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P3 and LPP

What is P3 and LPP event-related potentials?

The P3 component can be divided into the P3a and P3b, with the P3a signifying attention to a novel stimulus, and the P3b being associated with the motivational salience of a stimulus. P3b generally appears as a positive deflection over the parietal midline sagittal plane (Pz) from 250 to 500 ms following stimulus presentation. The amplitude of the P3b is modulated by motivation. P3 has been used to examine responses to emotional stimuli by capturing attention and requiring additional processing because of the emotional content.

Another event related potential component closely related to attentional allocation to emotional stimuli is the late positive potential (LPP), which appears mostly over central parietal sites from 300 to 2000ms post-stimulus and continuing for up to several seconds. The LPP is also thought to reflect sustained attention to and processing of stimuli that are intrinsically motivating, such as emotional images. LPP is often considered a sustained P3 response.

What is the evidence for P3 and LPP?

Moderate to high quality evidence suggests P3b and LPP amplitude is reduced in people with schizophrenia compared to controls in response to negative stimuli, particularly negative faces. There were no differences with positive or neutral stimuli.

October 2020

Last updated at: 10:46 pm, 29th October 2020
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