A Techy’s Introduction to Neuroscience

Some Facts I Wish I Knew When I Started Hacking EEG

I know I’ve said this before, but it’s worth saying again: we live in amazing times. We can now conduct neuroscience experiments in the comfort of our own homes, using equipment that was until recently very expensive and available only in research labs/universities. Now that the equipment has become more readily affordable, more people are exploring what they can do with the technology, and lucky for us, there is a worldwide community of researchers that is accessible online.

Over the course of the past few months, I’ve found myself entering the amazing world of neuroscience and have learned a lot — though in this process I sometimes got confused by all the technical and domain-specific terms when I tried to read articles or check out examples.

In this post, I will try to summarize all my learnings from the past year. While I’ll present these things from my perspective as a web developer, I am pretty sure this introduction will be helpful to anyone who is interested in getting into the subject.

I want to extend special thanks to Alexandre Barachant and Hubert Banville from the NeuroTechX community. They spent numerous hours helping me to find my way as a beginner in the neuroscience world, and much of the information presented here was first presented to me by them.

BCI? EEG?

Coming to neuroscience from a computer background, two of the first terms I encountered were “BCI” and “EEG.” BCI stands for Brain Computer Interface (or BMI for Brain Machine Interface). A BCI is essentially any method that directly transfers information between a brain and some external device, usually a scientific instrument or, for our purposes, a computer.

A BCI method is made up of three parts:

A brain sensing device (EEG, fNIRS, ECoG, fMRI, etc.)

A decoding algorithm, which translates the brain activity measured withthe sensor to a command

And a machine (or a computer) that executes the command

EEG is perhaps the most common brain sensing modality within BCI. EEG stands for Electroencephalography. To be honest, I never remember this word — what is important to remember, is the EEG records the electrical activity around you scalp, using electrodes, in order to measure brain activity. This is a very coarse, inaccurate way to measure the brain activity — as the electromagnetic waves are attenuated by the skull. However, there are still very interesting things we can do with EEG, and the fact that it’s non-invasive — unlike MRI, doesn’t require a specific environment in which to take readings — means it’s an excellent candidate for tinkering with at home.

There are several other bio-sensing techniques that use a similar method to measure your body — ECG for measuring heart activity (see below), EMG for measuring muscle activity and EOG for measuring eye movements (we’ll talk about that later). All the above work by measuring electrical voltage difference between two or more points in your body.

In addition to EEG, there are a number of other BCIs, such as fMRI, but since you’re not able to do fMRI and many of the other BCIs at home (yet!), we will focus on EEG.

First of All: Some Things to Know About EEG

When I first learned about EEG, I discovered that I had a few ideas about EEG that didn’t match up with reality… so, before we dive into the specifics, I’d like to take a minute get a few things straight.

You can’t really “read the brain” in the EEG graph. When I initially started with EEG, I expected I could learn how to “read minds” through the EEG graphs and develop some kind of ability to tell what each spike means in its context. Later, I discovered that the things you can see in the graph are primarily noise and things which are not “EEG” per-se, such as eye blinks, jaw clenches.

With EEG, you will only be able to see very strong brain activity, such as an epileptic seizure (which I really hope you never need to see). The general rule of thumb is, “If you can see it with your eyes unaided, it’s probably not EEG.”

For anything more than that, you would need to process that data, and in some cases, run several iterations of the experiment until you can actually get the signal you’re looking for. So remember: a good EEG graph is a clean one.

You can’t read thoughts. You can’t get very specific information using EEG, such as what the patient is seeing or hearing. The only information you get in the sum of the activity of many neurons in your brain — you’ll only ever be able to identify something if it’s really drastic and involves a lot of neurons firing in sync.

A common analogy is standing outside a big sports stadium — you will not be able to hear specific conversations between the people inside the stadium, but you will be able to discern an empty stadium v.s. a very full stadium, and you’ll also be able to detect when a goal is scored — as you will hear sudden loud applause and cheering coming from the audience in sync.

EEG doesn’t work for everyone. Some people have what they call “BCI illiteracy,” i.e.. we can’t pick up any signal for specific brain patterns on some subjects. This is, in fact, pretty common — about 20% of the population have some sort of BCI illiteracy, and there is research going on how to work around that.

EEG is READ-ONLY. I often get asked if an EEG headset can be used to inject thoughts or modify people’s behavior by affecting their brains. The short answer is no: you can’t control people’s minds with EEG.