This experiment was performed on an acute hippocampal slice on a Multi-Electrode Array (MEA) with 64 channels with the aim to analyze long-term potentiation (LTP) following electrical stimulation.

The 300 µm thick acute hippocampus slice was prepared from a 21 days old rat.
The slice was stimulated every 60 s with the test stimulus, a single biphasic pulse with 1.5 V amplitude and 100 µs duration per phase, by using one of the embedded MEA-electrodes (No. 75).

Test stimulus for LTP experiment

The screen shot from the MC_Stimulus program shows the biphasic test pulse (amplitude: 1.5 V, duration: 100 µs per phase, inter-stimulus-interval: 60 s). The red trace is the Sync Out (TTL) pulse that was used for triggering the recording.

LTP was induced by an LTP train with 100 pulses of same amplitude and duration as the test stimulus, and a frequency of 100 Hz. The SyncOut signal of the STG (stimulus generator) has been used to trigger the recording, with a pre-trigger of 30 ms and a time window of 100 ms. Data was recorded before and after the LTP induction; the LTP induction itself was not recorded.

Pulse train of 100 biphasic pulses for LTP induction

Amplitude: 1.5 V, duration: 100 µs per phase, inter-stimulus-interval/frequency: 10 ms / 100 Hz)

As the data was acquired with a MEA1060-BC amplifier with blanking circuit, all MEA electrodes were disconnected from the amplifier shortly during stimulation, in this case for 540 µs (300 µs Sync Out pulse of the STG, plus intrinsic Wait of 40 µs, plus user-defined Wait of 200 µs). This efficiently prevented stimulus artifacts.

The demo data used in this part of the tutorial was kindly provided by Dr. Frank Hofmann, University of Heidelberg, Germany.

Task:

Show the impact of an LTP train on the LTP peak-to-peak amplitude by an offline analysis; graph, print and save the results.

Note:

In the downloadable tutorial, you will set up an offline analysis rack (for the demo data file) step by step. You can set up a virtual rack for online recordings and analysis likewise, simply add the MC_Card as the data source to the rack instead of the Replayer.