NTZ blog has been paying close attention to neural prosthetic devices aimed at improving cognitive functions. We have presented the beneficial effects of direct current stimulation (tDCS) of the temporal lobe and frontal cortex, DBS of the fornix, and recording in CA3 region coupled with stimulation of CA1 region in the hippocampus. The last-mentioned study was performed using a rat preparation in 2011 by a Prof. Ted Berger at the University of Southern California and Prof. Samuel Deadwyler at Wake Forest University. Merely a year later, the same group of researchers has accomplished a new feat – a closed loop recording and stimulation in the rhesus monkey’s prefrontal cortex, an important location for decision-making and short-term memory processes. The same nonlinear dynamic model (MIMO) was applied for decoding, enhancing, and re-encoding of the firing patterns. To access the prefrontal cortex, the ceramic-substrate multisite electrodes were chronically implanted, targeting the supra-granular layer 2/3 and infra-granular layer 5. Cocaine was used to disrupt cognitive activity, simulating the brain injury. As you can see in the graph above, the memory task performance was fully restored by MIMO-patterned electrical stimulation during the task execution. The far-reaching goal of the project is to replace the memory forming process in the brain area damaged by stroke, dementia or other disorder by using a neuroprosthetic device interfaced to the healthy decision-making area of the brain.