Once we crack the neurological code and develop genuine brain-machine interfaces, all previous methods of torture will look like child's play.
Past torture has necessarily focused on the body and senses as the means to induce pain, but these methods are indirect in the sense that you're relying on the victim's nervous system to transmit that pain to the brain. This indirect method has many obvious drawbacks, such as the victim's nervous system acclimating to the stimuli and reducing the felt pain, or releasing endorphins, and many torture methods damage the body in a way that limits how long you can make it last.
Once we establish a direct connection to a person's CNS, all of that goes out the window. You could simulate literally any type of pain at intensities that shouldn't even be possible just by mimicking the right neural signals, and since the body is obviously not being damaged by this, there's no limit to how long you can make it last. I'm sure we'll also have ways to counter the brain's built-in responses to intense pain, like preventing the release of endorphins and adrenaline, or disabling whatever neural circuit breaker causes people to faint from pain.
On the plus side, we'll also get true immersive VR and soma-like virtual drugs that have no unpleasant side-effects, so it's a tradeoff in the end.
