Innovative rodent touchscreen technology to assess gender differences and feeding regimes of adolescent cognitive performance and motivation
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2018-07-01
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en
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Excessive sugar consumption is known to impair cognition in both children and adults. These cognitive problems have been associated with changes in blood sugar regulation and can be influenced by diet. Innovative touchscreen technology enables assessment of adolescent cognitive development, but the effect of feeding regime on cognition within touchscreen tasks is rarely examined. Therefore, this study investigated whether differences in cognitive development and motivation were based on the feeding regime and whether this is furthermore influenced by touchscreen type, gender or age.
Adult and adolescent Long Evans rats, of both sexes, were tested on a visual discrimination- and/or progressive ratio task in an operant conditioning box with either a capacitive or infrared touchscreen. Two adolescent groups, on either food restriction receiving grain rewards or ad libitum feeding receiving sucrose rewards (i.e. feeding regime), received an alternation of palatable grain and sucrose across five consecutive sessions at the end of the progressive ratio task. Furthermore, across the testing period blood samples were collected to assess fasted blood glucose and insulin levels. Lastly, liver and white adipose tissues (WAT) were dissected and weighted.
A better cognitive performance on the visual discrimination task was found in 1) adults compared to adolescents, 2) females compared to males, and 3) in rats on the infrared touchscreen versus the capacitive touchscreen. Female rats and rats using the capacitive touchscreen showed a higher motivation for a reward on the progressive ratio task. In general, rats were more motivated for a sucrose- compared to a grain reward. The feeding regime of the rat furthermore influenced their motivation for sucrose and blood glucose levels, but had no effect on cognitive performance. Males showed higher glucose and insulin levels, with glucose decreasing and insulin increasing over weeks. Finally, males showed higher liver and WAT weights compared to females and ad libitum fed rats showed higher liver and WAT weights compared to food restricted rats.
Our results indicate gender-related differences in both cognition, motivation and blood glucose levels. The results of touchscreen type remain inconclusive and further research is needed to indicate which touchscreen shows the best potential to study cognition and motivation across the rodents’ lifespan. Sucrose consumption during adolescence might furthermore reduce the motivational effort. Importantly, sucrose consumption might also alter the glucose-, fat- and liver metabolism of the rats, indicating the importance of the feeding regime in touchscreen-based studies.
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Faculteit der Sociale Wetenschappen