I want to record LFP in free moving mice but I have no idea how to do this experiment.
Frist, what type of recording electrode and reference electrode to be used in recording LFP, metal or glass electrode?
There are some differences in the position of reference electrode in each lab. For example, some labs put the reference electrode about 200um away from recording electrode. Other lab put the reference electrode on the scalp. In other lab, the reference electrode was place d in the cerebellum.
Second, can the place of the reference electrode influence the results? If yes, and why?
Last, where to put the ground electrode?
1. For chronic LFP recording metal electrode would be the first choice. Depending on how much you can spend - platinum-iridium or tungsten :-). The size (surface) of an active tip would determine what would you have in the signal. With a small tip (10-25 µm) you can see also multi-unit spikes. With larger tips spikes would not be visible (due to signal averaging on the electrode large surface).
2. As concern reference - you need to remember that the recorded signal is differential : reference signal is subtracted from 'active' electrode signal. So - whatever you record on reference would be present in you recorded data. If the reference is close to 'active' electrode and its signal is similar - the effect of this subtraction can be almost zero. It is useful in single unit recording - if the reference is recording LFP but not spikes it reduces slow wave component in a signal from electrode with spikes.
However - it is not so good for LFP which you want to record - here you want to have the reference in a place as neutral as possible - it should record all the general fluctuations of the field around the brain but not the neural signal. In a perfect situation it can eliminate all the noise without adding any neural activity from it's location.
Bipolar recording might be sometimes interesting - when you want to see the difference between two recording locations. But today it can be easily obtained with an off-line analysis and 'rereferencing' in the software.
3. Ground - for monopolar recording the same place (like screw in a nasal bone) can be used for connected reference and ground.
regards
ewka
Hi ....
Maybe check some literature from Denis Manahan Vaugan from Bochum Uni and Didier Pinault from Strasbourg Uni.
The location of reference electrode changes the voltage deflection (i.e. an ERP might change from positive to negative if you change the ref-electrode from left to right side of the recording electrode, for example). Hope it gave some hint...
For most of your queries please see this article
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3036539/
hope this help
good luck
just searching with key words in google would give many papers. There might be little variation in methodology. You could gather the best information and apply to your research work.
1. For chronic LFP recording metal electrode would be the first choice. Depending on how much you can spend - platinum-iridium or tungsten :-). The size (surface) of an active tip would determine what would you have in the signal. With a small tip (10-25 µm) you can see also multi-unit spikes. With larger tips spikes would not be visible (due to signal averaging on the electrode large surface).
2. As concern reference - you need to remember that the recorded signal is differential : reference signal is subtracted from 'active' electrode signal. So - whatever you record on reference would be present in you recorded data. If the reference is close to 'active' electrode and its signal is similar - the effect of this subtraction can be almost zero. It is useful in single unit recording - if the reference is recording LFP but not spikes it reduces slow wave component in a signal from electrode with spikes.
However - it is not so good for LFP which you want to record - here you want to have the reference in a place as neutral as possible - it should record all the general fluctuations of the field around the brain but not the neural signal. In a perfect situation it can eliminate all the noise without adding any neural activity from it's location.
Bipolar recording might be sometimes interesting - when you want to see the difference between two recording locations. But today it can be easily obtained with an off-line analysis and 'rereferencing' in the software.
3. Ground - for monopolar recording the same place (like screw in a nasal bone) can be used for connected reference and ground.
regards
ewka
Hi,
recorded signal is a mixture of both electrodes (with an oposite sign) so the ansewe is yes - recorded data can include activity from cerebellum.
People rather put the reference/ground in the thick bone _over_ the cerebellum - not into the cerebellum itself. So the reference signal has some geneal eeg-like and noisy fluctuations, but not cerebellal LFP.
It is olso possible to connect the wires (and thus average the signals) from the more then one screw placed e.g. over the cerebellum and in the nasal bone.
regards,
ewka
Is it possible to purchase microelectrode arrays that can be placed above skull for LFP or EEG recordings in mice.