Neurons are powerups that are utilized in Space Invaders Infinity Gene.
Appearance[]
Neurons, despite their name, look like molecules, or more notably, Newalone from Metal Black.
Function[]
Neurons are used to upgrade a ship's attributes. For example, collecting Neurons increases the Field's range. In Metal Black, Newalone is used similarly.
The aliens from Metal Black also use Newalone to power their laser weapons, so the Invaders likely use it in a similar manner.
Relations to Metal Black[]
While it may seem like an odd choice to reference, Metal Black has been referenced many times in other games, due to its status of being a Darius game removed from the lore. This makes its ultimately unused ideas valuable for other Taito properties.