# EEG Data Documentation

This document describes the EEG/brain activity data contained in the `Data_Gabor_EEG` and `Data_MNIST_EEG` directories, collected from SSVEP-based brain-computer interface experiments.

## Data_Gabor_EEG

Brain activity recordings during Gabor-inspired visual stimulus experiments. Subjects (Sub1-Sub8 and Sub_a_SD, Sub_b_SD, Sub_c_SD) performed iterative selection-based mind-drawing tasks.

### Data Variables (per .mat file)

- `SSVEP_all` (Array): 4s × 25 trials raw brain activity signals from single-channel EEG electrodes; sample rate: 1000 Hz
- `Index_points_all` (Array): Position coordinates of 10 disc probes on screen (N×N matrix) across iterations `[P=zeros(N),P(Index_points_all(:,1))=1;]`; Shape: 10 × 25

- `Freq_list` (Vector): Stimulus frequencies (10-19 Hz)
- `N` (Integer): Screen/image resolution (144×144 pixels)
- `Img_ref` (Image): Reference hand-drawn target image

### File Format

- `Sub<number>_<timestamp>.mat` (e.g., `Sub1_20250619_143379.mat`)

**Note**: CCA analysis uses different harmonic orders:
- **Subject 5**: 2nd harmonic only (to test the robustness of reduced harmonic content)
- **Other subjects**: Up to 3rd harmonic

---

## Data_MNIST_EEG

Brain activity recordings during MNIST-based digit reconstruction tasks using data-driven policy. Subject: Sub1.

### Data Variables (per .mat file)

- `SSVEP_all` (Array): Brain activity signals from single-channel EEG electrodes; sample rate: 1000 Hz
- `Index_points_all` (Array): 10 probe positions across iterations; Shape: 10 × n
- `Freq_list` (Vector): Stimulus frequencies (10-19 Hz)
- `Pattern_` (Matrix): Selected basis patterns/atoms for reconstruction
- `B_` (Vector): CCA weights for each selected pattern
- `N` (Integer): Screen/image resolution (144×144 pixels)
- `Img_ref` (Image): Reference target image

### File Format

- `Sub<number>_<timestamp>EEG.mat` (e.g., `Sub1_20250619_143379EEG.mat`)