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Environmental enrichment does not influence hypersynchronous network activity in the Tg2576 mouse model of Alzheimer's disease.

Bezzina C, Verret L, Halley H, Dahan L, Rampon C - Front Aging Neurosci (2015)

Bottom Line: The cognitive reserve hypothesis claims that the brain can overcome pathology by reinforcing preexistent processes or by developing alternative cognitive strategies.Epidemiological studies have revealed that this reserve can be built throughout life experiences as education or leisure activities.As aberrant oscillatory activity can contribute to memory deficits, we wondered whether the long-lasting memory improvements observed after EE were associated with a reduction of neuronal network hypersynchrony.

View Article: PubMed Central - PubMed

Affiliation: UMR5169 CNRS, Centre de Recherches sur la Cognition Animale, Université de Toulouse, Université Paul Sabatier Toulouse, France ; CNRS, Centre de Recherches sur la Cognition Animale Toulouse, France.

ABSTRACT
The cognitive reserve hypothesis claims that the brain can overcome pathology by reinforcing preexistent processes or by developing alternative cognitive strategies. Epidemiological studies have revealed that this reserve can be built throughout life experiences as education or leisure activities. We previously showed that an early transient environmental enrichment (EE) durably improves memory performances in the Tg2576 mouse model of Alzheimer's disease (AD). Recently, we evidenced a hypersynchronous brain network activity in young adult Tg2576 mice. As aberrant oscillatory activity can contribute to memory deficits, we wondered whether the long-lasting memory improvements observed after EE were associated with a reduction of neuronal network hypersynchrony. Thus, we exposed non-transgenic (NTg) and Tg2576 mice to standard or enriched housing conditions for 10 weeks, starting at 3 months of age. Two weeks after EE period, Tg2576 mice presented similar seizure susceptibility to a GABA receptor antagonist. Immediately after and 2 weeks after this enrichment period, standard and enriched-housed Tg2576 mice did not differ with regards to the frequency of interictal spikes on their electroencephalographic (EEG) recordings. Thus, the long-lasting effect of this EE protocol on memory capacities in Tg2576 mice is not mediated by a reduction of their cerebral aberrant neuronal activity at early ages.

No MeSH data available.


Related in: MedlinePlus

Housing conditions and experimental plan. (A) Photographs illustrating a standard laboratory cage (left; standard housing, SH) and an enriched environment (EE; right). (B) Experimental timeline depicting the mouse groups, housing conditions, enrichment period and experimental schedule. Abbreviations: SH, Standard Housing; EE, Environmental Enrichment; EEG, Electroencephalography; PTZ, Pentylenetetrazole; NTg, non-transgenic.
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Figure 1: Housing conditions and experimental plan. (A) Photographs illustrating a standard laboratory cage (left; standard housing, SH) and an enriched environment (EE; right). (B) Experimental timeline depicting the mouse groups, housing conditions, enrichment period and experimental schedule. Abbreviations: SH, Standard Housing; EE, Environmental Enrichment; EEG, Electroencephalography; PTZ, Pentylenetetrazole; NTg, non-transgenic.

Mentions: At 3 months of age, Tg2576 and NTg mice were arbitrary divided in two groups. One group (SH) was housed in standard laboratory cages, by lots of 2–5 mice, until the age of 6 months (Figure 1A, left). The other group was housed in an enriched environment (EE; Figure 1A, right), as previously described (Verret et al., 2013) until mice reached the age of 5.5 months after which they were returned to their standard cages until the age of 6 months (Figure 1B). Whatever the housing conditions, mice were given ad libitum access to food and water. As previously described (Verret et al., 2013), EE was composed of a large box (150 × 80 × 80 cm) containing various objects of different size, shape, color and material (wood, plastic, glass, metal), excluding running wheels. The configuration of the objects was modified and new objects were introduced every other day in order to stimulate mice exploratory behavior. Mice were exposed to the enriched environment by groups of 7–12 individuals (Figure 1A, right).


