In mammalian cortex, this means (much) faster than 10 kHz. The stumbling block is that dynamic clamp calculations must be done in real time, which is to say faster than any meaningful changes in channel properties or in membrane potential. The idea of dynamic clamp is simple, but how to implement it is not. The shift in emphasis requires that the electrophysiological system monitor membrane potential and use it, in real time, to calculate what current simulated channels would have passed had they been physically present. Introduced independently and concurrently by two different groups ( Sharp et al., 1992, 1993 Robinson and Kawai, 1993), dynamic clamp is grounded in the idea that the effects that voltage-gated and ligand-gated channels have on a neuron’s membrane potential can best be understood as changes in conductance rather than in current. And yet there is a third extant and potentially useful configuration: dynamic clamp (a.k.a., conductance clamp Prinz et al., 2004 Destexhe and Bal, 2009 Prinz and Cudmore, 2011). Every trained electrophysiologist is familiar with their properties, and every standard electrophysiological system incorporates them. We demonstrate the system’s utility by implementing conductances as fast as a transient sodium conductance and as complex as the Ornstein–Uhlenbeck conductances of the “point conductance” model of synaptic background activity.Ĭurrent clamp and voltage clamp are the standard configurations of cellular electrophysiology.
Moreover, the process of assembling, modifying, and using the system constitutes a useful pedagogical exercise for students and researchers with no background but an interest in electronics and programming. The system works together with existing electrophysiology data acquisition systems (for Macintosh, Windows, and Linux) it does not attempt to supplant them. Modifying it-for example, to add Hodgkin–Huxley-style conductances-requires no prior programming experience. The overall cost of the system is less than USD$100, and assembling it requires no prior electronics experience. We demonstrate this by implementing a fast (∼100 kHz) dynamic clamp system using an inexpensive microcontroller (Teensy 3.6). Technological advances associated with the so-called maker movement render them moot. These have been valid and limiting issues in the past, but no longer. That it is not, even 25 years after its introduction, comes down to three issues: money, the disruption that adding dynamic clamp to an existing electrophysiology rig entails, and the technical prowess required of experimenters. The dynamic clamp should be a standard part of every cellular electrophysiologist’s toolbox.
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