Selective Silencing of Hippocampal Parvalbumin Interneurons Induces Development of Recurrent Spontaneous Limbic Seizures in Mice

In Figure 2 panels H and I of this paper, Prof. Drexel and colleagues analyzed mEPSC and mIPSC amplitudes and frequencies in subiculum pyramidal neurons from Pvalb tm1(cre) Arbr mice injected with AAV-GFP (n= 10 cells for mEPSC recordings; n= 9 cells for mIPSC recordings) and AAV-TeLC ( n= 11 cells for mEPSC recordings; n 10 cells for mIPSC recordings). They stated that data are not significantly different between the two experimental groups. We would like to make two points about the article:
First, it would be better if the authors reported Mean±SEM for Fig 2.
Second, based on the data shown in Figure 2 H,I we estimated mean and SEM, and calculated power as follows:
For Fig 2H:
Amplitude, GFP: 12±22, Telc: 11±5; power = 0.072
Frequency, GFP: 2.5±3.5, Telc: 1.5±1; power = 0.78
For FIg 2I:
Amplitude, GFP: 18±2, Telc: 18±2.5; power = 0.05
Frequency GFP: 2.5±1.5, Telc: 2.5±1; power = 0.05

It has been demonstrated that low-powered studies (an adequate power is equal or more than 80%) produce more false negatives than high-powered studies. When studies in a given field are designed with a power of 20%, it means that if there are 100 genuine non-null effects to be discovered in that field, these studies are expected to discover only 20 of them (Button, 2013; Sterne & Smith, 2001). Thus, based on our calculation of statistical power, one cannot be sure that there is no difference between the two groups. A larger number of cells would be required to make this judgment.

References:
Button KS, Ioannidis JP, Mokrysz C, Nosek BA, Flint J, Robinson ES, et al. Power failure: why small sample size undermines the reliability of neuroscience. Nature Reviews Neuroscience. 2013;14(5):365.
Sterne JA, Smith GD. Sifting the evidence—what's wrong with significance tests? Physical Therapy. 2001;81(8):1464-9.