The hippocampal PVB circuit underwent neuroplastic reorganisation with increased dendritic length and complexity in 9- and 12-month-old TgF344-AD rats, before atrophy at 15 months. SST interneurons exhibited tau inclusions and atrophy from 9 months, whereas PVB interneurons were resilient until 15 months. β-Amyloid and tau pathology accumulated continuously across age. By 15 months, the TgF344-AD rats had robust loss of excitatory and inhibitory neurons. Hippocampal neuronal compensation was observed in 12-month TgF344-AD rats, with upregulation of GABAergic interneuronal markers. The 9-month-old TgF344-AD rats exhibited loss of neurons in the entorhinal cortex and hippocampus. Somatostatin (SST) and parvalbumin (PVB) interneurons, i.e GABAergic inhibitory neurons which prevent signal generation were traced to examine hippocampal neuroplasticity.Ĭognition was tested in the Barnes maze (a tool used in psychological lab experiments to measure spatial learning and memory in rats). Hippocampus plays a critical role in learning, emotional response, spatial navigation and memory while the entorhinal cortex is the gateway for information entering and leaving the hippocampus.
Neurons, β-amyloid plaques and tau inclusions were quantified in hippocampus and entorhinal cortex. compared TgF344-AD (a unique rat model with pathological hallmarks of AD) and non-transgenic littermate rats at 9, 12, and 15 months of age. This greater degree of activation correlated with improved task performance such that individuals with AD who demonstrated increased brain activation in these regions were able to perform both semantic and episodic memory tasks with more accuracy than those who demonstrated less brain activation.Ĭristopher Daniel Morrone et al. Specifically, the AD group demonstrated a more extensive recruitment of brain regions in response to task demands including the prefrontal and temporo-parietal cortices bilaterally. the concept of what a ‘cat’ is) and episodic memory tasks (recollection of specific events, situations and experiences-eg. The AD and control groups differed in the magnitude of brain activation when completing semantic memory tasks (ability to remember factual and conceptual information-eg.
explored the relationship between increased prefrontal rCBF (regional cerebral blood flow) using PET (imaging technique that uses radioactive substance to visualise and measure metabolic and biochemical processes in the body) and successful task performance in normal older adults and individuals with probable early-stage AD. Improved task performance in AD individuals 6 ( 2003 study )
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