THE ROLE OF THALAMIC CONNECTIVITY IN WORKING MEMORY IMPAIRMENT IN SCHIZOPHRENIA: MERGING EVIDENCE FROM FMRI AND EEG

Visual working memory impairments have been consistently found in people with schizophrenia, however, there is no consensus on the neural mechanisms behind these deficits. The current study aims to build a more cohesive conceptualization of the neural correlates of visual working memory impairment in people with schizophrenia (PSZ) by taking advantage of the strengths from different types of recording methodologies. To do this, non-simultaneous EEG and fMRI recordings of neural signatures were performed in a sample of 5 PSZ and 8 healthy controls (HCS) while performing an identical visual working memory visual change-detection task with varying memory load conditions. PSZ and trials with smaller memory loads showed less intense event related desynchronization of the alpha frequency band in the EEG measures and less BOLD activation in the posterior parietal cortex (PPC) and middle occipital gyrus (MOG) during fMRI. However, these differences were not significant. The load dependent modulation of event related desynchronization of the alpha frequency band was negatively related to load dependent BOLD activation for both the PSZ and HCS groups. In other words, neural signal intensity magnitude was related between recording methodologies. Additionally, the mediating role of thalamic connectivity for the EEG and fMRI signal modulation by load was examined. PSZ were found to have higher task connectivity between the posterior thalamus and PPC and MOG while HCS were found to have higher resting-state connectivity. No mediating role was found for thalamic connectivity on modulation of event related desynchronization of the alpha frequency band and BOLD activation in the PPC or MOG

Neural basis of the visual working memory deficit in schizophrenia: Merging evidence from fMRI and EEG

Although people with schizophrenia (PSZ) exhibit robust and reliable deficits in working memory (WM) capacity, the neural processes that give rise to this impairment remain poorly understood. One reason for this lack of clarity is that most studies employ a single neural recording modality-each with strengths and weaknesses-with few examples of integrating results across modalities. To address this gap, we conducted a secondary analysis that combined data from an overlapping set of subjects in previously published electroencephalographic and functional magnetic resonance imaging studies that used nearly identical working memory tasks (visual change detection). The prior studies found similar patterns of results for both posterior parietal BOLD activation and suppression of the alpha frequency band within the EEG. Specifically, both signals exhibited abnormally shallow modulation as a function of the amount of information being stored in WM in PSZ. In the present study, both alpha suppression and posterior parietal BOLD activity increased as the number of items stored in WM increased. The magnitude of alpha suppression modulation was correlated with the magnitude of BOLD signal modulation in PSZ, but not in HCS. This finding suggests that the same illness-related biological processes constrain both alpha suppression and BOLD signal modulation as a function of WM storage in PSZ. The complementary strengths of these two techniques may thus combine to advance the identification of the processes underlying WM deficits in PSZ

Is Cortical Theta-Gamma Phase-Amplitude Coupling Memory-Specific?

One of the proposed neural mechanisms involved in working memory is coupling between the theta phase and gamma amplitude. For example, evidence from intracranial recordings shows that coupling between hippocampal theta and cortical gamma oscillations increases selectively during working memory tasks. Theta-gamma phase-amplitude coupling can also be measured non-invasively through scalp EEG; however, EEG can only assess coupling within cortical areas, and it is not yet clear if this cortical-only coupling is truly memory-specific, or a more general phenomenon. We tested this directly by measuring cortical coupling during three different conditions: a working memory task, an attention task, and a passive perception condition. We find similar levels of theta-gamma coupling in all three conditions, suggesting that cortical theta-gamma phase-amplitude coupling is not a memory-specific signal, but instead reflects some other attentional or perceptual processes. Implications for understanding the brain dynamics of visual working memory are discussed

Imaging social and environmental factors as modulators of brain dysfunction: time to focus on developing, non-Western societies

