The human brain contains a massive variety of nerve cells, or neurons, of all different functions, shapes, and sizes. This wide diversity of cells makes it difficult for researchers to pinpoint certain mechanisms of neurological disease, including those associated with neurodegenerative conditions like Alzheimer’s disease. However, researchers are still discovering new neuron subtypes — and each new discovery represents renewed hope for neurological research. A new study published in Nature Communications outlines one such discovery. The study, orchestrated by researchers at the University of British Columbia (UBC), hones in on a new type of brain cell: so-called “ovoid cells,” which may play a central role in our ability to remember and recognize important objects. Read on for a summary of the study, which could have groundbreaking implications for research into neurodegenerative conditions.
Ovoid Cells Discovered “Hiding in Plain Sight”
Ovoid cells are named for the distinct shape of their cell body, which resembles that of an egg. The UBC researchers identified relatively small numbers of these cells within the human hippocampus; the cells are non-pyramidal excitatory neurons located adjacent to subiculum pyramidal cells but can be distinguished from them by different gene expression, physiology, morphology and connectivity. The cells were also identified in mice and other animals. Lead author Adrienne Kinman discovered the cell subtype while analyzing a mouse brain sample, noting that the ovoid cells were “hiding right there in plain sight.” The cells seemed to exhibit a highly unique gene expression, in addition to unique neural circuitry. With further analysis, Kinman and her fellow researchers saw that ovoids were “quite distinct from other neurons at a cellular and functional level.”
Exploring the Mechanisms of Ovoid Cells
Kinman and her colleagues noted that ovoid cells were distinct on multiple levels; however, the team was uncertain what role the cells play in the neural network. To find out, Kinman manipulated the cells in mice so the ovoids would glow when active inside the brain. The team observed the glowing cells using a miniature single-photon microscope.
Fascinatingly, the ovoid cells lit up when the mice encountered an unfamiliar object in their environment — but, as they grew accustomed to the object, the cells stopped responding. “What’s remarkable is how vividly these cells react when exposed to something new,” said Kinman. “It’s rare to witness such a clear link between cell activity and behavior.” The researchers concluded that ovoid cells trigger a process that stores objects in memory, allowing us to recognize objects. In essence, ovoid cells are the reason you can look at a family photo and recognize a parent or sibling.
Applying Ovoid Cell Research to Brain Disorders
Knowing that ovoid cells contribute to object recognition and memory, the researchers are now investigating the role that these unique cells play in certain brain disorders, including Alzheimer’s disease and epilepsy. The team is exploring a hypothesis: that, when the cells become dysregulated, they could drive the symptoms of certain neurological diseases. “Recognition memory is one of the hallmarks of Alzheimer’s disease — you forget what keys are, or that photo of a person you love,” said Kinman. “What if we could manipulate these cells to prevent or reverse that?” For epilepsy treatment, the team is exploring whether ovoid cells “could be playing a role in seizure initiation and propagation.”
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The exploration of this previously undiscovered neuron type could have stunning implications for the treatment of numerous neurological diseases.
To study non-spatial object learning in mice, Scantox Neuro offers preclinical studies using the novel recognition test. Additional tests such as the Morris water maze, Barnes maze, Y-maze, contextual fear conditioning, passive avoidance, and the two-choice swim test are also available to evaluate other types of learning as well as memory. Analysis of cell morphology can be performed by histological staining or immunofluorescent labeling of brain tissue. Quantification of cells can be performed from histological staining or labeling by a rater-independent approach.
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