mania and schizophrenia is in order. In principle, such quantification could be achieved by the analysis of speech graphs. A graph represents a network with nodes connected by edges; in speech graphs, nodes correspond to words and edges correspond to semantic and grammatical relationships. METHODOLOGY/PRINCIPAL FINDINGS To quantify speech differences related to psychosis, interviews with schizophrenics, manics and normal subjects were recorded and represented as graphs. Manics scored significantly higher than schizophrenics in ten graph measures. Psychopathological symptoms such as logorrhea, poor speech, and flight of thoughts were grasped by the analysis even when verbosity differences were discounted. Binary classifiers based on speech graph measures sorted schizophrenics from manics with up to 93.8% of sensitivity and 93.7% of specificity. In contrast, sorting based on the scores of two standard psychiatric scales (BPRS and PANSS) reached only 62.5% of sensitivity and specificity. CONCLUSIONS/SIGNIFICANCE The results demonstrate that alterations of the thought process manifested in the speech of psychotic patients can be objectively measured using graph-theoretical tools, developed to capture specific features of the normal and dysfunctional flow of thought, such as divergence and recurrence. The quantitative analysis of speech graphs is not redundant with standard psychometric scales but rather complementary, as it yields a very accurate sorting of schizophrenics and manics. Overall, the results point to automated psychiatric diagnosis based not on what is said, but on how it is said.
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Affiliation(s)
- Natalia B. Mota
- Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
- Hospital Onofre Lopes, Federal University of Rio Grande do Norte, Natal, Brazil
- Edmond and Lily Safra International Institute of Neuroscience of Natal, Natal, Brazil
| | - Nivaldo A. P. Vasconcelos
- Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
- Faculdade Natalense para o Desenvolvimento do Rio Grande do Norte, Natal, Brazil
- Department of Systems and Computation, Federal University of Campina Grande, Campina Grande, Brazil
| | - Nathalia Lemos
- Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Ana C. Pieretti
- Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Osame Kinouchi
- Department of Physics, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Guillermo A. Cecchi
- Biometaphorical Computing, Computational Biology Center, IBM Research Division, IBM T. J. Watson Research Center, Yorktown Heights, New York, United States of America
| | - Mauro Copelli
- Department of Physics, Federal University of Pernambuco, Recife, Brazil
| | - Sidarta Ribeiro
- Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
- * E-mail:
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38
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Gollo LL, Kinouchi O, Copelli M. Statistical physics approach to dendritic computation: the excitable-wave mean-field approximation. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 85:011911. [PMID: 22400595 DOI: 10.1103/physreve.85.011911] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 11/23/2011] [Indexed: 05/31/2023]
Abstract
We analytically study the input-output properties of a neuron whose active dendritic tree, modeled as a Cayley tree of excitable elements, is subjected to Poisson stimulus. Both single-site and two-site mean-field approximations incorrectly predict a nonequilibrium phase transition which is not allowed in the model. We propose an excitable-wave mean-field approximation which shows good agreement with previously published simulation results [Gollo et al., PLoS Comput. Biol. 5, e1000402 (2009)] and accounts for finite-size effects. We also discuss the relevance of our results to experiments in neuroscience, emphasizing the role of active dendrites in the enhancement of dynamic range and in gain control modulation.
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Affiliation(s)
- Leonardo L Gollo
- IFISC (CSIC - UIB), Instituto de Física Interdisciplinar y Sistemas Complejos, Campus Universitat Illes Balears, E-07122 Palma de Mallorca, Spain.
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Matias FS, Carelli PV, Mirasso CR, Copelli M. Anticipated synchronization in a biologically plausible model of neuronal motifs. Phys Rev E Stat Nonlin Soft Matter Phys 2011; 84:021922. [PMID: 21929034 DOI: 10.1103/physreve.84.021922] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Indexed: 05/31/2023]
Abstract
Two identical autonomous dynamical systems coupled in a master-slave configuration can exhibit anticipated synchronization (AS) if the slave also receives a delayed negative self-feedback. Recently, AS was shown to occur in systems of simplified neuron models, requiring the coupling of the neuronal membrane potential with its delayed value. However, this coupling has no obvious biological correlate. Here we propose a canonical neuronal microcircuit with standard chemical synapses, where the delayed inhibition is provided by an interneuron. In this biologically plausible scenario, a smooth transition from delayed synchronization (DS) to AS typically occurs when the inhibitory synaptic conductance is increased. The phenomenon is shown to be robust when model parameters are varied within a physiological range. Since the DS-AS transition amounts to an inversion in the timing of the pre- and post-synaptic spikes, our results could have a bearing on spike-timing-dependent plasticity models.