Environmental enrichment does not influence hypersynchronous network activity in the Tg2576 mouse model of Alzheimer's disease.

Bezzina C, Verret L, Halley H, Dahan L, Rampon C - Front Aging Neurosci (2015)

Housing conditions and experimental plan. (A) Photographs illustrating a standard laboratory cage (left; standard housing, SH) and an enriched environment (EE; right). (B) Experimental timeline depicting the mouse groups, housing conditions, enrichment period and experimental schedule. Abbreviations: SH, Standard Housing; EE, Environmental Enrichment; EEG, Electroencephalography; PTZ, Pentylenetetrazole; NTg, non-transgenic.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585132&req=5

Figure 1: Housing conditions and experimental plan. (A) Photographs illustrating a standard laboratory cage (left; standard housing, SH) and an enriched environment (EE; right). (B) Experimental timeline depicting the mouse groups, housing conditions, enrichment period and experimental schedule. Abbreviations: SH, Standard Housing; EE, Environmental Enrichment; EEG, Electroencephalography; PTZ, Pentylenetetrazole; NTg, non-transgenic.
Mentions: At 3 months of age, Tg2576 and NTg mice were arbitrary divided in two groups. One group (SH) was housed in standard laboratory cages, by lots of 2–5 mice, until the age of 6 months (Figure 1A, left). The other group was housed in an enriched environment (EE; Figure 1A, right), as previously described (Verret et al., 2013) until mice reached the age of 5.5 months after which they were returned to their standard cages until the age of 6 months (Figure 1B). Whatever the housing conditions, mice were given ad libitum access to food and water. As previously described (Verret et al., 2013), EE was composed of a large box (150 × 80 × 80 cm) containing various objects of different size, shape, color and material (wood, plastic, glass, metal), excluding running wheels. The configuration of the objects was modified and new objects were introduced every other day in order to stimulate mice exploratory behavior. Mice were exposed to the enriched environment by groups of 7–12 individuals (Figure 1A, right).

Bottom Line: The cognitive reserve hypothesis claims that the brain can overcome pathology by reinforcing preexistent processes or by developing alternative cognitive strategies.Epidemiological studies have revealed that this reserve can be built throughout life experiences as education or leisure activities.As aberrant oscillatory activity can contribute to memory deficits, we wondered whether the long-lasting memory improvements observed after EE were associated with a reduction of neuronal network hypersynchrony.

View Article: PubMed Central - PubMed

Affiliation: UMR5169 CNRS, Centre de Recherches sur la Cognition Animale, Université de Toulouse, Université Paul Sabatier Toulouse, France ; CNRS, Centre de Recherches sur la Cognition Animale Toulouse, France.

ABSTRACT
The cognitive reserve hypothesis claims that the brain can overcome pathology by reinforcing preexistent processes or by developing alternative cognitive strategies. Epidemiological studies have revealed that this reserve can be built throughout life experiences as education or leisure activities. We previously showed that an early transient environmental enrichment (EE) durably improves memory performances in the Tg2576 mouse model of Alzheimer's disease (AD). Recently, we evidenced a hypersynchronous brain network activity in young adult Tg2576 mice. As aberrant oscillatory activity can contribute to memory deficits, we wondered whether the long-lasting memory improvements observed after EE were associated with a reduction of neuronal network hypersynchrony. Thus, we exposed non-transgenic (NTg) and Tg2576 mice to standard or enriched housing conditions for 10 weeks, starting at 3 months of age. Two weeks after EE period, Tg2576 mice presented similar seizure susceptibility to a GABA receptor antagonist. Immediately after and 2 weeks after this enrichment period, standard and enriched-housed Tg2576 mice did not differ with regards to the frequency of interictal spikes on their electroencephalographic (EEG) recordings. Thus, the long-lasting effect of this EE protocol on memory capacities in Tg2576 mice is not mediated by a reduction of their cerebral aberrant neuronal activity at early ages.

No MeSH data available.


Related in: MedlinePlus