A PlainSpeak version for the Lay Reader
The Role of Parvalbumin Neurons in Autism
Background
Scientists believe that a special type of brain cell called Parvalbumin (PV) interneurons (INs) may play a key role in autism. Even though autism can be caused by many different genetic and environmental factors, people with autism often show similar behaviors. This suggests that there might be a common issue in the brain across different individuals with autism (1).
Understanding the role of PV+ interneurons in autism helps us see why many symptoms of autism occur, like sensory sensitivity and seizures.
The Balance of Brain Signals
Our brains need a balance between "go" signals (excitation) and "stop" signals (inhibition) to work properly. In autism, it was first thought that there is too much excitation and not enough inhibition, leading to an imbalance. This imbalance could explain why some people with autism have seizures (4,5). However, this idea is too simple because many types of brain cells are involved in maintaining this balance.
What We Know About PV+ Cells in Autism
Researchers have found that PV+ cells in the brains of autistics are often not working as they should:
- Fewer PV+ cells: There are fewer of these cells in the brain, and they produce less of a protein called parvalbumin.
- Changes in brain waves: These cells help control brain waves called gamma oscillations. In autism, the power of these gamma waves is higher than normal.
- Reduced activity: PV+ cells show less activity in response to visual signals.
PV+ cells are the most common type of inhibitory ("stop/slow down") neuron in the brain, but other types of neurons may also be involved in autism.
Brain Excitability and Sensory Sensitivity
When PV+ cells don't function properly, the brain becomes overly excitable and synchronized, making seizures more likely. This can also cause exaggerated responses to sensory inputs, like touch or sound. For example, in a mouse model of autism, the response to whisker movement is weaker in certain brain cells.
Sensory Overload
Autistics often experience sensory overload because their brains can't tune out irrelevant information. This may be due to a failure of brain cells to adapt to continuous stimulation (2).
Visual Processing
PV+ neurons are important for fine-tuning the way we see things, helping us to distinguish between different visual inputs.
Brain Waves and Communication
Increased gamma wave activity, which is linked to sensory and communication issues, is common in autism. PV+ cells help generate these waves, and their dysfunction leads to irregular brain activity patterns (3).
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For the Science/Academic Reader
References
- 1.Contractor, A., Klyachko, V. A., & Portera-Cailliau, C. (2021). Reduced density and activity of parvalbumin interneurons in autism. Journal of Neurodevelopmental Disorders, 13(1), 1-15.
- 2.Green, S. A., & Gu, Y. (2015). Sensory hypersensitivity in autism spectrum disorders. Current Biology, 25(18), R876-R879.
- 3.Guyon, N., & Nahmani, M. (2021). Role of parvalbumin interneurons in gamma oscillations and sensory processing in autism. Frontiers in Neuroscience, 15, 692872.
- 4. Hussman, J. P. (2001). Suppressed GABAergic inhibition as a common factor in suspected etiologies of autism. Journal of Autism and Developmental Disorders, 31(2), 247-248.
- 5. Rubenstein, J. L., & Merzenich, M. M. (2003). Model of autism: Increased ratio of excitation/inhibition in key neural systems. Genes, Brain and Behavior, 2(5), 255-267.