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Affiliation(s)
- Fernanda S Matias
- Departamento de Física, Universidade Federal de Pernambuco, Recife, Pernambuco 50670-901, Brazil
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Ribeiro TL, Copelli M, Caixeta F, Belchior H, Chialvo DR, Nicolelis MAL, Ribeiro S. Spike avalanches exhibit universal dynamics across the sleep-wake cycle. PLoS One 2010; 5:e14129. [PMID: 21152422 PMCID: PMC2994706 DOI: 10.1371/journal.pone.0014129] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Accepted: 10/27/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Scale-invariant neuronal avalanches have been observed in cell cultures and slices as well as anesthetized and awake brains, suggesting that the brain operates near criticality, i.e. within a narrow margin between avalanche propagation and extinction. In theory, criticality provides many desirable features for the behaving brain, optimizing computational capabilities, information transmission, sensitivity to sensory stimuli and size of memory repertoires. However, a thorough characterization of neuronal avalanches in freely-behaving (FB) animals is still missing, thus raising doubts about their relevance for brain function. METHODOLOGY/PRINCIPAL FINDINGS To address this issue, we employed chronically implanted multielectrode arrays (MEA) to record avalanches of action potentials (spikes) from the cerebral cortex and hippocampus of 14 rats, as they spontaneously traversed the wake-sleep cycle, explored novel objects or were subjected to anesthesia (AN). We then modeled spike avalanches to evaluate the impact of sparse MEA sampling on their statistics. We found that the size distribution of spike avalanches are well fit by lognormal distributions in FB animals, and by truncated power laws in the AN group. FB data surrogation markedly decreases the tail of the distribution, i.e. spike shuffling destroys the largest avalanches. The FB data are also characterized by multiple key features compatible with criticality in the temporal domain, such as 1/f spectra and long-term correlations as measured by detrended fluctuation analysis. These signatures are very stable across waking, slow-wave sleep and rapid-eye-movement sleep, but collapse during anesthesia. Likewise, waiting time distributions obey a single scaling function during all natural behavioral states, but not during anesthesia. Results are equivalent for neuronal ensembles recorded from visual and tactile areas of the cerebral cortex, as well as the hippocampus. CONCLUSIONS/SIGNIFICANCE Altogether, the data provide a comprehensive link between behavior and brain criticality, revealing a unique scale-invariant regime of spike avalanches across all major behaviors.
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Affiliation(s)
- Tiago L. Ribeiro
- Department of Physics, Federal University of Pernambuco (UFPE), Recife, Pernambuco, Brazil
| | - Mauro Copelli
- Department of Physics, Federal University of Pernambuco (UFPE), Recife, Pernambuco, Brazil
- Neuroscience Graduate Program, Federal University of Rio Grande do Norte (UFRN), Natal, Rio Grande do Norte, Brazil
| | - Fábio Caixeta
- Neuroscience Graduate Program, Federal University of Rio Grande do Norte (UFRN), Natal, Rio Grande do Norte, Brazil
- Edmond and Lily Safra International Institute of Neuroscience of Natal (ELS-IINN), Natal, Rio Grande do Norte, Brazil
| | - Hindiael Belchior
- Edmond and Lily Safra International Institute of Neuroscience of Natal (ELS-IINN), Natal, Rio Grande do Norte, Brazil
- Department of Physiology, Federal University of Rio Grande do Norte (UFRN), Natal, Rio Grande do Norte, Brazil
| | - Dante R. Chialvo
- Department of Physiology, Northwestern University, Chicago, Illinois, United States of America
| | - Miguel A. L. Nicolelis
- Neuroscience Graduate Program, Federal University of Rio Grande do Norte (UFRN), Natal, Rio Grande do Norte, Brazil
- Edmond and Lily Safra International Institute of Neuroscience of Natal (ELS-IINN), Natal, Rio Grande do Norte, Brazil
- Department of Neurobiology, Center for Neuroengineering, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States of America
- Department of Psychological and Brain Sciences, Duke University, Durham, North Carolina, United States of America
| | - Sidarta Ribeiro
- Neuroscience Graduate Program, Federal University of Rio Grande do Norte (UFRN), Natal, Rio Grande do Norte, Brazil
- Edmond and Lily Safra International Institute of Neuroscience of Natal (ELS-IINN), Natal, Rio Grande do Norte, Brazil
