System introduction Stimulus and response recording with multiple simultaneous measurementsSignal is a sweep based data acquisition and analysis package. Its uses range from a simple storage oscilloscope to complex applications requiring stimulus generation, data capture, control of external equipment and custom analysis. This flexibility makes it ideal for a wide range of applications including transient capture, patch and voltage clamp, LTP studies and evoked response.
Signal is simple to set up for data capture and analysis.
Signal includes a number of functions for specific application areas including whole cell and patch clamp electrophysiology and evoked response including control of magnetic and other stimulus devices.
Signal has the sampling and analysis features most researchers need, in a user-friendly environment. There is also a built-in script language that allows automation of repetitive tasks and provides additional tools for researchers who prefer to write their own applications.
Signal can import data recorded by many other systems, so you can take advantage of this extremely versatile system to analyse existing data away from the recording system.
The powerful data capture and time-saving analysis functions of Signal together with one of the CED 1401 family of laboratory interfaces make an extremely flexible and cost effective addition to any laboratory.
Features Automated action potential analysis
Record sweeps of waveform and marker data, free-running or time-locked to a stimulus or response
Perform analysis on-line and off-line including waveform averaging (with error bars), power spectra and amplitude histograms
Detect and measure waveform features both on-line and off-line to generate XY plots from raw data and averages
Generate simple and complex protocols of waveform and digital output and modify the output interactively even while sampling
Overlay data from multiple sweeps and channels
Automate and customise analyses and repetitive tasks
Use advanced tools for whole-cell voltage clamp, current clamp and single channel patch clamp analysis (leak subtraction, open/closed time histograms)
Digitally filter (FIR and IIR) via interactive dialogs or scripts
Apply curve fitting using a variety of fit equations; fit coefficients can be plotted automatically to an XY view
Configure multiple views of the same data file, even during sampling
Display linear and logarithmic axes and define tick spacing and number
Design stimulus outputs graphically, react to sampled data and apply complex interaction with scripts
Communicate with and control a range of external devices including amplifiers and stimulators using built-in functions
Acquisition
Record and display fast sweeps of waveform data to disk with over 15 million data points per sweep with a Power1401
Output pulse, sine, ramp and stored waveforms while sampling
Generate sets of varying stimuli on up to 8 waveform and 16 digital outputs
Sample multiple waveform inputs at aggregate rates up to 1MHz
Easily switch sampling configurations or output protocols
Capture free-running or triggered sweeps with post or peri-trigger modes
Trigger sweeps of data from external pulse, waveform threshold crossing or internal clock
Sample variable numbers of points in different sweeps to match experimenters’ requirements
Tag frames to indicate state or artefacts for selective review and analysis
Perform built-in and custom analyses on incoming sampled data
Configure dynamically programmable amplifiers including the CED 1902 low-noise isolated pre-amplifier, the Power1401 gain option and stimulators such as the CED 3304 constant current stimulator
Read back settings and configuration from Axon Multiclamp 700A/B
Sample at arbitrary or varying rates with external convert input option
Typical applications and script-driven functions Data capture with independent frame length per stimulus type Evoked response and TMS Output fixed, random and pseudo-random pulse outputs with on-line and off-line waveform averages and measurements of latencies, amplitudes and areas. Auto-averaging enables the user to specify the last n frames to form an average and measurements can be taken automatically from the results. Signal can control Magstim transcranial magnetic stimulators during data acquisition, including adjusting stimulator amplitude and timing and checks on stimulator condition. Settings are stored with the corresponding data frame.
LTP / LTD Generate single, paired and trains of pulses on multiple outputs. Signal automatically measures baselines, amplitudes, latencies, areas, durations, percentage rise and decay times, and population spike parameters for single or multiple responses per frame.
Whole cell voltage and current clamp Interactively control holding potentials and pulse outputs using the graphical sequencer. Construct I/V plots, leak subtraction and curve fits on-line and off-line.
Single channel patch clamp Detect single and multi-level channel openings on-line and off-line automatically. Produce measurements such as open/closed times and amplitudes and display result histograms.
EMG Record single and multiple channels of EMG with software control of amplifiers such as the CED 1902. Perform rectification and smoothing at the touch of a button or under script control. Produce power spectra that update as new data sweeps are captured.
