The hippocampal circuit is crucial for memory formation, consolidation, and spatial navigation. In Alzheimer's disease, the hippocampus is one of the earliest and most affected brain regions, with tau pathology spreading from entorhinal cortex to hippocampal subfields. This leads to episodic memory deficits that are the hallmark of early AD.
The hippocampal formation is one of the earliest and most severely affected brain regions in Alzheimer's disease, accounting for the characteristic memory deficits.
- Perforant path: Entorhinal cortex → Dentate gyrus granule cells
- Mossy fiber pathway: Dentate gyrus → CA3 pyramidal neurons
- Schaffer collateral: CA3 → CA1 pyramidal neurons
- Dentate gyrus granule cells: Pattern separation
- CA3 pyramidal neurons: Pattern completion
- CA1 pyramidal neurons: Sequence memory
- Hippocampal interneurons: Inhibition control
- Entorhinal cortex layer II: Early tau neurofibrillary tangles
- Dentate gyrus granule cells: Adult neurogenesis declines
- CA1 pyramidal neurons: Selective vulnerability
- Synaptic loss in perforant pathway
- Impaired pattern separation and completion
- Disrupted theta-gamma coupling
- Place cell remapping
- Anterograde amnesia: Cannot form new memories
- Spatial navigation deficits
- Contextual memory impairment
The study of Alzheimer Hippocampal Circuit has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
- Palop and Mucke, Network abnormalities in AD (2010)
- Busche et al., Neuronal hyperactivity in AD models (2015)
- Haas and Miller, Adult neurogenesis in AD (2022)