EEG experiments with visual stimuli (videos, images) often focus on effects in occipital regions. All the things that we see are processed here (although some processing does also occur before and after the signal arrives). The occipital cortex is the visual processing center of our brain, located in the rearmost portion of the skull. How can EEG data be interpreted?Īs EEG monitors the time course of electrical activity generated by the brain, you can interpret which areas of the cortex are responsible for processing information at a given time: Areas of the brain and what they do But that’s just the beginning – you also need to understand what the data is telling you. One hundred years ago the time course of an EEG was plotted on paper– nowadays the data is (thankfully) displayed digitally as a continuous flow of voltages on a screen. Price differences in EEG systems are typically due to the number of electrodes, the quality of the digitization, the quality of the amplifier, and the number of snapshots the device can take per second (this is the sampling rate in Hz).ĮEG is one of the fastest imaging techniques available as it often has a high sampling rate.
The amplified data can then be displayed as a sequence of voltage values.
provides excellent time resolution, allowing you to detect activity within cortical areas -even at sub-second timescalesĪs the voltage fluctuations measured at the electrodes are very small, the recorded data is digitized and sent to an amplifier. measures electrical activity generated by the synchronized activity of thousands of neurons (in volts). For faster application, electrodes are mounted in elastic caps similar to bathing caps, ensuring that the data can be collected from identical scalp positions across all respondents.ĭespite its somewhat daunting name (and pronunciation), grasping the essentials of electroencephalography is surprisingly simple: Electroencephalography (EEG) Definition: What is EEG and how does it work?Įlectroencephalography, or EEG, is the physiological method of choice to record the electrical activity generated by the brain via electrodes placed on the scalp surface. Taken by itself, each burst might be too small to notice, but if several of them occur at the same time, in the same location, and in the same rhythm, they all add up to a mega-quake that will be noticeable even hundreds of miles away. Think of this as a constant rumble of subtle earthquakes. Eventually, it can be measured on the head surface. However, whenever thousands of neurons fire in sync, they generate an electrical field which is strong enough to spread through tissue, bone, and skull. Of course, the burst of a single neuron is difficult to reliably detect without direct contact with it. These neurons are densely interconnected via synapses, which act as gateways of inhibitory or excitatory activity.Īny synaptic activity generates a subtle electrical impulse referred to as a postsynaptic potential. The brain consists of billions of cells, half of which are neurons, half of which help and facilitate the activity of neurons. EEG Measures Electrical Activity of the BrainĮEG measures electrical activity of the brain. In this article you will get a basic overview of EEG and how it works: It creates its own stories based on your thoughts, emotions, desires and experiences, ultimately driving your behavior. Your brain shapes how you see your environment, filters or highlights objects and information most relevant to you. For you, that experience constitutes your reality. Recall the last time you woke up in the middle of a weird dream or needed to find your way in a city you have never been before.Īs you think, dream, see, and sense, your brain is constantly active, absorbing all information, compacting and re-connecting existing data, and integrating everything into a consistent experience. Think of the last time you tried to solve a crossword puzzle or started to learn a new language.
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