# Effects of Multi-Sensory Stimulation on Brain Functional Connectivity in Patients with Disorders of Consciousness

## TL;DR

Combining visual and olfactory stimulation may improve brain connectivity in patients with disorders of consciousness, potentially aiding recovery.

## Contribution

This study introduces a novel approach using multi-sensory stimulation to enhance brain connectivity in DOC patients.

## Key findings

- Visual–olfactory stimulation enhances directed functional connectivity in DOC patients.
- Combined stimulation increases information transfer beyond directly stimulated brain regions.
- Olfactory stimulation reduces individual variability and improves global brain efficiency.

## Abstract

What are the main findings?
By combining high-density EEG with conditional Granger causality, this work suggests that visual–olfactory combined stimulation may enhance directed functional connectivity in patients with disorders of consciousness (DOC).Visual–olfactory stimulation not only activates connections in brain regions corresponding to single-modality stimulation, but may also enhance the exchange of information between brain regions that are not directly stimulated and other brain regions.

By combining high-density EEG with conditional Granger causality, this work suggests that visual–olfactory combined stimulation may enhance directed functional connectivity in patients with disorders of consciousness (DOC).

Visual–olfactory stimulation not only activates connections in brain regions corresponding to single-modality stimulation, but may also enhance the exchange of information between brain regions that are not directly stimulated and other brain regions.

What are the implications of the main findings?
These findings reveal how cross-modal collaboration upon stimulation temporarily opens dormant information pathways in patients with DOC, linking sensory neuroscience to clinical recovery.The portable, low-cost paradigm is suitable for ICU and rehabilitation settings, offering a bedside approach that can be used alongside or while awaiting invasive interventions.

These findings reveal how cross-modal collaboration upon stimulation temporarily opens dormant information pathways in patients with DOC, linking sensory neuroscience to clinical recovery.

The portable, low-cost paradigm is suitable for ICU and rehabilitation settings, offering a bedside approach that can be used alongside or while awaiting invasive interventions.

Background/Objectives: This study investigates the effects of multi-sensory stimulation on brain functional connectivity in patients with disorders of consciousness (DOC). DOC patients experience prolonged loss of consciousness due to brain injury, posing significant challenges for rehabilitation. Methods: In the study, visual, olfactory, and visual–olfactory (V-O) combined stimulation were applied to DOC patients while their EEG signals were recorded. A brain functional network was constructed based on the conditional Granger causality (CGC) method to analyze its topological characteristics. Results: The results revealed that the strength of brain functional connectivity in Minimally Conscious State (MCS) patients was significantly higher than that in Vegetative State (VS) patients, indicating a strong correlation between the intensity of synergistic activity in brain functional connectivity and the level of consciousness. Furthermore, V-O combined stimulation significantly enhanced brain functional connectivity compared to single-modality stimulation. The selection of different stimulation also differentially affected brain functional connectivity, with olfactory stimulation exhibiting high pleasure, arousal, and dominance (Self-Assessment Manikin) values demonstrating unique advantages in reducing individual variability and improving global efficiency. Conclusions: The study provides a theoretical foundation for the application of multi-sensory stimulation in the rehabilitation of DOC patients. V-O stimulation not only enhances information transmission in brain regions corresponding to visual and olfactory processing under single-modality stimulation but also increases the intensity of information transfer to other brain regions; this may serve as a reference for understanding the effects of multi-sensory stimulation on brain networks.