A neural implementation of cognitive reserve: insights from a longitudinal fMRI study of set-switching in aging

The dataset (Data.mat) comprises variables extracted from demographic information, cognitive task performance, and MRI/fMRI imaging of a longitudinal study of 52 adults aged 60–71, evaluated at baseline and after a 5-year follow-up. The analysis code is structured into two main codes: (A) Main Analysis in MATLAB (Code1_MainAnalysis_Matlab.m), which utilizes the primary dataset (Data.mat) to examine brain variables, model cognitive trajectories, and prepare data for further interaction analysis. (B) Interaction Visualization in R (Code2_Johnson-Neyman_R.R), which produces interaction effect visualizations using the output from MATLAB analysis., This dataset does not contain any direct fMRI data. The fMRI data in our study were analyzed using a specific technique called Ordinal Trend Canonical Variates Analysis (OrT CVA). Through this approach, we derived a measure known as the OrT score, which was calculated for both single and dual-task conditions. This OrT score is the only fMRI-related variable included in the dataset that we uploaded.
To provide further details, OrT CVA is a multivariate data-driven technique that identifies patterns of regional functional activation that show a monotonic change across multiple experimental conditions (in the current study single and dual conditions). The extracted functional activation patterns, called ordinal trends (OrT), indicate sustained activity across graduated increase in task demand (Habeck, Krakauer, et al., 2005; Habeck, Rakitin, et al., 2005). The technique utilizes a specialized design matrix to enhance variance contributions from patterns that exhibit within-subject increase..., , # A neural implementation of cognitive reserve: insights from a longitudinal fMRI study of set-switching in aging

This document provides documentation for the dataset and code used in the paper by Fatemeh Hasanzadeh, Christian Habeck, Yunglin Gazes, and Yaakov Stern.

## **Dataset: Data.mat**

The following section describes the variables contained in the Data.mat file, which includes longitudinal measurements from 52 older adults at baseline and 5-year follow-up. The dataset contains demographic, behavioral, and neuroimaging data collected as part of the study.

**Demographic and Study Variables**

| **Variable** | **Description** |
| :----------------- | :--------------------------------------------------- |
| subid | Unique participant identifier |
| TimePoint | Study timepoint (1 = baseline, 2 = 5-year follow-up) |
| scannerID | MRI scanner identifier (1= Philips/ 3= PRISMA) |
| ...