CED Signal: Patch clamp

Signal incorporates many powerful features for whole cell and single channel experiments that make it ideal for electrophysiological recording. Familiar terms, and easily set up protocols for standard requirements enable the user to get started quickly using Signal and a CED 1401 data acquisition interface. Signal also incorporates an import function allowing you to analyse data from other recording systems.

Clamp specific sampling support

Nominate a particular recording state to be used for seal and membrane resistance measurements.

Easy adjustment of holding potentials.

Dynamic readout of seal resistance.

Support for dynamic clamp studies with up to 15 selectable conductance models. Update rates of over 300kHz without timing jitter - see details.

Single channel patch clamp analysis

Membrane analysis option displays measurements of total resistance, access and membrane conductance, capacitive transient decay time constant and membrane capacitance.

Display selected measurements as a graph against time.

Amplifier communication

Telegraph communication to set channel scales based on voltages supplied from a wide range of patch clamp amplifiers.

Direct software communication with Molecular Devices MultiClamp 700 and Axoclamp 900 amplifiers. Reads values for gains, filter settings, membrane capacitance, series resistance and external command sensitivity. The values read are stored in the Signal data file.

Membrane analysis during sampling

Stimulus generation

Generate stimuli on up to 8 DACs and 8 TTL lines

Define as many as 256 sets of up to 500 pulses

Set stimuli at a fixed level or relative to an adjustable holding potential or current

Output multiple sets of arbitrary waveforms per sweep. Waveforms are held in 1401 memory for very accurate timing

Sequence through sets of pulses manually, cyclically, randomly or by user-defined protocol

Interactively edit, add and remove stimuli while recording

Define pulses with fixed or stepping amplitudes and durations

Pulse types include square waves, ramp, sinusoid, pulse trains and pre-recorded or user-generated waveforms, for example, recorded action potentials

Pulse configuration dialog

Analysis

Leak subtraction

3 methods of defining leak data on-line and off-line
On-line and off-line subtraction of scaled leak trace, including capacitive transients
Subtract specific leaks on-line in current clamp using a selection of dynamic clamp models

Measurement plots

The trend and measurement plot function in Signal generate graphs of measurements taken from the recorded data both on-line and off-line. For each frame selected, measurements are taken from individual or multiple events and plotted as X and Y coordinates. Typical examples would be the generation of an IV curve or measurements from multiple action potentials.

Analysis of paired recording from a pyramidal cell
connected with a fast spiking interneurone in the cortex†

Curve fits

Fit mathematical functions to original or leak subtracted data and trend plots.

Fit types include:
- Exponential, first or second order
- Gaussian, one or two
- Polynomials from first to fifth order
- Sigmoid (Boltzmann) curve

Gives best fit coefficients and an estimate of confidence

Display fit coefficients in trend plots

Exponential curve fitting on multiple traces

Single channel analysis

Idealised trace generation converts the waveform to a set of events describing the state of the channel(s) at the time of each transition point. Details include time, duration, mean amplitude and flags for open/closed, first latency and level - see a video demonstration.