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

Picq JL, Villain N, Gary C, Pifferi F, Dhenain M - PLoS ONE (2015)

Bottom Line: The locomotor behavior of this arboreal primate is characterized by jumps to and from trunks and branches.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.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de psychopathologie et de neuropsychologie, E.A. 2027, Université Paris 8, 2 rue de la liberté, 93000 St Denis, France.

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.

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Jumping stand apparatus for mouse lemurs (a) and pairs of stimuli used for the two discrimination problems (b).
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pone.0146238.g001: Jumping stand apparatus for mouse lemurs (a) and pairs of stimuli used for the two discrimination problems (b).

Mentions: Experiments were performed in a separate testing room containing the apparatus. The apparatus (see Fig 1) was a big vertical cage (height = 150 cm) made of plywood walls except the front panel that was a one-way mirror to allow observation. It was illuminated by 50-W bulb attached to the center of the cage ceiling. The mouse lemur was placed inside the cage on the center of an elevated plastic starting platform (the jumping stand) through an open-ended dark cylinder that opened in the roof of the cage. After this cylinder was gently lifted, the mouse lemur was required to jump from the elevated stand onto one of two landing platforms (15 cm x 30 cm) across a 35-cm gap. If it did not jump within one minute the starting stand was progressively tilted downwardly causing a slippery slope pushing the mouse lemur to jump. If it jumped onto the correct platform, it could pass under an opaque Plexiglass screen to access its nestbox placed behind the wall of the cage. This opaque screen prevented mouse lemurs from jumping directly to the opening of the nestbox. If it jumped onto the incorrect platform, the platform swung down and the mouse lemur fell into the bottom of the cage on a wide soft pillow to avoid any risk of injury. A small door at the base of the right wall of the cage allowed to take back the mouse lemur and to put it back on the starting platform for another trial. The correct and the incorrect platforms were distinguished by visual stimuli placed on them. The training pairs of stimuli were randomly drawn from a pool of 20 pairs. Within each pair, stimuli were chosen to be easily discriminable as the goal was to test cognitive and not visual capacities. Accordingly the two stimuli of the same pair differed both in shape, texture, brightness or pattern. Practically, they were made of different materials (cardboard, plastic, polystyrene, fabric…).


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

Picq JL, Villain N, Gary C, Pifferi F, Dhenain M - PLoS ONE (2015)

Jumping stand apparatus for mouse lemurs (a) and pairs of stimuli used for the two discrimination problems (b).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4696676&req=5

pone.0146238.g001: Jumping stand apparatus for mouse lemurs (a) and pairs of stimuli used for the two discrimination problems (b).
Mentions: Experiments were performed in a separate testing room containing the apparatus. The apparatus (see Fig 1) was a big vertical cage (height = 150 cm) made of plywood walls except the front panel that was a one-way mirror to allow observation. It was illuminated by 50-W bulb attached to the center of the cage ceiling. The mouse lemur was placed inside the cage on the center of an elevated plastic starting platform (the jumping stand) through an open-ended dark cylinder that opened in the roof of the cage. After this cylinder was gently lifted, the mouse lemur was required to jump from the elevated stand onto one of two landing platforms (15 cm x 30 cm) across a 35-cm gap. If it did not jump within one minute the starting stand was progressively tilted downwardly causing a slippery slope pushing the mouse lemur to jump. If it jumped onto the correct platform, it could pass under an opaque Plexiglass screen to access its nestbox placed behind the wall of the cage. This opaque screen prevented mouse lemurs from jumping directly to the opening of the nestbox. If it jumped onto the incorrect platform, the platform swung down and the mouse lemur fell into the bottom of the cage on a wide soft pillow to avoid any risk of injury. A small door at the base of the right wall of the cage allowed to take back the mouse lemur and to put it back on the starting platform for another trial. The correct and the incorrect platforms were distinguished by visual stimuli placed on them. The training pairs of stimuli were randomly drawn from a pool of 20 pairs. Within each pair, stimuli were chosen to be easily discriminable as the goal was to test cognitive and not visual capacities. Accordingly the two stimuli of the same pair differed both in shape, texture, brightness or pattern. Practically, they were made of different materials (cardboard, plastic, polystyrene, fabric…).

Bottom Line: The locomotor behavior of this arboreal primate is characterized by jumps to and from trunks and branches.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.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de psychopathologie et de neuropsychologie, E.A. 2027, Université Paris 8, 2 rue de la liberté, 93000 St Denis, France.

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.

Show MeSH