Social and environmental factors are known risk factors and modulators of mental health disorders. We here conducted a nonsystematic review of the neuroimaging literature studying the effects of poverty, urbanicity, and community violence, highlighting the opportunities of studying non-Western developing societies such as those in Latin America. Social and environmental factors in these communities are widespread and have a large magnitude, as well as an unequal distribution, providing a good opportunity for their characterization. Studying the effect of poverty in these settings could help to explore the brain effect of economic improvements, disentangle the effect of absolute and relative poverty, and characterize the modulating impact of poverty on the underlying biology of mental health disorders. Exploring urbanicity effects in highly unequal cities could help identify the specific factors that modulate this effect as well as examine a possible dose–response effect by studying megacities. Studying brain changes in those living among violence, which is particularly high in places such as Latin America, could help to characterize the interplay between brain predisposition and exposure to violence. Furthermore, exploring the brain in an adverse environment should shed light on the mechanisms underlying resilience. We finally provide examples of two methodological approaches that could contribute to this field, namely a big cohort study in the developing world and a consortium-based meta-analytic approach, and argue about the potential translational value of this research on the development of effective social policies and successful personalized medicine in disadvantaged societies.Fil: Crossley, Nicolas A.. Pontificia Universidad Católica de Chile; ChileFil: Alliende, Luz Maria. Pontificia Universidad Católica de Chile; ChileFil: Ossandon, Tomas. Pontificia Universidad Católica de Chile; ChileFil: Castañeda, Carmen Paz. Instituto Psiquiátrico Dr. José Horwitz Barak; ChileFil: González Valderrama, Alfonso. Instituto Psiquiátrico Dr. José Horwitz Barak; Chile. Universidad Finis Terrae.; ChileFil: Undurraga, Juan. Universidad del Desarrollo; Chile. Instituto Psiquiátrico Dr. José Horwitz Barak; ChileFil: Castro, Mariana Nair. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; Argentina. Universidad de Buenos Aires. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Guinjoan, Salvador Martín. Universidad de Buenos Aires. Facultad de Medicina; Argentina. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Díaz Zuluaga, Ana M.. Universidad de Antioquia; ColombiaFil: Pineda-Zapata, Julián A.. Instituto de Alta Tecnología Médica; ColombiaFil: López-Jaramillo, Carlos. Hospital Universitario San Vicente Fundación; Colombia. Universidad de Antioquia; ColombiaFil: Reyes Madrigal, Francisco. Instituto Nacional de Neurología y Neurocirugía; MéxicoFil: León-Ortíz, Pablo. Instituto Nacional de Neurología y Neurocirugía; MéxicoFil: de la Fuente-Sandoval, Camilo. Instituto Nacional de Neurología y Neurocirugía; MéxicoFil: Czepielewski, Leticia Sanguinetti. Hospital de Clinicas de Porto Alegre; BrasilFil: Gama, Clarissa S.. Hospital de Clinicas de Porto Alegre; BrasilFil: Zugman, Andre. Universidade Federal de Sao Paulo; BrasilFil: Gadelha, Ary. Universidade Federal de Sao Paulo; BrasilFil: Jackowski, Andrea. Universidade Federal de Sao Paulo; BrasilFil: Bressan, Rodrigo. Universidade Federal de Sao Paulo; Brasi

Effects of socioeconomic status in cognition of people with schizophrenia:Results from a Latin American collaboration network with 1175 subjects

