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?

High quality evidence shows a medium to large increase in P50 ratio in people with bipolar disorder compared to controls without a psychiatric disorder. The effect was largest in people with bipolar disorder and a history of psychotic symptoms.

April 2019

Last updated at: 4:15 am, 9th April 2019
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Fact Sheet Technical Commentary

NeuRA Libraries

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