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How Brain-Controlled Devices Actually Work: Decoding EEG Signals

How Brain-Controlled Devices Actually Work: Decoding EEG Signals

2.) How the EEG Signals Correspond To Our Thoughts

The human brain comprises of three main regions: the forebrain, the midbrain, and the hindbrain. The forebrain consists of the cerebrum, the thalamus, and the hypothalamus. The cerebrum or cortex is the largest part of the human brain and is associated with the higher brain functions, such as thought and action. The cerebral cortex is further divided into four sections, called “lobes”.

Human Brain Anatomy

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The frontal lobe occupies the front portion of the brain and is responsible for brain functions such as motor skills, reasoning, and cognition. The motor cortex lies towards the back of the frontal lobe, close to the central sulcus. This part of the brain receives information from different lobes and utilizes the same to carry out movements of the body parts.

The parietal lobe occupies the mid portion of the brain and is responsible for interpreting tactile sensory information i.e. pain, touch, and pressure. Within this lobe resides the somatosensory cortex, which is the primary sensory receptor in the brain.

The temporal lobe occupies the lower portion of the brain. This lobe contains the primary auditory cortex that is responsible for decoding sounds and languages. Also, the hippocampus is located in this region, hence the temporal lobe is also responsible for the creation of memories.


The occipital lobe occupies the back portion of the brain and is responsible for processing any visual stimulus or information. The occipital lobe contains the primary visual cortex that receives information from the retinas of the eyes and processes the same.

Understanding which part of the brain is associated with which sensory function is crucial for designing a brain-controlled device. For example, the motor cortex produces signals related to muscle movement, so a device that moves an artificial limb should process the waves being generated by the motor cortex. Similarly, the occipital lobe interprets visual stimuli and therefore an EEG of this region can be helpful if the device has to perform some action based on the visual stimuli presented to the user. Recognising and interpreting the fluctuations in the brain waves generated by a specific portion of the brain can help us interpret the thoughts corresponding to the same.

Therefore, if you have a targeted problem statement at hand, then analysing the brain activity of the respective lobe or cortex can help you in designing an algorithm that performs specific actions as per the corresponding thoughts of the user. This is a two-fold problem, you will need to develop a machine learning software that can correctly decode the thoughts of the user based on the EEG input, however, first and foremost, you will need a mechanism to record the brain activity in the form of an EEG.

In the next section, we will discuss how the EEG signals can be recorded and processed, so as to generate an input for a brain-controlled device.


3.) How the EEG Signals Are Recorded and Processed