Event related potentials recorded during an auditory oddball paradigm show a component peaking around 300 milliseconds whose amplitude and latency reflect allocation of attention and working memory resources. In schizophrenia, this component characteristically shows:
- A Shortened latency with increased amplitude
- B Prolonged latency and reduced amplitude (the P300 abnormality) ✓
- C Complete absence only in medicated patients
- D No difference from healthy controls
Correct answer: B. Prolonged latency and reduced amplitude (the P300 abnormality)
Explanation
The P300 is an endogenous event related potential elicited by attended rare targets in the oddball task. Patients with schizophrenia consistently show delayed latency and diminished amplitude, interpreted as impaired attention and context updating, and it is one of the most replicated biological markers in the illness. The P50, a separate midlatency component studied with paired click paradigms, reflects sensory gating rather than the attention dependent response described here.
Reference: Kaplan and Sadock's Synopsis of Psychiatry, 12th ed.
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