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The Light Bulb Moment for Brain Development

A zebrafish head viewed from front-on showing neurons in a slice of its brain labelled with a fluorescent calcium indicator.

A zebrafish head viewed from front-on showing neurons in a slice of its brain labelled with a fluorescent calcium indicator.

By Geoffrey Goodhill & Lilach Avitan

Some elegant experiments in zebrafish have revealed how sensory experience during infancy can have long-lasting effects on the brain.

The full text of this article can be purchased from Informit.

The brain develops through a combination of innate and environmental factors. The initial patterns of wiring are specified genetically, but this provides only a rough starting framework. From there, neural activity is required to refine these patterns. Using the zebrafish as a model, we have now discovered more about how this process works.

Neural activity in the brain is generated in two ways. Most obviously it is caused by sensory inputs such as sights, sounds and smells. However, it can also be generated spontaneously within the brain without an external stimulus. It’s as if the brain is internally rehearsing the kind of input patterns it expects to encounter from sensory stimuli.

How does this spontaneous activity change over development, and how is it affected by the sensory environment? It’s obviously hard to study this in humans, but zebrafish offer an attractive alternative.

Unlike humans, zebrafish grow very quickly. Within only 5 days of the egg being fertilised, when they are only a few millimetres long, they are mature enough to begin hunting fast-swimming paramecia.

Larval zebrafish are also transparent, and their neurons can be genetically labelled with a fluorescent calcium indicator. When a neuron fires, calcium flows into it so that labelled neurons glow brighter when they are active.

We can therefore study brain activity...

The full text of this article can be purchased from Informit.