The Princeton University Cognitive Electrophysiology Laboratory studies neuronal firing patterns via EEG (electroencephalography), giving it the locally known name of "EEG Lab".
The Cognitive Electrophysiology Laboratory is located on the third floor of Green Hall in 3-C-24. The 350 square foot laboratory consists of a control room, a magnetic and electrostatically shielded subject testing room, and separate computer room for data analysis.
EEG Recording Equipment
There are currently two available equipment systems in the lab.
The 1st system is a BioSemi package, composed of 64-channel and 128-channel caps, pin and flat-type active electrodes, and battery powered ActiveTwo DC amplifier. The ActiveTwo system records EEG at a sampling rate of 2048 Hz and applies a DC-400Hz bandwidth. ActiView software is used for data acquisition. The USB2 receiver converts optical data coming from the DC amplifier into a USB2 output, which is connected to the data collection computer. The receiver also contains 16 independent trigger inputs and outputs, which allows for event markers for event-related potential experiments. Event information can be extracted during offline processing.
The 2nd system utilizes 128-channel NeuroScan Quik Caps, a custom EPA-6 preamplifier system from Sensorium Inc. and two 64 channel 12 bit digitizer cards from National Instruments controlled by a custom Windows XP software package developed in the laboratory. The EPA-6 preamplifier system contains 16 channels, which can be used for bipolar recording. It records EEG at a sampling rate of 1000 Hz and applies a 0.02 Hz-300Hz bandpass filter. CogniScan software is used for data acquisition. The event marker for event-related potential experiments is recorded as an analog signal on EEG channel number 128 through the amplifier, and event information can be extracted from this channel during offline processing.
In order to reduce the common problem of 60 Hz electrical noise in the EEG data, power supplies for all EEG equipment are kept outside of the shielded subject testing room.
Stimuli for behavioral tasks are presented using Psychtoolbox (MATLAB) or E-Prime software. There are two 120Hz LCD BenQ monitors set up for stimulus display. One sits in the control room and the other in the subject testing room, which clones the display of the stimulus presentation computer in the control room. The stimulus computer is synchronized with the data acquisition computer and event marker, and there is an average 4ms delay between stimulus onset and stimulus display on the LCD monitor.
For specifications on the monitors, data collection, and stimulus presentation computers, please contact the Lab Manager.
Two EEG analysis computers are located in 3-C-25 of Green Hall. Brain Products' Analyzer software, and EEGLAB, a toolbox for MATLAB, are currently used for data analysis. A Polhemus Fastrack apparatus can be used to create a three dimensional montage of electrode locations unique to each subject. Users are also welcome to perform data analysis on their personal machines.