What's New in LTP24?

 

Corrected the calculation of Rm input resistance measurement in the on-line manual, Section 4.7.10  (October, 2006)

In previous versions the on-line manual of the LTP Program (prior to October, 2006), the cell input resistance Rm was incorrectly said to be calculated using  

            Rm = VPulse / ISteadyState 

and is now correctly calculated using  

            Rm = VPulse / ISteadyState - Rs           

 where Vpulse is the amplitude of the RsRm voltage clamp test pulse relative to baseline of the preceding epoch, ISteadyState is the amplitude of the current measured between the baseline and 50% and 90% of the pulse when the current has reached steady state, and Rs is the patch electrode series resistance.  

Because Rs is usually much less than Rm,  Rm ~ VPulse / ISteadyState  still is roughly true, but since Rs values are typically 5% to 10% of Rm values, previous calculation of Rm values (before October, 2006) were roughly 5% to 10% too high.  Since Rm = VPulse / ISteadySstate - Rs  is the theoretically correct function, it should be used in the Rm calculation when Rs is measured.  Note, however, that since Rs is usually slightly overestimated, Rm now will be slightly too low!

In the LTP Program, Rs is almost always measured during patch clamp voltage clamping (assuming you click the AnalysesToDo Rs check box), but is not measured during patch clamp current clamping, and therefore Rs = 0 in this case, and Rm = VPulse / ISteadyState.  Furthermore, during whole cell single electrode voltage clamping, where series resistance is theoretically zero, you would not measure Rs and it would therefore be set to Rs = 0, and Rm = VPulse / ISteadyState.  For intracellular current clamping using a bridge circuit, Rs would also not be measured and  would therefore be set to Rs = 0, and Rm = VPulse / ISteadyState.

 

Changes from  LTP230D to LTP24  (Aug, 2005)

     Bug fixes

 

Changes from  LTP222A  to  LTP230D  (Jan, 2002)

     Implementation of CIO-DAS08/JR-AO - an inexpensive, multichannel data acquisition board for the ISA bus (from Measurement Computing)
          Capabilities used by LTP230D include: 2 AD channels and 2 DA channels  (CIO-DAS08/JR-AO board only)
          Low Cost: $200/£180 including AD chip (CIO-DAS08/JR-A0); $150/£140 without AD chip (CIO-DAS08/JR)
          Software calibration: AD offset and gain adjust; DA offset and gain adjust
    
     Software calibration for Pico Technology's ADC-42 board
          AD offset and gain adjust
    
     Improved interaction with other data acquisition and analysis programs
          Reanalysis of ASCII ADsweep files (with or without a header)
Save reanalyzed ASCII sweep files (useful for saving averaged, blanked and/or filtered sweeps)

atf2swps.exe - Convert an Axon Text File (*.ATF) to many single sweep ASCII files for importing into LTP230D

dv2swps.exe - Convert a multisweep DataView ASCII text file to many single sweep ASCII files for importing into LTP230D
    
     Improved Stimulus Artifact Blanking: adding Slope blanking and Hold blanking to the Average blanking method

 

Changes from  LTP114J  to  LTP222A  (May, 2001)

    

2 AD channel acquisition
    
    

Analyze all S0- and S1-evoked postsynaptic responses in both AD channels in a sweep
    
    

Special analyses of trains
          1.

Analyze every pulse in train, but use the baseline of the first pulse as the baseline for each pulse
2. Analyze whole train by analyzing only first pulse in train but detecting whole train
3. Analyze train using baseline of the first pulse and response of the last pulse
    

Automatic blanking of stimulus artifacts to allow accurate determination of peaks and areas in a train
    

(Icon startup from Windows 98 desktop - has been removed in LTP230D)
    
    

Automatic data folder creation at startup when in acquisition mode

AutoCreate a new data Folder (using CTL-F) while running an experiment 

Change data folder during acquisition or reanalysis
Reanalyze files from a CD-ROM
    
     Off-line signal averaging
On-line digital filtering while averaging sweeps
    
     Minor enhancements
          1.

Train ViewPg is gone, and now the latest Pulse ADsweep or Train ADsweep are plotted on the same page
2.

Change screen colors (Now you can have graphs with white background color)
    
    

If you are upgrading from earlier versions of the LTP program, you will have write new *.pro protocol files. However, you can analyze the same ADsweep files with LTP114J that were obtained with all earlier versions of the LTP program.
   
     If you have only 8MB of memory in your computer you have to upgrade to at least 16 MB (up to 64 MB can be used by the LTP Program).

 

Changes from  LTP113E  to  LTP114J  (Oct, 1999)

    

LTP113E has a Year 2000 bug which does not allow it to save data after Dec 31, 1999. This has been fixed in LTP114J.

 

Changes from  LTP101M (Dec, 1997)  to  LTP113E (Sept, 1998)

    

Upgrading from LTP101M is a modest upgrade that primarily fixes to quite a few bugs most of which deal with LTP's stimulation capabilities.
    
     In addition, it contains a few more waveform analysis capabilities
          1. PopSpike Amplitude
  2. PopSpike Latency (time from stimulus to pop-spike peak)
  3. Duration
  4. Area
  5. 10-90% Rise Time
  6. 10-90% Decay Time
  7. Coastline (for epilepsy studies)
  8. Peak Latency  (time from stimulus to peak amplitude)

 

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