Introduction

Introduction

EEGer is a software suite designed to provide visual and audible feedback based on electroencephalograph (EEG) brainwave signals. An EEGer System [See

Figure A: System Overview Diagram], is comprised of a Therapist and Client station, each with its own computer, monitor, keyboard and mouse. The Therapist Station has a battery-powered Amplifier/Encoder Unit connected by a fiber optic cable with a serial (RS232 compatible) converter to the Therapist computer. In order to run the EEGer software, a software security device must be plugged into the Therapist computer. The Client Station has a set of amplified (stereo) audio speakers connected to the Client computer with its power supply. A serial (RS232) cable connects the Therapist to the Client computer. An optional laser printer is often added, usually with an automatic switch that allows both computers to share a printer. The client is connected to the Amplifier/Encoder Unit through an EEG Preamplifier. The EEG Preamplifier is connected with a cable to the Amplifier/Encoder Unit using either channel A or B. The EEG Preamplifier is connected to the client through extender lead cables with attached single electrodes: signal, ground, reference. The signal electrode is pasted to the client's scalp with conductive paste and the reference and ground electrodes are clipped to the client's earlobes.

Figure A: System Overview Diagram

A continuous train of varying voltages comes from the client's brain, which the EEG Preamplifier senses through the

signal electrode pasted to the client's scalp. The EEG Preamplifier, specially designed for sensing EEG signals, amplifies the EEG signals to boost the signal to noise ratio, and sends the signals to the Amplifier/Encoder Unit. The Amplifier/Encoder Unit magnifies the EEG signal (10,000 gain), converts the signal from Analog to Digital format, and sends it to the Therapist computer. The EEG signal samples are taken 256 times per second and digitized. The EEGer software processes the converted digital signal samples and stores, filters, separates them into several frequency bands and displays raw and filtered signals on the Therapist computer at 256 samples per second. The data about the amplitude of the brainwave in each of the frequency bands and its relationship to the amplitude targets (goals) is transmitted by the Therapist computer to the Client computer, where it is shown (in the form of a game) to the client.

The Therapist Station monitors the brainwave activity and sets goals that require the client to voluntarily produce more beneficial brainwave patterns, while the Client Station is displaying responsive feedback (in game form) to the client. As the client exercises the ability to voluntarily change brain activity, the signals are carried to the Therapist Station, where reward requirements can be adjusted and displayed back to the client screen. This process is called "feedback" because it informs the client about his or her momentary success in making the desired brain changes.