Transdermal nicotine administration enhances automatic auditory processing reflected by mismatch negativity

Mismatch negativity (MMN) is a component of event-related potentials (ERPs) with a wide-ranging applicability to the investigation of neuronal substrates of information processing in normal and psychopathological states. Nicotine has been shown to be implicated in the pathophysiology of psychiatric disorders as schizophrenia or Alzheimer's disease, and has also been proposed as a self-administered drug in schizophrenia. The goal of the present study is to elucidate the effect of nicotine on the auditory automatic processing reflected by MMN. Nicotine was administered transdermally under controlled dosage. Ten healthy volunteers attended the laboratory for one baseline session and two test sessions. The test sessions involved administration of a placebo patch and a nicotine skin patch, which were counter-balanced. The ERPs were recorded passively during an auditory oddball paradigm. Nicotine administration shortened the MMN latencies, and these effects were independent of the earlier ERP components, N100 and P200. In conclusion, nicotine enhances preattentive and automatic processing such as MMN system and these effects appear to be quite specific and independent of earlier cognitive stages than preattentive mismatch processing. The shortened MMN latency may be interpreted as a reduction of the amount of time required to complete a neuronal mismatch process through the ascending auditory pathway.