How and how much to change the brain

Our expert voices conversation on "When computers merge with our minds."

When we're awake, the 100 billion intricately connected neurons in our brain are entirely active, receiving, analyzing, and responding to the inputs we're collecting from the world. The idea then of inserting a machine into that complexity in order to enhance or suppress behavior comes with many challenges.

Problem to be solved: How do we pick a target? The brain is a mesh of multiple networks associated with different functions, so you can actually cause impulsivity or depression in patients with Parkinson's because stimulating one network means you can accidentally activate another. Some conditions, like depression, have several possible targets within the brain. Which of the many candidates should be stimulated — and how?

Where to draw the line: Research has shown that stimulating certain brain areas increases memory capabilities and improves learning. Treating disease serves the public — but enhancing our cognitive abilities runs the risk of only serving some. If we could design a brain chip to enhance memory, how would we price it and keep a level playing field?

The other voices in the conversation:

• Steven Chase, biomedical engineer, Carnegie Mellon University: What to fear
• Andrew Hires, neurobiologist, University of Southern California: An optical link to the brain
• Sliman Bensmaia, neurobiologist, University of Chicago: The internet inside your mind