The Biodigital Brain

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Science Translational Medicine  29 Jun 2011:
Vol. 3, Issue 89, pp. 89ec101
DOI: 10.1126/scitranslmed.3002801


When a memory chip in our laptop goes bad, we simply plug in a replacement chip. When our own biological computer (our brain) malfunctions—for example, because of stroke, trauma, or degenerative disease—can we too just swap in a new chip? Neuroprosthetic research is now at the tipping point of unveiling such possibilities: Berger et al. demonstrate a prosthetic system that can partially reestablish the broken linkage between two cortical areas, restoring normal nervous system function.

Berger and colleagues used a rat model to study memory formation and enhancement with their neuroprosthetic system. Thirty-two micro-wire electrodes were implanted bilaterally in the CA3 and CA1 areas of hippocampus—the brain structure that is responsible for memory formation—and were used for multichannel neural stimulation and recording. The authors modeled neuronal activity patterns at CA3 and CA1 as a multi-input/multi-output system; from this, they could predict CA1 neuronal activity (output) on the basis of CA3 neuronal activity (input). Using this computational model and the neuroprosthetic hardware, they were able to form an information pathway that bypassed damaged neuronal connections between those areas. To demonstrate the effectiveness of their device in memory function, the authors tested whether the rats could memorize which lever (left or right) it had pushed up to 60 seconds prior. Importantly, when the CA3–CA1 circuit was damaged artificially with a pharmacologic agent that blocks synapses, the neuroprosthetic device was able to restore memory function in the rats, thus demonstrating the potential clinical use of such devices. Although this study focused on hippocampus and memory, the implication is broad for repairing or replacing any damaged neuronal circuit, which will hopefully lead to a new paradigm for treating stroke, spinal cord injury, and other neurological disorders.

T. W. Berger et al., A cortical neural prosthesis for restoring and enhancing memory. J. Neural Eng. 8, 046017 (2011). [Abstract]