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Applications of Independent Component Analysis. Terrence Sejnowski. Computational Neurobiology Laboratory The Salk Institute. PCA finds the directions of maximum variance ICA finds the directions of maximum independence. Principle: Maximize Information .
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Applications of Independent Component Analysis Terrence Sejnowski Computational Neurobiology Laboratory The Salk Institute
PCA finds the directions of maximum variance ICA finds the directions of maximum independence
Principle: Maximize Information • ICA produces brain-like visual filters for natural images. • A: ICA does this -- it maximizes joint entropy & minimizes mutual information between output channels (Bell & Sejnowski, 1995). • Q: How to extract maximum information from multiple visual channels? Set of 144 ICA filters
Example: Audio decomposition Perform ICA Mic 1 Mic 2 Mic 3 Mic 4 Terry Scott Te-Won Tzyy-Ping Play Mixtures Play Components
Sound source separation Image processing Sonar target identification Underwater communications Wireless communications Brain wave analysis (EEG) Brain imaging (fMRI) ICA Applications
Recordings in real environments Separation of Music & Speech Experiment-Setup: - office room (5m x 4m) - two distant talking mics - 16kHz sampling rate 60cm 40cm
Barcode Classification Matrix Linear Postal
Learned ICA Output Filters Matrix Linear Postal
Barcode Classification Results Classifying 4 data sets: linear, postal, matrix, junk
ICA applied to Brainwaves An EEG recording consists of activity arising from many brain and extra-brain processes
Eye movement Muscle activity
WHAT ARE THE INDEPENDENT COMPONENTS OF BRAIN IMAGING? Task-related activations Arousal Measured Signal Physiologic Pulsations Machine Noise ?
Functional Brain Imaging • Functional magnetic resonance imaging (fMRI) data are noisy and complex. • ICA identifies concurrent hemodynamic processes. • Does not require a priori knowledge of time courses or spatial distributions.
Contact: terry@salk.edu ICA-2001: http://www.ica2001.org