Citation
(Sridharan, Levitin, & Menon, 2008)
Link
https://www.pnas.org/doi/10.1073/pnas.0800005105
PDF
A critical role for the right fronto-insular cortex in switching between central-executive and default-mode networks.pdf
Type
Empirical Study
Methodolgy:
The study used three separate fMRI experiments:
- Experiment 1 - Auditory Event Segmentation (primary experiment):
- 18 right-handed participants (ages 19-27, 8 females) with minimal musical training
- Listened to Baroque music by William Boyce inside the scanner with focused attention
- Analyzed brain responses during "movement transitions" (salient boundaries between musical movements)
- Experiment 2 - Visual Oddball Task:
- 13 subjects (mean age 24 years, 8 females)
- 200 visual stimuli (colored circles: blue or green) presented for 150ms with 2000ms intervals
- Frequency of colored circles counterbalanced across subjects
- Experiment 3 - Resting State:
- 22 subjects (ages 19-21, 11 females)
- 8-minute resting state scan with eyes closed
Analysis Methods:
- General Linear Model (GLM) Analysis: Identified activation/deactivation patterns in three networks (CEN, DMN, SN)
- Independent Component Analysis (ICA): Model-free analysis to identify spatially independent networks
- Latency Analysis:
- Used Henson et al.'s method to estimate peak latency of BOLD responses
- Computed onset latencies using Sterzer and Kleinschmidt's method
- Determined which regions activated earliest
- Granger Causality Analysis (GCA):
- Applied bivariate model to examine causal interactions between six key regions
- Used bootstrap techniques to create null distributions
- Constructed causal connectivity graphs showing directionality of influence
- Network Analysis:
- Calculated graph metrics: out-degree, in-degree, path length
- Identified hub regions based on connectivity patterns
Region of Interest Selection: Six key nodes defined from ICA peaks: right FIC, ACC, right DLPFC, right PPC, VMPFC, and PCC
