To successfully manipulate cognitive processes, the first step is to read and interpret the brain's signals. Only when we understand how the brain processes and represents information can we hope to alter that language when it goes wrong or to improve upon its baseline functioning. A wide range of technologies, from deeply invasive brain implants to non-invasive wearables, are now in various stages of sophistication.⁵ Some are beginning to emerge into the clinic and — as with many medical interventions that start as therapy — into the general population. Major invasive techniques are deep brain stimulation (DBS), cortical stimulation and opto- and chemogenetics, which are used mostly in animal research.

Non-invasive techniques to record brain activity are electroencephalography (EEG), magnetoencephalography (MEG), and functional magnetic resonance imaging (fMRI).⁶ Each class of technology has benefits and trade-offs; invasive technology yields higher resolution data yet non-invasive is more convenient and will get us more generalisable data in the general population.⁷