Invasive vs. Non-Invasive BCI: Understanding the Differences

This page describes types of BCIs such as Invasive BCI, Partially invasive BCI and Non-invasive BCI. It highlights the key differences between Invasive BCI and Non-invasive BCI.

Introduction

Our brains work by transmitting signals to induce movement in different body parts through nerves and muscles. BCI (Brain Computer Interface) has been developed to provide efficient and accurate communication between the brain and an external device. This external device can be an artificial limb or any other device that can be interfaced with a computer.

Another related technology called “brain to brain communication” is also under development and being used. In this technique, brain signals from a sender are converted to electrical activities and transmitted to a receiver to simulate the brain.

What is BCI?

A brain computer interface facilitates bi-directional communication between the brain and an external device. It acquires, analyzes, and translates brain signals into electrical signals to perform specific actions as desired based on brain activity.

Different brain waves, such as Delta, Theta, Alpha, Beta, and Gamma, have unique frequencies and amplitudes. These waves indicate different states of mind. These brain waves or signals are acquired using sensors placed on the scalp or within it.

Image courtesy : www.researchgate.net

The figure above illustrates the workings of the BCI technique. BCI offers an output channel from the brain to control an external device.

Refer to the advantages and disadvantages of Brain Computer Interface.

Based on the technology and implantation of electrodes, there are different types of BCIs: Invasive BCI, non-invasive BCI, and partially invasive BCI.

Invasive BCI

In this technique, electrodes or sensors are implanted inside the skull after surgery to detect the electrical activities of brain cells. This provides a high-quality output as sensors are in direct contact with grey matter.

However, this technique is prone to scar tissue build-up in the brain, and the body might reject the electrodes or sensors due to certain medical conditions.

Invasive BCIs are very useful to provide functionalities for paralyzed patients. For example, patients with brain chip implants can control artificial arms, lights, TVs, or computer cursors.

Partially Invasive BCI

In this technique, medical devices are implanted inside the skull but outside the grey matter. It generates higher resolution signals compared to non-invasive BCI.

It has a low risk of scar tissue formation in the brain and eliminates the need for open brain surgery as devices can be inserted through the vascular system.

The benefits of partially invasive BCI techniques include low complexity, low clinical risk, and superior long-term stability.

Non-Invasive BCI

In this technique, sensors are installed on or very close to the head to measure brain signals. Surgery is not required, making it simple to implement on patients. EEGs and MEGs are commonly used in non-invasive BCIs.

The advantages of non-invasive BCI include lower costs, greater portability, and ease of measurement. However, this technique offers poor spatial resolution as the skull dampens brain signals. Due to the greater distance from the brain, it is also more susceptible to noise and offers worse signal resolution.

Difference between Invasive BCI and Non-Invasive BCI

The following points summarize the difference between Invasive BCI and Non-Invasive BCI:

• Electrode Placement: In invasive BCI, electrodes are implanted directly onto the patient’s brain. In non-invasive BCI, sensors or medical scanning devices are mounted on caps or headbands that read brain signals.

• Surgery Requirement: Invasive BCI requires surgery to implant sensors inside the brain, whereas non-invasive BCI does not.

• Risk Factors: Invasive BCI carries the risk of infection or brain damage, whereas Non-invasive BCI is a safer technique.

• Signal Effectiveness: Non-invasive BCI reads signals less effectively compared to the invasive technique, which provides more accurate results.

• Signal Coverage: Non-invasive BCI has the ability to read signals from multiple points of the brain via easy tapping without any surgery. This non-invasive method identifies a wide range of brain activity compared to the invasive technique. However, it is difficult to process and analyze the large amount of acquired neuron data.

• Noise Susceptibility: Non-invasive BCI is more susceptible to noise compared to invasive BCI, resulting in poorer signal resolution.