- Department of Physiology, Federal University of Rio Grande do Norte (UFRN), Natal, Rio Grande do Norte, Brazil
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Assis VRV, Copelli M. Discontinuous nonequilibrium phase transitions in a nonlinearly pulse-coupled excitable lattice model. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 80:061105. [PMID: 20365116 DOI: 10.1103/physreve.80.061105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Indexed: 05/29/2023]
Abstract
We study a modified version of the stochastic susceptible-infected-refractory-susceptible (SIRS) model by employing a nonlinear (exponential) reinforcement in the contagion rate and no diffusion. We run simulations for complete and random graphs as well as d-dimensional hypercubic lattices (for d=3,2,1). For weak nonlinearity, a continuous nonequilibrium phase transition between an absorbing and an active phase is obtained, such as in the usual stochastic SIRS model [Joo and Lebowitz, Phys. Rev. E 70, 036114 (2004)]. However, for strong nonlinearity, the nonequilibrium transition between the two phases can be discontinuous for d>or=2, which is confirmed by well-characterized hysteresis cycles and bistability. Analytical mean-field results correctly predict the overall structure of the phase diagram. Furthermore, contrary to what was observed in a model of phase-coupled stochastic oscillators with a similar nonlinearity in the coupling [Wood, Phys. Rev. Lett. 96, 145701 (2006)], we did not find a transition to a stable (partially) synchronized state in our nonlinearly pulse-coupled excitable elements. For long enough refractory times and high enough nonlinearity, however, the system can exhibit collective excitability and unstable stochastic oscillations.
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Affiliation(s)
- Vladimir R V Assis
- Laboratório de Física Teórica e Computacional, Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brazil.
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42
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Abstract
Since the first experimental evidences of active conductances in dendrites, most neurons have been shown to exhibit dendritic excitability through the expression of a variety of voltage-gated ion channels. However, despite experimental and theoretical efforts undertaken in the past decades, the role of this excitability for some kind of dendritic computation has remained elusive. Here we show that, owing to very general properties of excitable media, the average output of a model of an active dendritic tree is a highly non-linear function of its afferent rate, attaining extremely large dynamic ranges (above 50 dB). Moreover, the model yields double-sigmoid response functions as experimentally observed in retinal ganglion cells. We claim that enhancement of dynamic range is the primary functional role of active dendritic conductances. We predict that neurons with larger dendritic trees should have larger dynamic range and that blocking of active conductances should lead to a decrease in dynamic range. Most neurons present cellular tree-like extensions known as dendrites, which receive input signals from synapses with other cells. Some neurons have very large and impressive dendritic arbors. What is the function of such elaborate and costly structures? The functional role of dendrites is not obvious because, if dendrites were an electrical passive medium, then signals from their periphery could not influence the neuron output activity. Dendrites, however, are not passive, but rather active media that amplify and support pulses (dendritic spikes). These voltage pulses do not simply add but can also annihilate each other when they collide. To understand the net effect of the complex interactions among dendritic spikes under massive synaptic input, here we examine a computational model of excitable dendritic trees. We show that, in contrast to passive trees, they have a very large dynamic range, which implies a greater capacity of the neuron to distinguish among the widely different intensities of input which it receives. Our results provide an explanation to the concentration invariance property observed in olfactory processing, due to the very similar response to different inputs. In addition, our modeling approach also suggests a microscopic neural basis for the century old psychophysical laws.
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Affiliation(s)
- Leonardo L Gollo
- Laboratório de Física Teórica e Computacional, Departamento de Física, Universidade Federal de Pernambuco, Recife, Brazil.
