Spontaneous neural activity necessary for vision

Researchers at the Yale School of Medicine have demonstrated in living mice that a spontaneous wave of neural activity occuring in early mammalian development is crucial for proper brain development.

Michael Crair, professor of neurobiology at the Yale School of Medicine, James Ackman, postdoctoral fellow and Timothy Burbridge GRD ’14 published an article in the Oct. 10 issue of the scientific journal “Nature” presenting their findings. Crair said the findings have “fundamental implications” for understanding diseases and that mental illnesses such as autism or schizophrenia could potentially be linked to disruptions of the neural burst.

“For the first time, we’ve shown explicitly that this spontaneous activity exists in vivo and propagates all the way up into the higher-order brain structures, like the cortex,” Crair said. This wave of neural activity, which originates in the retina, plays an important role in priming the development of vision, Ackman said.

Research on this topic has been conducted in the past, but Crair’s study is the first to observe the activity in live animals.

This study has “confirmed a lot that people have suspected for a long time,” Burbridge said.

Using a technique called 2-photon microscopy, Crair and his team created a fluroescent image of the mouse nervous system that allowed them to visualize the burst.

Ackman said the waves are caused by interactions between different cells in the retina, but the precise mechanism remains unknown. The wave is spontaneous, meaning that it does not require external sensory input to occur. This phenomenon is analogous to dreaming, in which human brains exhibit spontaneous activity even though we are not receiving significant environmental stimuli.

“I think it’s amazing that even in the womb there is ongoing, patterned activity in the developing brain, which is essential for wiring the brain,” Crair said. “If you disrupt that activity, then the wiring of the brain gets messed up.”

This research could provide a more complete explanation as to why smoking and drinking alcohol are detrimental to a baby’s growth in the womb. For instance, the study shows that the neural burst involves acetylcholine receptors, which are the same neural receptors involved in nicotine addiction. Because nicotine activates these receptors, the presence of the drug could alter the neural burst and potentially affect the development of the fetus’s nervous system.

Though the research was conducted in mice, the information can be applied to understanding how human brains develop. Ackman said mammalian nervous systems follow similar principles of organization.

“The power of genetic technologies in mice makes them a very powerful model.”

Further study is necessary to elucidate the exact relationship between developmental diseases and the spontaneous burst of neural activity.

Correction: Oct. 16

An earlier version of this article misidentified 2-photon microscopy as photon microscopy.

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