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• NMDA antagonist dizocilpine selectively impaired accuracy on the odor span task. • Drug effects were exacerbated by increases in memory load and distraction. • Both attentional and capacity deficits in schizophrenia are modeled in the task. The rodent odor span task (OST) uses an incrementing non-matching to sample procedure in which a series of odors is presented and selection of the session-novel odor is reinforced. An OST is frequently used to test the effects of neurobiological variables on memory capacity as the number of odors to remember increases during the course of the session. In this regard, one important finding has been that NMDA receptor antagonists selectively impair OST performance at doses that spare accuracy on control tasks. However, in many versions of the odor span task the number of stimuli to remember is confounded with the number of distractor odors presented to the rat on each trial. The present study compared the effects of the NMDA antagonist dizocilpine when the number of choices was held constant at two (one novel odor—S+ and one previously presented distractor odor—S−) and when the number of choice stimuli was permitted to increase up to 10 (one S+ and 9 S−). Dizocilpine impaired OST accuracy at doses that had no effect on a reference memory control task in both 2-choice and 10-choice conditions; however, the dose-response function was shifted to the left in the 10-choice tests. The impairments produced by dizocilpine were exacerbated as the memory load increased in both 2- and 10-choice conditions. These findings support the hypothesis that NMDA antagonism reduces the number of stimuli that rats can remember accurately, but the interaction between the effective DZP dose and the number of distractors shows that drug effects on OST performances may involve attentional factors in addition to memory capacity. The findings also demonstrate that variations in number of OST distractors can be used to alter sensitivity of the task. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sixteen male participants were enrolled in a randomized crossover control study involving three sleep-deprivation sessions. • The study investigated the effect of modafinil on working memory decline caused by sleep deprivation, by studying ERPs. • Modafinil may effectively improve the decline in pronunciation-related working memory after sleep deprivation. We aimed to explore whether modafinil mitigates the working memory decline induced by 36 h of acute total sleep deprivation (36-h TSD). Sixteen healthy male participants were enrolled in a randomized double-blind crossover control study involving three sleep-deprivation sessions. Participants were administered 400 mg of placebo, caffeine, or modafinil during these sessions. Behavior and EEG data were recorded while participants performed pronunciation-related working memory tasks. Behavioral indicators showed that, compared with placebo, modafinil improved the accuracy of pronunciation-related working memory tasks and reduced the response time. Compared with before sleep deprivation, the amplitudes of the event-related potentials (ERPs) increased in the N2 component and decreased in the P3 component after sleep deprivation in the placebo condition. In the caffeine condition, the amplitude of the P3 component decreased, the latency of the N2 component was prolonged, and the N2 amplitude remained unchanged. In the modafinil condition, the P3 latency was shortened, and no significant difference was found in the amplitude of the N2 or P3 ERPs; no significant difference was recorded in the N2 latency. Modafinil (400 mg) effectively ameliorated the decline in pronunciation-related working memory after 36-h TSD, suggesting that it may effectively counteract cognitive decline caused by acute sleep deprivation. [ABSTRACT FROM AUTHOR]

Freely-moving rodents can solve short-term memory (STM) tasks using "response bridging" strategies, relying on motor patterns instead of mnemonic functions. This limits the interpretational power of results yielded by some STM tasks in rodents. To determine whether head-fixed monkeys can employ parallel non-mnemonic strategies, we measured eye position and velocity of two head-fixed monkeys performing a delayed response reaching and grasping task. We found that eye position during the delay period was correlated with reach direction. Moreover, reach direction as well as grasp object could be predicted from eye kinematics during the delay. Both eye velocity and eye position contributed to the prediction of reach direction. These results show that motor signals carry sufficient information to allow monkeys to solve STM tasks without using any mnemonic functions. Thus, the potential of animals to solve STM tasks using motor patterns is more diverse than previously recognized. [ABSTRACT FROM AUTHOR]