AUTHOR=Wallach Avner 

TITLE=The response clamp: functional characterization of neural systems using closed-loop control

JOURNAL=Frontiers in Neural Circuits

VOLUME=Volume 7 - 2013

YEAR=2013

URL=https://www.frontiersin.org/journals/neural-circuits/articles/10.3389/fncir.2013.00005

DOI=10.3389/fncir.2013.00005

ISSN=1662-5110

ABSTRACT=The voltage clamp method, pioneered by Hodgkin, Huxley and Katz, laid the foundations to neurophysiological research.  Its core rationale is the use of closed-loop control as a tool for system characterization.  A recently introduced method, the response clamp, extends the voltage clamp rationale to the functional, phenomenological level.  The method consists of on-line estimation of a response variable of interest (e.g. the probability of response or its latency) and a simple feedback control mechanism designed to tightly converge this variable towards a desired trajectory.  In the present contribution I offer a perspective on this novel method and its applications in the broader context of system identification and characterization.  First, I demonstrate how internal state variables are exposed using the method, and how the use of several controllers may allow for a detailed, multi-variable characterization of the system. Second, I discuss three different categories of applications of the method: (i) exploration of intrinsically generated dynamics, (ii) exploration of extrinsically generated dynamics and (iii) generation of input-output trajectories. The relation of these categories to similar uses in the voltage clamp and other techniques is also discussed.  Finally, I discuss the method’s limitations, as well as its possible synthesis with existing complementary approaches.