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The P300 wave of Event-Related-Potential.

Sheshav Somani , and Jyostna Shukla

The brain is capable of elaborating and executing different stages of information processing. However, exactly how these stages are processed in the brain is still unknown. Discovery of the P300 event-related potential (ERP) stimulated the use of brain recording methods to assess human cognition. The P300 wave is considered to reflect an information processing cascade associated with attention and memory mechanisms. The P300 wave is a positive wave deflection in the human event related potential. The P300 wave is commonly elicited in an Oddball paradigm when a subject detects an occasional target stimulus in a regular train of standard stimuli. The P300 wave only occurs if the subject is actively involved in detecting the target stimuli. Its amplitude varies with the improbability of the target. Its latency varies with the difficulty to discriminate the target with standard stimuli. In patients with decreased cognitive ability, amplitude is smaller and latency is longer than age matched control subjects. The P300 is comprised of P3a that results from an early attention related process stemming from a working memory representational change, and P3b occurs when the attention-driven stimulus signal is transmitted to temporal and parietal structures. The exact neural origin of P300 wave is not known and its role in cognition is not clearly understood. The P300 wave may have multiple intracerebral generators including hippocampus and various association areas of neocortex. As the relationship between neurotransmitter function and the concomitant neuro electric signals recorded at the scalp are clarified, articulating how these variables interact will fulfil the cognitive promise that the P300 inspired when it was discovered over 40 years ago