27-06-2012, 04:04 PM
The Thought Translation device
The Thought Translation device.pptx (Size: 4.48 MB / Downloads: 86)
What is an EEG?
An electroencephalogram is a measure of the brain's voltage fluctuations as detected from scalp electrodes.
It is an approximation of the cumulative electrical activity of neurons.
Electrodes Used
EEG electrodes are small metal plates that are attached to the scalp using a conducting electrode gel. They can be made from various materials. Most frequently, tin (Sn) and silver/silver-chloride (Ag/AgCl) electrodes are used but there are gold (Au) and platinum (Pt) electrodes as well.
An EEG amplifier measure voltage difference between points on the scalp. This implies that each channel is connected to two electrodes. Usually, measurement is "unipolar" rather than "bipolar", which means that the second electrode is identical for all channels, and called "reference" (Ref). Also, amplifier inputs must be kept within a small voltage range relative to the amplifier's zero (ground) voltage level.
Other Components
A single program (BCI-2000) which runs on all MS versions, performs the task of EEG-acquisition, storage,signal processing,classification and various BCI applications.
TTD software is connected to certain EEG-amplifier systems, with a time constant of 16s is then connected to an A/D converter(PCIM-DAS 1602/16).
An interface to an MRI-compatible 16/32 channel EEG amplifier allows TTD to be used in functional magnetic resonance imaging (fMRI).
Translation Algorithm
Changes independent variables (signal features) into dependent variables (device commands). This is done using linear or non-linear methods.
Effective algorithms adapt to user on 3 levels:
When a new user first accesses the BCI, the algorithm adapts to that users signal features.
Periodic online adjustments to reduce the impact of spontaneous
variations such as hormonal levels, temperature, fatigue, illness.
Dependence on the effective interaction between two adaptive controllers, the brain and the BCI.