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43
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Ribeiro TL, Copelli M. Deterministic excitable media under Poisson drive: power law responses, spiral waves, and dynamic range. Phys Rev E Stat Nonlin Soft Matter Phys 2008; 77:051911. [PMID: 18643106 DOI: 10.1103/physreve.77.051911] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Indexed: 05/26/2023]
Abstract
When each site of a spatially extended excitable medium is independently driven by a Poisson stimulus with rate h , the interplay between creation and annihilation of excitable waves leads to an average activity F . It has recently been suggested that in the low-stimulus regime (h approximately 0) the response function F(h) of hypercubic deterministic systems behaves as a power law, F approximately h{m} . Moreover, the response exponent m has been predicted to depend only on the dimensionality d of the lattice, m=1/(1+d) [T. Ohta and T. Yoshimura, Physica D 205, 189 (2005)]. In order to test this prediction, we study the response function of excitable lattices modeled by either coupled Morris-Lecar equations or Greenberg-Hastings cellular automata. We show that the prediction is verified in our model systems for d=1 , 2, and 3, provided that a minimum set of conditions is satisfied. Under these conditions, the dynamic range-which measures the range of stimulus intensities that can be coded by the network activity-increases with the dimensionality d of the network. The power law scenario breaks down, however, if the system can exhibit self-sustained activity (spiral waves). In this case, we recover a scenario that is common to probabilistic excitable media: as a function of the conductance coupling G among the excitable elements, the dynamic range is maximized precisely at the critical value G_{c} above which self-sustained activity becomes stable. We discuss the implications of these results in the context of neural coding.
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Affiliation(s)
- Tiago L Ribeiro
- Laboratório de Física Teórica e Computacional, Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brazil.
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44
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Assis VRV, Copelli M. Dynamic range of hypercubic stochastic excitable media. Phys Rev E Stat Nonlin Soft Matter Phys 2008; 77:011923. [PMID: 18351892 DOI: 10.1103/physreve.77.011923] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Revised: 12/11/2007] [Indexed: 05/26/2023]
Abstract
We study the response properties of d-dimensional hypercubic excitable networks to a stochastic stimulus. Each site, modeled either by a three-state stochastic susceptible-infected-recovered-susceptible system or by the probabilistic Greenberg-Hastings cellular automaton, is continuously and independently stimulated by an external Poisson rate h. The response function (mean density of active sites rho versus h) is obtained via simulations (for d=1,2,3,4) and mean-field approximations at the single-site and pair levels (for all d). In any dimension, the dynamic range and sensitivity of the response function are maximized precisely at the nonequilibrium phase transition to self-sustained activity, in agreement with a reasoning recently proposed. Moreover, the maximum dynamic range attained at a given dimension d is a decreasing function of d.
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Affiliation(s)
- Vladimir R V Assis
- Laboratório de Física Teórica e Computacional, Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brazil.
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45
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Copelli M, Kinouchi O. Physics of psychophysics: optimal dynamic range of critical excitable networks. BMC Neurosci 2007. [PMCID: PMC4436100 DOI: 10.1186/1471-2202-8-s2-p174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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46
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Roa MAD, Copelli M, Kinouchi O, Caticha N. Scaling law for the transient behavior of type-II neuron models. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 75:021911. [PMID: 17358371 DOI: 10.1103/physreve.75.021911] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2006] [Revised: 10/23/2006] [Indexed: 05/14/2023]
Abstract
We study the transient regime of type-II biophysical neuron models and determine the scaling behavior of relaxation times tau near but below the repetitive firing critical current, tau approximately or equal to C(I(c)-I)(-Delta). For both the Hodgkin-Huxley and Morris-Lecar models we find that the critical exponent is independent of the numerical integration time step and that both systems belong to the same universality class, with Delta=1/2. For appropriately chosen parameters, the FitzHugh-Nagumo model presents the same generic transient behavior, but the critical region is significantly smaller. We propose an experiment that may reveal nontrivial critical exponents in the squid axon.
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Affiliation(s)
- M A D Roa
- Laboratório de Física Teórica e Computacional, Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brazil
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Furtado LS, Copelli M. Response of electrically coupled spiking neurons: a cellular automaton approach. Phys Rev E Stat Nonlin Soft Matter Phys 2006; 73:011907. [PMID: 16486185 DOI: 10.1103/physreve.73.011907] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Revised: 09/06/2005] [Indexed: 05/06/2023]
Abstract
Experimental data suggest that some classes of spiking neurons in the first layers of sensory systems are electrically coupled via gap junctions or ephaptic interactions. When the electrical coupling is removed, the response function (firing rate vs. stimulus intensity) of the uncoupled neurons typically shows a decrease in dynamic range and sensitivity. In order to assess the effect of electrical coupling in the sensory periphery, we calculate the response to a Poisson stimulus of a chain of excitable neurons modeled by n-state Greenberg-Hastings cellular automata in two approximation levels. The single-site mean field approximation is shown to give poor results, failing to predict the absorbing state of the lattice, while the results for the pair approximation are in good agreement with computer simulations in the whole stimulus range. In particular, the dynamic range is substantially enlarged due to the propagation of excitable waves, which suggests a functional role for lateral electrical coupling. For probabilistic spike propagation the Hill exponent of the response function is alpha=1, while for deterministic spike propagation we obtain alpha=1/2, which is close to the experimental values of the psychophysical Stevens exponents for odor and light intensities. Our calculations are in qualitative agreement with experimental response functions of ganglion cells in the mammalian retina.
