Neural implants? Sure: molecular electronics; NEMS extruding CNT fibers like feelers right into the midst of synapses; sniffing at neurotransmitters and emitting their own. Whatever sort of mental boost you wanted, there was a plug-in for it.
We wanted something more flexible. What if we could shrink the device and stick it between neurons? Make it a gateway: switch the neuron on and off or allow it to work like normal. Give them their own signal molecules; have them sip at blood-borne sugars via protein-derived fuel cells. Fill your head with billions of them. Like a supercharged neural-net FPGA.
It was like overlaying a computing substrate on the entire brain… or vice versa. A leap in our intelligence unprecedented since the invention of language or the emergence of consciousness itself — ironic, I suppose. The learning algorithms dictating the behaviour of our little pets took one look at all the activity in the prefrontal cortex, decided it was a massive waste of resources, and turned it off.