· Brain
Computer Interfaces (BCI) = communication systems in which users send commands
to computers via brain activity
o Used
in virtual reality (vr)
o Involves
neurophysiology, signal processing and interaction, computer graphics &
programming
o We
need a general software platform that provides the necessary functionalities to
easily design BCI and connect them with VR
· OpenVibe
is one such software platform
o Modularity
and reusability
o Different
type of users
o Portability
o Connection
with VR
· How
OpenVibe compares to other available BCI platforms
o Highly
modular & customizable
o No
need for writing code
o Entirely
based on free and open-source softwares
· Different
Types of Users
o The
developer
§ kernel
developers: enhance and modify existing kernel functionalities
§ plugin
developers: create new modules
o The
application developer: creates standalone applications using the OpenVibe
library
o The
author: “authors” the BCI system; utilizes the visual scenario editor to
configure boxes into a scenario to produce a complete BCI system
o The
operator: generally a clinician & is in charge of implementing the
pre-built scenarios created by the author
o The
BCI user: wears brain activity acquisition hardware and interacts with an
application via mental activity.
· Designing
a BCI using OpenVibe
o There
are 3 distinct steps
§ 1.
acquire training data for the subject, while he performs mental tasks
§ 2.
analyze the data to determine the best calibration parameters
§ 3.
Use the BCI in a closed loop process (6 phases)
·
brain activity measurements using an
electroencephalography (EEG)
·
preprocessing: denoising the acquired signals
·
feature extraction: values that describe
relevant information embedded in the signals. Features are then gathered into a
“feature vector”
·
classification: an algorithm known as
“classifier” assigns a class to each feature vector, which is an identifier of
the brain signal that has been recognized.
·
translation into command: after identifying the
class of the signal, it is associated with a command sent to a computer to
control an object.
·
feedback: provided in the form classical raw
signal, spectra, time/frequency visualization modules that allow the user to
determine whether he performed the brain signal correctly.
· There
are 5 complete scenarios available to date
o Hand
motor imagery based BCI
o Self-paced
BCI based on foot movements
o Neurofeedback
o Real-time
visualization of brain activity in 2D/3D
o P300-Speller
MindWave User Guide
· NeuroSky’s
MindWave turns brainwaves into actions
o headset
consists of: adjustable headband, power switch, battery area, flexible ear arm,
ear clip, & sensor tip/arm
o Light
color:
§ off
- powered off
§ red
- powered on but not connected
§ blue
- powered on and connected
§ red
or blue & blinking - low battery
· Brainwaves
o delta
§ frequency:
0.1Hz - 3Hz
§ mental
state: deep, dreamless sleep, non-Rem sleep, unconscious
o theta
§ frequency:
4Hz - 7Hz
§ mental
state: intuitive, creative, imaginary, dream
o alpha
§ frequency:
8Hz - 12Hz
§ mental
state: relaxed, tranquil, conscious
o low
beta
§ frequency:
12Hz - 15Hz
§ mental
state: relaxed yet focused, integrated
o midrange
beta
§ frequency:
16Hz - 20Hz
§ mental
state:Thinking, aware of self & surroundings
o high
beta
§ frequency:
21Hz - 30Hz
§ mental
state: alertness, agitation
