Research FAQ’s

 


 

Research FAQ’s
1. How do I correctly set the values on the NL403 Delay/Width module?
2. I’m using the NeuroLog system to record extracellular potentials. How do I use the NL120S Audio Amplifier to monitor spikes audibly? Can I use the “Mon” output of the NL201 Spike Trigger?
3. I see that the NeuroLog Case is now called the NL900D – why has it changed and is it compatible with older NeuroLog modules?

 

 

 

NeuroLog System


1.  How do I correctly set the values on the NL403 Delay/Width module?
2.  I’m using the NeuroLog system to record extracellular potentials.  How do I use the NL120S Audio Amplifier to monitor spikes audibly?  Can I use the “Mon” output of the NL201 Spike Trigger?
3.  I see that the NeuroLog Case is now called the NL900D  – why has it changed and is it compatible with older NeuroLog modules?
4.  I want to feed my output signal from the NeuroLog system into a data acquisition board fitted with BNC sockets, what is the easiest way to do this?
5.  I am using more than one NL100AK headstage in order to make extracellular recordings, however I seem to be picking up a large amount of noise.  When I use each headstage on its own, the problem goes away.  What is happening?
6.  I am using the NL100AK headstage and NL104A AC Preamplifier to record extracellular spike potentials, however I find that my signal is intermittently lost for a few seconds.  This loss of signal seems to occur shortly after electrical stimulation of the tissue.
7.  I am intending to use the NL107 Transducer Amplifier to make field potential recordings from brain slices, can you tell me how the amplifier should be configured?
8.  Is it possible to use a trigger input to gate the NL512 Biphasic Buffer, thereby controlling timing and pulse duration, and a computer DAC to separately control the output amplitude?

 

1.  How do I correctly set the values on the NL403 Delay/Width module?

The NL403 has both a Range Control and Variable Control which allows precise setting of the values of Delay and Width.  Click here to view a PDF file which explains how to use these setting controls.

 

2.  I’m using the NeuroLog system to record extracellular potentials.  How do I use the NL120S Audio Amplifier to monitor spikes audibly?  Can I use the “Mon” output of the NL201 Spike Trigger?

It is easy to do this, but you MUST NOT use the “Mon” output of the NL201 as this would generate an unpleasant “ringing” noise.  The Monitor output is intended to provide an oscilloscope display of the input signal with the upper and lower window levels superimposed.
To listen to the spiking, you should actually take the raw or filtered output from your NL104A AC preamplifier or NL106 AC/DC Amplifier and feed this into (i) your data acquisition system and (ii) the input of the NL120S using an NL961 “T” connector and a couple of cables.  The threshold of the NL120S can then be adjusted and the output listened to using the NL985 Speaker connected to the Audio Amplifier.

  

3.  I see that the NeuroLog Case is now called the NL900D  – why has it changed and is it compatible with older NeuroLog modules?

The NL900C has now been superceded by the NL900D, which was introduced due to discontinuance of certain components.  The new case system is fully backwards compatible with older NeuroLog modules.

 

4.  I want to feed my output signal from the NeuroLog system into a data acquisition board fitted with BNC sockets, what is the easiest way to do this?

The NeuroLog system uses micro-miniature Lemo coaxial cables, plugs and sockets, while many other devices use more common BNC connectors.  We supply single pole Lemo cables of various lengths (NL951) with a Lemo plug at both ends, however you can purchase an NL960 adaptor from us which fits one of the Lemo plugs and turns it into a BNC plug.  As an alternative, we can offer 1m and 2m cables with Lemo plugs on one end and BNC plugs on the other (NL951B-1m or NL951B-2m).

 

5.  I am using more than one NL100AK headstage in order to make extracellular recordings, however I seem to be picking up a large amount of noise.  When I use each headstage on its own, the problem goes away.  What is happening?

When using multiple NL100AK headstages it is important to ensure that you maintain a single grounding point when wiring up the headstages, as you may be setting up ground loops.  In order to avoid ground loops, please follow this Application Note.

 

6.  I am using the NL100AK headstage and NL104A AC Preamplifier to record extracellular spike potentials, however I find that my signal is intermittently lost for a few seconds.  This loss of signal seems to occur shortly after electrical stimulation of the tissue.

If your signal appears to be fine most of the time and you only see this loss of response at the point of stimulation, then I would check the setting of the low frequency cut-off filter on the NL104A front panel.  In order to produce a flat baseline, the NL104A uses this low frequency cut-off filter to remove unwanted DC potentials from the signal.  The switch can be set to 0.1Hz or 10Hz.  At 0.1Hz the amplifier will not filter out your stimulus artefact and as a result, the large DC offset will temporarily prevent the amplifier from working correctly.  If you change the setting to 10Hz, you should solve your problem.

 

7.  I am intending to use the NL107 Transducer Amplifier to make field potential recordings from brain slices, can you tell me how the amplifier should be configured?

Extending what the NL107 Users Manual says.  The amplifier differentially amplifies the signal between the A-in and B-in (“A-B”) thereby removing any Common-Mode interference that is present on both inputs.  Connections MUST be made to both inputs and if the preparation is grounded/earthed it is preferable to perform this using the Ground from the NL107 input – the shell or braid.  If full differential recordings are not required, it is best if the “B-in” is connected to the point that is grounded actually AT the preparation.  The Balance control sums a DC potential with the input signal. The control can be locked using the small side lever.  Note that the AC/DC switch on the unit must be set to “DC” to record same.

 

8.  Is it possible to use a trigger input to gate the NL512 Biphasic Buffer, thereby controlling stimulus timing and pulse duration, and a computer DAC to separately control the NL512 output amplitude?

Yes, the NL512 has two inputs (GATE & IN).  An incoming trigger pulse at GATE can be used to gate the voltage applied at IN.  As a result, even with a voltage applied at IN, there will be no output from the NL512 until the GATE input is made high by the trigger pulse.

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