From the Guidelines
Hippocampal place cells play a crucial role in spatial navigation and memory formation, and their disruption can lead to cognitive impairment, as seen in chemotherapy-induced cognitive impairment, where chemotherapeutic agents can reduce hippocampal cell proliferation and impair neurogenesis, highlighting the need for neuroprotective strategies, such as fluoxetine, which has been shown to stimulate hippocampal neurogenesis and improve neuronal survival rates 1.
Key Characteristics of Hippocampal Place Cells
- Specialized neurons in the hippocampus that fire when an animal enters a specific location in its environment, creating a cognitive map of space
- Each place cell has a preferred spatial location called its "place field" where it becomes most active
- Place cells can maintain stable representations of familiar environments for weeks or months, yet they can also rapidly remap when entering a new environment
- Work in conjunction with other specialized neurons like grid cells, head direction cells, and boundary cells to form a comprehensive neural navigation system
Impact of Chemotherapy on Hippocampal Place Cells
- Chemotherapeutic agents can reduce hippocampal cell proliferation and impair neurogenesis, leading to cognitive impairment
- Pro-inflammatory cytokines, such as TNF-α, elevated during chemotherapy, can also decrease hippocampal cell proliferation
- Even at low doses, certain chemotherapeutic agents, such as cisplatin, can reduce hippocampal dendritic spine density and induce neuronal apoptosis, impairing neurogenesis 1
Potential Neuroprotective Strategies
- Fluoxetine, an antidepressant, has been shown to stimulate hippocampal neurogenesis, increase BDNF, and improve neuronal survival rates, making it a potential treatment for chemotherapy-induced cognitive impairment 1
- Other potential neurogenesis-targeted treatments include metformin, an anti-hyperglycemic therapy, which may promote neurogenesis by activating a protein kinase CPB transcriptional coactivator pathway involved in the typical genesis of neurons from neural progenitor cells 1
From the Research
Hippocampus Place Cells
- Hippocampal place cells exhibit spatially selective activity within an environment and have been proposed to form the neural basis of a cognitive map of space that supports spatial navigation and episodic memory formation 2.
- The activity of place cells is influenced by the context, even when the contexts are defined by abstract task demands rather than the spatial geometry of the environment, and place fields reflect a more general context processing function of the hippocampus 3.
- Place cells collectively map spatial locations, with each cell firing only when the animal occupies that cell's "place field," a particular subregion of the larger environment, and their activity is influenced by vestibular input 4.
- Hippocampal place cells encode global location but not connectivity in a complex space, and they provide a spatial map that does not explicitly include connectivity 5.
Role in Memory and Navigation
- Hippocampal spatial view cells respond to the spatial location being looked at and provide a basis for navigation to a series of viewed landmarks, with the orbitofrontal cortex reward inputs to the hippocampus providing the goals for navigation 6.
- The representation of spatial view cells is allocentric, in that the responses are to locations "out there" in the world, and are relatively invariant with respect to retinal position, eye position, head direction, and the place where the individual is located 6.
- Hippocampal place cells actively support spatial navigation and memory, and targeted stimulation of a small number of place cells can bias the behavior of animals during a spatial memory task 2.