In Sid Meier's Alpha Centauri (SMAC), the Neural Amplifier is a Secret Project. It may be built at a cost of 270 minerals, on discovery of Neural Grafting (B3). It gives +50% Psi Defense rating for all your units.

How useful is this? Although this Project is a natural pursuit if you (or a hostile neighbor!) have invested heavily in a Psi-oriented military (i.e. lots of captured and/or bred Mind Worms), it's useful for any faction, as it increases all your units' chances of surviving an attack of wild Mind Worms. It's particularly useful for the Gaian (green, Deirdre Skye) faction, as the faction design encourages investment in native, Psi-combatant units right from the start of the game. There's really no escaping occasional Psi skirmishes, but if the Gaians are neighbors at higher difficulty levels and they're not playing nice, this is an excellent defensive Project. The complementary +50% Psi Attack doesn't show up until the discovery of The Will to Power (E9), enabling the building of the Dream Twister Secret Project.

Secret Project animation narrative:
"Against such abominations, we organize our defenses on the principle that one strong and able mind can shield the many."
   -- Spartan Battle Manual