Moderate Differences in Feeding Diets Largely Affect Motivation and Spatial Cognition in Adult and Aged but Less in Young Male Rats

Abstract

Nutrition can have significant effects on behavior and cognitive processes. Most of the studies related to this use extremely modified diets, such as high fat contents or the exclusion of distinct components needed for normal development and bodily homeostasis. Here we report significant effects of diets with moderate differences in compositions on food rewarded spatial learning in young (3–4 months), adult (6–7 months), and aged (17–18 months) rats. Young rats fed with a lower energy diet showed better performance only during aquisition of the spatial task when compared to rats fed with a standard diet. Adult rats (6–7 months) fed with a standard diet performed less well in the spatial learning task, than rats fed with lower energy diet. Aged rats fed with a lower energy diet (from 13 to 18 months of age) performed better during all training phases, as in a previous test when they were adult and fed with a standard diet. This difference could only be partly explained by lower motivation to search for food in the first test. Correspondingly, the variability of individual performance was significantly higher and increased over trials in adult rats fed with the standard diet as compared to adult rats fed with lower energy diet. Thus, moderate changes in feeding diets have large effects on motivation and cognition in elderly and less in young rats in a food rewarded spatial learning task. Therefore, nutrition effects upon food rewarded spatial learning and memory should be considered especially in aging studies.

Striatal Transcriptome Reveals Differences Between Cognitively Impaired and Unimpaired Aged Male Rats

“…Lipid composition changes in the hippocampus, a brain structure being strongly involved in spatial memory processes, can also lead to specific differences in spatial learning. In a previous study we found nutrition induced lower sphingomyelin amounts in the hippocampal dentate gyrus in rats with impairments of spatial cognitive flexibility (Maliković et al, 2018). The striatum and the hippocampus play different roles in spatial learning and memory (Torromino et al, 2019) and are highly interconnected.…”

“…The here used animals were fed with the low energy diet as described in Maliković et al ( 2018 ). In order to distinct between old male rats with impaired and unimpaired memory, a hole-board memory test was performed according to a previously described protocol (Maliković et al, 2018 ; Daba Feyissa et al, 2019 ). The spatial memory performance was evaluated based on Reference Memory Index (RMI) calculated as: (first + revisits of baited holes) / total visits of all holes).…”

“…In this study the effects of different diets on memory were studied. The here used animals were fed with the low energy diet as described in Maliković et al (2018). In order to distinct between old male rats with impaired and unimpaired memory, a hole-board memory test was performed according to a previously described protocol (Maliković et al, 2018;Daba Feyissa et al, 2019).…”

Sensitivity to outcome devaluation in operant tasks is better predicted by food restriction level than reinforcement training schedule in mice

“…Both the preferential reinforcement of long inter-response times (IRT) in RI schedules (Krame & Rilling, 1970; Kuch & Platt, 1976) and the stronger action-outcome correlation in RR schedules (Dickinson, 1985; Ferster & Skinner, 1957; Pérez et al, 2019 although see Garr et al, 2020) are thought to contribute to generating this difference, and our finding that response rates are more sensitive to food restriction level in mice trained on RR schedules compared to RI schedules complements these interpretations. Furthermore, previous work has shown that while training schedule has little effects on motivation (Johnson et al, 2022), food restriction levels do impact it (Dietze et al, 2016; Malikovic et al, 2018). By manipulating food restriction levels, our findings provide further support to the notion that the ability to control one’s own reinforcement rate explains the difference in response rates generated by RR and RI schedules.…”

Molecular species of oxidized phospholipids in brain differentiate between learning- and memory impaired and unimpaired aged rats

“…All subjects were on a low-calorie diet (ssniff, R/M-H Ered II, Soest, Germany) for a period of 4 months (in case of aged animals) or 7 weeks (in case of young animals) prior to behavioral and physiological assessment. The aged animals represent a subgroup of animals from a previous study (Malikovic et al 2018).…”