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[Summer’16 Internship] Neuroscience of Grasshopper Jumps: New & improved ITI test

In the ‘Preliminary data‘ log, I had begun my data collection and analysis journey. I first performed the intertrial interval, or ITI, test, to determine the ideal time between 2 stimuli so that the time is long enough to avoid the grasshoppers’ habituation to the simulated balls. The results figures I showed in that previous log showed that the 45s ITI was better than the other ITIs in giving us a nice profile of the DCMD neuron activity over time. However, of course, the data visualization could be much improved, and I have been doing that by importing the recordings (stored in JSON files by the SpikeRecorder app) into MatLab (using JSONlab). MatLab yields cleaner and to-scale figures that give us an even better idea of the DCMD profiles in different ITIs.

Here, compare! These are the old figures, not to scale and all are the same height. So I had to label them all with their frequencies:

I performed a new ITI experiment on a new grasshopper, G25-072416-01. This time, I used 3 different ITIs that I think are sufficient: 45s, 22.5s, and 1s. All other experimental parameters are kept constant: iPad screen is 0.10m from the grasshopper’s eye, balls of 0.06m radius approach at -2m/s (negative for the increasingly shortened distance between the eye and the object). 30 trials per ITI test. And the data is processed in MatLab, and it looks beautiful!

Sorry the axis labels are too small to read. Horizontal axis: time to collision, from -2 to 2 seconds. Vertical axis: Firing frequency in Hz. Firing frequency is much higher in the 45s ITI, making it a “good” ITI to use for the subsequent experiments.

By Dieu My Nguyen


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