Non-invasive local field potential (LFP) recordings

Brain activity of 4 dpf zebrafish larvae was assessed by performing non-invasive local field potential (LFP) recordings, reading the electrical signal from the skin of the larvae’s head (Zdebik et al., 2013). g3bp1 MO or control MO injected zebrafish larvae were treated on 3 dpf for 24 hours with rapamycin or left untreated. A glass pipet (containing the recording electrode), filled with artificial cerebrospinal fluid (124 mM NaCl, 2 mM KCl, 2 mM MgSO4, 2 mM CaCl2, 1.25 mM KH2PO4, 26 mM NaHCO3 and 10 mM glucose), was positioned on the skin above the optic tectum or the pallium using a stereomicroscope. The differential signal between the recording electrode and the reference electrode was amplified 10,000 times by DAGAN 2400 amplifier (Minnesota, USA), band pass filtered at 0.3-300 Hz and digitized at 2 kHz via a PCI-6251 interface (National Instruments, UK) with WinEDR (John Dempster, University of Strathclyde, UK). Recordings lasted for 10 min and were analyzed with Clampfit 10.2 software (Molecular Devices Corporation, USA). A polyspiking discharge was scored positive when its amplitude exceeded three times the amplitude of the baseline and it had a duration of at least 50 ms. At least n = 34 larvae for LFPs of zebrafish pallia (Figure 7L) and at least n = 20 larvae for LFPs of zebrafish optic tecta (Figure 7N) were analyzed.

Three representative 10 minute LFP recordings are shown for control and g3bp1 MO without and with rapamycin, respectively in Figure 7M (pallia) and Figure 7O (optic tecta).