Background Cognition heavily relies on social determinants and genetic background. Latin America comprises approximately 8% of the global population and faces unique challenges, many derived from specific demographic and socioeconomic variables, such as violence and inequality. While such factors have been described to influence mental health outcomes, no large-scale studies with Latin American population have been carried out. Therefore, we aim to describe the cognitive performance of a representative sample of Latin American individuals with schizophrenia and its relationship to clinical factors. Additionally, we aim to investigate how socioeconomic status (SES) relates to cognitive performance in patients and controls. Methods We included 1175 participants from five Latin American countries (Argentina, Brazil, Chile, Colombia, and Mexico): 864 individuals with schizophrenia and 311 unaffected subjects. All participants were part of projects that included cognitive evaluation with MATRICS Consensus Cognitive Battery and clinical assessments. Results Patients showed worse cognitive performance than controls across all domains. Age and diagnosis were independent predictors, indicating similar trajectories of cognitive aging for both patients and controls. The SES factors of education, parental education, and income were more related to cognition in patients than in controls. Cognition was also influenced by symptomatology. Conclusions Patients did not show evidence of accelerated cognitive aging; however, they were most impacted by a lower SES suggestive of deprived environment than controls. These findings highlight the vulnerability of cognitive capacity in individuals with psychosis in face of demographic and socioeconomic factors in low-and middle-income countries.Fil: Sanguinetti Czepielewski, Letícia. Hospital de Clinicas de Porto Alegre; Brasil. Universidade Federal do Rio Grande do Sul; BrasilFil: Alliende, Luz Maria. Pontificia Universidad Católica de Chile; Chile. Instituto Psiquiátrico Dr. Horwitz Barak; ChileFil: Castañeda, Carmen Paz. Instituto Psiquiátrico Dr. Horwitz Barak; ChileFil: Castro, Mariana Nair. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia. Instituto de Neurociencias - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Neurociencias; Argentina. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Ciencias Fisiológicas; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Salud Mental; ArgentinaFil: Guinjoan, Salvador Martín. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia. Instituto de Neurociencias - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Neurociencias; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Salud Mental; ArgentinaFil: Massuda, Raffael. Universidade Federal do Paraná; BrasilFil: Berberian, Arthur A.. Universidade Federal de Sao Paulo; BrasilFil: Fonseca, Ana Olivia. Universidade Federal de Sao Paulo; BrasilFil: Gadelha, Ary. Universidade Federal de Sao Paulo; BrasilFil: Bressan, Rodrigo. Universidade Federal de Sao Paulo; BrasilFil: Crivelaro, Marisa. Universidade de Sao Paulo; BrasilFil: Louzã, Mario. Universidade de Sao Paulo; BrasilFil: Undurraga, Juan. Universidad del Desarrollo; Chile. Instituto Psiquiátrico Dr. Horwitz Barak; ChileFil: González Valderrama, Alfonso. Instituto Psiquiátrico Dr. Horwitz Barak; Chile. Universidad Finis Terrae; ChileFil: Nachar, Rubén. Instituto Psiquiátrico Dr. Horwitz Barak; Chile. Universidad Finis Terrae; ChileFil: Nieto, Rodrigo. Universidad de Chile; ChileFil: Montes, Cristian. Universidad de Chile; ChileFil: Silva, Hernan. Universidad de Chile; ChileFil: Langer, Álvaro I.. Millennium Nucleus To Improve The Mental Health Of Adolescents And Youths; Chile. Millennium Institute For Research In Depression And Personality; Chile. Universidad Austral de Chile; ChileFil: Schmidt, Carlos. Universidad de Barcelona; España. Millennium Institute For Research In Depression And Personality; ChileFil: Mayol Troncoso, Rocío. Universidad de Chile. Facultad de Medicina; Chile. Millennium Nucleus To Improve The Mental Health Of Adolescents And Youths; ChileFil: Díaz Zuluaga, Ana M.. Universidad de Antioquia; ColombiaFil: Valencia Echeverry, Johanna. Universidad de Antioquia; ColombiaFil: López Jaramillo, Carlos. Universidad de Antioquia; ColombiaFil: Solís Vivanco, Rodolfo. Instituto Nacional de Neurología y Neurocirugía; MéxicoFil: Reyes Madrigal, Francisco. Instituto Nacional de Neurología y Neurocirugía; MéxicoFil: De La Fuente Sandoval, Camilo. Instituto Nacional de Neurología y Neurocirugía; MéxicoFil: Crossley, Nicolás A.. Universidad Católica de Chile; Chile. Pontificia Universidad Católica de Chile; Chile. King's College London; Reino UnidoFil: Gama, Clarissa S.. Universidade Federal do Rio Grande do Sul; Brasil. Hospital de Clinicas de Porto Alegre; Brasi