Transients Detect waveforms rising or falling below a threshold as a trigger. Capture peri-trigger data up to the available size of memory inside your CED 1401. Optionally output stimuli in response to the trigger.
Auditory evoked potentials Generate complex stimulus protocols and reports under script control. Features include: automatic artefact rejection, digital filtering, generation of sub and grand averages and feature detection using active cursors. LTP analysis with tabulated results
Output pulse editor
Output states control
Single channel patch clamp analysis
Complex stimuli and experimental control
Signal generates a large range of output stimuli, with two methods available for specifying outputs. The graphical pulse editor covers the majority of stimulus requirements in an easy to use drag and drop environment where you build up to 256 sets of up to 500 pulses. Outputs are fixed or they can change amplitude and duration on repeats. You can also modify them while sampling continues.
If your requirements cannot be met with the pulse editor you can define your outputs as a text sequence of instructions. This makes it possible to control the sequence interactively through the script language by use of variables and tables.
The script language has further experimental control options including communication through serial lines, files and commands for starting and stopping other programs.
Advanced features
Multiple sampling conditions Signal includes a comprehensive multiple output states system that provides differing pulse outputs or stimuli while sampling. The order and repeats of each stimulus can be sequenced using a predefined protocol or executed semi-randomly or randomly. Each frame of data is marked to indicate the stimulus that was used.
Voltage and current clamp Signal generates all of the stimuli needed for voltage and current clamp protocols, including pre-recorded action potential waveforms. Multiple sets of stimuli can be stored in one sampling configuration and selected manually or automatically sequenced. Voltage stimuli levels are either relative to an adjustable holding potential or fixed. Automated on-line measurement of seal and membrane resistance can be made during recordings. Leak-subtraction and I/V plots are always available even while sampling. Curve fitting can be applied to raw waveform data, leak subtracted data and I/V plots.
Single channel patch clamp Signal produces idealised current traces from patch data showing detected transition events. The idealised trace is editable by dragging open/closed times and amplitudes; there are additional tools for splitting and combining events. Amplitude histograms from raw or idealised data and dwell time histograms from idealised traces are available. Derived histograms can be characterised by a number of fit types.
A special feature is the reverse convolution fitting of an amplifier's step response to filtered single channel patch clamp data allowing superior time resolution of events.
Script language
From complete beginners to experienced programmers, everybody can benefit from the built-in script language. Even simple automation of repetitive tasks with known parameters can save hours or even days of tedious analysis. Advanced scripts can provide complete experiment control with on-line application of original algorithms to sampled data in real-time.
The script language allows you to generate your own interface and design algorithms. There is a macro recording facility to provide a starting point for new scripts. The script language also includes data manipulation tools such as multi-dimensional arrays and matrix functions.
CED maintains a library of example scripts for a wide range of common and specialised applications. If the scripts included with the Signal software or those available from our web site do not fulfil your exact requirements, please contact us to discuss the available options. These include modification of existing scripts and a dedicated script-writing service.
Signal version 4 features
Single channel (SCAN) analysis provides incremental processing of single channel data to produce an idealised trace by reverse convolution fitting of the amplifier's step response function with the raw data
Enhanced multiple states sequencing with automatic cycling and protocol execution at start
Multiple or averaged measurements, generated using active cursor iteration across data frames, can be placed in an XY display
Gap-free sampling records sweeps continuously with no missing points
Variable number of points can be sampled in different sweeps to match experimenters’ requirements
New script editor with options including intelligent hiding of blocks of script, auto formatting, auto complete and call tips
Capability added for script code sharing and re-use through include files
Interactive IIR filtering and improvements to the FIR filtering dialog
Enhanced Power-Spectrum analysis, up to 16384 point FFT and windowing
Extended header and footer customisation for printed output
Improved XY plot display options including fill of looped areas
User defined keyboard shortcuts for use with single channel analysis
Control of muscle length with analysis of resultant tension slopes
Signal on-line help: Digital filtering
Hardware requirements
Signal version 4 requires a CED Micro1401, Power1401 or 1401plus intelligent laboratory interface and a PC with Windows 98SE, ME, NT 2000, XP, XP64 or Vista™. We recommend that the PC has a minimum of 1GB of RAM.
Signal can export data to other applications as text, binary or image files. The Signal data format (CFS) is freely available to programmers wishing to read and write Signal data filesWindows®, Magstim and Multiclamp are registered trademarks of their respective holders.
System introduction