Noninvasive Multielectrode Array for Brain and Spinal Cord Local Field Potential Recordings from Live Zebrafish Larvae

Zebrafish are an important and expanding experimental system for brain research. We describe a noninvasive electrophysiology technique that can be used in living larvae to measure spontaneous activity in the brain and spinal cord simultaneously. This easy-to-use method uses a commercially available multielectrode array to detect local field potential parameters, and allows for relative coordinated (network) measurements of activity. We demonstrate sensitivity of this system by measuring activity in larvae treated with the antiepileptic drug valproic acid. Valproic acid decreased larval movement and startle response, and decreased spontaneous brain activity. Spinal cord activity did not change after treatment, suggesting valproic acid primarily affects brain function. The observed differences in brain activity, but not spinal cord activity, after valproic acid treatment indicates that brain activity differences are not a secondary effect of decreased startle response and movement. We provide a step-by-step protocol for experiments presented that a novice could easily follow. This electrophysiological method will be useful to the zebrafish neuroscience community.