Navegando por Autor "Sigman, Mariano"

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Automated analysis of free speech predicts psychosis onset in high-risk youths
(Nature, 2015-08-26) Bedi, Gillinder; Carrillo, Facundo; Cecchi, Guillermo A; Slezak, Diego Fernández; Sigman, Mariano; Mota, Natália B; Ribeiro, Sidarta Tollendal Gomes; Javitt, Daniel C; Copelli, Mauro; Corcoran, Cheryl M
Educating to Build Bridges
(2013-05-17) Goldin, Andrea Paula; Calero, Cecilia Inés; Peña, Marcela; Ribeiro, Sidarta Tollendal Gomes; Sigman, Mariano
In March 2012, 30 faculty and 49 students from all over the world met in El Calafate, Argentina, during two intense weeks. It was the second Latin American School for Education, Cognitive, and Neural Sciences (LASchool), sponsored by the James S. McDonnell Foundation. The LA School seeks to critically examine research findings potentially relevant to the development, design, and implementation of effective educational practices, and to foster a new generation of researchers able to operate at the interface between education and science. Here we introduce a special issue which brings together theory, experiments, and educational interventions which emerged from ideas presented and discussed during the 2012 LASchool.
Imagetic and affective measures of memory reverberation diverge at sleep onset in association with theta rhythm
(Elsevier BV, 2022-10) Mota, Natália Bezerra; Soares, Ernesto Saias; Altszyler, Edgar; Sánchez-Gendriz, Ignacio; Muto, Vincenzo; Heib, Dominik; Slezak, Diego F.; Sigman, Mariano; Copelli, Mauro; Schabus, Manuel; Ribeiro, Sidarta Tollendal Gomes
The 'day residue' - the presence of waking memories into dreams - is a century-old concept that remains controversial in neuroscience. Even at the psychological level, it remains unclear how waking imagery cedes into dreams. Are visual and affective residues enhanced, modified, or erased at sleep onset? Are they linked, or dissociated? What are the neural correlates of these transformations? To address these questions we combined quantitative semantics, sleep EEG markers, visual stimulation, and multiple awakenings to investigate visual and affect residues in hypnagogic imagery at sleep onset. Healthy adults were repeatedly stimulated with an affective image, allowed to sleep and awoken seconds to minutes later, during waking (WK), N1 or N2 sleep stages. 'Image Residue' was objectively defined as the formal semantic similarity between oral reports describing the last image visualized before closing the eyes ('ground'), and oral reports of subsequent visual imagery ('hypnagogic imagery). Similarly, 'Affect Residue' measured the proximity of affective valences between 'ground' and 'hypnagogic imagery'. We then compared these grounded measures of two distinct aspects of the 'day residue', calculated within participants, to randomly generated values calculated across participants. The results show that Image Residue persisted throughout the transition to sleep, increasing during N1 in proportion to the time spent in this stage. In contrast, the Affect Residue was gradually neutralized as sleep progressed, decreasing in proportion to the time spent in N1 and reaching a minimum during N2. EEG power in the theta band (4.5-6.5 Hz) was inversely correlated with the Image Residue during N1. The results show that the visual and affective aspects of the 'day residue' in hypnagogic imagery diverge at sleep onset, possibly decoupling visual contents from strong negative emotions, in association with increased theta rhythm
Neuroscience and education: prime time to build the bridge
(Nature Neuroscience, 2014-03-26) Sigman, Mariano; Peña, Marcela; Goldin, Andrea P; Ribeiro, Sidarta Tollendal Gomes
The history of writing reflects the effects of education on discourse structure: implications for literacy, orality, psychosis and the axial age
(Elsevier, 2020-10-01) Pinheiro, Sylvia; Mota, Natália Bezerra; Sigman, Mariano; Fernández-Slezak, Diego; Guerreiro, Antonio; Tófoli, Luís Fernando; Cecchi, Guillermo; Copelli, Mauro; Ribeiro, Sidarta Tollendal Gomes
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
The language of geometry: Fast comprehension of geometrical primitives and rules in human adults and preschoolers
(2017-01-26) Amalric, Marie; Wang, Liping; Pica, Pierre; Figueira, Santiago; Sigman, Mariano
During language processing, humans form complex embedded representations from sequential inputs. Here, we ask whether a “geometrical language” with recursive embedding also underlies the human ability to encode sequences of spatial locations. We introduce a novel paradigm in which subjects are exposed to a sequence of spatial locations on an octagon, and are asked to predict future locations. The sequences vary in complexity according to a well-defined language comprising elementary primitives and recursive rules. A detailed analysis of error patterns indicates that primitives of symmetry and rotation are spontaneously detected and used by adults, preschoolers, and adult members of an indigene group in the Amazon, the Munduruku, who have a restricted numerical and geometrical lexicon and limited access to schooling. Furthermore, subjects readily combine these geometrical primitives into hierarchically organized expressions. By evaluating a large set of such combinations, we obtained a first view of the language needed to account for the representation of visuospatial sequences in humans, and conclude that they encode visuospatial sequences by minimizing the complexity of the structured expressions that capture them.
