Browsing by Author "Iruretagoyena, Barbara"

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    Dysconnectivity in Schizophrenia Revisited: Abnormal Temporal Organization of Dynamic Functional Connectivity in Patients With a First Episode of Psychosis
    (2023) Ramirez-Mahaluf, Juan P.; Tepper, Angeles; Maria Alliende, Luz; Mena, Carlos; Castaneda, Carmen Paz; Iruretagoyena, Barbara; Nachar, Ruben; Reyes-Madrigal, Francisco; Leon-Ortiz, Pablo; Mora-Duran, Ricardo; Ossandon, Tomas; Gonzalez-Valderrama, Alfonso; Undurraga, Juan; De la Fuente-Sandoval, Camilo; Crossley, Nicolas A.
    Background and Hypothesis Abnormal functional connectivity between brain regions is a consistent finding in schizophrenia, including functional magnetic resonance imaging (fMRI) studies. Recent studies have highlighted that connectivity changes in time in healthy subjects. We here examined the temporal changes in functional connectivity in patients with a first episode of psychosis (FEP). Specifically, we analyzed the temporal order in which whole-brain organization states were visited. Study Design Two case-control studies, including in each sample a subgroup scanned a second time after treatment. Chilean sample included 79 patients with a FEP and 83 healthy controls. Mexican sample included 21 antipsychotic-naive FEP patients and 15 healthy controls. Characteristics of the temporal trajectories between whole-brain functional connectivity meta-states were examined via resting-state functional MRI using elements of network science. We compared the cohorts of cases and controls and explored their differences as well as potential associations with symptoms, cognition, and antipsychotic medication doses. Study Results We found that the temporal sequence in which patients' brain dynamics visited the different states was more redundant and segregated. Patients were less flexible than controls in changing their network in time from different configurations, and explored the whole landscape of possible states in a less efficient way. These changes were related to the dose of antipsychotics the patients were receiving. We replicated the relationship with antipsychotic medication in the antipsychotic-naive FEP sample scanned before and after treatment. Conclusions We conclude that psychosis is related to a temporal disorganization of the brain's dynamic functional connectivity, and this is associated with antipsychotic medication use.
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    Functional Dysconnectivity in Ventral Striatocortical Systems in 22q11.2 Deletion Syndrome
    (OXFORD UNIV PRESS, 2021) Tepper, Angeles; Cuiza Vasquez Analia; Alliende, Luz María; Mena, Carlos; Ramirez Mahaluf, Juan Pablo; Iruretagoyena, Barbara; Ornstein, Claudia; Fritsch, Rosemarie; Nachar, Ruben; Gonzalez Valderrama, Alfonso; Undurraga, Juan; Pablo Cruz, Juan; Tejos, Cristian; Fornito, Alex; Repetto, Gabriela; Crossley, Nicolas
    22q11.2 deletion syndrome (22q11.2DS) is a genetic neurodevelopmental disorder that represents one of the greatest known risk factors for psychosis. Previous studies in psychotic subjects without the deletion have identified a dopaminergic dysfunction in striatal regions, and dysconnectivity of striatocortical systems, as an important mechanism in the emergence of psychosis. Here, we used resting-state functional MRI to examine striatocortical functional connectivity in 22q11.2DS patients. We used a 2 x 2 factorial design including 125 subjects (55 healthy controls, 28 22q11.2DS patients without a history of psychosis, 10 22q11.2DS patients with a history of psychosis, and 32 subjects with a history of psychosis without the deletion), allowing us to identify network effects related to the deletion and to the presence of psychosis. In line with previous results from psychotic patients without 22q11.2DS, we found that there was a dorsal to ventral gradient of hypo- to hyperstriatocortical connectivity related to psychosis across both patient groups. The 22q11.2DS was additionally associated with abnormal functional connectivity in ventral striatocortical networks, with no significant differences identified in the dorsal system. Abnormalities in the ventral striatocortical system observed in these individuals with high genetic risk to psychosis may thus reflect a marker of illness risk.