We are attempting to use a SR530 Lock-In Amplifier by Stanford Research Systems to amplify neural signals recorded from rat hippocampus, however we have no working knowledge of how to set up the system. Currently I have it connected to an osciliscope and frequency generator and am attempting to simply amplify the signal coming in, however I am getting a lot of noise or a flat line. I have read the manual and am still in the dark about how to set this machine up. Is something supposed to be plugged into reference? How to the signal inputs relate to the channels?
Any assistance would be greatly appriciated.
Hi Carlay,
I have never tried to use a "lock-in" amplifier for electrophysiological recordings, but it doesn't seem to be the appropriate hardware for this purpose. The signals of interest - LFPs and neuron action potentials - are highly variable (compared to signals from electronic sources) and typically unknown to the experimenter during recording. This is why I think that the lock-in amp is probably not suited for electrophysiology; however, I would be very interested if anyone else out there has had success using a "lock-in" amplifier for electrophysiological recordings and what it's advantages may be over more common amplifiers.
You should be able to use one of many single-ended or differential amplifier solutions. Here are a few (of many) companies that manufacture headstages and amplifiers for this purpose: Tucker-Davis Technologies, Neuralynx, Plexon, Cabridge Electronic Design. Open-Ephys is an open source hardware/software solution for neurophysiology.
I hope this was helpful,
Dan
The lock in amplifier is intended to measure the amplitude of a sinusoidal signal contaminated by white noise. In your case of biosignals, the wave-forms are complex which means that it is require to analyse it using spectrum analyzer. This can be done by the lock in amplifier as explained in the following paragraph.
In your case you want to recover the biosignal from noise, so , it is so that we have to select the frequency to be recovered and obtain it from a reference oscillator say this frequency is wr. So, one has to input a sinusoidal wave from with wr from a standard laboratory oscillator with amplitude say one volt. Then you input your signal to be recovered and set the required gain at the input say G. Then according to the operation of the instrument you will have two outputs: Y output and an X output. After the low pass filter with very narrow bandwidth the DC values will represent the sine and cosine components of the signal. amplitude.
This is if you want to recover and analyse your signal into frequency components.
However you can use the amplifier section of the instrument to amplify your signal.
wish you success