The language of geometry: Fast comprehension of geometrical primitives and rules in human adults and preschoolers
(Plos computational Biology, 2017-01-26) Amalric, Marie; Wang, Liping; Pica, Pierre; Figueira, Santiago; Sigman, Mariano; Dehaene, Stanislas
During language processing, humans form complex embedded representations from sequential inputs. Here, we ask whether a “geometrical language” with recursive embedding also underlies the human ability to encode sequences of spatial locations. We introduce a novel paradigm in which subjects are exposed to a sequence of spatial locations on an octagon, and are asked to predict future locations. The sequences vary in complexity according to a well-defined language comprising elementary primitives and recursive rules. A detailed analysis of error patterns indicates that primitives of symmetry and rotation are spontaneously detected and used by adults, preschoolers, and adult members of an indigene group in the Amazon, the Munduruku, who have a restricted numerical and geometrical lexicon and limited access to schooling. Furthermore, subjects readily combine these geometrical primitives into hierarchically organized expressions. By evaluating a large set of such combinations, we obtained a first view of the language needed to account for the representation of visuospatial sequences in humans, and conclude that they encode visuospatial sequences by minimizing the complexity of the structured expressions that capture them.
The maturation of speech structure in psychosis is resistant to formal education
(2018-12-07) Mota, Natália Bezerra; Sigman, Mariano; Cecchi, Guillermo; Copelli, Mauro; Ribeiro, Sidarta Tollendal Gomes
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 longrange 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
The ontogeny of discourse structure mimics the development of literature
(2016) Mota, Natália B.; Pinheiro, Sylvia; Sigman, Mariano; Slezak, Diego Fernandez; Cecchi, Guillermo; Copelli, Mauro; Ribeiro, Sidarta Tollendal Gomes
Discourse varies with age, education, psychiatric state and historical epoch, but the ontogenetic and cultural dynamics of discourse structure remain to be quantitatively characterized. To this end we investigated word graphs obtained from verbal reports of 200 subjects ages 2-58, and 676 literary texts spanning ~5,000 years. In healthy subjects, lexical diversity, graph size, and long-range recurrence departed from initial near-random levels through a monotonic asymptotic increase across ages, while short-range recurrence showed a corresponding decrease. These changes were explained by education and suggest a hierarchical development of discourse structure: short-range recurrence and lexical diversity stabilize after elementary school, but graph size and long-range recurrence only stabilize after high school. This gradual maturation was blurred in psychotic subjects, who maintained in adulthood a near-random structure. In literature, monotonic asymptotic changes over time were remarkable: While lexical diversity, long-range recurrence and graph size increased away from near-randomness, short-range recurrence declined, from above to below random levels. Bronze Age texts are structurally similar to childish or psychotic discourses, but subsequent texts converge abruptly to the healthy adult pattern around the onset of the Axial Age (800-200 BC), a period of pivotal cultural change. Thus, individually as well as historically, discourse maturation increases the range of word recurrence away from randomness.

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Navegando por Autor "Sigman, Mariano"