FPGA implementation of a “dynamic-clamp” system

Abstract

The dynamic-clamp electrophysiological technique allows the mimicking of the electrical effects of ion channels embedded into the membrane of an intracellularly recorded cell. Dynamic-clamp relies on the establishing of a loop between the injected current and the recorded membrane potential. In this work, a real-time dynamic-clamp system was implemented on a Field Programmable Gate Array (FPGA). The system proposed allows the concurrent controlling of the activation of several ion channels. The architecture of the instrument developed is based on two main modules: a state machine (as the logic arbiter) with the ADC and DAC interface, and a signal processing module. The state machine controls the converters along with the serial data-transfer interface (SPI). The signal processing module implements the algorithms needed to mimic several HH-type ion channel conductances. Extensive simulations of the device operation were made, showing that the instrument developed implements effectively the dynamic-clamp control loop, with a maximum operation frequency of 532 kHZ. The main application of this instrument is the manipulation of ion channels.