Brain-machine interface for declarative memory in humans


Development of brain-machine interfaces (BMI) greatly accelerated in the last decade, shifting from the monkey feasibility studies toward actual human testing. The pioneering studies with the BrainGate implantable array of microelectrodes proved the usefulness of BMI to a paralyzed person for variety of everyday functions. The latest study, published in October 28, 2010 issue of Nature, provides further evidence that BMI can be used for providing access to specific visual memories.  Researchers at the California Institute of Technology and UCLA Ronald Reagan Medical Center evaluated the single-unit neuronal activity from the microelectrode arrays implanted in the medial temporal lobe of patients with severe treatment-resistant epilepsy. The recording sites spanned the parahyppocampal cortex, hippocampus, and amygdala. These brain regions are intimately involved in declarative memory processes. Accessing declarative memory with a closed-loop BMI interface is challenging to setup in monkeys as it requires sophisticated behavioral methods for reading out the animal’s responses. In contrast, visual memories in human subjects can be easily interrogated using images projected on a computer monitor and their feedback for decoding algorithms can be collected by pressing the keyboard buttons. Looking a bit into the future, one can speculate that larger BMI arrays can be used for a comprehensive cognitive interface allowing paralyzed humans to apply their conscious thoughts for controlling their environment.