DARPA Wants Bidirectional Brain Implants, 1 Million Neuron Resolution a “Starting Point”
July 11th, 2017Via: IEEE:
DARPA is known for issuing big challenges. Still, the mission statement for its new Neural Engineering Systems Design program is a doozy: Make neural implants that can record high-fidelity signals from 1 million neurons.
Today’s best brain implants, like the experimental system that a paralyzed man used to control a robotic arm, record from just a few hundred neurons. Recording from 1 million neurons would provide a much richer signal that could be used to better control external devices such as wheelchairs, robots, and computer cursors.
What’s more, the DARPA program calls for the tech to be bidirectional; the implants must be able to not only record signals, but also to transmit computer-generated signals to the neurons. That feature would allow for neural prosthetics that provide blind people with visual information or deaf people with auditory info.
Today the agency announced the six research groups that have been awarded grants under the NESD program. In a press release, DARPA says that even the 1-million-neuron goal is just a starting point. “A million neurons represents a miniscule percentage of the 86 billion neurons in the human brain. Its deeper complexities are going to remain a mystery for some time to come,” says Phillip Alvelda, who launched the program in January. “But if we’re successful in delivering rich sensory signals directly to the brain, NESD will lay a broad foundation for new neurological therapies.”
There is a lateral geniculate nucleus (LGN) at the other end of each optic nerve. Every visual input goes through these before reaching the visual cortex.
http://slideplayer.com/slide/8109458/25/images/17/Optic+nerve+Optic+tract.+Optic.+chiasm.+Hypo-+thalamus.+Lateral.+geniculate.+nucleus.+Pretectum..jpg
“To our knowledge, stereologic analysis of total cell number has not been performed in the adult human LGN prior to the present study. A previous study of adult human LGN volume (Andrews et al., 1997) found larger mean volumes for parvocellular (90.42 mm3) and magnocellular (28.03 mm3) layers than measured in the present study. The discrepancy probably is due to differential shrinkage resulting from differing postmortem processing methodologies in the two studies. The one study of total cell number in the human LGN, which examined only 2 late-gestational fetuses and utilized non-stereologic methods, found total neuronal counts in LGN of 1.68 million (Khan et al., 1993). LGN volume and neuronal number exhibit a high degree (at least two-fold) of variability among individuals (Spear et al., 1996; Andrews et al., 1997, present study) so that any estimate of neuronal number based on two cases might be skewed far from the true mean. Estimates of total cell number based on stereologic methods are independent of measured volume, cell size and section thickness and therefore can more reliably be compared across studies.
Several studies in non-human primates have utilized stereologic cell counting methods to estimate the number of neurons in the normal, young adult LGN either as a control for experimental manipulation (Berman et al., 1998; Boire et al., 2002), development (Willliams and Rakic, 1988), aging (Ahmad and Spear, 1993), or as a primary interest (Sunner and Rakic, 1996; Blasco et al., 1999). Despite differences in methodology and species examined, these studies are generally in agreement in estimating approximately 1.4 million neurons in the whole LGN; neuronal number in the pigtail monkey (1.79 million) was slightly higher (Blasco et al., 1999). In the present study, we estimated approximately 2.5 times as many neurons (3.4 million; range 2.5–5.1 million) in the combined parvocellular and magnocellular subdivisions of the human LGN compared to the non-human primate LGN.”
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2048985/
err the first link doesn’t work properly. Here’s another picture : https://i.pinimg.com/originals/5a/ac/39/5aac39c69574ad4d3d3c810391d928d3.jpg