Jumping Stand Apparatus Reveals Rapidly Specific Age-Related Cognitive Impairments in Mouse Lemur Primates

Abstract

The mouse lemur (Microcebus murinus) is a promising primate model for investigating normal and pathological cerebral aging. The locomotor behavior of this arboreal primate is characterized by jumps to and from trunks and branches. Many reports indicate insufficient adaptation of the mouse lemur to experimental devices used to evaluate its cognition, which is an impediment to the efficient use of this animal in research. In order to develop cognitive testing methods appropriate to the behavioral and biological traits of this species, we adapted the Lashley jumping stand apparatus, initially designed for rats, to the mouse lemur. We used this jumping stand apparatus to compare performances of young (n = 12) and aged (n = 8) adults in acquisition and long-term retention of visual discriminations. All mouse lemurs completed the tasks and only 25 trials, on average, were needed to master the first discrimination problem with no age-related differences. A month later, all mouse lemurs made progress for acquiring the second discrimination problem but only the young group reached immediately the criterion in the retention test of the first discrimination problem. This study shows that the jumping stand apparatus allows rapid and efficient evaluation of cognition in mouse lemurs and demonstrates that about half of the old mouse lemurs display a specific deficit in long-term retention but not in acquisition of visual discrimination.

Physiological and cognitive consequences of a daily 26h photoperiod in a primate(M. murinus)

“…Regarding cognitive outcomes, only seven animals reached the success criterion to the learning task, which is one-third of the total number of individuals. This result may seem low but it lies close to the success rate observed in other experiments using the same cognitive apparatus (Picq et al, 2015; Royo et al, 2018). The resulting interpretations must though be viewed cautiously.…”

“…The cognitive task was first described by Picq et al (2015), inspired from apparatus designed by Lashley (1930) for rodents and based on visual discrimination. In the present study, it was conducted over a two-day period, 3h hours before the light extinction.…”

“…The animal was given 30 trials to reach the success criterion consisting in 8 jumps on the positive platform within 10 consecutive trials. For each animal, we measured the number of trials needed to reach the success criterion (for more details, see Picq et al, 2015).…”

“…This small Malagasy lemur is an emerging model in neurosciences since it displays aged-related impairments similar to those found in humans (e.g. spontaneous neurodegenerative diseases or cognitive deficiencies, Bons et al, 2006; Joly et al, 2014; Languille et al, 2012; Picq et al, 2015), including circadian rhythms alteration, such as locomotor activity fragmentation or sleep deterioration (see Hozer et al, 2019 for review). On the other hand, its small body size and light body mass make it an ideal and promising laboratory model.…”

The Exceptional Vulnerability of Humans to Alzheimer’s Disease

“…Behaviorally, performance on certain tasks declines in old monkeys [37–40] and prosimians [36, 41], but there is no clear evidence yet of severe cognitive and behavioral impairments comparable to those that characterize dementia [2, 42]. Cognitive capacity also weakens somewhat in normal aged humans, but (at least with regard to hippocampal function) the pattern of change differs from that in AD [43].…”