Total sleep deprivation and novelty processing: implications for frontal lobe functioning.
OBJECTIVE: Mounting evidence suggests that the frontal lobes are particularly vulnerable to total sleep deprivation (TSD). Detection of novelty involves the frontal lobes. The presentation of rare, novel stimuli elicits an event-related potential (novel P3), which maximizes over anterior regions of the scalp. We hypothesized that TSD would impair novelty detection, resulting in a smaller novel P3 over the frontal region, with a topographic shift toward posterior areas. METHODS: An auditory novelty oddball task was administered to a TSD group after 36 h of waking and again following recovery sleep, and to a control group after 12 h of waking. EEG was recorded from Fz, Cz and Pz. RESULTS: A large anterior P3 was elicited in the control group. In the TSD group, this novel P3 was smaller at Fz. A later novel positivity appeared in parietal areas. The novel P3 returned to baseline levels and the late novel P3 was difficult to observe following recovery sleep. CONCLUSIONS: TSD appears to compromise the usual automatic detection of novelty probably due to frontal deactivation. Participants may compensate by relying on posterior brain mechanisms involving active memory comparison. The late novel P3 component may also reflect a secondary effortful attempt to encode and to categorize novel stimuli. SIGNIFICANCE: This study suggests that TSD may compromise cognitive functioning in different regions of the brain. The detection of novelty, probably mediated by the frontal lobes, is particularly at risk.