Multichannel Acquisition Processor (MAP)

The Plexon Multichannel Acquisition Processor (MAP) sets the standard for programmable amplification, filtering, and real-time spike sorting of multi-electrode signals acquired in neurophysiological research.

The MAP is a modular system of plug-in circuit boards that are mounted in a stand-alone box. This unique architecture results in a robust and reliable system that is easily scalable in capacities of 16, 32, 48, 64, 80, 96 and 128 channels. Upgrade boards- including signal boards, DSP boards, digital input boards, digital output boards, and host link boards- are also available. The MAP system can also record up to 64 continuous analog signals at 40 KHz using National Instruments Data Acquisition (NI DAQ) devices. For example these signals can be field potentials, eye position, or blood pressure. The analog channel count is dependent upon the acquisition speed. Decreasing the acquisition speed to 10 KHz increases the channel count to 256 channels.

A powerful component of the MAP system is the Plexon MAP Control Software, or Real-Time Acquisition System Programs for Unit Timing in Neuroscience (RASPUTIN), a suite of client/server programs that control spike sorting in the MAP and provide real-time data visualization and analysis. The RASPUTIN program records spike, digital-event data, and analog signals in to a single data file.

• Powerful, large-scale neuronal waveform recording and real-time spike sorting using digital signal processing (DSP) hardware
• Supports stereotrode and tetrode data acquisition
• Independent programmable referencing for spikes and field potentials
• Easily scalable from 16 to 128 channels
• Capable of synchronizing all of the components in the data acquisition system via internal clock
• Simultaneous 40 kHz (25-µsec) analog-to-digital (A/D) conversion on each channel at 12-bit resolution
• Ten-pole, total high-cut filtering across the system completely eliminates high-frequency noise from industry-leading eye coil systems (typically using pairs of frequencies above 50 kHz
• Multiple digital inputs for external synchronization and experiment-state of variables from behavioral equipment, such as individual TTL lines of multi-bit strobed word data
• Optional analog signal acquisition for continuous recording of spike, field potential, physiological, and behavioral signals
• Optional rack-mount configuration
• TCP/IP and UDP packet data link for real-time applications, ~2ms total latency

RASPUTIN is a suite of applications for control, visualization, and data analysis. RASPUTIN's primary application/user interface is Sort Client. Sort Client visualizes, analyzes, and records spike waveforms that have been filtered and sorted by the MAP. The main window of Sort Client, shown at the right, displays the waveforms in several different views to facilitate detection and classification of spikes. One method the MAP uses to identify neurons is displaying waveforms as data points in three-dimensional principal component analysis (PCA) space.

As shown in the close up view of the 3D Cluster Display at the lower right, a cluster of points, which represents an individual spike, can be easily selected by drawing a boundary around it, which then establishes a template that is sent back to the MAP for real-time sorting.

Sort Client Features

• Real-time spike waveform detection and classification via template matching or time-voltage window discrimination
• Programmable gain and spike detection thresholds 
• Online viewing of continuous signals, thresholded spikes, activity rasters and 2D and 3D cluster displays;
• Multi-channel waveform display 
• Open file format allows recorded spikes or continuous real-time signals to be accessed via NeuroExplorer®, MATLAB®, or C/C++® 

Additional RASPUTIN Applications In addition to Sort Client, RASPUTIN includes the clients in the table below, all of which provide on-line functionality.