Alzheimer’s disease affects 5.4 million Americans. Evidence suggests that individuals who are positive for the apolipoprotein E ε4 allele are at higher risk for developing the disease. Studies have also shown that the ε4 allele is linked to olfactory decline. Olfactory functioning may be investigated using olfactory event-related potentials (OERPs). The high temporal resolution of OERPs enables an understanding of the neural correlates of olfactory processing and functioning. This study investigated the effects of age, ApoE ε4 status, response type, and electrode site on OERP latency and amplitude during encoding and retrieval in an odor recognition memory task. The 60 participants were equally divided into 3 age groups matched on ε4 status – younger, middle, and older. Odors were presented using a computer-controlled olfactometer. Participants were notified during encoding that this was a task of odor memory. Results indicated differences in OERP activity as a function of age, ApoE ε4 status, response type, and electrode site. These findings highlight the potential of OERPs to distinguish ε4− and ε4+ individuals and to contribute to an earlier diagnosis of AD.

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Rats and mice were studied for changes in meal-taking structure in a closed operant food economy, in which the consummatory or unit prices for food were increased. In experiment 1, as food price increased, male rats modestly decreased the number of meals per day and increased mean meal size. Female rats were similar to males but had smaller meal size and, at low costs, took more meals per day. In experiment 2, male and female B6 mice reduced food intake as price increased, accompanied by decreased meal number without change in meal size. They showed grazing-like behavior in the first part of the night. In contrast, we report in experiment 3, a large increase in intake and meal size during the final trimester of pregnancy. In experiment 4, we report that CD1 male mice subjected to a unit price series performed comparably to rats, and not like B6 mice. Other CD1 mice were tested using an interval schedule, and we found that mice were able to adapt eating patterns to greatly increased time demands without compromising total intake. Data are discussed in terms of the intercalation of food acquisition with global patterns of activity. Such interactions of organism and food environment are in particular need of mechanistic investigation.

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The purpose of this study is to compare the effect of unpredictable (U) or predictable (P) food delivery on health and longevity in mice. From 2 months of age until end of life, singly-housed male C57BL/6 mice were fed a semisynthetic diet either ad libitum (AL), or as imposed meals delivered as small pellets at either P or U times, frequencies, or amounts. The total daily food consumed by all groups was the same. The AL group gained body weight faster than either P or U groups, and had ~12% shorter median life span compared with either P or U groups. Bimonthly noninvasive body composition determinations showed that the differences in body weights were due to differences in fat and lean mass. Postmortem examinations revealed that the organ pathologies were similar in all groups, but a larger fraction of P and U mice were euthanized due to end-of-life suffering. There were no systematic differences in outcome measures between P and U groups suggesting that, within the range studied, the temporal pattern of food delivery did not have a significant metabolic effect.