Brain-Computer Interfaces

What is a BCI

A Brain–Computer Interface (BCI) is a system that creates a direct communication pathway between the brain and an external device. Instead of relying on muscles or speech, BCIs translate patterns of brain activity into signals that can control software, hardware, or other outputs. This makes them especially valuable in fields like rehabilitation, assistive technology, and experimental research.

EEG: How We Measure Brain Activity

The most common way to record brain signals for BCI is through Electroencephalography (EEG). EEG uses small sensors placed on the scalp to detect the brain’s natural electrical rhythms. These rhythms change depending on what we’re doing, thinking, or imagining. For example:

Alpha waves – relaxed, calm states
Beta waves – active thinking and focus
Mu rhythms – linked to motor activity and the imagination of movement

By analyzing these patterns, a BCI can detect when someone is imagining moving their hand, focusing on a visual cue, or engaging in a specific mental task.

The Motor Cortex: Why It Matters

The motor cortex, located across the top of the brain, plays a central role in planning and executing movement. In many BCI systems, users are asked to imagine moving their left or right hand, or even their feet. These imagined movements create distinct EEG patterns in the motor cortex, which the system can learn to recognize.

The Cerebral Cortex

Figure: The cerebral cortex and its main functional areas. The motor cortex (highlighted near the central sulcus) is especially important for Brain–Computer Interfaces, since imagined movements here create EEG patterns that can be translated into computer commands. Sensory and association areas are shown for context.

The cerebral cortex is divided into three main types of regions:

Sensory areas – receive input from the body and environment
Motor areas – control voluntary muscle movement
Association areas – support higher functions such as learning, planning, and complex actions like writing

The central sulcus separates the primary sensory cortex from the primary motor cortex. Both regions are organized like a map of the body: different parts of the cortex correspond to different body areas. Notice how the lips, face, and fingers occupy a larger portion—these areas require finer control and have more sensory receptors..

Why BCIs Are Exciting

BCIs are not science fiction—they are already being used to:

Help people with paralysis control cursors, keyboards, or robotic arms
Enable hands-free interaction with computers and games
Explore new ways of understanding how the brain works

For this project, the focus is on making BCI approachable: showing how signals are recorded, how they appear on screen, and how they can be used in structured sessions.