High Temporal Resolution

• EEG can be captured a very high speeds, often ~512Hz or faster
• fMRI and NIRS measure blood flow and have ~1 second resolution limit
• Neuronal action potentials are ~1-2 milliseconds in duration

Moderate Spatial Resolution

• Up to 512 channel EEGs are available
• Analytical techniques improve resolution
• Sensor engineering improves resolution

DIY-able

• No huge equipment like MRI or MEG
• Less than $200 off-the-shelf options are growing every year (see below)

Single channel EEG might be somewhat akin to sticking a very sensitive non-directional microphone on a satelite orbiting the earth and using it to try to understand human behavior. There are indeed things about human behavior you could gather. Likely day/night cycles. Possibly changes in amount of construction work like as during recession or spurred by stimulus. Maybe even whether or not large events that coordinate large populations of people like the the World Cup or Olympics are taking place. But you might also imagine there is a LOT you can't really discern very easily. Personal conversations are very unlikely, especially if they're indoors. It's hard to tell without knowing something a priori about human behavior what jobs people do and how the hustle and bustle of daily life contributes to their endeavors. The situation gets a bit better, of course, when you can employ more and more satelites to triangulate and uncover regional localization of the sounds, but it is still a difficult problem where certain kinds of information can be more readily extracted, while others very hard to obtain.

Science Fiction Expectations

One of the biggest hurdles to using EEG (or any brain measurement) in an art or consumer context is the unreasonably high expectation of what is currently possible. People often ask, "what am I thinking?" expecting an answer like "red truck" with an honest level of dismay when you explain the magnitude of that problem. It's also a common dream to use your mind to control your mouse or keyboard, not realizing that your brain already controls your mouse and keyboard through your fingers and that it took years to develop those (already primed) neural connections beginning at birth and continuing beyond your middle school typing class. So when you make a new app or a new art installation using EEG, it often takes a high degree of imagination to create something that manages and channels these enormous expectations.

Signal Separation

A major difficulty of EEG is that the brain signal is small relative to EMG electrical signals created by muscle fibers. The scalp is surrounded in muscles and those muscle fibers create electrical signals that can be 3 orders of magnitude larger than the EEG signal we're interested in. Every time you blink, chew, yawn, talk, move your neck or make a facial expression, etc., artifacts are introduced into the EEG signal that can quickly swamp the signal.

Sensor Engineering

Picking up the microvolt EEG signals is not totally trivial. One of the biggest hurdles to date is the use of electrodes that need to contact the skin. Problem is that many people have a bunch of hair covering their brain and hair isn't very conductive. So the solution is often to use saline gel that is both messy and laborious to apply and pushes the technology well out of the mainstream. Good news, however, is that around the corner there are electrodes that are using capacitive sensing technology that is able to read EEG through hair (Chi et al. 2010). But, until non-contact EEG becomes mainstream, we're stuck with either gooping up our heads or only getting frontal recordings.

Neurons Communicate with Electrical Signals

Neurons communicate by sending electrical signals down their axons. An individual firing neuron creates a current that can typically only be seen at a short distance from the cell.

Synchrony

Synchrony is critical to coordinate the activity of the ~100 billion neurons in your brain.

• Communication

Neurons that fire in sync with one another are better able to transmit their signals to each other and downstream neurons.

• Plasticity (Learning)

"Neurons that fire together wire together"

• Oscillations

Oscillations create a method by which neurons can selectively synchronize with specific sub-groups of neurons, thereby creating selective communication and learning channels.

Functions are Localized in the Brain

Different parts of the brain specialize in certain functions. Wernicke's area specializes in the recognition of speech, which the primary motor cortex controls the body's appendages.