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Affiliation(s)
- Lucas S Furtado
- Laboratório de Física Teórica e Computacional, Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brazil.
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Copelli M, Roque AC, Oliveira RF, Kinouchi O. Physics of psychophysics: Stevens and Weber-Fechner laws are transfer functions of excitable media. Phys Rev E Stat Nonlin Soft Matter Phys 2002; 65:060901. [PMID: 12188696 DOI: 10.1103/physreve.65.060901] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2001] [Indexed: 11/07/2022]
Abstract
Sensory arrays made of coupled excitable elements can improve both their input sensitivity and dynamic range due to collective nonlinear wave properties. This mechanism is studied in a neural network of electrically coupled (e.g., via gap junctions) elements subject to a Poisson signal process. The network response interpolates between a Weber-Fechner logarithmic law, and a Stevens power law depending on the relative refractory period of the cell. Therefore, these nonlinear transformations of the input level could be performed in the sensory periphery simply due to a basic property: the transfer function of excitable media.
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Affiliation(s)
- Mauro Copelli
- Instituto de Física, Universidade Federal Fluminense, Avenida Litorânea, s/n, 24210-340, Niterói, RJ, Brazil.
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49
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Bena I, Van den Broeck C, Kawai R, Copelli M, Lindenberg K. Collective behavior of parametric oscillators. Phys Rev E Stat Nonlin Soft Matter Phys 2002; 65:036611. [PMID: 11909289 DOI: 10.1103/physreve.65.036611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2000] [Revised: 10/05/2001] [Indexed: 05/23/2023]
Abstract
We revisit the mean-field model of globally and harmonically coupled parametric oscillators subject to periodic block pulses with initially random phases. The phase diagram of regions of collective parametric instability is presented, as is a detailed characterization of the motions underlying these instabilities. This presentation includes regimes not identified in earlier work [I. Bena and C. Van den Broeck, Europhys. Lett. 48, 498 (1999)]. In addition to the familiar parametric instability of individual oscillators, two kinds of collective instabilities are identified. In one the mean amplitude diverges monotonically while in the other the divergence is oscillatory. The frequencies of collective oscillatory instabilities in general bear no simple relation to the eigenfrequencies of the individual oscillators nor to the frequency of the external modulation. Numerical simulations show that systems with only nearest-neighbor coupling have collective instabilities similar to those of the mean-field model. Many of the mean-field results are already apparent in a simple dimer [M. Copelli and K. Lindenberg, Phys. Rev. E 63, 036605 (2001)].
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Affiliation(s)
- I Bena
- Limburgs Universitair Centrum, B-3590 Diepenbeek, Belgium
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50
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Copelli M, Lindenberg K. Phase-induced stability in a parametric dimer. Phys Rev E Stat Nonlin Soft Matter Phys 2001; 63:036605. [PMID: 11308786 DOI: 10.1103/physreve.63.036605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2000] [Revised: 10/20/2000] [Indexed: 05/23/2023]
Abstract
We report results on a model of two coupled oscillators that undergo periodic parametric modulations with a phase difference straight theta. Being to a large extent analytically solvable, the model reveals a rich straight theta dependence of the regions of parametric resonance. In particular, the intuitive notion that antiphase modulations are less prone to parametric resonance is confirmed for sufficiently large coupling and damping. Some general results concerning synchronization properties in this system are presented. We also compare our results to a recently reported mean-field model of collective parametric instability, showing that the two-oscillator model captures much of the qualitative behavior of the infinite system.
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Affiliation(s)
- M Copelli
- Department of Chemistry and Biochemistry 0340, University of California San Diego, La Jolla, California 92093-0340, USA
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