Onset of hippocampus-dependent memory impairments in 5XFAD transgenic mouse model of Alzheimer's disease.

The 5XFAD mice are an early-onset transgenic model of Alzheimer's disease (AD) in which amyloid plaques are first observed between two and four months of age in the cortical layer five and in the subiculum of the hippocampal formation. Although cognitive alterations have been described in these mice, there are no studies that focused on the onset of hippocampus-dependent memory deficits, which are a hallmark of the prodromal stage of AD. To identify when the first learning and memory impairments appear, 5XFAD mice of two, four, and six months of age were compared with their respective wild-type littermates using the olfactory tubing maze, which is a very sensitive hippocampal-dependent task.

Evidence for early cognitive impairment related to frontal cortex in the 5XFAD mouse model of Alzheimer's disease.

The frontal cortex is a brain structure that plays an important role in cognition and is known to be affected in Alzheimer's disease (AD) in humans. Over the past years, transgenic mouse models have been generated to recapitulate the main features of this disease, including cognitive impairments. This study investigates frontal cortex dependent learning abilities in one of the most early-onset transgenic murine model of AD, the 5XFAD mice.

Enhancement of reference memory in aged rats by specific activation of 5-HT(4) receptors using an olfactory associative discrimination task.

In normal aging, or pathological brain diseases in humans, implicit memory (or procedural memory in rats) is spared while explicit memory (or reference memory in rats) is deeply impaired. Selective activation of 5-HT(4) receptors by a partial 5-HT(4) receptor agonist (SL65.0155) improved memory performance in an olfactory associative discrimination task in aged rats.