Lab 01

PSYC480

Dr Usman Afzali

University of Canterbury

2/22/23

MATLAB and EEGLab

What is MATLAB?

  • Programming language
  • Matrix manipulations, plotting, implementing algorithms etc.
  • Toolboxes and apps

What is EEGLab?

  • A MATLAB toolbox
  • Used for processing and analysing EEG, MEG and other electrophysiological signals.
  • It has a GUI

Processing and analysing EEG data

  • MATLAB command line
  • The standalone EEGLab software
  • Use EEGLab in association with MATLAB

Demonstration

How to process using EEGLab

  • Use the available dataset from Learn Lab demo dataset.
  • Note “Channels per frame, Frames per epoch, epoch, events, sampling rate, reference and other attributes.

How to process using EEGLab

  • Epoch: A procedure in which specific time-windows are extracted from the continuous EEG signal. These time windows are called “epochs”, and usually are time-locked with respect an event e.g. a visual stimulus.

Attributes contd…

  • Event: a visual stimuli or a task
  • Sampling rate (Hz): the number of samples (of electrical activity) recorded per second
  • Frames: Frames in EEGLAB are the same as samples (so if you sampled at 500 Hz your data will have 500 frames each second)
  • Referencing: EEG recordings measure differences in electrical potentials between two points (Voltages). This means the signal displayed at any channel is in fact the difference in electrical potential to some other recording site (or reference).

Visualising EEG data

  • Use Plot -> Channel data (scroll).

Exercise

To submit

  • Use the the Lab 1 exercise dataset on Learn.
  • Read it in to the EEGLab
  • Report all attributes
  • Insert a screenshot of the attributes
  • Plot data using the scroll option
  • Insert a screenshot
  • Report your observation: do the data look similar to demonstration? What do you see as a potential difference?
  • Submit this as a pdf on Learn.

The END