Last weekend the name was all over the internet – just not on ChatGPT. David Mayer became famous for a moment on social media because the popular chatbot appeared to want nothing to do with him. Legions of chatbot wranglers spent days trying – and failing – to make ChatGPT write the words "David Mayer". But the chatbot refused to comply, with replies alternating between "something seems to have gone wrong" to "I'm unable to produce a response" or just stopping at "David". This produced a blizzard of online speculation about Mayer's identity.

We introduce Brain-Artificial Intelligence Interfaces (BAIs) as a new class of Brain-Computer Interfaces (BCIs). Unlike conventional BCIs, which rely on intact cognitive capabilities, BAIs leverage the power of artificial intelligence to replace parts of the neuro-cognitive processing pipeline. BAIs allow users to accomplish complex tasks by providing high-level intentions, while a pre-trained AI agent determines low-level details. This approach enlarges the target audience of BCIs to individuals with cognitive impairments, a population often excluded from the benefits of conventional BCIs. We present the general concept of BAIs and illustrate the potential of this new approach with a Conversational BAI based on EEG. In particular, we show in an experiment with simulated phone conversations that the Conversational BAI enables complex communication without the need to generate language. Our work thus demonstrates, for the first time, the ability of a speech neuroprosthesis to enable fluent communication in realistic scenarios with non-invasive technologies.