Banca de DEFESA: ALEX SANDRO DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ALEX SANDRO DA SILVA
DATE: 01/12/2025
TIME: 08:50
LOCAL: https://meet.google.com/che-cdte-zhj
TITLE:

DISTINCT AND SHARED FUNCTIONAL CONNECTIVITY ALTERATIONS IN SCHIZOPHRENIA AND AYAHUASCA-INDUCED STATES: A DIRECT FMRI COMPARISON

KEY WORDS:

schizophrenia; psychedelics; ayahuasca; functional connectivity; thalamo-cortical; DMN;

 

 

 

PAGES: 80
BIG AREA: Ciências Biológicas
AREA: Fisiologia
SUMMARY:

Due to the phenomenological similarity between psychotic symptoms and the effects produced by classic psychedelics, the first clinical models proposed for schizophrenia were based on the effects of these substances. Although this relationship has been discussed in the literature for over a century, a consensus has only emerged in the last two decades that the effects caused by classic psychedelics and psychotic symptoms do not exhibit strong functional or structural equivalence. However, a history of psychiatric illness or previous psychotic symptomatology still constitutes a key exclusion criterion in clinical trials involving psychedelics. Given that most comparisons between the effects of psychedelics and the symptoms of schizophrenia have been performed indirectly in the literature, the central objective of this work was to directly compare the neural dynamics observed in schizophrenia and in states induced by ayahuasca, a preparation rich in N,N-dimethyltryptamine (DMT). To this end, we investigated patterns of resting-state functional brain connectivity (rs-fMRI) in four groups: healthy volunteers (n = 19), patients with schizophrenia (n = 18), and healthy volunteers under the acute (n = 9) and subacute (n = 21) effects of ayahuasca. The results revealed that both schizophrenia and the acute ayahuasca state are characterized by alterations in thalamo-cortical communication and connectivity within the Default Mode Network (DMN). Compared to healthy volunteers, patients with schizophrenia exhibited thalamo-cortical hyperconnectivity (involving temporal, sensorimotor, and occipital regions) and hypoconnectivity within the DMN, as well as between the occipital, somatosensory, and temporal cortices. Similarly, subjects in the acute ayahuasca state displayed thalamo-cortical hyperconnectivity (encompassing auditory and somatosensory areas), hypoconnectivity in the DMN, and increased interhemispheric limbic connectivity. Congruence analysis confirmed several similarities, including thalamo-temporal/somatosensory hyperconnectivity and hypoconnectivity in the DMN. Crucial differences were, however, observed: the thalamo-cortical hyperconnectivity under the acute effect of ayahuasca was more restricted to the superior temporal cortex, while in schizophrenia it appeared more diffuse, associated with regions exhibiting reduced functional integration. Furthermore, schizophrenia showed decreased fronto-temporal connectivity, in contrast to the enhanced integration observed during the acute ayahuasca state. Our work underscores the necessity of expanding theoretical models, such as the cortico-striato-thalamo-cortical (CSTC) circuit applied to schizophrenia, to incorporate structural and physiological alterations, as well as the chronic nature of this condition. 

 

COMMITTEE MEMBERS:
Externa à Instituição - LIA LIRA OLIVIER SANDERS - UFC
Presidente - 1243905 - DRAULIO BARROS DE ARAUJO
Interno - 1660044 - SIDARTA TOLLENDAL GOMES RIBEIRO