Saturday, September 14, 2013

MOM and MCS 2.0: now with resonant scanning

Resonant scanning allows video rate two-photon imaging at 31 frames per second, a near 10-fold increase in frame rate over conventional scanning. Sutter Instrument is now proposing its Moveable Objective Microscope with either conventional or resonant scanners.  Current owners of the MOM can also benefit from the advantages of resonant scanning without having to buy a new microscope. The unique design of the resonant scanning unit allows swapping it with conventional scanners in a matter of minutes. The resonant scanning module provides also much needed sound muffling. 

MCS, the computer system of the MOM, has been upgraded in version 2.0 to control either type of scanning from the same Windows 64-bit MCS workstation. There is, by design, much commonality between the hardware and wiring of the two systems. Switching between conventional and scanning mode in MScan 2.0, the acquisition program of MCS, requires only restarting the application.

Notable features of MScan 2.0. operating in resonant scanning mode include the possibility to:
  • acquire and display 31 frames per second on two channels with 512 x 512 frames, or even at a higher rate by selecting a subframe (e.g., 124 fps with 128 x 512 frames), while simultaneously
  • perform the "Sanderson correction" to linearize the field of view
  • acquire up to 8 analog channels
  • stimulate the preparation with 2 analog channels and 8 digital channels
  • plot intensities of regions of interest in real-time (very useful when doing calcium imaging)
  • run JavaScript or VBScript automation programs in the background
  • and stream data to disk.

Because resonant scanning generates a large number of frames very quickly, it is a challenge to store the incoming data on file. Many programs other than MScan use TIFF as their main data file format, which is inadequate for resonant scanning due to the 4 GB limitation in size of these files. With two imaging channels, it would take only 2 minutes and 16 seconds to fill a TIFF file to capacity. To allow continuous recordings on a much longer scale, MScan features a high-speed, large capacity disk streaming system. This allows MScan to record more than 100 GB of uninterrupted imaging data in the same file. In addition, a new triggering mode allows starting and stopping imaging and data streaming upon sensing the level of a TTL line. The possibility to perform gap-free resonant imaging for several hours is a major advantage of using MCS in experiments involving behavior.

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