PhD Scientific Days 2024

Poster Session I - Neurosciences 2.

Lag-structure in fMRI across three psychiatric groups: resting-state, state-dependency and clinical-behavioral correlates

Text of the abstract

Introduction:
fMRI measures beyond zero-lag functional connectivity could serve as useful tools for understanding the distinct spatio-temporal dynamics characterizing psychiatric conditions.

Aims:
The primary objective was to compare lag-structure at resting-state between 95 healthy controls and three psychiatric conditions (35 ADHD, 38 bipolar disorder and 23 schizophrenia patients, DSM-IV-TR diagnosis). The secondary aims were to investigate whether and how state-dependence influences lag-structure in healthy controls and clinical-behavioral correlates of lag-structure in psychiatric groups.

Methods:
Lag-structure was computed from cross-correlation coefficients in resting-state and stop-signal task scans. Between and within-group differences were compared through non-parametric tests. Correlations with clinical-behavioral parameters were evaluated using linear regressions (Brief Psychiatric Rating Scale - BPRS, task reaction time).

Results:
Compared to healthy controls, lag-structure within default-mode, executive-control and salience networks was generally increased in ADHD (min Z-score -3.983), generally decreased in Schizophrenia (min Z-score -3.716) and with mixed increases/decreases in Bipolar patients (min Z-score -3.912, max 4.739). Widespread state-dependent reductions of lag-structure across the whole brain were observed across all groups from rest to task (max Q-statistics: healthy controls 58; ADHD 22; Bipolar 26; Schizophrenia 17). Correlations with clinical-behavioral variables (BPRS, reaction time) were positive in executive-control network and negative in bilateral thalamus for ADHD, negative in the cerebellum for Schizophrenia and positive in right temporal gyri, amygdala, hippocampus, and cerebellum for Bipolar (p=0.05).

Conclusion:
Differences in lag-structure in comparison to healthy controls progressively increased in magnitude from ADHD to Bipolar Disorder and Schizophrenia. Clinical groups exhibited different lag-structure state-dependence in executive-control, salience, and default-mode regions.

Funding:
no funding was received