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P50

What is the P50?

The P50 event-related potential is interpreted as a physiological substrate for an inability to “gate” or inhibit irrelevant sensory information. In this paradigm, paired auditory clicks are presented, separated by a 500ms interval. The first click initiates or conditions the inhibition, while the second (test) click indexes the strength of the inhibition. P50 ratio is quantified as the amplitude of the response to the second click divided by the first. An absence of a reduced response to the second stimulus is interpreted as a failure of inhibitory mechanisms, postulated to represent a defect in sensory gating, and a larger ratio is indicative of reduced cortical inhibition.

What is the evidence for P50 anomalies in people with bipolar disorder?

Moderate quality evidence shows large effects of increased P50 S2/S1 ratio and decreased P50 S1-S2 difference in people with bipolar disorder compared to controls. Medication may improve the S2/S1 ratio. There were no moderating effects of having or not having psychotic symptoms.

December 2021

Image: ©Dmitry Volochek – stock.adobe.com

Last updated at: 12:45 pm, 13th December 2021
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Fact Sheet Technical Commentary

NeuRA Libraries

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Orange - Topic summary is being compiled.
Red - Topic summary has no current systematic review available.