This work was supported in part by the National Institutes of Health (NS054809), the Emory University Neurosciences Initiative, a Coulter Foundation Translational Research Award, the National Science Foundation (EFRI 0836017), and an Epilepsy Research Foundation New Therapy Grant. We also thank the students of Georgia Tech's Hybrid Neural Microsystems course (Robert Ortman, Jeff Bingham, Wafa Soofi, and Ryan Hooper) and Dr. Chad Hales for helping adapt NeuroRighter for use in vitro. 1http://www.gnu.org/copyleft/gpl.html.
2http://creativecommons.org/licenses/by-sa/3.0/us/.
Key Concept
Open loop  A system which creates output regardless of external conditions, or which reads input and takes no action to affect further input. A simple example is a quartz watch, which tracks time, but receives no feedback from the world outside.
Closed loop A system where a sensed signal alters the system output which, in turn, may alter the sensed signals. A prototypical example is an air conditioner, where a thermometer measures temperature, which will determine whether more or less cold air is pumped out. Because this cold air alters the temperature, the system is a closed loop.
Hybrot A hybrid of a living neuronal system and a robot. It is most often used to refer to a mobile robot controlled by a neuronal network maintained in vitro. With such artificially embodied in vitro networks, the experimenter has complete control of the inputs to a simplified nervous system. The term can also describe animals or people with neural interfaces to robotic limbs or other mechanical actuators.
Efferents Signals, such as action potentials, emanating from the living neural system. In the natural context, efferents cause muscles to contract (or glands to secrete). Any signal recorded artificially from the neural system can be viewed as an efferent, and used to control external actuators, or to trigger stimulation.
Afferents Signals carried into the neural system, such as action potentials from sensory organs. Electrical stimuli can serve as artificial afferents, to carry sensory information, induce plasticity, or modulate ongoing activity.
Stimulation artifact Large-amplitude signal picked up by recording electrodes during and after an electrical stimulation pulse. The artifacts obscure underlying neural signals, like action potentials or the local field potential. They occur because the amplitude of stimulation (on the order of volts) is orders of magnitude greater than extracellular signal (10–100s of microvolts).
Open source Practice by which software or hardware is released along with its underlying code, schematics, or other source materials. Open-source projects, depending on their licensing, allow users to explore, validate, and modify the sources, potentially bringing about more stable, useful products.
Closed source Practice by which software or hardware is released without providing users access to the underlying code, schematics, or other source materials. This provides some protection of intellectual property for the creator, though does not prevent reverse engineering.
Interictal spike Burst of neural activity, lasting 10–100s of milliseconds, observed in the extracellular field potential (e.g., EEG, LFP). Indicative of epilepsy or seizures, but occurring between seizures – inter meaning between, ictal meaning seizure (when used in medical literature).
Steve M. Potter is the Director of the Laboratory for Neuroengineering at the Georgia Institute of Technology, and an associate professor in the Coulter Department of Biomedical Engineering. He has combined engineering and neuroscience to build research tools to study learning mechanisms in living networks, including multi-electrode neural interfaces, a high-speed neuroimaging CCD camera and two-photon laser-scanning microscopes. He founded the field of embodied cultured networks, in which robots or simulated animals are controlled by neuronal networks grown in vitro on multi-electrode arrays.